Publications by authors named "Majid Mohiuddin"

22 Publications

  • Page 1 of 1

Feasibility of 18-MV grid therapy from radiation protection aspects: unwanted dose and fatal cancer risk caused by photoneutrons and scattered photons.

Comput Methods Programs Biomed 2022 Jan 12;213:106524. Epub 2021 Nov 12.

Department of Radiation Oncology, Advocate Lutheran General Hospital, 1700 Lutheran, Park Ridge, Illinois, USA. Electronic address:

Purpose: Photoneutron production is a common concern when using 18-MV photon beams in radiation therapy. In Spatially Fractionated Grid Radiation Therapy (SFGRT), the grid block in the collimation system modifies the neutron production, photon scattering, and electron contamination in and out of the radiation field. Such an effect was studied with grids made of different high-Z materials by Monte Carlo simulations. The results were also used to evaluate the lifetime risk of fatal cancers.

Methods: MCNPX® code (2.7.0 extensions) was employed to simulate an 18-MV LINAC (Varian 2100 C/D). Three types of grid made of brass, cerrobend, and lead were used to study the neutron and electron fluence. Output factors for each grid with different field sizes were calculated. A revised female MIRD phantom with an 8-cm spherical tumor inside the liver was used to estimate the dose to the tumor and the critical organs. A 20-Gy SFGRT plan with Anterior Posterior (AP) - Posterior Anterior (PA) grid beams was compared with a Conventional Fractionated Radiation Therapy (CFRT) plan which delivered 40-Gy to the tumor by AP-PA open beams. Neutron equivalent dose, photon equivalent dose, as well as lifetime risks of fatal cancer were calculated in the organs at risk.

Results: The grid blocks reduced the fluence of contaminant electrons inside the treatment field by more than 50%. The neutron fluences per electron-history in SFGRT plans with brass, cerrobend and lead were on average 55%, 31% and 31% less than that of the CFRT plan, respectively. However, when converting to fluences per delivered dose (Gy), the cerrobend and lead grid may incur higher neutron dose for 20 × 20 cm field size and above. The changes in neutron mean energy, as well as the correlated radiation weighting factors, were insignificant. The total risk due to the photoneutrons in the SFGRT plans was 87% or lower than that in the CFRT plans. In both SFGRT and CFRT plans, the contribution of the primary and scattered photons to the fatal cancer risk was 2 times or more than the photoneutrons. The total risks from photons in SFGRT with brass, cerrobend, and lead blocks were 1.733, 1.374, and 1.260%, respectively, which were less than 30% of the total photon-risk in CFRT (5.827%).

Conclusion: In the brass, cerrobend, and lead grids, the attenuation of photoneutrons outweighs its photoneutron production in 18-MV SFGRT. The total cancer risks from photons and photoneutrons in the SFGRT plans were 30% or less of the risks in the CFRT plans (5.911%). Using 18 MV photon beams with brass, cerrobend, and lead grid blocks is still a feasible option for SFGRT.
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http://dx.doi.org/10.1016/j.cmpb.2021.106524DOI Listing
January 2022

Understanding High-Dose, Ultra-High Dose Rate, and Spatially Fractionated Radiation Therapy.

Int J Radiat Oncol Biol Phys 2020 07 13;107(4):766-778. Epub 2020 Apr 13.

Division of Cancer Treatment and Diagnosis, Rockville, Maryland.

The National Cancer Institute's Radiation Research Program, in collaboration with the Radiosurgery Society, hosted a workshop called Understanding High-Dose, Ultra-High Dose Rate and Spatially Fractionated Radiotherapy on August 20 and 21, 2018 to bring together experts in experimental and clinical experience in these and related fields. Critically, the overall aims were to understand the biological underpinning of these emerging techniques and the technical/physical parameters that must be further defined to drive clinical practice through innovative biologically based clinical trials.
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http://dx.doi.org/10.1016/j.ijrobp.2020.03.028DOI Listing
July 2020

Early clinical results of proton spatially fractionated GRID radiation therapy (SFGRT).

Br J Radiol 2020 Mar 7;93(1107):20190572. Epub 2019 Nov 7.

Northwestern Medicine Chicago Proton Center 4455 Weaver Pkwy, Warrenville, IL 60555.

Objective: Approximately 70 patients with large and bulky tumors refractory to prior treatments were treated with photon spatially fractionated GRID radiation (SFGRT). We identified 10 additional patients who clinically needed GRID but could not be treated with photons due to adjacent critical organs. We developed a proton SFGRT technique, and we report treatment of these 10 patients.

Methods: Subject data were reviewed for clinical results and dosimetric data. 50% of the patients were metastatic at the time of treatment and five had previous photon radiation to the local site but not via GRID. They were treated with 15-20 cobalt Gray equivalent using a single proton GRID field with an average beamlet count of 22.6 (range 7-51). 80% received an average adjuvant radiation dose to the GRID region of 40.8Gy (range 13.7-63.8Gy). Four received subsequent systemic therapy.

Results: The median follow-up time was 5.9 months (1.1-18.9). At last follow-up, seven patients were alive and three had died. Two patients who had died from metastatic disease had local shrinkage of tumor. Of those alive, four had complete or partial response, two had partial response but later progressed, and one had no response. For all patients, the tumor regression/local symptom improvement rate was 80%. 50% had acute side-effects of grade1/2 only and all were well-tolerated.

Conclusion: In circumstances where patients cannot receive photon GRID, proton SFGRT is clinically feasible and effective, with a similar side-effect profile.

Advances In Knowledge: Proton GRID should be considered as a treatment option earlier in the disease course for patients who cannot be treated by photon GRID.
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http://dx.doi.org/10.1259/bjr.20190572DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7066961PMC
March 2020

Colon cancer presenting as a testicular metastasis.

Transl Gastroenterol Hepatol 2016 2;1:89. Epub 2016 Dec 2.

Advocate Lutheran General Hospital, IL 60068, USA.

We report a case of a 43-year-old male who initially presented with intermittent testicular pain as the first sign of metastatic stage IV colon cancer. Physical examination revealed a normal penis, scrotum and testes. Magnetic resonance imaging (MRI) of pelvis showed an irregular 3 cm mass of the spermatic cord and right radical inguinal orchiectomy was performed. The pathological diagnosis was metastatic adenocarcinoma. In conclusion, even though metastases to the testes are rare, they should be considered in clinical practice especially in older men who present with a testicular mass or discomfort.
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http://dx.doi.org/10.21037/tgh.2016.10.03DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5244763PMC
December 2016

High-Dose Radiation as a Dramatic, Immunological Primer in Locally Advanced Melanoma.

Cureus 2015 Dec 18;7(12):e417. Epub 2015 Dec 18.

Medical Oncology, Advocate Lutheran General Hospital.

A 53-year-old white male presented with a right axillary melanoma that became widely metastatic and progressive despite multiple systemic treatments. He became refractory to ipilimumab (Yervoy) and pembrolizumab (Keytruda). He presented with a very large, painful left posterior neck mass that was 18 x 15 x 8 cm in size clinically. He was treated with a single fraction of 20 Gy using parallel opposed, spatially fractionated GRID radiation therapy (SFGRT), along with concurrent pembrolizumab. He also received 50 Gy in 25 fractions of conventional radiation. After five months of concurrent treatment, the refractory neck mass had completely resolved and he had no lasting side effects. Our dramatic case confirms the synergistic effect of high-dose GRID radiation as a primer for renewed, enhanced immunological response, and we have used this approach successfully on a number of similar patients with rapid and durable results.
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http://dx.doi.org/10.7759/cureus.417DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4725734PMC
December 2015

The international cancer expert corps: a unique approach for sustainable cancer care in low and lower-middle income countries.

Front Oncol 2014 19;4:333. Epub 2014 Nov 19.

Radiation Research Program, National Cancer Institute , Bethesda, MD , USA.

The growing burden of non-communicable diseases including cancer in low- and lower-middle income countries (LMICs) and in geographic-access limited settings within resource-rich countries requires effective and sustainable solutions. The International Cancer Expert Corps (ICEC) is pioneering a novel global mentorship-partnership model to address workforce capability and capacity within cancer disparities regions built on the requirement for local investment in personnel and infrastructure. Radiation oncology will be a key component given its efficacy for cure even for the advanced stages of disease often encountered and for palliation. The goal for an ICEC Center within these health disparities settings is to develop and retain a high-quality sustainable workforce who can provide the best possible cancer care, conduct research, and become a regional center of excellence. The ICEC Center can also serve as a focal point for economic, social, and healthcare system improvement. ICEC is establishing teams of Experts with expertise to mentor in the broad range of subjects required to establish and sustain cancer care programs. The Hubs are cancer centers or other groups and professional societies in resource-rich settings that will comprise the global infrastructure coordinated by ICEC Central. A transformational tenet of ICEC is that altruistic, human-service activity should be an integral part of a healthcare career. To achieve a critical mass of mentors ICEC is working with three groups: academia, private practice, and senior mentors/retirees. While in-kind support will be important, ICEC seeks support for the career time dedicated to this activity through grants, government support, industry, and philanthropy. Providing care for people with cancer in LMICs has been a recalcitrant problem. The alarming increase in the global burden of cancer in LMICs underscores the urgency and makes this an opportune time fornovel and sustainable solutions to transform cancer care globally.
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http://dx.doi.org/10.3389/fonc.2014.00333DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4237042PMC
December 2014

Adjuvant pelvic irradiation for cervical cancer in the setting of a transplanted pelvic kidney.

J Cancer Res Ther 2012 Jul-Sep;8(3):427-9

Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

Postoperative radiation therapy is often needed following resection for gynecological cancers. A pelvic kidney, whether ectopic or transplanted, is considered an absolute contraindication for radiation if the organ is left in place. A 45-year-old, immunosuppressed patient with FIGO IB1 cervical adenocarcinoma was treated with intensity-modulated radiation therapy (IMRT) to 45 Gy to the modified whole pelvis with a boost to 59.4 Gy to high-risk areas despite having a transplanted kidney in the right iliac fossa. The irradiation prevented further local failure in the pelvis at 36-month follow-up with no decrement in renal function. Radiation to the modified pelvis using IMRT while avoiding the renal allograft is technically feasible and should be offered to more high-risk patients.
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http://dx.doi.org/10.4103/0973-1482.103525DOI Listing
June 2013

Decrease of the lumpectomy cavity volume after whole-breast irradiation affects small field boost planning.

Med Dosim 2012 4;37(3):339-43. Epub 2012 Feb 4.

Northwest Radiation Oncology & Division of Oncology, UT Medical School at Houston, Houston, TX, USA.

To determine whether small field boost (SFB) replanning is necessary when the lumpectomy cavity (LPC) decreases during whole-breast irradiation (WBI) and what parameters might predict a change in the SFB plan. Forty patients had computed tomography (CT) simulation (CT1) within 60 days of surgery and were resimulated (CT2) after 37.8-41.4 Gy for SFB planning. A 3-field photon plan and a single en face electron plan were created on both CTs and compared. In the 26 patients who had a ≥5 cm(3) and a ≥25% decrease in lumpectomy cavity volume (LCV) between CT scans, the SFB plan using photons was different in terms of normal breast tissue volume irradiated (BTV) (p < 0.001), and field dimensions (p < 0.001). In 20/35 patients, the energy or field size changed for electron plans on CT2, but no tested characteristics predicted for a change. Less BTV was irradiated using electrons than photons in 29% (CT1) to 37% (CT2). SFB replanning needs to be individualized to each patient because of the variety of factors that can impact dosimetric planning. Replanning is recommended when using 3-field photons if the patient has experienced a ≥5 cm(3) and a ≥25% decrease in LCV during WBI. Some patients may benefit from electron SFB replanning but no tested characteristics reliably predict those who may benefit the most. The amount of BTV irradiated is less with electrons than in photon plans and this has the potential to improve cosmesis, a clinically important outcome in breast-conserving therapy.
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http://dx.doi.org/10.1016/j.meddos.2011.11.008DOI Listing
January 2013

High-dose spatially fractionated GRID radiation therapy (SFGRT): a comparison of treatment outcomes with Cerrobend vs. MLC SFGRT.

Int J Radiat Oncol Biol Phys 2012 Apr 29;82(5):1642-9. Epub 2011 Apr 29.

Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA.

Purpose: Spatially fractionated GRID radiotherapy (SFGRT) using a customized Cerrobend block has been used to improve response rates in patients with bulky tumors. The clinical efficacy of our own multileaf collimator (MLC) technique is unknown. We undertook a retrospective analysis to compare clinical response rates attained using these two techniques.

Methods And Materials: Seventy-nine patients with bulky tumors (median diameter, 7.6 cm; range, 4-30 cm) treated with SFGRT were reviewed. Between 2003 and late 2005, the Cerrobend block technique (n = 39) was used. Between late 2005 and 2008, SFGRT was delivered using MLC-shaped fields (n = 40). Dose was prescribed to dmax (depth of maximum dose) and was typically 15 Gy. Eighty percent of patients in both groups received external beam radiotherapy in addition to SFGRT. The two-sided Fisher-Freeman-Halton test was used to compare pain and mass effect response rates between the two groups.

Results: Sixty-one patients (77%) were treated for palliative intent and 18 (23%) for curative intent. The majority of patients had either lung or head-and-neck primaries in both groups; the most frequent site of SFGRT application was the neck. The majority of patients complained of either pain (65%) or mass effect (58%) at intake. Overall response rates for pain and mass response were no different between the Cerrobend and MLC groups: pain, 75% and 74%, respectively (p = 0.50), and mass effect, 67% and 73%, respectively (p = 0.85). The majority of toxicities were Grade 1 or 2, and only 3 patients had late Grade 3-4 toxicities.

Conclusions: MLC-based and Cerrobend-based SFGRT have comparable and encouraging response rates when used either in the palliative or curative setting. MLC-based SGFRT should allow clinics to more easily adopt this novel treatment approach for the treatment of bulky tumors.
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http://dx.doi.org/10.1016/j.ijrobp.2011.01.065DOI Listing
April 2012

Neoadjuvant chemoradiation in rectal cancer: time to start in a new direction.

J Clin Oncol 2011 Apr 14;29(12):e350-1; author reply e352-3. Epub 2011 Mar 14.

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http://dx.doi.org/10.1200/JCO.2010.34.0935DOI Listing
April 2011

Helical tomotherapy versus single-arc intensity-modulated arc therapy: a collaborative dosimetric comparison between two institutions.

Int J Radiat Oncol Biol Phys 2011 Sep 13;81(1):284-96. Epub 2011 Jan 13.

Department of Human Oncology and Medical Physics, University of Wisconsin-Madison, Madison, WI, USA.

Purpose: Both helical tomotherapy (HT) and single-arc intensity-modulated arc therapy (IMAT) deliver radiation using rotational beams with multileaf collimators. We report a dual-institution study comparing dosimetric aspects of these two modalities.

Methods And Materials: Eight patients each were selected from the University of Maryland (UMM) and the University of Wisconsin Cancer Center Riverview (UWR), for a total of 16 cases. Four cancer sites including brain, head and neck (HN), lung, and prostate were selected. Single-arc IMAT plans were generated at UMM using Varian RapidArc (RA), and HT plans were generated at UWR using Hi-Art II TomoTherapy. All 16 cases were planned based on the identical anatomic contours, prescriptions, and planning objectives. All plans were swapped for analysis at the same time after final approval. Dose indices for targets and critical organs were compared based on dose-volume histograms, the beam-on time, monitor units, and estimated leakage dose. After the disclosure of comparison results, replanning was done for both techniques to minimize diversity in optimization focus from different operators.

Results: For the 16 cases compared, the average beam-on time was 1.4 minutes for RA and 4.8 minutes for HT plans. HT provided better target dose homogeneity (7.6% for RA and 4.2% for HT) with a lower maximum dose (110% for RA and 105% for HT). Dose conformation numbers were comparable, with RA being superior to HT (0.67 vs. 0.60). The doses to normal tissues using these two techniques were comparable, with HT showing lower doses for more critical structures. After planning comparison results were exchanged, both techniques demonstrated improvements in dose distributions or treatment delivery times.

Conclusions: Both techniques created highly conformal plans that met or exceeded the planning goals. The delivery time and total monitor units were lower in RA than in HT plans, whereas HT provided higher target dose uniformity.
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http://dx.doi.org/10.1016/j.ijrobp.2010.10.059DOI Listing
September 2011

Comparative analysis of the post-lumpectomy target volume versus the use of pre-lumpectomy tumor volume for early-stage breast cancer: implications for the future.

Int J Radiat Oncol Biol Phys 2010 May;77(1):197-202

Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

Purpose: Three-dimensional conformal accelerated partial breast irradiation (APBI-3D-CRT) is commonly associated with the treatment of large amounts of normal breast tissue. We hypothesized that a planning tumor volume (PTV) generation based on an expansion of the pre-lumpectomy (pre-LPC) intact tumor volume would result in smaller volumes of irradiated normal breast tissue compared with using a PTV based on the post-lumpectomy cavity (post-LPC). Use of PTVs based on the pre-LPC might also result in greater patient eligibility for APBI-3D-CRT.

Methods And Materials: Forty-one early-stage breast cancers were analyzed. Preoperative imaging was used to determine a pre-LPC tumor volume. PTVs were developed in the pre- and post-LPC settings as per National Surgical Breast and Bowel Project (NSABP)-B39 guidelines. The pre- and post-LPC PTV volumes were compared and eligibility for APBI-3D-CRT determined using NSABP-B39 criteria.

Results: The post-LPC PTV exceeded the pre-LPC PTV in all cases. The median volume for the pre- and post-LPC PTVs were 93 cm(3) (range, 24-570 cm(3)) and 250 cm(3) (range, 45-879 cm(3)), respectively, p <0.001. The difference between pre- and post-LPC PTVs represented a median of 165 cc (range, 21-482 cc) or 16% (range, 3%-42%) of the whole breast volume. Three of 41 vs. 13 of 41 cases were ineligible for APBI-3D-CRT when using the pre- and post-LPC PTVs, respectively.

Conclusion: PTVs based on pre-LPC tumor expansion are likely associated with reduced amounts of irradiated normal breast tissue compared with post-LPC PTVs, possibly leading to greater patient eligibility for APBI-3D-CRT. These findings support future investigation as to the feasibility of neoadjuvant APBI-3D-CRT.
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http://dx.doi.org/10.1016/j.ijrobp.2009.04.063DOI Listing
May 2010

Comparing radiation treatments using intensity-modulated beams, multiple arcs, and single arcs.

Int J Radiat Oncol Biol Phys 2010 Apr;76(5):1554-62

Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA.

Purpose: A dosimetric comparison of multiple static-field intensity-modulated radiation therapy (IMRT), multiarc intensity-modulated arc therapy (IMAT), and single-arc arc-modulated radiation therapy (AMRT) was performed to evaluate their clinical advantages and shortcomings.

Methods And Materials: Twelve cases were selected for this study, including three head-and-neck, three brain, three lung, and three prostate cases. An IMRT, IMAT, and AMRT plan was generated for each of the cases, with clinically relevant planning constraints. For a fair comparison, the same parameters were used for the IMRT, IMAT, and AMRT planning for each patient.

Results: Multiarc IMAT provided the best plan quality, while single-arc AMRT achieved dose distributions comparable to those of IMRT, especially in the complicated head-and-neck and brain cases. Both AMRT and IMAT showed effective normal tissue sparing without compromising target coverage and delivered a lower total dose to the surrounding normal tissues in some cases.

Conclusions: IMAT provides the most uniform and conformal dose distributions, especially for the cases with large and complex targets, but with a delivery time similar to that of IMRT; whereas AMRT achieves results comparable to IMRT with significantly faster treatment delivery.
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http://dx.doi.org/10.1016/j.ijrobp.2009.04.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2846542PMC
April 2010

Consenting the patient with early-stage breast cancer: "informed" only after multi-discliplinary evaluation.

J Clin Oncol 2009 Oct 17;27(30):e158-9; author reply e160-3. Epub 2009 Aug 17.

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http://dx.doi.org/10.1200/JCO.2009.22.6332DOI Listing
October 2009

Improved survival with radiation therapy in high-grade soft tissue sarcomas of the extremities: a SEER analysis.

Int J Radiat Oncol Biol Phys 2010 May 11;77(1):203-9. Epub 2009 Aug 11.

Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

Purpose: The benefit of radiation therapy in extremity soft tissue sarcomas remains controversial. The purpose of this study was to determine the effect of radiation therapy on overall survival among patients with primary soft tissue sarcomas of the extremity who underwent limb-sparing surgery.

Methods And Materials: A retrospective study from the Surveillance, Epidemiology, and End Results (SEER) database that included data from January 1, 1988, to December 31, 2005. A total of 6,960 patients constituted the study population. Overall survival curves were constructed using the Kaplan-Meir method and for patients with low- and high-grade tumors. Hazard ratios were calculated based on multivariable Cox proportional hazards models.

Results: Of the cohort, 47% received radiation therapy. There was no significant difference in overall survival among patients with low-grade tumors by radiation therapy. In high-grade tumors, the 3-year overall survival was 73% in patients who received radiation therapy vs. 63% for those who did not receive radiation therapy (p < 0.001). On multivariate analysis, patients with high-grade tumors who received radiation therapy had an improved overall survival (hazard ratio 0.67, 95% confidence interval 0.57-0.79). In patients receiving radiation therapy, 13.5% received it in a neoadjuvant setting. The incidence of patients receiving neoadjuvant radiation did not change significantly between 1988 and 2005.

Conclusions: To our knowledge, this is the largest population-based study reported in patients undergoing limb-sparing surgery for soft tissue sarcomas of the extremities. It reports that radiation was associated with improved survival in patients with high-grade tumors.
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http://dx.doi.org/10.1016/j.ijrobp.2009.04.051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3812813PMC
May 2010

Future directions in neoadjuvant therapy of rectal cancer: maximizing pathological complete response rates.

Cancer Treat Rev 2009 Nov 17;35(7):547-52. Epub 2009 Jun 17.

Geisinger Cancer Institute, 1000 E. Mountain Blvd., Wilkes Barre, PA 18711, USA.

Neoadjuvant therapy is widely accepted as the current standard of care for localized rectal cancer. Downstaging of disease has been significantly improved and pathological complete response rates (pCR) which were historically below 10% with preoperative radiation alone, now range from 15% to 30% with preoperative chemo-radiation. While the availability of new chemotherapeutic drugs (Irinotecan, Oxaliplatin, etc.) and molecular targeted agents (Bevacizamab, Cetuximab, etc.) hold a great deal of promise, results of recent studies indicate that the pCR rate with neoadjuvant therapy appears to have plateaued at 20-30%. The use of more intensive multidrug combinations has, however, significantly increased the toxicity of treatment. New paradigms in neoadjuvant therapy are therefore needed to further improve results of treatment. This review presents strategies for neoadjuvant therapy, with the potential to improve pCR rates and also survival of patients.
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http://dx.doi.org/10.1016/j.ctrv.2009.05.002DOI Listing
November 2009

Repeat computed tomography simulation to assess lumpectomy cavity volume during whole-breast irradiation.

Int J Radiat Oncol Biol Phys 2009 Nov 14;75(3):751-6. Epub 2009 Mar 14.

Department of Radiation Oncology, University of Maryland School of Medicine, 22 S. Greene Street, Baltimore, MD 21201, USA.

Purpose: To determine whether the lumpectomy cavity (LPC) decreases in volume during whole-breast radiotherapy (RT) and what factors influence the decrease.

Patients And Methods: Forty-three women with 44 breast lesions were prospectively enrolled. Eligible patients underwent lumpectomy followed by a CT simulation (CT1) within 60 days of surgery. Patients were treated to the entire breast to a dose of 45-50.4 Gy. After 21-23 treatments, a second planning CT simulation (CT2) was done. The LPC was contoured on CT2, and the volumes (LCV) were compared between CT1 and CT2.

Results: The median LCV on CT1 and CT2 was 38.2 cm(3) and 21.7 cm(3), respectively. The median percent change and volume decrease between CT1 and CT2 was -32.0% and 11.2 cm(3), respectively (n = 44). The LCV decreased in 38 of 44 patients (86%). There was a significant correlation between initial LCV and decrease in volume (p = 0.001) and initial LCV and percent decrease in volume (p < 0.001). There was no correlation between time from surgery to CT1, to start of RT, or to CT2 and change in volume.

Conclusions: Patients who undergo lumpectomy almost always have a decrease in their LCV during whole-breast RT. There was a correlation between the initial LCV and decrease in volume on repeat CT simulation. Evaluating patients for this change can potentially lead to decreased doses of radiation to the remaining breast and other critical structures when delivering a small-field boost. Repeat CT simulation should be considered in patients with larger cavities or cavities near critical structures.
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http://dx.doi.org/10.1016/j.ijrobp.2008.11.024DOI Listing
November 2009

Effects of tumor motion in GRID therapy.

Med Phys 2008 Oct;35(10):4435-42

Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.

Clinical and biological evidence suggest that the success of GRID therapy in debulking large tumors depends on the high peak-to-valley contrast in the dose distribution. In this study, we show that the peaks and valleys can be significantly blurred out by respiration-induced tumor motion, possibly affecting the clinical outcome. Using a kernel-based Monte Carlo dose engine that incorporates phantom motion, we calculate the dose distributions for a GRID with hexagonally arranged holes. The holes have a diameter of 1.3 cm and a minimum center-to-center separation of 2.1 cm (projected at the isocenter). The phantom moves either in the u parallel direction, which is parallel to a line joining any two nearest neighbors, or in the perpendicular u perpendicular direction. The displacement-time waveform is modeled with a cosn function, with n assigned 1 for symmetric motion, or 6 to simulate a large inhale-exhale asymmetry. Dose calculations are performed on a water phantom for a 6 MV x-ray beam. Near dmax, the static valley dose is 0.12D0, where D0 is the peak static dose. For motion in the u parallel direction, the peak and valley doses vary periodically with the amplitude of motion a and the transverse dose profiles are maximally flat near a=0.8 cm and a=1.9 cm. For the cos waveform, the minimum peak dose (Dpmin) is 0.67D0 and the maximum valley dose (Dvmax) is 0.60D0. Less dose blurring is seen with the cos6 waveform, with Dpmin=0.77D0 and Dvmax=0.45D0. For motion in the u perpendicular direction, the maximum flattening of dose profiles occurs at a=1.5 cm. GRIDs with smaller hole separations produce similar blurring at proportionally smaller amplitudes. The reported clinical response data from GRID therapy seem to indicate that mobile tumors, such as those in the thorax and abdomen, respond worse to GRID treatments than stationary tumors, such as those in the head and neck. To establish a stronger correlation between clinical response and tumor motion, and possibly improve the clinical response rates, it is recommended that prospective GRID therapy trials be conducted with motion compensation strategies, such as respiratory gating.
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http://dx.doi.org/10.1118/1.2977538DOI Listing
October 2008

The role of radiation therapy in non-small cell lung cancer.

Semin Respir Crit Care Med 2005 Jun;26(3):278-88

Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA 02114, USA.

Thoracic irradiation historically plays a strong role in the management of non-small cell lung cancer (NSCLC). Though surgery is the mainstay of early-stage (I and II) disease, adjuvant radiation therapy confers better local control than surgery alone in advanced disease (III). Combining chemotherapy with radiation can help decrease systemic tumor burden and confer an overall survival advantage. Patients with medically inoperable early-stage disease can be treated with radiation alone, and bulky advanced-stage tumors can be treated definitively with platinum-based concurrent chemotherapy and radiation. The success of chemotherapy with radiation together has led to trials of induction treatment for borderline surgical candidates, allowing for downstaging and more complete resection. Local control remains a challenge, and dose escalation as well as more conformal treatment planning studies need to be explored to overcome this problem.
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http://dx.doi.org/10.1055/s-2005-871986DOI Listing
June 2005

Current perceptions regarding surgical margin status after breast-conserving therapy: results of a survey.

Ann Surg 2005 Apr;241(4):629-39

Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Cox 302, 100 Blossom Street, Boston, MA 02114, USA.

Objective: The surgical margin status after breast-conserving surgery is considered the strongest predictor for local failure. The purpose of this study is to survey how radiation oncologists in North America (NA) and Europe define negative or close surgical margins after lumpectomy and to determine the factors that govern the decision to recommend reexcision based on the margins status.

Methods: A questionnaire was sent to active members of the European Society of Therapeutic Radiation Oncology and the American Society for Therapeutic Radiology and Oncology who had completed training in radiation oncology. Respondents were asked whether they would characterize margins to be negative or close for a variety of scenarios. A second survey was sent to 500 randomly selected radiation oncologists in the United States to assess when a reexcision would be recommended based on surgical margins.

Results: A total of 702 responses were obtained from NA and 431 from Europe to the initial survey. An additional 130 responses were obtained from the United States to the second survey regarding reexcision recommendations. Nearly 46% of the North American respondents required only that there be "no tumor cells on the ink" to deem a margin negative (National Surgical Adjuvant Breast and Bowel Project definition). A total of 7.4% and 21.8% required no tumor cells seen at <1 mm and <2 mm, respectively. The corresponding numbers from European respondents were 27.6%, 11.2%, and 8.8%, respectively (P <0.001). Europeans more frequently required a larger distance (>5 mm) between tumor cells and the inked edges before considering a margin to be negative.

Conclusion: This study revealed significant variation in the perception of negative and close margins among radiation oncologists in NA and Europe. Given these findings, a universal definition of negative margins and consistent recommendations for reexcision are needed.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1357067PMC
http://dx.doi.org/10.1097/01.sla.0000157272.04803.1bDOI Listing
April 2005
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