Publications by authors named "Melyssa Aronson"

73 Publications

Maximizing cancer prevention through genetic navigation for Lynch syndrome detection in women with newly diagnosed endometrial and nonserous/nonmucinous epithelial ovarian cancer.

Cancer 2021 Sep 13;127(17):3082-3091. Epub 2021 May 13.

Division of Gynecologic Oncology, Princess Margaret Cancer Centre/University Health Network/Sinai Health Systems, Toronto, Ontario, Canada.

Background: Despite recommendations for reflex immunohistochemistry (IHC) for mismatch repair (MMR) proteins to identify Lynch syndrome (LS), the uptake of genetic assessment by those who meet referral criteria is low. The authors implemented a comprehensive genetic navigation program to increase the uptake of genetic testing for LS in patients with endometrial cancer (EC) or nonserous/nonmucinous ovarian cancer (OC).

Methods: Participants with newly diagnosed EC or OC were prospectively recruited from 3 cancer centers in Ontario, Canada. Family history questionnaires were used to assess LS-specific family history. Reflex IHC for MMR proteins was performed with the inclusion of clinical directives in pathology reports. A trained genetic navigator initiated a genetic referral on behalf of the treating physician and facilitated genetic referrals to the closest genetics center.

Results: A total of 841 participants (642 with EC, 172 with OC, and 27 with synchronous EC/OC) consented to the study; 194 (23%) were MMR-deficient by IHC. Overall, 170 women (20%) were eligible for a genetic assessment for LS: 35 on the basis of their family history alone, 24 on the basis of their family history and IHC, 82 on the basis of IHC alone, and 29 on the basis of clinical discretion. After adjustments for participants who died (n = 6), 149 of 164 patients (91%) completed a genetic assessment, and 111 were offered and completed genetic testing. Thirty-four women (4.0% of the total cohort and 30.6% of those with genetic testing) were diagnosed with LS: 5 with mutL homolog 1 (MLH1), 9 with mutS homolog 2 (MSH2), 15 with mutS homolog 6 (MSH6), and 5 with PMS2.

Conclusions: The introduction of a navigated genetic program resulted in a high rate of genetic assessment (>90%) in patients with gynecologic cancer at risk for LS.
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http://dx.doi.org/10.1002/cncr.33625DOI Listing
September 2021

Survival Benefit for Individuals With Constitutional Mismatch Repair Deficiency Undergoing Surveillance.

J Clin Oncol 2021 Sep 4;39(25):2779-2790. Epub 2021 May 4.

Lebanese American University Medical Center-Rizk, Beirut, Lebanon.

Purpose: Constitutional mismatch repair deficiency syndrome (CMMRD) is a lethal cancer predisposition syndrome characterized by early-onset synchronous and metachronous multiorgan tumors. We designed a surveillance protocol for early tumor detection in these individuals.

Patients And Methods: Data were collected from patients with confirmed CMMRD who were registered in the International Replication Repair Deficiency Consortium. Tumor spectrum, efficacy of the surveillance protocol, and malignant transformation of low-grade lesions were examined for the entire cohort. Survival outcomes were analyzed for patients followed prospectively from the time of surveillance implementation.

Results: A total of 193 malignant tumors in 110 patients were identified. Median age of first cancer diagnosis was 9.2 years (range: 1.7-39.5 years). For patients undergoing surveillance, all GI and other solid tumors, and 75% of brain cancers were detected asymptomatically. By contrast, only 16% of hematologic malignancies were detected asymptomatically ( < .001). Eighty-nine patients were followed prospectively and used for survival analysis. Five-year overall survival (OS) was 90% (95% CI, 78.6 to 100) and 50% (95% CI, 39.2 to 63.7) when cancer was detected asymptomatically and symptomatically, respectively ( = .001). Patient outcome measured by adherence to the surveillance protocol revealed 4-year OS of 79% (95% CI, 54.8 to 90.9) for patients undergoing full surveillance, 55% (95% CI, 28.5 to 74.5) for partial surveillance, and 15% (95% CI, 5.2 to 28.8) for those not under surveillance ( < .0001). Of the 64 low-grade tumors detected, the cumulative likelihood of transformation from low-to high-grade was 81% for GI cancers within 8 years and 100% for gliomas in 6 years.

Conclusion: Surveillance and early cancer detection are associated with improved OS for individuals with CMMRD.
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http://dx.doi.org/10.1200/JCO.20.02636DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8407605PMC
September 2021

MLH1 epimutation is a rare mechanism for Lynch syndrome: A case report and review of the literature.

Genes Chromosomes Cancer 2021 Sep 15;60(9):635-639. Epub 2021 May 15.

Department of Pathology and Laboratory Medicine, Sinai Health System and University of Toronto, Toronto, Ontario, Canada.

Endometrial carcinoma is one of the prototypical malignancies associated with Lynch syndrome, an inherited cancer syndrome most commonly caused by germline mutations in DNA mismatch repair (MMR) genes, although rare alternative mechanisms also exist. In this report, we describe a patient first diagnosed with colorectal cancer at age 33, then vulvar squamous cell carcinoma, facial sebaceous adenoma/sebaceoma, and finally endometrial carcinoma at age 52. All tumors were MLH1/PMS2-deficient by immunohistochemistry, and MLH1 promoter methylation was identified in the endometrial cancer. Germline MLH1 testing was negative for pathogenic variants, but she was subsequently diagnosed with Lynch syndrome secondary to a germline monoallelic constitutional epimutation of the MLH1 promoter. Identification of patients displaying a Lynch syndrome phenotype but lacking germline MMR mutations is important to avoid delays in the diagnosis of Lynch syndrome as well as the initiation of appropriate cancer screening and genetic counseling.
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http://dx.doi.org/10.1002/gcc.22957DOI Listing
September 2021

Widening the lens of actionability: A qualitative study of primary care providers' views and experiences of managing secondary genomic findings.

Eur J Hum Genet 2021 Mar 29. Epub 2021 Mar 29.

University of Toronto, Toronto, Canada.

Most secondary genomic findings (SFs) fall in the scope of primary care practice. However, primary care providers' (PCPs) capacity to manage these findings is not well understood. We explored PCPs' views and experiences of managing SFs through a qualitative study. PCPs participated in semi-structured interviews about SFs from a patient in their practice or a hypothetical patient. The interpretive descriptive methodology was used to analyze transcripts thematically through constant comparison. Fifteen family physicians from Ontario, Canada participated (ten females; 6-40 years in practice across community and academic settings). PCPs made sense of SFs through the lens of actionability: they actively looked for clinical relevance by considering a wide range of immediate and future actions, including referrals, genetic testing, screening, lifestyle changes, counseling about family planning, informing family members, future medication choice, increased vigilance/surveillance, and managing results in the electronic medical record. PCPs saw clinical actionability as the main benefit mitigating the potential harms of learning SFs, namely patient anxiety and unnecessary investigations. PCPs conceptualized actionability more broadly than it is traditionally defined in medical genetics. Further research will be needed to determine if PCPs' emphasis on actionability conflicts with patients' expectations of SFs and if it leads to overutilization of healthcare resources.
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http://dx.doi.org/10.1038/s41431-021-00876-zDOI Listing
March 2021

Diagnostic criteria for constitutional mismatch repair deficiency (CMMRD): recommendations from the international consensus working group.

J Med Genet 2021 Feb 23. Epub 2021 Feb 23.

Division of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada.

Background: Constitutional mismatch repair deficiency syndrome (CMMRD) is the most aggressive cancer predisposition syndrome associated with multiorgan cancers, often presenting in childhood. There is variability in age and presentation of cancers and benign manifestations mimicking neurofibromatosis type 1. Genetic testing may not be informative and is complicated by pseudogenes associated with the most commonly associated gene, . To date, no diagnostic criteria exist. Since surveillance and immune-based therapies are available, establishing a CMMRD diagnosis is key to improve survival.

Methods: In order to establish a robust diagnostic path, a multidisciplinary international working group, with representation from the two largest consortia (International Replication Repair Deficiency (IRRD) consortium and European Consortium Care for CMMRD (C4CMMRD)), was formed to establish diagnostic criteria based on expertise, literature review and consensus.

Results: The working group established seven diagnostic criteria for the diagnosis of CMMRD, including four definitive criteria (strong evidence) and three likely diagnostic criteria (moderate evidence). All criteria warrant CMMRD surveillance. The criteria incorporate germline mismatch repair results, ancillary tests and clinical manifestation to determine a diagnosis. Hallmark cancers for CMMRD were defined by the working group after extensive literature review and consultation with the IRRD and C4CMMRD consortia.

Conclusions: This position paper summarises the evidence and rationale to provide specific guidelines for CMMRD diagnosis, which necessitates appropriate surveillance and treatment.
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http://dx.doi.org/10.1136/jmedgenet-2020-107627DOI Listing
February 2021

Mutations in the RAS/MAPK Pathway Drive Replication Repair-Deficient Hypermutated Tumors and Confer Sensitivity to MEK Inhibition.

Cancer Discov 2021 Jun 9;11(6):1454-1467. Epub 2021 Feb 9.

Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada.

The RAS/MAPK pathway is an emerging targeted pathway across a spectrum of both adult and pediatric cancers. Typically, this is associated with a single, well-characterized point mutation in an oncogene. Hypermutant tumors that harbor many somatic mutations may obscure the interpretation of such targetable genomic events. We find that replication repair-deficient (RRD) cancers, which are universally hypermutant and affect children born with RRD cancer predisposition, are enriched for mutations ( = 10). These mutations are not random, exist in subclones, and increase in allelic frequency over time. The RAS/MAPK pathway is activated both transcriptionally and at the protein level in patient-derived RRD tumors, and these tumors responded to MEK inhibition and . Treatment of patients with RAS/MAPK hypermutant gliomas reveals durable responses to MEK inhibition. Our observations suggest that hypermutant tumors may be addicted to oncogenic pathways, resulting in favorable response to targeted therapies. SIGNIFICANCE: Tumors harboring a single driver mutation are targeted individually for therapeutic purposes. We find that in RRD hypermutant cancers, mutations in the RAS/MAPK pathway are enriched, highly expressed, and result in sensitivity to MEK inhibitors. Targeting an oncogenic pathway may provide therapeutic options for these hypermutant polyclonal cancers..
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http://dx.doi.org/10.1158/2159-8290.CD-20-1050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8406556PMC
June 2021

Understanding the clinical implication of mismatch repair deficiency in endometrioid endometrial cancer through a prospective study.

Gynecol Oncol 2021 04 19;161(1):221-227. Epub 2021 Jan 19.

Division of Gynecologic Oncology, Princess Margaret Cancer Centre, University Health Network/Sinai Health Systems, Toronto, Ontario, Canada; Department of Obstetrics and Gynaecology, University of Toronto, Toronto, Canada; Zane Cohen Centre for Digestive Diseases, Familial Gastrointestinal Cancer Registry, Mount Sinai Hospital, Toronto, Ontario, Canada. Electronic address:

Objectives: Findings on impact of mismatch repair deficiency (MMRd) on patient outcomes in endometrial cancer (EC) have been inconsistent to date. The objective of this study was to compare the oncologic outcomes and recurrence patterns between MMRd and MMR-intact (MMRi) endometrioid EC (EEC).

Methods: Between 2015 and 2018, we prospectively recruited 492 EEC cases from three cancer centers in Ontario, Canada. Tumors were reflexively assessed for MMR protein expression by immunohistochemistry (IHC). Clinicopathological, survival and recurrence patterns were compared between MMRd and MMRi cases.

Results: Of 492 EEC, 348 were MMRi (71%) and 144 were MMRd (29%) with median follow-up of 16.8 months (0-69.6). MMRd tumors tended to be grade 2 or 3 (56% vs. 29%, p < 0.001), with propensity for lymphovascular space invasion (28% vs. 18%, p = 0.024), lymph node involvement (7% vs. 5%, p < 0.001) and received more adjuvant treatment (46% vs. 33%, p = 0.027). This group also had significantly lower 3-year recurrence-free survival (78% vs. 90%, p = 0.014) although there was no difference in OS (p = 0.603). MMRd cases were more likely to recur in retroperitoneal lymph nodes (p = 0.045). Upon subgroup analysis, MLH1 methylated tumors had the worst prognostic features and survival outcomes.

Conclusions: MLH1 methylated EECs exhibit more aggressive features compared to other MMRd and MMRi EECs. This may indicate an inherent difference in tumor biology, suggesting the importance of individualized management based on EC molecular phenotype.
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http://dx.doi.org/10.1016/j.ygyno.2021.01.002DOI Listing
April 2021

DNA Polymerase and Mismatch Repair Exert Distinct Microsatellite Instability Signatures in Normal and Malignant Human Cells.

Cancer Discov 2021 May 18;11(5):1176-1191. Epub 2020 Dec 18.

Department of Pediatric Hematology-Oncology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania.

Although replication repair deficiency, either by mismatch repair deficiency (MMRD) and/or loss of DNA polymerase proofreading, can cause hypermutation in cancer, microsatellite instability (MSI) is considered a hallmark of MMRD alone. By genome-wide analysis of tumors with germline and somatic deficiencies in replication repair, we reveal a novel association between loss of polymerase proofreading and MSI, especially when both components are lost. Analysis of indels in microsatellites (MS-indels) identified five distinct signatures (MS-sigs). MMRD MS-sigs are dominated by multibase losses, whereas mutant-polymerase MS-sigs contain primarily single-base gains. MS deletions in MMRD tumors depend on the original size of the MS and converge to a preferred length, providing mechanistic insight. Finally, we demonstrate that MS-sigs can be a powerful clinical tool for managing individuals with germline MMRD and replication repair-deficient cancers, as they can detect the replication repair deficiency in normal cells and predict their response to immunotherapy. SIGNIFICANCE: Exome- and genome-wide MSI analysis reveals novel signatures that are uniquely attributed to mismatch repair and DNA polymerase. This provides new mechanistic insight into MS maintenance and can be applied clinically for diagnosis of replication repair deficiency and immunotherapy response prediction..
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http://dx.doi.org/10.1158/2159-8290.CD-20-0790DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8223607PMC
May 2021

An Integrative DNA Sequencing and Methylation Panel to Assess Mismatch Repair Deficiency.

J Mol Diagn 2021 02 28;23(2):242-252. Epub 2020 Nov 28.

Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; Ontario Institute for Cancer Research, Toronto, Ontario, Canada. Electronic address:

Clinical testing for mismatch repair (MMR) deficiency often entails serial testing of tumor and constitutional DNA using multiple assays. To minimize cost and specimen requirements of MMR testing, we developed an integrated targeted sequencing protocol (termed MultiMMR) that tests for promoter methylation, mutations, copy number alterations, copy neutral loss of heterozygosity, and microsatellite instability from a single aliquot of DNA. Hybrid capture of DNA-sequencing libraries constructed with methylated adapters was performed on 142 samples (60 tumors and 82 constitutional samples) from 82 patients with MMR-associated colorectal, endometrial, and brain cancers as well as a synthetic DNA mix with 11 known mutations. The captured material was split to enable parallel bisulfite and conventional sequence analysis. The panel targeted microsatellite regions and 13 genes associated with MMR, hypermutation, and hereditary colorectal cancer. MultiMMR recapitulated clinical testing results in 23 of 24 cases, was able to explain MMR loss in an additional 29 of 48 patients with incomplete or inconclusive testing, and identified all 11 MMR variants within the synthetic DNA mix. Promoter methylation and microsatellite instability analysis found 95% and 97% concordance with clinical testing, respectively. We report the feasibility for amalgamation of the current stepwise and complex clinical testing workflow into an integrated test for hereditary and somatic causes of MMR deficiency.
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http://dx.doi.org/10.1016/j.jmoldx.2020.11.006DOI Listing
February 2021

Tumor site discordance in mismatch repair deficiency in synchronous endometrial and ovarian cancers.

Int J Gynecol Cancer 2020 12 20;30(12):1951-1958. Epub 2020 Oct 20.

Gynecologic Oncology, Princess Margaret Hospital Cancer Centre, Toronto, Ontario, Canada

Objectives: For synchronous endometrial and ovarian cancers, most centers rely on mismatch repair testing of the endometrial cancer to identify Lynch syndrome, and neglect the ovarian tumor site completely. We examined the mismatch repair immunohistochemistry and microsatellite instability results from the endometrium and ovary to assess discordance between the tumor sites and between tests.

Methods: 30 women with newly diagnosed synchronous endometrial and ovarian cancer were prospectively recruited from three cancer centers in Ontario, Canada. Both tumor sites were assessed for mismatch repair deficiency by immunohistochemistry and microsatellite instability test; discordance in results between tumor sites and discordance between test results at each site was examined. Cases with discordant results had tumors sequenced with a targeted panel in order to reconcile the findings. All women underwent mismatch repair gene germline testing.

Results: Of 30 patients, 11 (37%) were mismatch repair deficient or microsatellite instable at either tumor site, with 5 (17%) testing positive for Lynch syndrome. Mismatch repair immunohistochemistry expression was discordant between endometrial and ovarian tumor sites in 2 of 27 patients (7%) while microsatellite instability results were discordant in 2 of 25 patients (8%). Relying on immunohistochemistry or microsatellite instability alone on the endometrial tumor would have missed one and three cases of Lynch syndrome, respectively. One patient with Lynch syndrome with a pathogenic variant was not detected by either immunohistochemistry or microsatellite instability testing. The rate of discordance between immunohistochemistry and microsatellite instability test was 3.8% in the ovary and 12% in the endometrium.

Conclusions: There was discordance in immunohistochemistry and microsatellite instability results between tumor sites and between tests within each site. Endometrial tumor testing with mismatch repair immunohistochemistry performed well, but missed one case of Lynch syndrome. Given the high incidence of Lynch syndrome (17%), consideration may be given to germline testing in all patients with synchronous endometrial and ovarian cancers.
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http://dx.doi.org/10.1136/ijgc-2020-001927DOI Listing
December 2020

Cancers from Novel -Mutant Mouse Models Provide Insights into Polymerase-Mediated Hypermutagenesis and Immune Checkpoint Blockade.

Cancer Res 2020 12 16;80(24):5606-5618. Epub 2020 Sep 16.

Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada.

mutations are a major cause of hypermutant cancers, yet questions remain regarding mechanisms of tumorigenesis, genotype-phenotype correlation, and therapeutic considerations. In this study, we establish mouse models harboring cancer-associated mutations P286R and S459F, which cause rapid albeit distinct time to cancer initiation , independent of their exonuclease activity. Mouse and human correlates enabled novel stratification of mutations into three groups based on clinical phenotype and mutagenicity. Cancers driven by these mutations displayed striking resemblance to the human ultrahypermutation and specific signatures. Furthermore, -driven cancers exhibited a continuous and stochastic mutagenesis mechanism, resulting in intertumoral and intratumoral heterogeneity. Checkpoint blockade did not prevent lymphomas, but rather likely promoted lymphomagenesis as observed in humans. These observations provide insights into the carcinogenesis of -driven tumors and valuable information for genetic counseling, surveillance, and immunotherapy for patients. SIGNIFICANCE: Two mouse models of polymerase exonuclease deficiency shed light on mechanisms of mutation accumulation and considerations for immunotherapy..
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http://dx.doi.org/10.1158/0008-5472.CAN-20-0624DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8218238PMC
December 2020

Performance characteristics of screening strategies to identify Lynch syndrome in women with ovarian cancer.

Cancer 2020 11 18;126(22):4886-4894. Epub 2020 Aug 18.

Division of Gynecologic Oncology, Princess Margaret Cancer Centre, University Health Network, Sinai Health Systems, Toronto, Ontario, Canada.

Background: For women with ovarian cancer (OC), the optimal screening strategy to identify Lynch syndrome (LS) has not been determined. In the current study, the authors compared the performance characteristics of various strategies combining mismatch repair (MMR) immunohistochemistry (IHC), microsatellite instability testing (MSI), and family history for the detection of LS.

Methods: Women with nonserous and/or nonmucinous ovarian cancer were recruited prospectively from 3 cancer centers in Ontario, Canada. All underwent germline testing for LS and completed a family history assessment. Tumors were assessed using MMR IHC and MSI. The sensitivity, specificity, and positive and negative predictive values of screening strategies were compared with the gold standard of a germline result.

Results: Of 215 women, germline data were available for 189 (88%); 13 women (7%) had pathogenic germline variants with 7 women with mutS homolog 6 (MSH6); 3 women with mutL homolog 1 (MLH1); 2 women with PMS1 homolog 2, mismatch repair system component (PMS2); and 1 woman with mutS homolog 2 (MSH2). A total of 28 women had MMR-deficient tumors (13%); of these, 11 had pathogenic variants (39%). Sequential IHC (with MLH1 promoter methylation analysis on MLH1-deficient tumors) followed by MSI for nonmethylated and/or MMR-intact patients was the most sensitive (92.3%; 95% confidence interval, 64%-99.8%) and specific (97.7%; 95% confidence interval, 94.2%-99.4%) approach, missing 1 case of LS. IHC with MLH1 promoter methylation analysis missed 2 patients of LS. Family history was found to have the lowest sensitivity at 55%.

Conclusions: Sequential IHC (with MLH1 promoter methylation analysis) followed by MSI was found to be most sensitive. However, IHC with MLH1 promoter methylation analysis also performed well and is likely more cost-effective and efficient in the clinical setting. The pretest probability of LS is high in patients with MMR deficiency and warrants universal screening for LS.
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http://dx.doi.org/10.1002/cncr.33144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7693219PMC
November 2020

Barriers and facilitators to CDH1 carriers contemplating or undergoing prophylactic total gastrectomy.

Fam Cancer 2021 04 5;20(2):157-169. Epub 2020 Aug 5.

Zane Cohen Centre for Digestive Diseases, Sinai Health System, Box 24-60, Murray Street, Toronto, ON, M5T 3L9, Canada.

Hereditary diffuse gastric cancer (HDGC) is an inherited cancer syndrome associated with high lifetime risk of diffuse-type gastric cancer. Current guidelines recommend individuals with HDGC undergo prophylactic total gastrectomy (PTG) to eliminate this risk. However, PTG is associated with significant lifestyle changes, post-surgical recovery, and symptom burden. This study examined factors related to decision-making about PTG in three groups of individuals who: (1) underwent PTG immediately after receiving genetic testing results; (2) delayed PTG by ≥ 1 year or; (3) declined PTG. Participants were recruited from a familial gastric cancer registry at a tertiary care hospital. Patients with CDH1 pathogenic or likely pathogenic variants who contemplated and/or underwent PTG were eligible. 24 individuals contemplated PTG: 9 had immediate surgery (within a year), 8 delayed surgery, and 7 declined surgery. Data on PTG barriers and facilitators were obtained on all participants using quantitative surveys (n = 7), qualitative interviews (n = 8) or both methods (n = 9). PTG barriers included age, positive beliefs about screening, close relatives with negative PTG experiences, fertility-related concerns, and life stress. Facilitators included social support, trust in healthcare providers, understanding risk, negative beliefs about screening, family-related factors, positive or abnormal screening results, and positive attitude toward PTG. This study highlights factors related to the PTG decision-making process among individuals with HDGC from three distinct groups. Future research should explore educational interventions aimed at addressing surgery-related concerns and the limitations of screening, and might also consider incorporating close relatives as informational supports.
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http://dx.doi.org/10.1007/s10689-020-00197-yDOI Listing
April 2021

Exome and genome sequencing in adults with undiagnosed disease: a prospective cohort study.

J Med Genet 2021 04 24;58(4):275-283. Epub 2020 Jun 24.

Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.

Background: Exome and genome sequencing have been demonstrated to increase diagnostic yield in paediatric populations, improving treatment options and providing risk information for relatives. There are limited studies examining the clinical utility of these tests in adults, who currently have limited access to this technology.

Methods: Patients from adult and cancer genetics clinics across Toronto, Ontario, Canada were recruited into a prospective cohort study evaluating the diagnostic utility of exome and genome sequencing in adults. Eligible patients were ≥18 years of age and suspected of having a hereditary disorder but had received previous uninformative genetic test results. In total, we examined the diagnostic utility of exome and genome sequencing in 47 probands and 34 of their relatives who consented to participate and underwent exome or genome sequencing.

Results: Overall, 17% (8/47) of probands had a pathogenic or likely pathogenic variant identified in a gene associated with their primary indication for testing. The diagnostic yield for patients with a cancer history was similar to the yield for patients with a non-cancer history (4/18 (22%) vs 4/29 (14%)). An additional 24 probands (51%) had an inconclusive result. Secondary findings were identified in 10 patients (21%); three had medically actionable results.

Conclusions: This study lends evidence to the diagnostic utility of exome or genome sequencing in an undiagnosed adult population. The significant increase in diagnostic yield warrants the use of this technology. The identification and communication of secondary findings may provide added value when using this testing modality as a first-line test.
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http://dx.doi.org/10.1136/jmedgenet-2020-106936DOI Listing
April 2021

Effectiveness of the Genomics ADvISER decision aid for the selection of secondary findings from genomic sequencing: a randomized clinical trial.

Genet Med 2020 04 11;22(4):727-735. Epub 2019 Dec 11.

Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON, Canada.

Purpose: To evaluate the effectiveness of the Genomics ADvISER (www.genomicsadviser.com) decision aid (DA) for selection of secondary findings (SF), compared with genetic counseling alone.

Methods: A randomized controlled trial (RCT) was conducted to evaluate whether the Genomics ADvISER is superior to genetic counseling when hypothetically selecting SF. Participants were randomized to use the DA followed by discussion with a genetic counselor, or to genetic counseling alone. Surveys were administered at baseline and post-intervention. Primary outcome was decisional conflict. Secondary outcomes were knowledge, preparation for, and satisfaction with decision-making, anxiety, and length of counseling session.

Results: Participants (n = 133) were predominantly White/European (74%), female (90%), and ≥50 years old (60%). Decisional conflict (mean difference 0.05; P = 0.60), preparation for decision-making (0.17; P = 0.95), satisfaction with decision (-2.18; P = 0.06), anxiety (0.72; P = 0.56), and knowledge of sequencing limitations (0.14; P = 0.70) did not significantly differ between groups. However, intervention participants had significantly higher knowledge of SF (0.39; P < 0.001) and sequencing benefits (0.97; P = 0.01), and significantly shorter counseling time (24.40 minutes less; P < 0.001) CONCLUSIONS: The Genomics ADvISER did not decrease decisional conflict but reduced counseling time and improved knowledge. This decision aid could serve as an educational tool, reducing in-clinic time and potentially health care costs.
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http://dx.doi.org/10.1038/s41436-019-0702-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7425118PMC
April 2020

Cost-effectiveness of Active Identification and Subsequent Colonoscopy Surveillance of Lynch Syndrome Cases.

Clin Gastroenterol Hepatol 2020 11 17;18(12):2760-2767.e12. Epub 2019 Oct 17.

Department of Surgery, LiKaShing Knowledge Institute, St Michael's Hospital, Toronto, Canada.

Background & Aims: The province of Ontario, Canada is considering immunohistochemical followed by cascade analyses of all patients who received a diagnosis of colorectal cancer (CRC) at an age younger than 70 years to identify individuals with Lynch syndrome. We evaluated the costs and benefits of testing for Lynch syndrome and determined the optimal surveillance interval for first-degree relatives (FDRs) found to have Lynch syndrome.

Methods: We developed a patient flow diagram to determine costs and yield of immunohistochemical testing for Lynch syndrome in CRC cases and, for those found to have Lynch syndrome, their FDRs, accounting for realistic uptake. Subsequently, we used the MISCAN-colon model to compare costs and benefits of annual, biennial, and triennial surveillance in FDRs identified with Lynch syndrome vs colonoscopy screening every 10 years (usual care for individuals without a diagnosis of Lynch syndrome).

Results: Testing 1000 CRC cases was estimated to identify 20 CRC index cases and 29 FDRs with Lynch syndrome at a cost of $310,274. Despite the high cost of Lynch syndrome tests, offering the FDRs with Lynch syndrome biennial colonoscopy surveillance was cost-effective at $8785 per life-year gained compared with usual care because of a substantial increase in life-years gained (+122%) and cost savings in CRC care. Triennial surveillance was more costly and less effective, and annual surveillance showed limited additional benefit compared with biennial surveillance.

Conclusions: Immunohistochemical testing for Lynch syndrome in persons younger than 70 years who received a diagnosis of CRC and then testing FDRs of those found to have Lynch syndrome provide a good balance between costs and long-term benefits. Colonoscopy surveillance every 2 years is the optimal surveillance interval for patients with Lynch syndrome.
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http://dx.doi.org/10.1016/j.cgh.2019.10.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7162709PMC
November 2020

Health outcomes, utility and costs of returning incidental results from genomic sequencing in a Canadian cancer population: protocol for a mixed-methods randomised controlled trial.

BMJ Open 2019 10 7;9(10):e031092. Epub 2019 Oct 7.

Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada

Introduction: Genomic sequencing has rapidly transitioned into clinical practice, improving diagnosis and treatment options for patients with hereditary disorders. However, large-scale implementation of genomic sequencing faces challenges, especially with regard to the return of incidental results, which refer to genetic variants uncovered during testing that are unrelated to the primary disease under investigation, but of potential clinical significance. High-quality evidence evaluating health outcomes and costs of receiving incidental results is critical for the adoption of genomic sequencing into clinical care and to understand the unintended consequences of adoption of genomic sequencing. We aim to evaluate the health outcomes and costs of receiving incidental results for patients undergoing genomic sequencing.

Methods And Analysis: We will compare health outcomes and costs of receiving, versus not receiving, incidental results for adult patients with cancer undergoing genomic sequencing in a mixed-methods randomised controlled trial. Two hundred and sixty patients who have previously undergone first or second-tier genetic testing for cancer and received uninformative results will be recruited from familial cancer clinics in Toronto, Ontario. Participants in both arms will receive cancer-related results. Participants in the intervention arm have the option to receive incidental results. Our primary outcome is psychological distress at 2 weeks following return of results. Secondary outcomes include behavioural consequences, clinical and personal utility assessed over the 12 months after results are returned and health service use and costs at 12 months and 5 years. A subset of participants and providers will complete qualitative interviews about utility of incidental results.

Ethics And Dissemination: This study has been approved by Clinical Trials Ontario Streamlined Research Ethics Review System that provides ethical review and oversight for multiple sites participating in the same clinical trial in Ontario.Results from the trial will be shared through stakeholder workshops, national and international conferences, and peer-reviewed journals.

Trial Registration Number: NCT03597165.
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http://dx.doi.org/10.1136/bmjopen-2019-031092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6797333PMC
October 2019

Paediatric systemic lupus erythematosus as a manifestation of constitutional mismatch repair deficiency.

J Med Genet 2020 07 9;57(7):505-508. Epub 2019 Sep 9.

Recanati Genetics Institute, Rabin Medical Center, Petah Tikva, Israel

Biallelic mutations in any of the four mismatch repair genes , , and result in one of the most aggressive childhood cancer predisposition syndromes, termed constitutional mismatch repair deficiency (CMMRD) syndrome. In addition to a very high tumour risk, the CMMRD phenotype is often characterised by the presence of signs reminiscent of neurofibromatosis type 1. Although paediatric systemic lupus erythematosus (pSLE) has been reported so far in three patients with CMMRD, it has not been considered a diagnostic feature of the syndrome. We report here two additional female patients with pSLE and CMMRD due to biallelic pathogenic variants in Hence, there are a total of five out of approximately 200 (2.5%) currently reported patients with CMMRD that also have pSLE, suggesting pSLE should raise the suspicion of a diagnosis of CMMRD, especially if supported by additional indicative features.
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http://dx.doi.org/10.1136/jmedgenet-2019-106303DOI Listing
July 2020

Patient-physician relationships, health self-efficacy, and gynecologic cancer screening among women with Lynch syndrome.

Hered Cancer Clin Pract 2019 13;17:24. Epub 2019 Aug 13.

1Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3 Canada.

Background: Lynch syndrome, a hereditary cancer syndrome, predisposes women to colorectal, endometrial, and ovarian cancer. Current guidelines recommend that women with Lynch syndrome undergo risk-reducing gynecological surgery to reduce their chances of developing endometrial or ovarian cancer. Little is known about how women with Lynch syndrome perceive gynecological cancer screening, or the psychosocial factors associated with screening attitudes and behaviour.

Methods: This study used a cross-sectional, quantitative design. Using self-report questionnaire data from a sample of women with Lynch syndrome ( = 50) who had not undergone risk-reducing surgery, the current study sought to: 1) describe the gynecological cancer screening behaviours of women with Lynch syndrome, as well participant-reported sources of information about Lynch syndrome; 2) examine the extent to which women believe gynecological cancer screening is effective and provides them with reassurance and; 3) assess to what extent relationships with one's family physician were associated with gynecological cancer screening, perceptions about screening, and health self-efficacy. Data were analyzed using descriptive statistics and Spearman rank-ordered correlations.

Results: Data analyses showed that transvaginal ultrasound was the most common screening behaviour (57%) followed by pelvic ultrasound (47%). Only 22% of participants underwent endometrial biopsy. Patient-physician relationships were related to greater health self-efficacy to manage Lynch syndrome and greater perceived effectiveness of gynecological screening. However, health self-efficacy and better patient-physician relationships were not associated with increased engagement in gynecological cancer screening.

Conclusions: The data suggest that feeling efficacious about managing one's Lynch syndrome and screening is related to positive interactions and communication with one's family physician. While this is encouraging, future research should examine educating both family physicians and patients about current guidelines for Lynch syndrome gynecological screening recommendations.
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http://dx.doi.org/10.1186/s13053-019-0123-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6693236PMC
August 2019

Ongoing issues with the management of children with Constitutional Mismatch Repair Deficiency syndrome.

Eur J Med Genet 2019 Aug 21;62(8):103706. Epub 2019 Jun 21.

The Hospital for Sick Children, Toronto, Canada.

Constitutional Mismatch Repair Deficiency (CMMRD) is a rare cancer predisposition syndrome, presenting in childhood, in which affected patients develop various malignancies such as hematological, gastrointestinal and central nervous system tumors. Although guidelines are being increasingly developed for surveillance and early detection of cancers in affected families, there are no clear recommendations regarding choice of therapy and very scarce information about tolerance to chemotherapy and radiation in these patients. We report the pedigree of a consanguineous family with four affected children. Although clinical and molecular tests confirm CMMRD, genetic testing revealed heterogeneous mutations. The index case developed severe toxicity from therapy for glioblastoma and T-cell leukemia and died from an infection while in complete remission. His sister developed a malignant brain tumor while undergoing surveillance for a low grade brain lesion and is still undergoing follow-up. This family illustrates the difficulties and opportunities with challenging diagnosis, surveillance and choice of therapy for children with CMMRD and the need for increased awareness and more information about this rare but important syndrome.
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http://dx.doi.org/10.1016/j.ejmg.2019.103706DOI Listing
August 2019

Telephone versus in-person colorectal cancer risk and screening intervention for first-degree relatives: A randomized controlled trial.

Cancer 2019 07 12;125(13):2272-2282. Epub 2019 Mar 12.

Public Health Ontario, Toronto, Ontario, Canada.

Background: Having a first-degree relative (FDR) with colorectal cancer (CRC) is a significant risk factor for CRC. Counseling for FDRs regarding CRC risk factors and personalized risk is important to improve knowledge and screening compliance.

Methods: A 3-arm randomized controlled trial compared tailored in-person and telephone CRC counseling interventions with controls among FDRs who were not mutation carriers for known hereditary cancer syndromes, but who were considered to be at an increased risk based on family history. It was hypothesized that both telephone and in-person approaches would increase CRC knowledge, screening adherence, perceived risk accuracy, and psychosocial functioning compared with controls. The authors anticipated greater satisfaction with the in-person approach. CRC knowledge, risk perception, psychosocial functioning, and intention to screen were assessed at baseline and at 2-week and 2-month follow-ups (primary endpoint).

Results: A total of 278 FDRs (mean age, 47.4 years, standard deviation, 11.38 years) participated. At baseline, participants reported low to moderate CRC knowledge and overestimations of risk. Screening adherence was 73.7%. At 2 months, participants in the in-person arm and telephone arm demonstrated improvements in knowledge and perceived risk and were not found to be statistically different from each other. However, when comparing each intervention with controls, knowledge in the in-person arm was found to be statistically significantly higher, but the difference between the telephone and control arms was not. Cancer-related stress reduced over time in all groups. Intervention benefits were maintained at 1 year. Baseline screening intent/adherence were high, and therefore did not reach statistically significant improvement.

Conclusions: Tailored in-person or telephone formats for providing CRC risk counseling, incorporating behavioral interventions, appear to improve knowledge and risk perceptions, with high client satisfaction.
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http://dx.doi.org/10.1002/cncr.32032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6742581PMC
July 2019

Development of patient "profiles" to tailor counseling for incidental genomic sequencing results.

Eur J Hum Genet 2019 07 8;27(7):1008-1017. Epub 2019 Mar 8.

University of Toronto, Toronto, ON, Canada.

Guidelines recommend that providers engage patients in shared decision-making about receiving incidental results (IR) prior to genomic sequencing (GS), but this can be time-consuming, given the myriad of IR and variation in patients' preferences. We aimed to develop patient profiles to inform pre-test counseling for IR. We conducted semi-structured interviews with participants as a part of a randomized trial of the GenomicsADvISER.com, a decision aid for selecting IR. Interviews explored factors participants considered when deliberating over learning IR. Interviews were analyzed by thematic analysis and constant comparison. Participants were mostly female (28/31) and about half of them were over the age of 50 (16/31). We identified five patient profiles that reflect common contextual factors, attitudes, concerns, and perceived utility of IR. Information Enthusiasts self-identified as "planners" and valued learning most or all IR to enable planning and disease prevention because "knowledge is power". Concerned Individuals defined themselves as "anxious," and were reluctant to learn IR, anticipating negative psychological impacts from IR. Contemplators were discerning about the value and limitations of IR, weighing health benefits with the impacts of not being able to "un-know" information. Individuals of Advanced Life Stage did not consider IR relevant for themselves and primarily considered their implications for family members. Reassurance Seekers were reassured by previous negative genetic test results which shaped their expectations for receiving no IR: "hopefully [GS will] be negative, too. And then I can rest easy". These profiles could inform targeted counseling for IR by providing a framework to address common values, concerns. and misconceptions.
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http://dx.doi.org/10.1038/s41431-019-0352-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6777527PMC
July 2019

The impact of health anxiety on perceptions of personal and children's health in parents with Lynch syndrome.

J Genet Couns 2019 06 14;28(3):495-506. Epub 2019 Jan 14.

Department of Psychology, Ryerson University, Toronto, ON, Canada.

This study examined the differences in perceptions of one's health and one's child's health between parents with Lynch syndrome (LS) characterized with high versus low health anxiety. Twenty-one parents completed semistructured telephone interviews about their perceptions of their own health and the health of their children. Qualitative content analysis using a template coding approach examined the differences between parents with high and low health anxiety. Findings revealed that the most prevalent difference emerged on perceptions of personal health, showing individuals with high health anxiety reported more extreme worries, were more hypervigilant about physical symptoms, experienced the emotional and psychological consequences of LS as more negative and severe, and engaged in more dysfunctional coping strategies than those with low health anxiety. Unexpectedly, with regards to perceptions of their children, parents in the high and low health anxiety groups exhibited similar worries. However, high health anxiety parents reported using dysfunctional coping about their children's health more frequently than those with low health anxiety. The findings suggest that health anxiety is of clinical significance for individuals with LS. Accurately identifying and treating health anxiety among this population may be one avenue to reduce the distress experienced by LS carriers.
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http://dx.doi.org/10.1002/jgc4.1043DOI Listing
June 2019

Functional Repair Assay for the Diagnosis of Constitutional Mismatch Repair Deficiency From Non-Neoplastic Tissue.

J Clin Oncol 2019 02 4;37(6):461-470. Epub 2019 Jan 4.

23 Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.

Purpose: Constitutional mismatch repair deficiency (CMMRD) is a highly penetrant cancer predisposition syndrome caused by biallelic mutations in mismatch repair (MMR) genes. As several cancer syndromes are clinically similar, accurate diagnosis is critical to cancer screening and treatment. As genetic diagnosis is confounded by 15 or more pseudogenes and variants of uncertain significance, a robust diagnostic assay is urgently needed. We sought to determine whether an assay that directly measures MMR activity could accurately diagnose CMMRD.

Patients And Methods: In vitro MMR activity was quantified using a 3'-nicked G-T mismatched DNA substrate, which requires MSH2-MSH6 and MLH1-PMS2 for repair. We quantified MMR activity from 20 Epstein-Barr virus-transformed lymphoblastoid cell lines from patients with confirmed CMMRD. We also tested 20 lymphoblastoid cell lines from patients who were suspected for CMMRD. We also characterized MMR activity from patients with neurofibromatosis type 1, Li-Fraumeni syndrome, polymerase proofreading-associated cancer syndrome, and Lynch syndrome.

Results: All CMMRD cell lines had low MMR activity (n = 20; mean, 4.14 ± 1.56%) relative to controls (n = 6; mean, 44.00 ± 8.65%; P < .001). Repair was restored by complementation with the missing protein, which confirmed MMR deficiency. All cases of patients with suspected CMMRD were accurately diagnosed. Individuals with Lynch syndrome (n = 28), neurofibromatosis type 1 (n = 5), Li-Fraumeni syndrome (n = 5), and polymerase proofreading-associated cancer syndrome (n = 3) had MMR activity that was comparable to controls. To accelerate testing, we measured MMR activity directly from fresh lymphocytes, which yielded results in 8 days.

Conclusion: On the basis of the current data set, the in vitro G-T repair assay was able to diagnose CMMRD with 100% specificity and sensitivity. Rapid diagnosis before surgery in non-neoplastic tissues could speed proper therapeutic management.
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http://dx.doi.org/10.1200/JCO.18.00474DOI Listing
February 2019

Additional germline findings from a tumor profiling program.

BMC Med Genomics 2018 Aug 9;11(1):65. Epub 2018 Aug 9.

Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, 610 University Ave, Toronto, ON, M5G 2M9, Canada.

Background: Matched tumor-normal sequencing, applied in precision cancer medicine, can identify unidentified germline Medically Actionable Variants (gMAVS) in cancer predisposition genes. We report patient preferences for the return of additional germline results, and describe various gMAV scenarios delivered through a clinical genetics service.

Methods: Tumor profiling was offered to 1960 advanced cancer patients, of which 1556 underwent tumor-normal sequencing with multigene hotspot panels containing 20 cancer predisposition genes. All patients were provided with an IRB-approved consent for return of additional gMAVs.

Results: Of the whole cohort 94% of patients consented to be informed of additional germline results and 5% declined, with no statistically significant differences based on age, sex, race or prior genetic testing. Eight patients were found to have gMAVs in a cancer predisposition gene. Five had previously unidentified gMAVs: three in TP53 (only one fulfilled Chompret's Revised criteria for Li-Fraumeni Syndrome), one in SMARCB1 in the absence of schwannomatosis features and one a TP53 variant at low allele frequency suggesting an acquired event in blood.

Conclusion: Interest in germline findings is high among patients who undergo tumor profiling. Disclosure of previously unidentified gMAVs present multiple challenges, thus supporting the involvement of a clinical genetics service in all tumor profiling programs.
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http://dx.doi.org/10.1186/s12920-018-0383-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6085686PMC
August 2018

Delineating a new feature of constitutional mismatch repair deficiency (CMMRD) syndrome: breast cancer.

Fam Cancer 2019 01;18(1):105-108

Department of Medical Affairs, Ambry Genetics, 15 Argonaut, Aliso Viejo, CA, 92656, USA.

Constitutional mismatch repair deficiency (CMMRD) syndrome is a rare autosomal recessive hereditary cancer condition, characterized by an exceptionally high risk of cancer, a propensity for childhood malignancies, and cutaneous features reminiscent of neurofibromatosis type 1 (NF1). We report on two sisters originally suspected of having CMMRD syndrome due to their history of colonic polyps and NF1 associated skin findings, both were subsequently found to have biallelic MSH6 mutations. After years of CMMRD syndrome follow-up, the proband was diagnosed with breast cancer at age 29, while her sister was diagnosed with a glioblastoma at age 27. Immunohistochemistry analysis on the breast tumor tissue revealed weak MSH6 protein staining. Exome sequencing revealed a hypermutated breast tumor and an ultra-hypermutated brain tumor. Multi-gene panel testing was also performed and revealed no additional mutations which might explain the proband's early onset breast cancer. This is the first documented case of breast cancer in an individual with CMMRD syndrome. We summarize the evidence supporting the possible association between breast cancer and biallelic MMR mutations. Healthcare providers should be aware of this possible association and follow-up appropriately for suspicious breast findings. In addition, this case highlights the need for frequent central nervous system screenings due to rapid progression of brain tumors.
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http://dx.doi.org/10.1007/s10689-018-0088-0DOI Listing
January 2019

Evaluation of a decision aid for incidental genomic results, the Genomics ADvISER: protocol for a mixed methods randomised controlled trial.

BMJ Open 2018 04 26;8(4):e021876. Epub 2018 Apr 26.

University of Toronto, Toronto, Ontario, Canada.

Introduction: Genome sequencing, a novel genetic diagnostic technology that analyses the billions of base pairs of DNA, promises to optimise healthcare through personalised diagnosis and treatment. However, implementation of genome sequencing faces challenges including the lack of consensus on disclosure of incidental results, gene changes unrelated to the disease under investigation, but of potential clinical significance to the patient and their provider. Current recommendations encourage clinicians to return medically actionable incidental results and stress the importance of education and informed consent. Given the shortage of genetics professionals and genomics expertise among healthcare providers, decision aids (DAs) can help fill a critical gap in the clinical delivery of genome sequencing. We aim to assess the effectiveness of an interactive DA developed for selection of incidental results.

Methods And Analysis: We will compare the DA in combination with a brief Q&A session with a genetic counsellor to genetic counselling alone in a mixed-methods randomised controlled trial. Patients who received negative standard cancer genetic results for their personal and family history of cancer and are thus eligible for sequencing will be recruited from cancer genetics clinics in Toronto. Our primary outcome is decisional conflict. Secondary outcomes are knowledge, satisfaction, preparation for decision-making, anxiety and length of session with the genetic counsellor. A subset of participants will complete a qualitative interview about preferences for incidental results.

Ethics And Dissemination: This study has been approved by research ethics boards of St. Michael's Hospital, Mount Sinai Hospital and Sunnybrook Health Sciences Centre. This research poses no significant risk to participants. This study evaluates the effectiveness of a novel patient-centred tool to support clinical delivery of incidental results. Results will be shared through national and international conferences, and at a stakeholder workshop to develop a consensus statement to optimise implementation of the DA in practice.

Trial Registration Number: NCT03244202; Pre-results.
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http://dx.doi.org/10.1136/bmjopen-2018-021876DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5922516PMC
April 2018

Comprehensive Analysis of Hypermutation in Human Cancer.

Cell 2017 Nov 19;171(5):1042-1056.e10. Epub 2017 Oct 19.

Department of Pediatric Hematology-Oncology, Sheba Medical Center, Tel Hashomer, Israel.

We present an extensive assessment of mutation burden through sequencing analysis of >81,000 tumors from pediatric and adult patients, including tumors with hypermutation caused by chemotherapy, carcinogens, or germline alterations. Hypermutation was detected in tumor types not previously associated with high mutation burden. Replication repair deficiency was a major contributing factor. We uncovered new driver mutations in the replication-repair-associated DNA polymerases and a distinct impact of microsatellite instability and replication repair deficiency on the scale of mutation load. Unbiased clustering, based on mutational context, revealed clinically relevant subgroups regardless of the tumors' tissue of origin, highlighting similarities in evolutionary dynamics leading to hypermutation. Mutagens, such as UV light, were implicated in unexpected cancers, including sarcomas and lung tumors. The order of mutational signatures identified previous treatment and germline replication repair deficiency, which improved management of patients and families. These data will inform tumor classification, genetic testing, and clinical trial design.
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http://dx.doi.org/10.1016/j.cell.2017.09.048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5849393PMC
November 2017

Association between the Lynch syndrome gene MSH2 and breast cancer susceptibility in a Canadian familial cancer registry.

J Med Genet 2017 11 4;54(11):742-746. Epub 2017 Aug 4.

Department of Oncology, McMaster University, Hamilton, Canada.

Background: Previous studies assessing breast cancer risk in families with Lynch syndrome (LS) have yielded conflicting results. Furthermore, conclusions are limited by small sample size and few breast cancer outcomes. This study assesses breast cancer risk in a large prospectively followed LS cohort.

Methods: Pedigrees of 325 unrelated families with LS within the Familial Gastrointestinal Cancer Registry in Canada were examined for breast cancer diagnoses. Standardised incidence ratios (SIR) and lifetime cumulative incidence calculations were used to compare the incidence of breast cancer in mutation carriers with the general population.

Results: Forty-one mutation carriers diagnosed with breast cancer belonging to 34 unrelated families were identified. Mean age at diagnosis was 54 years. The mutation distribution among the LS patients with breast cancer was statistically different from those without breast cancer (p=0.015), reflecting the predominance of mutations among affected patients (74%). Eighty-eight per cent of LS families with breast cancer met Amsterdam criteria, compared with 49% of LS families without breast cancer (p=0.03). Lifetime cumulative incidence of breast cancer in female mutation carriers in our cohort was 22% (p<0.001). The SIR for breast cancer of female mutation carriers in our cohort was 3.11 (95% CI 1.95 to 4.71).

Conclusions: An increased risk of breast cancer in mutation carriers was demonstrated in a Canadian familial cancer registry. Women with breast cancer often had a personal and family history of multiple LS-related malignancies. These results suggest a potential role for intensified breast cancer surveillance among women with LS.
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http://dx.doi.org/10.1136/jmedgenet-2017-104542DOI Listing
November 2017

Prophylactic Total Gastrectomy: a Prospective Cohort Study of Long-Term Impact on Quality of Life.

J Gastrointest Surg 2016 12 17;20(12):1950-1958. Epub 2016 Oct 17.

Department of Surgery, University of Toronto, Toronto, ON, Canada.

Background: Hereditary diffuse gastric cancer (HDGC) syndrome is caused by germline mutations in the CDH1 gene and carries a lifetime gastric cancer risk of approximately 70 % in men and 56 % in women. Current consensus guidelines recommend that people of age ≥20 who harbor a CDH1 mutation undergo prophylactic total gastrectomy (PTG). However, the decision to proceed with a major visceral resection for prophylactic reasons may be difficult, especially since long-term outcomes are not well defined. We examined the decision-making process, physical symptoms, and psychosocial outcomes in adults who underwent PTG.

Methods: Participants completed pre- and post-operative questionnaires that included standardized measures of health-related quality of life (HRQOL), body image, psychological distress, regret, and decisional conflict. Those who declined surgery completed a questionnaire that measured decisional conflict and explored reasons for their choice.

Results: Forty of fifty (80 %) questionnaires distributed to 18 individuals were completed. In the 13 patients who underwent PTG, global HRQOL tended to decrease immediately post-operatively, climb to baseline by 6-12 months, then decrease again at 24 months. Body image and level of psychological distress remained relatively stable, and most patients expressed little decisional conflict or regret. All five individuals who declined surgery did so for practical reasons and would consider surgery in the future.

Conclusions: While most patients do not experience negative psychosocial consequences following PTG, mild physical symptoms persist and may affect long-term HRQOL. The present study emphasizes the need for long-term follow-up of this unique population of survivors.
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http://dx.doi.org/10.1007/s11605-016-3287-8DOI Listing
December 2016
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