Combined effects of endogenous sex hormone levels and mammographic density on postmenopausal breast cancer risk: results from the Breakthrough Generations Study.

BACKGROUND: Mammographic density and sex hormone levels are strong risk factors for breast cancer, but it is unclear whether they represent the same aetiological entity or are independent risk factors. METHODS: Within the Breakthrough Generations Study cohort, we conducted a case-control study of 265 postmenopausal breast cancer cases and 343 controls with prediagnostic mammograms and blood samples. Plasma was assayed for oestradiol, testosterone and sex hormone-binding globulin (SHBG) concentrations and mammographic density assessed by Cumulus. RESULTS: Oestradiol and testosterone were negatively and SHBG positively associated with percentage density and absolute dense area, but after adjusting for body mass index the associations remained significant only for SHBG. Breast cancer risk was independently and significantly positively associated with percentage density (P=0.002), oestradiol (P=0.002) and testosterone (P=0.007) levels. Women in the highest tertile of both density and sex hormone level were at greatest risk, with an odds ratio of 7.81 (95% confidence interval (CI): 2.89-21.1) for oestradiol and 4.57 (95% CI: 1.75-11.9) for testosterone and high density compared with those who were in the lowest tertiles. The cumulative risk of breast cancer in the highest oestradiol and density tertiles, representing 8% of controls, was estimated as 12.8% at ages 50-69 years and 19.4% at ages 20-79 years, and in the lowest tertiles was 1.7% and 4.3%, respectively. Associations of breast cancer risk with tertiles of mammographic dense area were less strong than for percentage density. CONCLUSIONS: Endogenous sex hormone levels and mammographic density are independent risk factors for postmenopausal breast cancer, which in combination can identify women who might benefit from increased frequency of screening and chemoprophylaxis.

The Breakthrough Generations Study: design of a long-term UK cohort study to investigate breast cancer aetiology.

BACKGROUND: The rationale, design, recruitment and follow-up methods are described for the Breakthrough Generations Study, a UK cohort study started in 2003, targeted at investigation of breast cancer aetiology. METHODS: Cohort members have been recruited by a participant referral method intended to assemble economically a large general population cohort from whom detailed questionnaire information and blood samples can be obtained repeatedly over decades, with high completeness of follow-up and inclusion of large numbers of related individuals. 'First-generation' recruits were women contacted directly, or who volunteered directly, to join the study. They nominated female friends and family, whom we contacted, and those who joined ('second generation') nominated others, reiterated for up to 28 generations. RESULTS: The method has successfully been used during 2003-2011 to recruit 112,049 motivated participants with a broad geographic and socioeconomic distribution, aged 16-102 years, who have completed detailed questionnaires; 92% of the participants gave blood samples at recruitment. When eligible, 2½ years after recruitment, >98% completed the first follow-up questionnaire. Thirty percent are first-degree relatives of other study members. CONCLUSION: The 'generational' recruitment method has enabled recruitment of a large cohort who appear to have the commitment to enable long-term continuing data and sample collection, to investigate the effects of changing endogenous and exogenous factors on cancer risk.

Determinants of age at menarche in the UK: analyses from the Breakthrough Generations Study.

BACKGROUND: Early menarche increases breast cancer risk but, aside from weight, information on its determinants is limited. METHODS: Age at menarche data were collected retrospectively by questionnaire from 81,606 women aged 16-98, resident in the UK and participating in the Breakthrough Generations Study. RESULTS: Menarche occurred earlier in women who had a low birthweight (P(trend)<0.001), were singletons (P<0.001), had prenatal exposure to pre-eclampsia (P<0.001) or maternal smoking (P=0.01), were not breastfed (P(trend)=0.03), were non-white (P<0.001), were heavy (P(trend)<0.001) or tall (P(trend)<0.001) compared with their peers at age 7 and exercised little as a child (P(trend)<0.001). Menarcheal age increased with number of siblings (P<0.001) independently of birth order, and had an inverse association with birth order after adjustment for sibship size (P<0.001). In a multivariate model, birthweight, ethnicity, weight, height, exercise, sibship size and birth order remained significant, and maternal age at birth became significant (positive association, P<0.001). CONCLUSION: Age at menarche was influenced by both pre- and post-natal factors, and these factors may affect breast cancer risk through this route.

Meningioma and mobile phone use--a collaborative case-control study in five North European countries.

BACKGROUND: Use of mobile telephones has been suggested as a possible risk factor for intracranial tumours. To evaluate the effect of mobile phones on risk of meningioma, we carried out an international, collaborative case-control study of 1209 meningioma cases and 3299 population-based controls. METHODS: Population-based cases were identified, mostly from hospitals, and controls from national population registers and general practitioners' patient lists. Detailed history of mobile phone use was obtained by personal interview. Regular mobile phone use (at least once a week for at least 6 months), duration of use, cumulative number and hours of use, and several other indicators of mobile phone use were assessed in relation to meningioma risk using conditional logistic regression with strata defined by age, sex, country and region. RESULTS: Risk of meningioma among regular users of mobile phones was apparently lower than among never or non-regular users (odds ratio, OR = 0.76, 95% confidence interval, CI 0.65, 0.89). The risk was not increased in relation to years since first use, lifetime years of use, cumulative hours of use or cumulative number of calls. The findings were similar regardless of telephone network type (analogue/digital), age or sex. CONCLUSIONS: Our results do not provide support for an association between mobile phone use and risk of meningioma.

Cancer risk in patients with constitutional chromosome deletions: a nationwide British cohort study.

The finding of increased risks of specific cancers in individuals with constitutional deletions of chromosomes 11p and 13q led to the discovery of cancer predisposition genes at these locations, but there have been no systematic studies of cancer risks in patients with constitutional deletions, across the chromosome complement. Therefore, we assessed cancer incidence in comparison with national cancer incidence rates in a follow-up of 2561 patients with constitutional autosomal chromosome deletions diagnosed by microscopy or fluorescence in situ hybridisation in Britain during the period 1965-2002. Thirty cancers other than non-melanoma skin cancer occurred in the cohort (standardised incidence ratio (SIR)=2.4, 95% confidence interval (CI) 1.6-3.5). There were significantly increased risks of renal cancer in persons with 11p deletions (SIR=1869, 95% CI 751-3850; P=4 x 10(-21)), eye cancer with 13q deletions (SIR=1084, 95% CI 295-2775; P=2 x 10(-11)), and anogenital cancer with 11q deletions (SIR=305, 95% CI 63-890; P=3 x 10(-7)); all the three latter cancers were in the 11 subjects with 11q24 deletions. The results strongly suggest that in addition to suppressor genes relating to Wilms' tumour risk on 11p and retinoblastoma on 13q, there are suppressor genes around 11q24 that greatly affect anogenital cancer risk.

Medical history, cigarette smoking and risk of acoustic neuroma: an international case-control study.

Acoustic neuroma (vestibular schwannoma) is a benign tumor of the vestibulocochlear nerve. Its recorded incidence is increasing but risk factors for this tumor have scarcely been investigated. We conducted a population-based case-control study of risk factors for acoustic neuroma in the UK and Nordic countries, including 563 cases and 2,703 controls. Tumor risk was analyzed in relation to medical history and cigarette smoking. Risk of acoustic neuroma was significantly raised in parous compared with nulliparous women (OR = 1.7, 95% CI: 1.1-2.6), but was not related to age at first birth or number of children. Risk was not associated with a history of allergic disease, past head injury, past diagnosis of a neoplasm or birth characteristics, but was significantly raised for past diagnosis of epilepsy (OR = 2.5, 95% CI: 1.3-4.9). Tumor risk was significantly reduced in subjects who had ever regularly smoked cigarettes (OR = 0.7, 95% CI: 0.6-0.9), but the reduction applied only to current smokers (OR = 0.5, 95% CI: 0.4-0.6), not ex-smokers (OR = 1.0, 95% CI: 0.8-1.3). The reduced risk of acoustic neuroma in smokers and raised risk in parous women might relate to sex hormone levels, or smoking might suppress tumor growth, but effects of parity and smoking on timing of diagnosis of the tumor are also a potential explanation. The raised risk in relation to past diagnosis of epilepsy might be a surveillance artefact or imply that epilepsy and/or antiepileptic medication use predispose to acoustic neuroma. These findings need replication by other studies and possible mechanisms need to be clarified.

History of allergic disease and risk of meningioma.

Epidemiologic studies have consistently shown inverse associations of allergic disease with risk of glioma, but it is unclear whether this association also applies to meningioma. The authors conducted a pooled analysis of meningioma risk in relation to a history of allergic disease based on data from two population-based, case-control studies with 475 cases and 1,716 controls in the United Kingdom (2001-2004). Meningioma risk was significantly reduced in relation to self-reported, physician-diagnosed allergic disease (odds ratio = 0.76, 95% confidence interval (CI): 0.61, 0.96) but was nonsignificantly reduced for individual conditions: asthma (odds ratio = 0.85, 95% CI: 0.61, 1.18), hay fever (odds ratio = 0.81, 95% CI: 0.62, 1.06), and eczema (odds ratio = 0.72, 95% CI: 0.51, 1.02). Risk reductions were greatest for asthma (odds ratio = 0.43, 95% CI: 0.21, 0.89) and hay fever (odds ratio = 0.50, 95% CI: 0.25, 1.00) with an early age at onset (<10 years) and for eczema (odds ratio = 0.46, 95% CI: 0.21, 1.07) with an onset at ages 10-19 years; they were near unity for onset in adulthood. This study suggests an inverse association between a history of allergies and meningioma risk, but with smaller risk reductions than for glioma. The reasons for this association need clarification, as well as an etiologic explanation. Consideration also needs to be given to confounding or bias.

Mobile phone use and risk of acoustic neuroma: results of the Interphone case-control study in five North European countries.

There is public concern that use of mobile phones could increase the risk of brain tumours. If such an effect exists, acoustic neuroma would be of particular concern because of the proximity of the acoustic nerve to the handset. We conducted, to a shared protocol, six population-based case-control studies in four Nordic countries and the UK to assess the risk of acoustic neuroma in relation to mobile phone use. Data were collected by personal interview from 678 cases of acoustic neuroma and 3553 controls. The risk of acoustic neuroma in relation to regular mobile phone use in the pooled data set was not raised (odds ratio (OR) = 0.9, 95% confidence interval (CI): 0.7-1.1). There was no association of risk with duration of use, lifetime cumulative hours of use or number of calls, for phone use overall or for analogue or digital phones separately. Risk of a tumour on the same side of the head as reported phone use was raised for use for 10 years or longer (OR = 1.8, 95% CI: 1.1-3.1). The study suggests that there is no substantial risk of acoustic neuroma in the first decade after starting mobile phone use. However, an increase in risk after longer term use or after a longer lag period could not be ruled out.

Lung cancer after Hodgkin's disease: a nested case-control study of the relation to treatment.

PURPOSE: To investigate the causes of the raised risk of lung cancer in patients who have had Hodgkin's disease, and in particular the relationship to treatment. PATIENTS AND METHODS: A nested case-control study was conducted within a cohort of 5,519 patients with Hodgkin's disease treated in Britain during 1963 through 1993. For 88 cases of lung cancer and 176 matched control subjects, information on treatment and other risk factors was extracted from hospital case-notes, and odds ratios for lung cancer in relation to these factors were calculated. RESULTS: Risk of lung cancer was borderline significantly greater in patients treated with mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) chemotherapy than those who did not receive this treatment (relative risk [RR] = 1.66; 95% confidence interval [CI], 0.99 to 2.82), and increased with number of cycles of MOPP (P =.07). Exclusion of lung cancers for which histologic confirmation was not available strengthened these associations (RR = 2.41; 95% CI, 1.33 to 4.51; P =.004 for any MOPP and P =.007 for trend with number of cycles of MOPP). Risks were not raised, however, after chlorambucil, vinblastine, procarbazine, and prednisone treatment. There was evidence that the raised risk of lung cancer occurring in relation to radiotherapy was restricted to histologies other than adenocarcinoma. CONCLUSION: The results suggest that MOPP chemotherapy may lead to elevated risk of lung cancer, at least in certain subgroups of patients. The role of chemotherapy in the etiology of lung cancer after Hodgkin's disease deserves further investigation.

Non-fatal work related injuries in a cohort of Brazilian steelworkers.

OBJECTIVES: Workers in the steel industry are exposed to various severe hazards. This study investigated risk factors for non-fatal injury occurring in the workplace and during travel to and from work in steelworkers in Brazil. METHODS: Non-fatal work related injuries during employment from January 1977 to September 1992 were analysed in a cohort of 21 732 male workers in the steel plant of USIMINAS, Brazil. RESULTS: There were 14 972 non-fatal injuries during follow up, with 10 891 injuries in the workplace and 4081 during travel to and from work (travel to work injury). The rate of injury in the workplace was 5.6/100 person-years and that of travel to work injury was 2.1/100 person-years. The most common injuries were to hands, arms, and eyes, with 90% of the eye injuries caused by a foreign body. Both rates of workplace and travel to work injury increased significantly with the number of injuries previously experienced, and decreased with number of years in employment and calendar period. The rates of travel to work injury also seemed to decrease with age, but age was not an independent predictor of workplace injury when we controlled for duration of employment. The rate of workplace injury was increased eightfold for workers who had experienced more than six previous injuries compared with those with no previous workplace injuries after adjusting for duration of employment and calendar period. Labourers were most at risk of workplace injury, with about eight injuries per 100 person-years. Travel to work injury was most common among support workers, with nearly half of the travel to work injuries affecting the eyes. CONCLUSION: The rate of injury was high in these steelworks, both for workplace and travel to work injuries. Characteristics of the work areas and the employees can identify high risk groups; protective measures, safety, health training, and injury programmes should concentrate particularly on these groups. Prevention of eye injury needs special attention in steelworks.

Predictors of first nonfatal occupational injury following employment in a Brazilian steelworks.

OBJECTIVES: This study investigated the influence of sociodemographic and occupational factors on the risk of 1st injury among Brazilian steelworkers. METHODS: Workers 1st employed between 1 January 1977 and 31 December 1985 and still employed on 1 December 1983 were followed from the date of hire until 30 October 1992. Occupational injuries were ascertained from a database. Kaplan-Meier curves for time to 1st injury were calculated for the total cohort and for different subgroups. A multivariate analysis of risk factors for 1st injury was carried out using the Cox proportional hazards regression model. RESULTS: Forty-one percent of the workers had > or = 1 occupational injuries, and 39% of 1st injuries occurred in the 1st year of employment. Lacerations, contusions, penetration by foreign bodies, bums, sprains, and fractures constituted the main diagnostic groups. Injuries to the hands, eyes, feet, arms, and legs dominated. Over 5% of the injured workers were on temporary disability leave (cumulative total 10,660 days). The probability for an occupational injury was 16% for the 1st year, rising to 25% in the 2nd year. The risk of nonfatal injury was highest for laborers [hazard ratio (HR) 1.76, 95% confidence interval (95% CI) 1.35-2.29] and employees in the steel mill (HR 1.40, 95% CI 1.21-1.63), and inversely related to worker age and educational level. The risk of injury decreased significantly with calendar period of employment. CONCLUSIONS: Substantial reductions in nonfatal injuries may reflect changes in work organization, increased automation, and improved safety standards. Knowledge of predictors of work-related injury may contribute to injury prevention strategies, especially among newly employed workers.

A progress report of the Marshall Islands nationwide thyroid study: an international cooperative scientific study.

The objective of this report is to present a summary of progress of the Marshall Islands Nationwide Thyroid Study. As well known, the US atomic weapons testing program in the Pacific was conducted primarily between 1946 and 1958 in the Marshall Islands. The nuclear tests resulted in radioactive contamination of a number of atolls and resulted in exposure of Marshallese to undefined levels before our study. Little information has been paid to health consequences among residents of the nearly twenty inhibited atolls except for some information about nodular thyroid disease which was reported on by an US group. In a cooperative agreement with the Government of the Marshall Islands, between 1993 and 1997 we studied the prevalence of both thyroid nodules and thyroid cancer among 4766 Marshallese potentially exposed to radioiodines from bomb test fallout. That group represents more than 65% of the population at risk. We diagnosed 45 thyroid cancers and 1398 benign thyroid nodules. In addition, 23 study participants had been operated on prior to our study for thyroid cancer. Presently, we are developing a database of information to estimate radiation doses and planning a statistical analysis to determine if a dose-response relationship exists. These data will be important for the health promotion of exposed people all over the world including Hiroshima, Nagasaki, Semipalatinsk, Chernobyl and other locations. A timely completion is important for purpose of assisting Marshallese as well as to add the global understanding of radiation induced thyroid cancer.

An investigation into the prevalence of thyroid disease on Kwajalein Atoll, Marshall Islands.

The prevalence of thyroid nodules and thyroid cancer was studied in the indigenous population residing on Ebeye Island, Kwajalein Atoll, in the Republic of the Marshall Islands. This island, centrally located in the nation, is home to about 25% of the nation's population, many who have migrated there from other atolls. The objective of the study was to obtain thyroid disease rate statistics on as much of the population as possible that was alive during the years of nuclear testing and to test the hypothesis that described a linearly decreasing prevalence of palpable nodules with increasing distance from the Bikini test site. 1,322 Marshallese born before 1965 were given a thyroid examination using neck palpation, fine needle aspiration biopsy, and high resolution ultrasound imaging. Approximately 40% of the total population living on this island who are at risk from exposure to radioactive fallout during the years 1946-1958 were screened. Of that group, 815 were alive at the time of the BRAVO test on 1 March 1954. Two hundred sixty-six people with thyroid nodules were found (32.6%): 132 were palpable nodules (16.2%), and 134 were nodules that could be diagnosed with ultrasound only (15.7%). Prevalence of palpable nodules was particularly high in men and women older than 60 y, in men who were 6 to 15 y of age at the time of the BRAVO test, and in women 1 to 10 y of age at the time of the BRAVO test. In 22 people, the clinical diagnosis was most likely cancer though histopathological evidence was only available from 11 operated cases. Of the 11 operated cases, 10 were cancer. Cancer prevalence was particularly high in those women born between 1944 and 1953 (7/220 = 3.2%), i.e., who were children during the early years of nuclear testing. The Ebeye data showed a marginally significant correlation between palpable nodule prevalence among women and distance to Bikini (r = -0.44, p = 0.06). This report summarizes the clinical findings of the thyroid examinations, the age distributions for nodular disease and cancer, and examines the relationship between prevalence of nodules and present day levels of 137Cs in the environment of each atoll.