[Show abstract][Hide abstract] ABSTRACT: Mammographic density (MD) is a quantitative trait, measurable in all women, and is among the strongest markers of breast cancer risk. The population-based epidemiology of MD has revealed genetic, lifestyle and societal/environmental determinants, but studies have largely been conducted in women with similar westernized lifestyles living in countries with high breast cancer incidence rates. To benefit from the heterogeneity in risk factors and their combinations worldwide, we created an International Consortium on Mammographic Density (ICMD) to pool individual-level epidemiological and MD data from general population studies worldwide. ICMD aims to characterize determinants of MD more precisely, and to evaluate whether they are consistent across populations worldwide. We included 11755 women, from 27 studies in 22 countries, on whom individual-level risk factor data were pooled and original mammographic images were re-read for ICMD to obtain standardized comparable MD data. In the present article, we present (i) the rationale for this consortium; (ii) characteristics of the studies and women included; and (iii) study methodology to obtain comparable MD data from original re-read films. We also highlight the risk factor heterogeneity captured by such an effort and, thus, the unique insight the pooled study promises to offer through wider exposure ranges, different confounding structures and enhanced power for sub-group analyses.
[Show abstract][Hide abstract] ABSTRACT: Little is known about the aetiology of childhood brain tumours. We investigated anthropometric factors (birth weight, length, maternal age), birth characteristics (e.g. vacuum extraction, preterm delivery, birth order) and exposures during pregnancy (e.g. maternal: smoking, working, dietary supplement intake) in relation to risk of brain tumour diagnosis among 7-19 year olds. The multinational case-control study in Denmark, Sweden, Norway and Switzerland (CEFALO) included interviews with 352 (participation rate=83.2%) eligible cases and 646 (71.1%) population-based controls. Interview data were complemented with data from birth registries and validated by assessing agreement (Cohen's Kappa). We used conditional logistic regression models matched on age, sex and geographical region (adjusted for maternal age and parental education) to explore associations between birth factors and childhood brain tumour risk. Agreement between interview and birth registry data ranged from moderate (Kappa=0.54; worked during pregnancy) to almost perfect (Kappa=0.98; birth weight). Neither anthropogenic factors nor birth characteristics were associated with childhood brain tumour risk. Maternal vitamin intake during pregnancy was indicative of a protective effect (OR 0.75, 95%-CI: 0.56-1.01). No association was seen for maternal smoking during pregnancy or working during pregnancy. We found little evidence that the considered birth factors were related to brain tumour risk among children and adolescents.
[Show abstract][Hide abstract] ABSTRACT: Little is known about the incidence patterns of hematologic malignancies in Sub-Saharan Africa, including South Africa. We estimated incidence rates of pathology-confirmed adult cases of leukemia, myeloma and related diseases (myeloma), Hodgkin lymphoma (HL), and non-Hodgkin lymphoma (NHL) reported to the National Cancer Registry of South Africa (NCR) between 2000 and2006, by age, gender, and population group (Black, White, Coloured, Asian/Indian). Gender-specific age-standardized rates were calculated overall and by population group and incidence rate ratios (IRRs) were estimated using Poisson regression models. Between 2000 and 2006, there were 14662 cases of leukemia, myeloma, HL, and NHL reported to the registry. Incidence rates of reported hematologic malignancies were generally 20-50% higher among males than females. Our analyses suggested marked differences in the rates of reported hematologic malignancies by population group which were most pronounced when comparing the White versus Black population groups (IRRs ranging from 1.6 for myeloma to 3.8 for HL for males and females combined). Challenges related to diagnosis and reporting of cancers may play a role in the patterns observed by population group while the set-up of the NCR (pathology-based) could lead to some degree of under-ascertainment in all groups. This is the first country-wide report of the incidence of hematologic malignancies in South Africa. Despite challenges, it is important to analyze and report available national cancer incidence data to raise awareness of the cancer burden and to characterize patterns by demographic characteristics so as ultimately to improve the provision of cancer-related health care.
[Show abstract][Hide abstract] ABSTRACT: The city of Ozyorsk (Southern Urals) was created as a secret city in 1945 and is a closed city until today. It housed workers of the earliest and one of the country’s largest nuclear facilities. Workers of the nuclear reactors, radiochemical or reprocessing plants were exposed to high levels of ionising radiation in the early years of operation and possibly further exposed from inhalation of plutonium aerosols.
The cause-of-death registry of Ozyorsk received paper copies of original death certificates of all deaths of residents of the city. Data were analysed for recent mortality rates (1998–2010) and time trends in age-standardised mortality rates between 1953 and 2010 of main groups of causes of deaths, in particular cancer.
Comparing workers of the three main plant types with the remainder of the Ozyorsk residents, and with national figures, all-cause mortality rates were lowest among workers, with ratios compared to national figures of 0.65 (men) and 0.56 (women), and compared to the other residents of 0.77 (men) and of 0.74 (women). For cancer overall, the differences were smaller in men (ratio between workers and national figures of 0.86) and there were no differences in women (ratio of 1.00), but ratios differed by cancer type. Most cancer deaths were however least common in the workers, including leukaemia. Over the last 60 years, all-cause mortality has gradually increased among men in all three groups but was stable among women, whereas cancer death rates have slightly declined in both sexes.
Healthy worker effect, relatively better living conditions in Ozyorsk and healthier lifestyles may explain the lower mortality rates in Ozyorsk. Overall mortality time trends in Ozyorsk were similar to the entire country. No apparent radiation-related effects were seen in this population-level analysis, but the radiation-related risks can be better addressed in individual-level studies.
Full-text · Article · Dec 2015 · Environmental Health
[Show abstract][Hide abstract] ABSTRACT: In October 2013, the Radiation Medical Science Center of the Fukushima Medical University and the Section of Environment and Radiation of the International Agency for Research on Cancer held a joint workshop in Fukushima, Japan to discuss opportunities and challenges for long-term studies of the health effects following the March 2011 Fukushima Daiichi Nuclear Power Plant Accident. This report describes four key areas of discussion - thyroid screening, dosimetry, mental health, and non-radiation risk factors - and summarizes recommendations resulting from the workshop. Four recommendations given at the workshop were to: 1) build-up a population-based cancer registry for long-term monitoring of the cancer burden in the prefecture; 2) enable future linkage of data from the various independent activities, particularly those related to dose reconstruction and health status ascertainment; 3) establish long-term observational studies with repeated measurements of lifestyle and behavioural factors to disentangle radiation and non-radiation factors; and 4) implement primary prevention strategies targeted for populations affected by natural disasters, including measures to better understand and address health risk concerns in the affected population. The workshop concluded that coordinated data collection between researchers from different institutes and disciplines can both reduce the burden on the population and facilitate efforts to examine the inter-relationships between the many factors at play.
Full-text · Article · Dec 2015 · Environmental Health
[Show abstract][Hide abstract] ABSTRACT: A low within-country variability and a large between-country variability in cancer incidence may indicate that ecologic factors are involved in the etiology of the disease. The aim of this study is to explore the within- and between-country variability of cancer incidence to motivate high-quality ecologic studies. We extracted age-standardized incidence rate estimates (world standard population) from 135 regions for the 10 most frequent invasive cancers in Europe for non-Hispanic white populations from Cancer Incidence in Five Continents, Volume X. We fitted weighted multilevel Poisson regression models with random country effects for each cancer and sex. We estimated intraclass correlation coefficients (ICC) and 95% confidence intervals (95%CI). A high ICC indicates a low within and a high between-country variability of rates. The two cancer sites with the highest ICC among men were prostate cancer (0.96, 95%CI: 0.92-0.99) and skin melanoma (0.78, 0.64-0.93). Among women, high ICC were observed for lung cancer (0.84, 0.73-0.95) and breast cancer (0.80, 0.69-0.91). The two most prominent sex differences for ICC occurred for cancers of the head and neck (men: 0.70, 0.55-0.85, women: 0.19, 0.08-0.30) and breast cancer (men: 0.04, 0.01-0.07, women: 0.80, 0.69-0.91). ICCs were relatively low for pancreatic cancer (men: 0.23, 0.10-0.35; women: 0.13, 0.04-0.21) and leukemia (men: 0.12, 0.04-0.21; women: 0.08, 0.02-0.14). For cancers with high ICC for which systematic factors of the health care system, screening and diagnostic activities are not plausible explanations for between-country variations in incidence, cross-country sex-specific ecologic studies may be especially promising. This article is protected by copyright. All rights reserved.
No preview · Article · Nov 2015 · International Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Background:
We previously reported that children exposed to elevated extremely low-frequency magnetic fields (ELF-MF) had a five to six times higher risk of leukaemia, central nervous system (CNS) tumour and malignant lymphoma. Here we extend the study from 1968 to 1986 through 2003.
We included 3277 children with leukaemia, CNS tumour or malignant lymphoma during 1968-2003 recorded in the Danish Cancer Registry and 9129 controls randomly selected from the Danish childhood population. ELF-MF from 50 to 400 kV facilities were calculated at the residences.
For recently diagnosed cases (1987-2003), the relative risk (RR) was 0.88 (95% confidence interval (CI): 0.32-2.42), while for the total period (1968-2003) it was 1.63 (95% CI: 0.77-3.46) for leukaemia, CNS tumour and malignant lymphoma combined for exposures ⩾0.4 μT compared with <0.1 μT. These results were based on five cases (recent period) and 11 cases (total period) in the highest exposure group.
We did not confirm the previous finding of a five- to six-fold higher risk for leukaemia, CNS tumour and malignant lymphoma when including data from the more recent time period. For the total time period, the results for childhood leukaemia were in line with large pooled analyses showing RRs between 1.5 and 2.British Journal of Cancer advance online publication, 20 October 2015; doi:10.1038/bjc.2015.365 www.bjcancer.com.
No preview · Article · Oct 2015 · British Journal of Cancer
[Show abstract][Hide abstract] ABSTRACT: Background:
The aetiology of Africa's easterly-lying corridor of squamous cell oesophageal cancer is poorly understood. Micronutrient deficiencies have been implicated in this cancer in other areas of the world, but their role in Africa is unclear. Without prospective cohorts, timely insights can instead be gained through ecological studies.
Across Africa we assessed associations between a country's oesophageal cancer incidence rate and food balance sheet-derived estimates of mean national dietary supplies of 7 nutrients: calcium (Ca), copper (Cu), iron (Fe), iodine (I), magnesium (Mg), selenium (Se) and zinc (Zn). We included 32 countries which had estimates of dietary nutrient supplies and of better-quality GLOBCAN 2012 cancer incidence rates. Bayesian hierarchical Poisson lognormal models were used to estimate incidence rate ratios for oesophageal cancer associated with each nutrient, adjusted for age, gender, energy intake, phytate, smoking and alcohol consumption, as well as their 95% posterior credible intervals (CI). Adult dietary deficiencies were quantified using an estimated average requirements (EAR) cut-point approach.
Adjusted incidence rate ratios for oesophageal cancer associated with a doubling of mean nutrient supply were: for Fe 0.49 (95% CI: 0.29-0.82); Mg 0.58 (0.31-1.08); Se 0.40 (0.18-0.90); and Zn 0.29 (0.11-0.74). There were no associations with Ca, Cu and I. Mean national nutrient supplies exceeded adult EARs for Mg and Fe in most countries. For Se, mean supplies were less than EARs (both sexes) in 7 of the 10 highest oesophageal cancer ranking countries, compared to 23% of remaining countries. For Zn, mean supplies were less than the male EARs in 8 of these 10 highest ranking countries compared to in 36% of other countries.
Ecological associations are consistent with the potential role of Se and/or Zn deficiencies in squamous cell oesophageal cancer in Africa. Individual-level analytical studies are needed to elucidate their causal role in this setting.
[Show abstract][Hide abstract] ABSTRACT: The European Code Against Cancer is a set of recommendations to give advice on cancer prevention. Its 4th edition is an update of the 3rd edition, from 2003. Working Groups of independent experts from different fields of cancer prevention were appointed to review the recommendations, supported by a Literature Group to provide scientific and technical support in the assessment of the scientific evidence, through systematic reviews of the literature. Common procedures were developed to guide the experts in identifying, retrieving, assessing, interpreting and summarizing the scientific evidence in order to revise the recommendations. The Code strictly followed the concept of providing advice to European Union citizens based on the current best available science. The advice, if followed, would be expected to reduce cancer risk, referring both to avoiding or reducing exposure to carcinogenic agents or changing behaviour related to cancer risk and to participating in medical interventions able to avert specific cancers or their consequences. The information sources and procedures for the review of the scientific evidence are described here in detail. The 12 recommendations of the 4th edition of the European Code Against Cancer were ultimately approved by a Scientific Committee of leading European cancer and public health experts.\.
[Show abstract][Hide abstract] ABSTRACT: Hardell and Carlberg claim in a recent article that both the Cause of Death Register and the National Inpatient Care Register indicate that there was a severe and increasing underreporting of malignant brain tumors to the Swedish Cancer Register during recent years . [...].
Preview · Article · Sep 2015 · International Journal of Environmental Research and Public Health
[Show abstract][Hide abstract] ABSTRACT: The 4th edition of the European Code against Cancer recommends limiting - or avoiding when possible - the use of hormone replacement therapy (HRT) because of the increased risk of cancer, nevertheless acknowledging that prescription of HRT may be indicated under certain medical conditions. Current evidence shows that HRT, generally prescribed as menopausal hormone therapy, is associated with an increased risk of cancers of the breast, endometrium, and ovary, with the risk pattern depending on factors such as the type of therapy (oestrogen-only or combined oestrogen-progestogen), duration of treatment, and initiation according to the time of menopause. Carcinogenicity has also been established for anti-neoplastic agents used in cancer therapy, immunosuppressants, oestrogen-progestogen contraceptives, and tamoxifen. Medical use of ionising radiation, an established carcinogen, can provide major health benefits; however, prudent practices need to be in place, with procedures and techniques providing the needed diagnostic information or therapeutic gain with the lowest possible radiation exposure. For pharmaceutical drugs and medical radiation exposure with convincing evidence on their carcinogenicity, health benefits have to be balanced against the risks; potential increases in long-term cancer risk should be considered in the context of the often substantial and immediate health benefits from diagnosis and/or treatment. Thus, apart from HRT, no general recommendations on reducing cancer risk were given for carcinogenic drugs and medical radiation in the 4th edition of European Code against Cancer. It is crucial that the application of these measures relies on medical expertise and thorough benefit-risk evaluation. This also pertains to cancer-preventive drugs, and self-medication with aspirin or other potential chemopreventive drugs is strongly discouraged because of the possibility of serious, potentially lethal, adverse events.
[Show abstract][Hide abstract] ABSTRACT: A potential impact of exposure to endocrine disruptors, including pesticides, during intrauterine life, has been hypothesised in testicular germ cell tumour (TGCT) aetiology, but exposure assessment is challenging. This large-scale registry-based case-control study aimed to investigate the association between parental occupational exposure to pesticides and TGCT risk in their sons.
Cases born in 1960 or onwards, aged between 14 and 49 years, and diagnosed between 1978 and 2013 in Denmark, Finland, Norway or Sweden, were identified from the respective nationwide cancer registries. Four controls per case were randomly selected from the general national populations, matched on year of birth. Information on parental occupation was collected through censuses or Pension Fund information and converted into a pesticide exposure index based on the Finnish National Job-Exposure Matrix.
A total of 9569 cases and 32 028 controls were included. No overall associations were found for either maternal or paternal exposures and TGCT risk in their sons, with ORs of 0.83 (95% CI 0.56 to 1.23) and of 1.03 (0.92 to 1.14), respectively. Country-specific estimates and stratification by birth cohorts revealed some heterogeneity. Cryptorchidism, hypospadias and family history of testicular cancer were risk factors but adjustment did not change the main results.
This is the largest study on prenatal exposure to pesticides and TGCT risk, overall providing no evidence of an association. Limitations to assess individual exposure in registry-based studies might have contributed to the null result.
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Full-text · Article · Aug 2015 · Occupational and environmental medicine
[Show abstract][Hide abstract] ABSTRACT: Many studies have investigated the possible association between birth order and risk of childhood cancer, although the evidence to date has been inconsistent. Birth order has been used as a marker for various in utero or childhood exposures and is relatively straightforward to assess.
Data were obtained on all children born in Denmark between 1973 and 2010, involving almost 2.5 million births and about 5,700 newly diagnosed childhood cancers before the age of 20 years. Data were analyzed using Poisson regression models.
We failed to observe associations between birth order and risk of any childhood cancer subtype, including acute lymphoblastic leukemia; all rate ratios were close to one. Further analyses stratified by birth cohort (those born between 1973 and 1990, and those born between 1991 and 2010) also failed to show any associations. Considering stillbirths and/or controlling for birth weight and parental age in the analyses had no effect on the results. Analyses by years of birth (those born between 1973 and 1990, and those born between 1991 and 2010) did not show any changes in the overall pattern of no association.
In this large cohort of all children born in Denmark over an almost 40-year period, we did not observe an association between birth order and the risk of childhood cancer.
No preview · Article · Aug 2015 · Cancer Causes and Control
[Show abstract][Hide abstract] ABSTRACT: Hot beverage consumption has been linked to oesophageal squamous cell cancer (EC), but its contribution to the poorly understood East African EC corridor is not known.
In a cross-sectional study of general-population residents in Kilimanjaro, North Tanzania, tea drinking temperatures and times were measured. Using linear regression models, we compared drinking temperatures to those in previous studies, by socio-demographic factors and tea type ("milky tea" which can be 50 % or more milk and water boiled together vs "black tea" which has no milk).
Participants started drinking at a mean of 70.6 °C (standard deviation 3.9, n = 188), which exceeds that in all previous studies (p ≤ 0.01 for each). Tea type, gender and age were associated with drinking temperatures. After mutual adjustment for each other, milky tea drinkers drank their tea 1.9 °C (95 % confidence interval: 0.9, 2.9) hotter than drinkers of black tea, largely because black tea cooled twice as fast as milky tea. Men commenced drinking tea 0.9 °C (-0.2, 2.1) hotter than women did and finished their cups 30 (-9, 69) seconds faster. 70 % and 39 % of milky and black tea drinkers, respectively, reported a history of tongue burning.
Hot tea consumption, especially milky tea, may be an important and modifiable risk factor for EC in Tanzania. The contribution of this habit to EC risk needs to be evaluated in this setting, jointly with that of the many risk factors acting synergistically in this multi-factorial disease.
No preview · Article · Aug 2015 · Cancer Causes and Control
[Show abstract][Hide abstract] ABSTRACT: Objectives Working in mines and quarries has been associated with an elevated lung cancer risk but with inconsistent results for coal miners. This study aimed to estimate the smoking-adjusted lung cancer risk among coal miners and compare the risk pattern with lung cancer risks among ore miners and quarrymen. Methods We estimated lung cancer risks of coal and ore miners and quarrymen among 14 251 lung cancer cases and 17 267 controls from the SYNERGY pooled case-control study, controlling for smoking and employment in other at-risk occupations. Results Ever working as miner or quarryman (690 cases, 436 controls) was associated with an elevated odds ratio (OR) of 1.55 [95% confidence interval (95% CI) 1.34-1.79] for lung cancer. Ore miners (53 cases, 24 controls) had a higher OR (2.34, 95% CI 1.36-4.03) than quarrymen (67 cases, 39 controls; OR 1.92, 95% CI 1.21-3.05) and coal miners (442 cases, 297 controls; OR 1.40, 95% CI 1.18-1.67), but CI overlapped. We did not observe trends by duration of exposure or time since last exposure. Conclusions This pooled analysis of population-based studies demonstrated an excess lung cancer risk among miners and quarrymen that remained increased after adjustment for detailed smoking history and working in other at-risk occupations. The increase in risk among coal miners were less pronounced than for ore miners or quarrymen.
No preview · Article · Jul 2015 · Scandinavian Journal of Work, Environment & Health