Publications by authors named "Anton Ryzhov"

28 Publications

  • Page 1 of 1

Comparability and validity of cancer registry data in the northwest of Russia.

Acta Oncol 2021 Oct 23;60(10):1264-1271. Epub 2021 Aug 23.

Cancer Surveillance Branch, International Agency for Research on Cancer, Lyon, France.

Background: Despite the elaborate history of statistical reporting in the USSR, Russia established modern population-based cancer registries (PBCR) only in the 1990s. The quality of PBCRs data has not been thoroughly analyzed. This study aims at assessing the comparability and validity of cancer statistics in regions of the Northwestern Federal District (NWFD) of Russia.

Material And Methods: Data from ten Russian regional PBCRs covering ∼13 million (∼5 million in St. Petersburg) were processed in line with IARC/IACR and ENCR recommendations. We extracted and analyzed all registered cases but focused on cases diagnosed between 2008 and 2017. For comparability and validity assessment, we applied established qualitative and quantitative methods.

Results: Data collection in NWFD is in line with international standards. Distributions of diagnosis dates revealed higher variation in several regions, but overall, distributions are relatively uniform. The proportion of multiple primaries between 2008 and 2017 ranged from 6.7% in Vologda Oblast to 12.4% in Saint-Petersburg. We observed substantial regional heterogeneity for most indicators of validity. In 2013-2017, proportions of morphologically verified cases ranged between 61.7 and 89%. Death certificates only (DCO) cases proportion was in the range of 1-14% for all regions, except for Saint-Petersburg (up to 23%). The proportion of cases with a primary site unknown was between 1 and 3%. Certain cancer types (e.g., pancreas, liver, hematological malignancies, and CNS tumors) and cancers in older age groups showed lower validity.

Conclusion: While the overall level of comparability and validity of PBCRs data of four out of ten regions of NWFD of Russia meets the international standards, differences between the regions are substantial. The local instructions for cancer registration need to be updated and implemented. The data validity assessment also reflects pitfalls in the quality of diagnosis of certain cancer types and patient groups.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/0284186X.2021.1967443DOI Listing
October 2021

Colorectal cancer incidence, mortality, and stage distribution in European countries in the colorectal cancer screening era: an international population-based study.

Lancet Oncol 2021 07 25;22(7):1002-1013. Epub 2021 May 25.

Department of Research and Development, Netherlands Comprehensive Cancer Organisation, Utrecht, Netherlands; Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands.

Background: Colorectal cancer screening programmes and uptake vary substantially across Europe. We aimed to compare changes over time in colorectal cancer incidence, mortality, and stage distribution in relation to colorectal cancer screening implementation in European countries.

Methods: Data from nearly 3·1 million patients with colorectal cancer diagnosed from 2000 onwards (up to 2016 for most countries) were obtained from 21 European countries, and were used to analyse changes over time in age-standardised colorectal cancer incidence and stage distribution. The WHO mortality database was used to analyse changes over time in age-standardised colorectal cancer mortality over the same period for the 16 countries with nationwide data. Incidence rates were calculated for all sites of the colon and rectum combined, as well as the subsites proximal colon, distal colon, and rectum. Average annual percentage changes (AAPCs) in incidence and mortality were estimated and relevant patterns were descriptively analysed.

Findings: In countries with long-standing programmes of screening colonoscopy and faecal tests (ie, Austria, the Czech Republic, and Germany), colorectal cancer incidence decreased substantially over time, with AAPCs ranging from -2·5% (95% CI -2·8 to -2·2) to -1·6% (-2·0 to -1·2) in men and from -2·4% (-2·7 to -2·1) to -1·3% (-1·7 to -0·9) in women. In countries where screening programmes were implemented during the study period, age-standardised colorectal cancer incidence either remained stable or increased up to the year screening was implemented. AAPCs for these countries ranged from -0·2% (95% CI -1·4 to 1·0) to 1·5% (1·1 to 1·8) in men and from -0·5% (-1·7 to 0·6) to 1·2% (0·8 to 1·5) in women. Where high screening coverage and uptake were rapidly achieved (ie, Denmark, the Netherlands, and Slovenia), age-standardised incidence rates initially increased but then subsequently decreased. Conversely, colorectal cancer incidence increased in most countries where no large-scale screening programmes were available (eg, Bulgaria, Estonia, Norway, and Ukraine), with AAPCs ranging from 0·3% (95% CI 0·1 to 0·5) to 1·9% (1·2 to 2·6) in men and from 0·6% (0·4 to 0·8) to 1·1% (0·8 to 1·4) in women. The largest decreases in colorectal cancer mortality were seen in countries with long-standing screening programmes.

Interpretation: We observed divergent trends in colorectal cancer incidence, mortality, and stage distribution across European countries, which appear to be largely explained by different levels of colorectal cancer screening implementation.

Funding: German Cancer Aid (Deutsche Krebshilfe) and the German Federal Ministry of Education and Research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/S1470-2045(21)00199-6DOI Listing
July 2021

Cervical cancer in the Newly Independent States of the former Soviet Union: Incidence will remain high without action.

Cancer Epidemiol 2021 08 8;73:101944. Epub 2021 May 8.

Cancer Surveillance Branch, International Agency for Research on Cancer, Lyon, France.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.canep.2021.101944DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8316603PMC
August 2021

Comparison of breast cancer and cervical cancer stage distributions in ten newly independent states of the former Soviet Union: a population-based study.

Lancet Oncol 2021 03 5;22(3):361-369. Epub 2021 Feb 5.

Cancer Surveillance Branch, International Agency for Research on Cancer, Lyon, France. Electronic address:

Background: Screening for breast cancer and cervical cancer in the newly independent states of the former Soviet Union is largely opportunistic, and countries in the region have among the highest cervical cancer incidence in the WHO European Region. We aimed to compare the stage-specific distributions and changes over time in breast cancer and cervical cancer incidence in the newly independent states of the former Soviet Union.

Methods: We collected breast cancer and cervical cancer incidence data from official statistics from Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Republic of Moldova, Russian Federation, Ukraine, and Uzbekistan for the years 2008-17 by tumour, node, metastasis (TNM) stage, and by age where population-based cancer registry data were available. We used log-linear regression to quantify the changes over time in age-standardised rates.

Findings: During the period 2013-17, more than 50% of breast cancer cases across the analysed countries, and more than 75% of breast cancer cases in Belarus, Kazakhstan, and Ukraine, were registered at stages I-II. The proportion of stage I breast cancer cases was highest in the screening age group (50-69 years) compared with other ages in Moldova and the Russian registries, but was highest in those aged 15-49 years in Georgia and Ukraine. Breast cancer stage-specific incidence rates increased over time, most prominently for stage I cancers. For cervical cancer, the proportions of cancers diagnosed at a late stage (stages III and IV) were high, particularly in Moldova and Armenia (>50%). The proportion of stage I cervical cancer cases decreased with age in all countries, whereas the proportions of late stage cancers increased with age. Stage-specific incidence rates of cervical cancer generally increased over the period 2008-17.

Interpretation: Our results suggest modest progress in early detection of breast cancer in the newly independent states of the former Soviet Union. The high proportions of early-stage disease in the absence of mammography screening (eg, in Belarus) provide a benchmark for what is achievable with rapid diagnosis. For cervical cancer, there is a need to tackle the high burden and unfavourable stage-specific changes over time in the region. A radical shift in national policies away from opportunistic screening toward organised, population-based, quality-assured human papillomavirus vaccination and screening programmes is urgently needed.

Funding: Union for International Cancer Control, WHO Regional Office for Europe, and Ministry of Health of Ukraine.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/S1470-2045(20)30674-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8014987PMC
March 2021

Breast cancer incidence in the regions of Belarus and Ukraine most contaminated by the Chernobyl accident: 1978 to 2016.

Int J Cancer 2021 04 29;148(8):1839-1849. Epub 2020 Oct 29.

Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France.

Even 30 years after the accident, an association between breast cancer incidence and ionizing radiation exposure from Chernobyl fallout remains uncertain. We studied breast cancer incidence in the most contaminated regions of Belarus (Gomel and Mogilev) and Ukraine (Kyiv, Zhytomyr and Chernihiv) before (1978-1986) and after (1987-2016) the accident. Breast cancer cases and female population size data were received from the national cancer registries and the state departments of statistics. The study included 85 132 breast cancers with 150 million person-years at risk. We estimated annual rayon (district)-average absorbed doses to the breast from external and internal irradiation of the adult female population over the period of 1986-2016. We studied an association between rayon-average cumulative absorbed breast dose with 5-year lag, that is, excluding the exposure in 5 years prior to breast cancer diagnosis, and breast cancer incidence using negative binomial regression models. Mean (median) cumulative breast dose in 2016 was 12.3 (5.0) milligray (mGy) in Belarus and 5.7 (2.3) mGy in Ukraine, with the maximum dose of 55 mGy and 54 mGy, respectively. Breast cancer incidence rates statistically significantly increased with calendar year and attained age, and were higher in urban than in rural residents. Adjusting for time, age and urbanicity effects, we found no evidence of increasing incidence with rayon-average 5-year lagged cumulative breast dose. Owing to ecological study design limitations, a case-control study covering this area with individually reconstructed absorbed breast doses is needed testing for association between low-dose protracted radiation exposure and breast cancer risk after Chernobyl.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ijc.33346DOI Listing
April 2021

Local recurrences after the treatment of soft tissue malignant fibrous histiocytoma (unclassified pleomorphic sarcoma) of the limbs

Wiad Lek 2019 Aug;72(8):1523-1526

Introduction: The treatment of patients with malignant fibrous histiocytoma as well as other soft tissue sarcomas is not sufficiently effective up to date, and has largely changed and reflects the alterations, occurred in oncology as a whole. The number of amputation decreased over the last 10-15 years. Some researchers associate the improvement of treatment outcomes with the development of combined and complex methods. The aim of the study is an improvement of the results of treatment of patients with soft tissue malignant histiocytoma on the basis of determination of factors, influencing local recurrence development.

Material And Methods: The basis of our study was a comprehensive analysis of examination and treatment results of 130 patients with MFH of the soft tissue of limbs, of them in 84 patients (64.6%) the recurrences developed. The group included 45 (53.6%) males and 39 (46.4%) females. The major part of patients – 82.1% (60 patients) wereolder than 40 years.

Results And Conclusions: Results and conclusions: The number of recurrences after the treatment in general surgical facilities is 86.9%, whereas in the patients after the treatment in the specialized oncological facilities this figure is twice lower (40%). The characteristic of the medical facility where the patient receives his/her primary treatment largely affects the development of local recurrences, patients’ quality of life and overall survival rates. The surgical method remains the leading modality in the treatment of MFH of ST. Wide and radical excision of tumors in the specialized oncological facilities allows achieving better survival outcomes of the patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
August 2019

Birth seasonality of childhood central nervous system tumors: Analysis of primary data from 16 Southern-Eastern European population-based registries.

Int J Cancer 2020 09 15;147(5):1252-1263. Epub 2020 Feb 15.

Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, Athens, Greece.

Season of birth, a surrogate of seasonal variation of environmental exposures, has been associated with increased risk of several cancers. In the context of a Southern-Eastern Europe (SEE) consortium, we explored the potential association of birth seasonality with childhood (0-14 years) central nervous system (CNS) tumors. Primary CNS tumor cases (n = 6,014) were retrieved from 16 population-based SEE registries (1983-2015). Poisson regression and meta-analyses on birth season were performed in nine countries with available live birth data (n = 4,987). Subanalyses by birth month, age, gender and principal histology were also conducted. Children born during winter were at a slightly increased risk of developing a CNS tumor overall [incidence rate ratio (IRR): 1.06, 95% confidence intervals (CI): 0.99-1.14], and of embryonal histology specifically (IRR: 1.13, 95% CI: 1.01-1.27). The winter peak of embryonal tumors was higher among boys (IRR: 1.24, 95% CI: 1.05-1.46), especially during the first 4 years of life (IRR: 1.33, 95% CI: 1.03-1.71). In contrast, boys <5 years born during summer seemed to be at a lower risk of embryonal tumors (IRR: 0.73, 95% CI: 0.54-0.99). A clustering of astrocytomas was also found among girls (0-14 years) born during spring (IRR: 1.23, 95% CI: 1.03-1.46). Although the present exploratory results are by no means definitive, they provide some indications for age-, gender- and histology-related seasonal variations of CNS tumors. Expansion of registration and linkage with cytogenetic reports could refine if birth seasonality is causally associated with CNS tumors and shed light into the complex pathophysiology of this lethal disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ijc.32875DOI Listing
September 2020

Recent cancer incidence trends in Ukraine and short-term predictions to 2022.

Cancer Epidemiol 2020 04 24;65:101663. Epub 2019 Dec 24.

Section of Cancer Surveillance, International Agency for Research on Cancer, Lyon, France.

Background: Using data from the National Cancer Registry of Ukraine (NCRU), we analyzed recent trends in incidence rates (2003-2012) and used these to predict the future cancer incidence burden up to 2022.

Methods: All cancer cases (excluding non-melanoma of skin) for the years 2003-2012 were retrieved from the NCRU's database (n = 1,459,851). Age-standardized incidence rates (ASRs) were estimated and the numbers of new cases and incidence rates predicted for 2022 using age-period modeling.

Results: ASR increased from 2003 to 2012 for most cancers except lip and stomach cancers (in both sexes) and laryngeal and lung cancers (in males). Assuming these trends will continue, lung cancer will remain the most common male cancer in 2022 (ASR 40.5/100,000), followed by prostate cancer (36.8/100,000), colorectal cancer (34.6/100,000), and cancers of the oral cavity and pharynx (18.5/100,000). In females, the order of the four most common cancers will not change in 2022 compared with 2012, with cervical cancer remaining the fourth most common cancer (17.5/100,000). We predict an overall increase of 18 % in the number of cancer cases in Ukraine (relative to 2012) to 179,493 cases in 2022.

Conclusion: The anticipated increase in the number of cancer patients in Ukraine clearly has knock-on effects on a healthcare system undergoing reforms. Tobacco control appears to be the only functioning aspect of cancer prevention in the country, and there is a need for a broader national cancer control plan. The continued monitoring and evaluation of implemented cancer control measures by the NCRU will help prioritize targets and allocate future resources to cancer services.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.canep.2019.101663DOI Listing
April 2020

Prostate cancer incidence and mortality in the Baltic states, Belarus, the Russian Federation and Ukraine.

BMJ Open 2019 10 9;9(10):e031856. Epub 2019 Oct 9.

Laboratory of Cancer Epidemiology, Nacionalinis vėžio institutas, Vilnius, Lithuania.

Background: Prostate cancer incidence varies internationally largely attributable to differences in prostate-specific antigen (PSA) use. The aim of this study was to provide the most recent detailed international epidemiological comparison of prostate cancer incidence and mortality in six north-eastern European countries (Belarus, Estonia, Latvia, Lithuania, the Russian Federation and Ukraine).

Methods: The number of incident prostate cancer cases was obtained from the countries national cancer registries. Prostate cancer mortality and corresponding population data were extracted from the WHO Mortality Database. Age-specific and age-standardised incidence and mortality rates were calculated (European Standard). The joinpoint regression model was used to provide an average annual percentage change and to detect points in time where significant changes in trends occurred. The observation period was between 13 (Ukraine) and 48 (Estonia) years regarding incidence and around 30 years regarding mortality.

Results: The comparison of prostate cancer incidence in six European countries showed almost sixfold differences in the age-adjusted rates in most recent years with highest incidence rates in Lithuania and Estonia. Through the observation period, overall a continuous rise was seen in incidence in all countries and a continuous rise in mortality, with a stabilisation in Estonia and a decrease in Lithuania in recent years. Data limitations included a descriptive design using ecological data.

Conclusions: A widespread use of PSA testing seems to be responsible for the changes in the epidemiology of the disease in north-eastern European countries. Substantial variation in the incidence of prostate cancer in the Baltic states suggests the possibility that PSA performance and utilisation spread have had a major influence on observed incidence trends, with a lack of effect on prostate cancer mortality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/bmjopen-2019-031856DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6797259PMC
October 2019

Photonic-crystal-based broadband graphene saturable absorber.

Opt Lett 2019 Oct;44(19):4785-4788

The enhanced saturable absorption (SA) of a one-dimensional (1D) photonic crystal (PC) made from polymers and graphene composites by spin coating is observed. It shows obvious bandgaps at two wavelengths in transmittance. Femtosecond Z-scan measurement at 515 nm and 1030 nm reveals a distinct enhancement in the effective nonlinear absorption coefficient β for graphene nanoflakes embedded in the PC, when compared with the bulk graphene-polymer composite. The effect is studied in a wide range of laser intensities. Graphene inclusion into a 1D PC remarkably decreases the SA threshold and saturation intensity, providing a desired solution for an advanced all-optical laser mode-locking device.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.44.004785DOI Listing
October 2019

Survival and mortality rates of Wilms tumour in Southern and Eastern European countries: Socioeconomic differentials compared with the United States of America.

Eur J Cancer 2018 09 17;101:38-46. Epub 2018 Jul 17.

Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Greece; Clinical Epidemiology Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden. Electronic address:

Background: Despite recent therapeutic advancements, Wilms tumour (WT) presents remarkable survival variations. We explored mortality and survival patterns for children (0-14 years) with WT in 12 Southern and Eastern European (SEE) countries in comparison with the United States of America (USA).

Methods: A total of 3966 WT cases (0-14 years) were registered by a network of SEE childhood cancer registries (N:1723) during available registration periods circa 1990-2016 and surveillance, epidemiology, and end results program (SEER) (N:2243; 1990-2012); mortality data were provided by the respective national statistical services. Kaplan-Meier curves and Cox proportional hazards models were used to assess the role of age, sex, year of diagnosis, urbanisation and Human Development Index (HDI) on overall survival (OS).

Results: Persisting regional variations shape an overall 78% 5-year OS in the participating SEE countries, lagging behind the USA figure (92%, p=0.001) and also reflected by higher SEE mortality rates. Worth mentioning is the gradually escalating OS in SEE (hazard ratio [HR]:0.67, 95% confidence interval [CI]:0.60, 0.75) vs. a non-significant 10% improvement in the SEER data, which had a high starting value. OS differentials [two-fold less favourable among children aged 10-14 years, boys and those living in rural SEE areas (HR:1.37; CI:1.10-1.71) or countries with inferior HDI (2-3-fold)] were minimal in the USA.

Conclusions: Children with WT residing in SEE countries do not equally enjoy the substantial survival gains, especially for those living in rural areas and in lower HDI countries. Noteworthy are steep and sizeable survival gains in SEE along with the newly presented Greek data pointing to achievable survival goals in SEE despite the financial crisis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejca.2018.06.012DOI Listing
September 2018

Persisting inequalities in survival patterns of childhood neuroblastoma in Southern and Eastern Europe and the effect of socio-economic development compared with those of the US.

Eur J Cancer 2018 06 16;96:44-53. Epub 2018 Apr 16.

Department of Hygiene, Epidemiology and Medical Statistics Medical School, National and Kapodistrian University of Athens, Athens Greece; Clinical Epidemiology Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden. Electronic address:

Aim: Neuroblastoma outcomes vary with disease characteristics, healthcare delivery and socio-economic indicators. We assessed survival patterns and prognostic factors for patients with neuroblastoma in 11 Southern and Eastern European (SEE) countries versus those in the US, including-for the first time-the Nationwide Registry for Childhood Hematological Malignancies and Solid Tumours (NARECHEM-ST)/Greece.

Methods: Overall survival (OS) was calculated in 13 collaborating SEE childhood cancer registries (1829 cases, ∼1990-2016) and Surveillance, Epidemiology, and End Results (SEER), US (3072 cases, 1990-2012); Kaplan-Meier curves were used along with multivariable Cox regression models assessing the effect of age, gender, primary tumour site, histology, Human Development Index (HDI) and place of residence (urban/rural) on survival.

Results: The 5-year OS rates varied widely among the SEE countries (Ukraine: 45%, Poland: 81%) with the overall SEE rate (59%) being significantly lower than in SEER (77%; p < 0.001). In the common registration period within SEE (2000-2008), no temporal trend was noted as opposed to a significant increase in SEER. Age >12 months (hazard ratio [HR]: 2.8-4.7 in subsequent age groups), male gender (HR: 1.1), residence in rural areas (HR: 1.3), living in high (HR: 2.2) or medium (HR: 2.4) HDI countries and specific primary tumour location were associated with worse outcome; conversely, ganglioneuroblastoma subtype (HR: 0.28) was associated with higher survival rate.

Conclusions: Allowing for the disease profile, children with neuroblastoma in SEE, especially those in rural areas and lower HDI countries, fare worse than patients in the US, mainly during the early years after diagnosis; this may be attributed to presumably modifiable socio-economic and healthcare system performance differentials warranting further research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejca.2018.03.003DOI Listing
June 2018

Childhood nephroblastoma in Southern and Eastern Europe and the US: Incidence variations and temporal trends by human development index.

Cancer Epidemiol 2018 06 11;54:75-81. Epub 2018 Apr 11.

Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Greece; Clinical Epidemiology Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden. Electronic address:

Background: Despite advances in the management of nephroblastoma (Wilms' tumor, WT), the etiology of the tumor remains obscure. We aimed to compare nephroblastoma incidence rates and time trends among children (0-14 years) in 12 Southern and Eastern European (SEE) countries and the Surveillance, Epidemiology, and End Results Program (SEER), USA, in relation to the human development index (HDI).

Methods: In total 1776 WT cases were recorded in 13 SEE collaborating registries (circa 1990-2016), whereas data on 2260 cases (1990-2012) were extracted from the SEER database. Age-standardized incidence rates (AIRs) were calculated and correlated with HDI, whereas temporal trends were evaluated using Poisson regression and Joinpoint analyses.

Results: The overall SEE AIR (9.2/10) was marginally higher than that of the SEER (8.3/10), whereas significant differences were noted among the 13 SEE registries which comprised mainly Caucasian populations. A statistically significant temporal increase in incidence was noted only in Belarus. Most cases (∼75%) were diagnosed before the fifth year of life, with rates steadily declining thereafter; median age at diagnosis was similar in SEE countries and SEER. A slight male preponderance in the first year of life (male:female = 1.1) was followed by a female preponderance in the older age groups (male:female = 0.7). Lastly, a statistically significant positive association between higher HDI and increasing nephroblastoma incidence was noted (regression coefficient: +3.25, 95%CI: +1.35, +5.15).

Conclusions: Variations in incidence and time trends across the examined registries, changing male-to-female patterns with advancement in age, and positive associations with the HDI imply a plausible role for environmental and genetic factors in disease etiology, and these need to be explored further.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.canep.2018.03.012DOI Listing
June 2018

Evaluation of data quality at the National Cancer Registry of Ukraine.

Cancer Epidemiol 2018 04 22;53:156-165. Epub 2018 Feb 22.

Cancer Surveillance Section, International Agency for Research on Cancer, Lyon, France. Electronic address:

Background: Cancer notification has been mandatory in Ukraine since 1953, with the National Cancer Registry of Ukraine (NCRU) established in 1996. The aim of this study was to provide a comprehensive evaluation of the data quality at the NCRU.

Methods: Qualitative and semi-quantitative methods were used to assess the comparability, completeness, validity and timeliness of cancer incidence data from the NCRU for the period 2002-2012.

Results: Cancer registration procedures at the NCRU are in accordance with international standards and recommendations. Semi-quantitative methods suggested the NCRU's data was reasonably complete, although decreases in age-specific incidence and mortality rates in the elderly indicated some missing cases at older ages. The proportion of microscopically-verified cases increased from 73.6% in 2002 to 82.3% in 2012, with death-certificate-only (DCO) proportions stable at around 0.1% and unknown stage recorded in 9.6% of male and 7.5% of female solid tumours. Timeliness was considered acceptable, with reporting >99% complete within a turn-around time of 15 months.

Conclusion: While timely reporting of national data reflects the advantages of a mandatory data collection system, a low DCO% and observed age-specific declines suggest possible underreporting of incidence and mortality data, particularly at older ages. Overall, the evaluation indicates that the data are reasonably comparable and thus may be used to describe the magnitude of the cancer burden in Ukraine. Given its central role in monitoring and evaluation of cancer control activities, ensuring the sustainability of NCRU operations throughout the process of healthcare system reform is of utmost importance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.canep.2018.02.002DOI Listing
April 2018

Cancer surveillance in northern Africa, and central and western Asia: challenges and strategies in support of developing cancer registries.

Lancet Oncol 2018 02;19(2):e85-e92

Section of Cancer Surveillance, International Agency for Research on Cancer, Lyon, France.

The Global Initiative for Cancer Registry Development partnership, led by the International Agency for Research on Cancer (IARC), was established in response to an overwhelming need for high-quality cancer incidence data from low-income and middle-income countries. The IARC Regional Hub for cancer registration in North Africa, Central and West Asia was founded in 2013 to support capacity building for cancer registration in each of the countries in this region. In this Series paper, we advocate the necessity for tailored approaches to cancer registration given the rapidly changing cancer landscape for this region, and the challenges faced at a national level in developing data systems to help support this process given present disparities in resources and health infrastructure. In addition, we provide an overview of the status of cancer surveillance and activities country-by-country, documenting tailored approaches that are informing local cancer-control policy, and potentially curbing the growing cancer burden across the region.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/S1470-2045(18)30019-6DOI Listing
February 2018

Neuroblastoma among children in Southern and Eastern European cancer registries: Variations in incidence and temporal trends compared to US.

Int J Cancer 2018 05 29;142(10):1977-1985. Epub 2017 Dec 29.

Department of Hygiene, Epidemiology and Medical Statistics Medical School, National and Kapodistrian University of Athens, Athens, Greece.

Neuroblastoma comprises the most common neoplasm during infancy (first year of life). Our study describes incidence of neuroblastoma in Southern-Eastern Europe (SEE), including - for the first time - the Nationwide Registry for Childhood Hematological Malignancies and Solid Tumors (NARECHEM-ST)/Greece, compared to the US population, while controlling for human development index (HDI). Age-adjusted incidence rates (AIR) were calculated for 1,859 childhood (0-14 years) neuroblastoma cases, retrieved from 13 collaborating SEE registries (1990-2016), and were compared to those of SEER/US (N = 3,166; 1990-2012); temporal trends were assessed using Poisson regression and Joinpoint analyses. The overall AIR was significantly lower in SEE (10.1/million) compared to SEER (11.7 per million); the difference was maximum during infancy (43.7 vs. 53.3 per million, respectively), when approximately one-third of cases were diagnosed. Incidence rates of neuroblastoma at ages <1 and 1-4 years were positively associated with HDI, whereas lower median age at diagnosis was correlated with higher overall AIR. Distribution of primary site and histology was similar in SEE and SEER. Neuroblastoma was slightly more common among males compared to females (male-to-female ratio: 1.1), mainly among SEE infants. Incidence trends decreased in infants in Slovenia, Cyprus and SEER and increased in Ukraine and Belarus. The lower incidence in SEE compared to SEER, especially in infants living in low HDI countries possibly indicates a lower level of overdiagnosis in SEE. Hence, increases in incidence rates in infancy noted in some subpopulations should be carefully monitored to avoid the unnecessary costs health impacts of tumors that could potentially spontaneously regress.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ijc.31222DOI Listing
May 2018

Central nervous system tumours among adolescents and young adults (15-39 years) in Southern and Eastern Europe: Registration improvements reveal higher incidence rates compared to the US.

Eur J Cancer 2017 11;86:46-58

Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Greece; Clinical Epidemiology Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden. Electronic address:

Aim: To present incidence of central nervous system (CNS) tumours among adolescents and young adults (AYAs; 15-39 years) derived from registries of Southern and Eastern Europe (SEE) in comparison to the Surveillance, Epidemiology and End Results (SEER), US and explore changes due to etiological parameters or registration improvement via evaluating time trends.

Methods: Diagnoses of 11,438 incident malignant CNS tumours in AYAs (1990-2014) were retrieved from 14 collaborating SEE cancer registries and 13,573 from the publicly available SEER database (1990-2012). Age-adjusted incidence rates (AIRs) were calculated; Poisson and joinpoint regression analyses were performed for temporal trends.

Results: The overall AIR of malignant CNS tumours among AYAs was higher in SEE (28.1/million) compared to SEER (24.7/million). Astrocytomas comprised almost half of the cases in both regions, albeit the higher proportion of unspecified cases in SEE registries (30% versus 2.5% in SEER). Similar were the age and gender distributions across SEE and SEER with a male-to-female ratio of 1.3 and an overall increase of incidence by age. Increasing temporal trends in incidence were documented in four SEE registries (Greater Poland, Portugal North, Turkey-Izmir and Ukraine) versus an annual decrease in Croatia (-2.5%) and a rather stable rate in SEER (-0.3%).

Conclusion: This first report on descriptive epidemiology of AYAs malignant CNS tumours in the SEE area shows higher incidence rates as compared to the United States of America and variable temporal trends that may be linked to registration improvements. Hence, it emphasises the need for optimisation of cancer registration processes, as to enable the in-depth evaluation of the observed patterns by disease subtype.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejca.2017.08.030DOI Listing
November 2017

Breast cancer in South-Eastern European countries since 2000: Rising incidence and decreasing mortality at young and middle ages.

Eur J Cancer 2017 09 14;83:43-55. Epub 2017 Jul 14.

Oegstgeest, Rotterdam, The Netherlands.

Background: Marked variations exist in the incidence and mortality trends of major cancers in South-Eastern European (SEE) countries which have now been detailed by age for breast cancer (BC) to seek clues for improvement.

Methods: We brought together and analysed data from 14 cancer registries (CRs), situated in SEE countries or directly adjacent. Age-standardised rate at world standard (ASRw) and truncated incidence and mortality rates during 2000-2010 by year, and for four age groups, were calculated. Average annual percentage change of rates was estimated using Joinpoint regression.

Results: Annual incidence rates increased significantly in countries and age groups, by 2-4% (15-39 years), 2-5% (40-49), 1-4% (50-69) and 1-6% (at 70+). Mortality rates decreased significantly in all age-groups in most countries, but increased up to 5% annually above age 55 in Ukraine, Serbia, Moldova and Cyprus. The BC data quality was evaluated by internationally agreed indicators which appeared suboptimal for Moldova, Bosnia and Herzegovina and Romania.

Conclusion: The observed variations of incidence trends reflect the influence of risk factors, as well as levels of early detection activities (screening). While mortality rates were mostly decreasing, probably due to improved cancer care and introduction of more effective systemic treatment regimens, the worrying increasing mortality trends in the 55-plus age groups in some countries have to be addressed by health professionals and policymakers. In order to assess and monitor the effects of cancer control activities in the region, the CRs need substantial investments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejca.2017.06.011DOI Listing
September 2017

Malignant central nervous system tumors among adolescents and young adults (15-39 years old) in 14 Southern-Eastern European registries and the US Surveillance, Epidemiology, and End Results program: Mortality and survival patterns.

Cancer 2017 Nov 14;123(22):4458-4471. Epub 2017 Jul 14.

Department of Hygiene, Epidemiology, and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.

Background: Unique features and worse outcomes have been reported for cancers among adolescents and young adults (AYAs; 15-39 years old). The aim of this study was to explore the mortality and survival patterns of malignant central nervous system (CNS) tumors among AYAs in Southern-Eastern Europe (SEE) in comparison with the US Surveillance, Epidemiology, and End Results (SEER) program.

Methods: Malignant CNS tumors diagnosed in AYAs during the period spanning 1990-2014 were retrieved from 14 population-based cancer registries in the SEE region (n = 11,438). Age-adjusted mortality rates were calculated and survival patterns were evaluated via Kaplan-Meier curves and Cox regression analyses, and they were compared with respective 1990-2012 figures from SEER (n = 13,573).

Results: Mortality rates in SEE (range, 11.9-18.5 deaths per million) were higher overall than the SEER rate (9.4 deaths per million), with decreasing trends in both regions. Survival rates increased during a comparable period (2001-2009) in SEE and SEER. The 5-year survival rate was considerably lower in the SEE registries (46%) versus SEER (67%), mainly because of the extremely low rates in Ukraine; this finding was consistent across age groups and diagnostic subtypes. The highest 5-year survival rates were recorded for ependymomas (76% in SEE and 92% in SEER), and the worst were recorded for glioblastomas and anaplastic astrocytomas (28% in SEE and 37% in SEER). Advancing age, male sex, and rural residency at diagnosis adversely affected outcomes in both regions.

Conclusions: Despite definite survival gains over the last years, the considerable outcome disparities between the less affluent SEE region and the United States for AYAs with malignant CNS tumors point to health care delivery inequalities. No considerable prognostic deficits for CNS tumors are evident for AYAs versus children. Cancer 2017;123:4458-71. © 2017 American Cancer Society.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cncr.30884DOI Listing
November 2017

Incidence and time trends of childhood lymphomas: findings from 14 Southern and Eastern European cancer registries and the Surveillance, Epidemiology and End Results, USA.

Cancer Causes Control 2016 11 18;27(11):1381-1394. Epub 2016 Oct 18.

Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, 75 Mikras Asias Str, 11527, Athens, Greece.

Purpose: To describe epidemiologic patterns of childhood (0-14 years) lymphomas in the Southern and Eastern European (SEE) region in comparison with the Surveillance, Epidemiology and End Results (SEER), USA, and explore tentative discrepancies.

Methods: Childhood lymphomas were retrieved from 14 SEE registries (n = 4,702) and SEER (n = 4,416), diagnosed during 1990-2014; incidence rates were estimated and time trends were evaluated.

Results: Overall age-adjusted incidence rate was higher in SEE (16.9/10) compared to SEER (13.6/10), because of a higher incidence of Hodgkin (HL, 7.5/10 vs. 5.1/10) and Burkitt lymphoma (BL, 3.1 vs. 2.3/10), whereas the incidence of non-Hodgkin lymphoma (NHL) was overall identical (5.9/10 vs. 5.8/10), albeit variable among SEE. Incidence increased with age, except for BL which peaked at 4 years; HL in SEE also showed an early male-specific peak at 4 years. The male preponderance was more pronounced for BL and attenuated with increasing age for HL. Increasing trends were noted in SEER for total lymphomas and NHL, and was marginal for HL, as contrasted to the decreasing HL and NHL trends generally observed in SEE registries, with the exception of increasing HL incidence in Portugal; of note, BL incidence trend followed a male-specific increasing trend in SEE.

Conclusions: Registry-based data reveal variable patterns and time trends of childhood lymphomas in SEE and SEER during the last decades, possibly reflecting diverse levels of socioeconomic development of the populations in the respective areas; optimization of registration process may allow further exploration of molecular characteristics of disease subtypes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10552-016-0817-3DOI Listing
November 2016

Incidence, time trends and survival patterns of childhood pilocytic astrocytomas in Southern-Eastern Europe and SEER, US.

J Neurooncol 2017 01 14;131(1):163-175. Epub 2016 Oct 14.

Department of Pathology, Medical School, National and Kapodistrian University of Athens, 75 Mikras Asias, 11527, Athens, Greece.

Pilocytic astrocytomas (PA) comprise the most common childhood central nervous system (CNS) tumor. Exploiting registry-based data from Southern and Eastern Europe (SEE) and SEER, US, we opted to examine incidence, time trends, survival and tentative outcome disparities of childhood PA by sociodemographic and clinical features. Childhood PA were retrieved from 12 SEE registries (N = 552; 1983-2014) and SEER (N = 2723; 1973-2012). Age-standardized incidence rates (ASR) were estimated and survival was examined via Kaplan-Meier and Cox regression analysis. ASR of childhood PA during 1990-2012 in SEE was 4.2/10, doubling in the USA (8.2/10). Increasing trends, more prominent during earlier registration years, were recorded in both areas (SEE: +4.1 %, USA: +4.6 %, annually). Cerebellum comprised the most common location, apart from infants in whom supratentorial locations prevailed. Age at diagnosis was 1 year earlier in SEE, whereas 10-year survival was 87 % in SEE and 96 % in SEER, improving over time. Significant outcome predictors were age <1 year at diagnosis diagnosis (hazard ratio, HR [95% confidence intervals]: 3.96, [2.28-6.90]), female gender (HR: 1.38, [1.01-1.88]), residence in SEE (HR: 4.07, [2.95-5.61]) and rural areas (HR: 2.23, [1.53-3.27]), whereas non-cerebellar locations were associated with a 9- to 12-fold increase in risk of death. The first comprehensive overview of childhood PA epidemiology showed survival gains but also outcome discrepancies by geographical region and urbanization pointing to healthcare inequalities. The worse prognosis of infants and, possibly, females merits further consideration, as it might point to treatment adjustment needs, whereas expansion of systematic registration will allow interpretation of incidence variations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11060-016-2284-9DOI Listing
January 2017

Survival trends in childhood chronic myeloid leukaemia in Southern-Eastern Europe and the United States of America.

Eur J Cancer 2016 11 24;67:183-190. Epub 2016 Sep 24.

Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, University of Athens, 75 Mikras Asias Str, Athens, 11527, Greece. Electronic address:

Aim: To assess trends in survival and geographic disparities among children (0-14 years) with chronic myeloid leukaemia (CML) before and after the introduction of molecular therapy, namely tyrosine kinase inhibitors (TKIs) in Southern-Eastern European (SEE) countries and the USA.

Methods: We calculated survival among children with CML, acute lymphoblastic (ALL) and acute myeloid leukaemia (AML) in 14 SEE (1990-2014) cancer registries and the U.S. Surveillance, Epidemiology and End Results Program (SEER, 1990-2012). We used Kaplan-Meier curves and multivariate Cox regression models to calculate hazard ratios (HRs) with 95% confidence intervals (CIs).

Results: Among 369 CML cases, substantial improvements were noted in 2-year survival during the post-TKI (range: 81-89%) compared to pre-TKI period (49-66%; HR: 0.37, 95% CI: 0.23-0.60). Risk of death was three times higher for <5-year-old children versus those aged 10-14 years (HR: 3.03, 95% CI: 1.85-4.94) and 56% higher for those living in SEE versus SEER (HR: 1.56, 95% CI: 1.01-2.42). Regardless of geographic area and period of TKI administration, however, age seems to be a significant determinant of CML prognosis (pre-TKI period, HR: 2.71, 95% CI: 1.53-4.79; post-TKI period, HR: 3.38, 95% CI: 1.29-8.85). Noticeably, post-TKI survival in CML overall approximates that for ALL, whereas therapeutic advancements for AML remain modest.

Conclusion: Registry data show that introduction of molecular therapies coincides with revolutionised therapeutic outcomes in childhood CML entailing dramatically improved survival which is now similar to that in ALL. Given that age disparities in survival remain substantial, offering optimal therapy to entire populations is an urgent priority.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejca.2016.08.011DOI Listing
November 2016

Mortality and survival patterns of childhood lymphomas: geographic and age-specific patterns in Southern-Eastern European and SEER/US registration data.

Hematol Oncol 2017 Dec 19;35(4):608-618. Epub 2016 Sep 19.

Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, University of Athens, Athens, Greece.

Childhood (0-14 years) lymphomas, nowadays, present a highly curable malignancy compared with other types of cancer. We used readily available cancer registration data to assess mortality and survival disparities among children residing in Southern-Eastern European (SEE) countries and those in the United States. Average age-standardized mortality rates and time trends of Hodgkin (HL) and non-Hodgkin (NHL; including Burkitt [BL]) lymphomas in 14 SEE cancer registries (1990-2014) and the Surveillance, Epidemiology, and End Results Program (SEER, United States; 1990-2012) were calculated. Survival patterns in a total of 8918 cases distinguishing also BL were assessed through Kaplan-Meier curves and multivariate Cox regression models. Variable, rather decreasing, mortality trends were noted among SEE. Rates were overall higher than that in SEER (1.02/10 ), which presented a sizeable (-4.8%, P = .0001) annual change. Additionally, remarkable survival improvements were manifested in SEER (10 years: 96%, 86%, and 90% for HL, NHL, and BL, respectively), whereas diverse, still lower, rates were noted in SEE. Non-HL was associated with a poorer outcome and an amphi-directional age-specific pattern; specifically, prognosis was inferior in children younger than 5 years than in those who are 10 to 14 years old from SEE (hazard ratio 1.58, 95% confidence interval 1.28-1.96) and superior in children who are 5 to 9 years old from SEER/United States (hazard ratio 0.63, 95% confidence interval 0.46-0.88) than in those who are 10 to 14 years old. In conclusion, higher SEE lymphoma mortality rates than those in SEER, but overall decreasing trends, were found. Despite significant survival gains among developed countries, there are still substantial geographic, disease subtype-specific, and age-specific outcome disparities pointing to persisting gaps in the implementation of new treatment modalities and indicating further research needs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/hon.2347DOI Listing
December 2017

Childhood central nervous system tumour mortality and survival in Southern and Eastern Europe (1983-2014): Gaps persist across 14 cancer registries.

Eur J Cancer 2015 Nov 3;51(17):2665-77. Epub 2015 Sep 3.

2nd Department of Radiology, Radiotherapy Unit, Medical School, National Kapodistrian University of Athens, Athens, Greece.

Aim: Childhood central nervous system (CNS) tumour registration and control programs in Southern and Eastern Europe remain thin, despite the lethal nature of the disease. Mortality/survival data were assembled to estimate the burden of malignant CNS tumours, as well as the potential role of sociodemographic survival determinants across 14 cancer registries of this region.

Methods: Average age-adjusted mortality rates were calculated, whereas time trends were quantified through Poisson and Joinpoint regressions. Kaplan-Meier curves were derived for the maximum and the more recent (10 and 5 year) registration periods. Multivariate Cox regression models were used to assess demographic and disease-related determinants.

Results: Variations in mortality (8-16 per million) and survival (5-year: 35-69%) were substantial among the participating registries; in most registries mortality trend was stable, whereas Bulgaria, having the highest starting rate, experienced decreasing annual mortality (-2.4%, p=0.001). A steep decrease in survival rates was evident before the second year of follow-up. After controlling for diagnostic subgroup, age, gender and diagnostic year, Greece seemed to present higher survival compared with the other contributing registries, although the follow-up period was short. Irrespective of country, however, rural residence was found to impose substantial adverse repercussions on survival (hazard ratio (HR): 1.2, 95% confidence interval (CI): 1.1-1.4).

Conclusion: Cross-country mortality and survival variations possibly reflect suboptimal levels of health care delivery and cancer control in some regions of Southern and Eastern Europe, notwithstanding questionable death certification patterns or follow-up procedures. Continuous childhood cancer registration and linkage with clinical data are prerequisite for the reduction of survival inequalities across Europe.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejca.2015.08.018DOI Listing
November 2015

Childhood central nervous system tumours: Incidence and time trends in 13 Southern and Eastern European cancer registries.

Eur J Cancer 2015 Jul 9;51(11):1444-55. Epub 2015 May 9.

Department of Neurosurgery, St. Luke's Hospital, Panorama, Thessaloniki, Greece.

Aim: Following completion of the first 5-year nationwide childhood (0-14 years) registration in Greece, central nervous system (CNS) tumour incidence rates are compared with those of 12 registries operating in 10 Southern-Eastern European countries.

Methods: All CNS tumours, as defined by the International Classification of Childhood Cancer (ICCC-3) and registered in any period between 1983 and 2014 were collected from the collaborating cancer registries. Data were evaluated using standard International Agency for Research on Cancer (IARC) criteria. Crude and age-adjusted incidence rates (AIR) by age/gender/diagnostic subgroup were calculated, whereas time trends were assessed through Poisson and Joinpoint regression models.

Results: 6062 CNS tumours were retrieved with non-malignant CNS tumours recorded in eight registries; therefore, the analyses were performed on 5191 malignant tumours. Proportion of death certificate only cases was low and morphologic verification overall high; yet five registries presented >10% unspecified neoplasms. The male/female ratio was 1.3 and incidence decreased gradually with age, apart from Turkey and Ukraine. Overall AIR for malignant tumours was 23/10(6) children, with the highest rates noted in Croatia and Serbia. A statistically significant AIR increase was noted in Bulgaria, whereas significant decreases were noted in Belarus, Croatia, Cyprus and Serbia. Although astrocytomas were overall the most common subgroup (30%) followed by embryonal tumours (26%), the latter was the predominant subgroup in six registries.

Conclusion: Childhood cancer registration is expanding in Southern-Eastern Europe. The heterogeneity in registration practices and incidence patterns of CNS tumours necessitates further investigation aiming to provide clues in aetiology and direct investments into surveillance and early tumour detection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejca.2015.04.014DOI Listing
July 2015

Optical limiting properties of a nonlinear multilayer Fabry-Perot resonator containing niobium pentoxide as nonlinear medium.

Opt Lett 2014 Aug;39(16):4847-50

The optical limiting effect was numerically simulated and experimentally observed for a 25-layer thin-film Fabry-Perot microresonator by 7 ns laser pulses at 532 nm. The sample, made by vacuum evaporation and consisting of alternating Nb2O5 and SiO2 layers, has an ultranarrow line of transparency at near 532 nm within a wide spectral band of reflection. By adjusting simulated results in accordance with experimental dependencies of transmittance, reflectance, and absorbance on incident light intensity, the coefficient of optical nonlinearity of Nb2O5 was estimated at (6+1i)·10(-12)  cm2/W.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.39.004847DOI Listing
August 2014

Combinatorics of reaction-network posets.

Comb Chem High Throughput Screen 2008 Nov;11(9):723-33

Texas A&M University at Galveston, Galveston, Texas 77553-1675, USA.

Reaction networks are viewed as derived from ordinary molecular structures related in reactant-product pairs so as to manifest a chemical super-structure. Such super-structures then are candidates for applications in a general combinatoric chemistry. Notable additional characterization of a reaction super-structure occurs when such reaction graphs are directed, as for example when there is progressive substitution (or addition) on a fixed molecular skeleton. Such a set of partially ordered entities is in mathematics termed a poset, which further manifests a number of special properties, as then might be utilized in different applications. Focus on the overall "super-structural" poset goes beyond ordinary molecular structure in attending to how a structure fits into a (reaction) network, and thereby brings an extra "dimension" to conventional stereochemical theory. The possibility that different molecular properties vary smoothly along chains of interconnections in such a super-structure is a natural assumption for a novel approach to molecular property and bioactivity correlations. Different manners to interpolate/extrapolate on a poset network yield quantitative super-structure/activity relationships (QSSARs), with some numerical fits, e.g., for properties of polychlorinated biphenyls (PCBs) seemingly being quite reasonable. There seems to be promise for combinatoric posetic ideas.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/138620708786306050DOI Listing
November 2008

Breast cancer in Belarus and Ukraine after the Chernobyl accident.

Int J Cancer 2006 Aug;119(3):651-8

Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.

An increase in breast cancer incidence has been reported in areas of Belarus and Ukraine contaminated by the Chernobyl accident and has become an issue of public concern. The authors carried out an ecological epidemiological study to describe the spatial and temporal trends in breast cancer incidence in the most contaminated regions of Belarus and Ukraine, and to evaluate whether increases seen since 1986 correlate to radiation exposure from the Chernobyl accident. The authors investigated the trends through age-cohort-period-region analyses of district-specific incidence rates of breast cancer for Gomel and Mogilev regions of Belarus and Chernigiv, Kyiv and Zhytomir regions of Ukraine. Dose-response analyses were based on Poisson regression, using average district-specific whole body doses accumulated since the accident from external exposure and ingestion of long-lived radionuclides. The study demonstrated increases in breast cancer incidence in all areas following the Chernobyl accident, reflecting improvements in cancer diagnosis and registration. In addition, a significant 2-fold increase in risk was observed, during the period 1997-2001, in the most contaminated districts (average cumulative dose of 40.0 mSv or more) compared with the least contaminated districts (relative risk [RR] in Belarus 2.24, 95% confidence interval [CI] 1.51-3.32 and in Ukraine 1.78, 95% CI=1.08-2.93). The increase, though based on a relatively small number of cases, appeared approximately 10 years after the accident, was highest among women who were younger at the time of exposure and was observed for both localised and metastatic diseases. It is unlikely that this excess could be entirely due to the increased diagnostic activity in these areas.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ijc.21885DOI Listing
August 2006
-->