Breast cancer risk in relation to occupations with exposure to carcinogens and endocrine disruptors: a Canadian case-control study.

BACKGROUND: Endocrine disrupting chemicals and carcinogens, some of which may not yet have been classified as such, are present in many occupational environments and could increase breast cancer risk. Prior research has identified associations with breast cancer and work in agricultural and industrial settings. The purpose of this study was to further characterize possible links between breast cancer risk and occupation, particularly in farming and manufacturing, as well as to examine the impacts of early agricultural exposures, and exposure effects that are specific to the endocrine receptor status of tumours. METHODS: 1005 breast cancer cases referred by a regional cancer center and 1146 randomly-selected community controls provided detailed data including occupational and reproductive histories. All reported jobs were industry- and occupation-coded for the construction of cumulative exposure metrics representing likely exposure to carcinogens and endocrine disruptors. In a frequency-matched case-control design, exposure effects were estimated using conditional logistic regression. RESULTS: Across all sectors, women in jobs with potentially high exposures to carcinogens and endocrine disruptors had elevated breast cancer risk (OR = 1.42; 95% CI, 1.18-1.73, for 10 years exposure duration). Specific sectors with elevated risk included: agriculture (OR = 1.36; 95% CI, 1.01-1.82); bars-gambling (OR = 2.28; 95% CI, 0.94-5.53); automotive plastics manufacturing (OR = 2.68; 95% CI, 1.47-4.88), food canning (OR = 2.35; 95% CI, 1.00-5.53), and metalworking (OR = 1.73; 95% CI, 1.02-2.92). Estrogen receptor status of tumors with elevated risk differed by occupational grouping. Premenopausal breast cancer risk was highest for automotive plastics (OR = 4.76; 95% CI, 1.58-14.4) and food canning (OR = 5.70; 95% CI, 1.03-31.5). CONCLUSIONS: These observations support hypotheses linking breast cancer risk and exposures likely to include carcinogens and endocrine disruptors, and demonstrate the value of detailed work histories in environmental and occupational epidemiology.

Cancer and construction: what occupational histories in a Canadian community reveal.

From 2000 to 2002, male patients at a Canadian cancer treatment center with new-incident head-and-neck or esophageal cancers were invited to participate in a population-based study. The study population included 87 cases and 172 controls. A lifetime-history questionnaire was administered. Odds ratios (ORs) were calculated for occupational groups with a minimum of five cases, adjusted for duration of employment, age, smoking, alcohol, education, and income. A significantly increased risk was shown for construction workers (OR = 2.20; 95% CI 1.25-3.91). This investigation of a set of rare cancers over a limited time period demonstrates the feasibility of this research approach. The increased risk among construction workers supports the need for more comprehensive study of exposures in this occupational group.

Occupation and breast cancer: a Canadian case-control study.

A local collaborative process was launched in Windsor, Ontario, Canada to explore the role of occupation as a risk factor for cancer. An initial hypothesis-generating study found an increased risk for breast cancer among women aged 55 years or younger who had ever worked in farming. On the basis of this result, a 2-year case-control study was undertaken to evaluate the lifetime occupational histories of women with breast cancer. The results indicate that women with breast cancer were nearly three times more likely to have worked in agriculture when compared to the controls (OR = 2.80 [95% CI, 1.6-4.8]). The risk for those who worked in agriculture and subsequently worked in automotive-related manufacturing was further elevated (OR = 4.0 [95% CI, 1.7-9.9]). The risk for those employed in agriculture and subsequently employed in health care was also elevated (OR = 2.3 [95% CI, 1.1-4.6]). Farming tended to be among the earlier jobs worked, often during adolescence. While this article has limitations including the small sample size and the lack of information regarding specific exposures, it does provide evidence of a possible association between farming and breast cancer. The findings indicate the need for further study to determine which aspects of farming may be of biological importance and to better understand the significance of timing of exposure in terms of cancer risk.

Helping patients make informed choices: a randomized trial of a decision aid for adjuvant chemotherapy in lymph node-negative breast cancer.

BACKGROUND: In recent years, patients have indicated a desire for more information about their disease and to be involved in making decisions about their care. We developed an aid called the "Decision Board" to help clinicians inform patients with lymph node-negative breast cancer of the risks and benefits of adjuvant chemotherapy. We determined whether adding the Decision Board to the medical consultation improved patient knowledge and satisfaction compared with the medical consultation alone. METHODS: Between October 1995 and March 2000, 176 women with lymph node-negative breast cancer who were candidates for adjuvant chemotherapy were randomly assigned to receive the Decision Board plus the medical consultation (83 patients) or the medical consultation alone (93 patients). One week after the consultation, patients completed a questionnaire assessing their knowledge about breast cancer and chemotherapy. Satisfaction with decision making was assessed 1 week and 3, 6, and 12 months after randomization, and differences between groups were analyzed by a repeated measures analysis of variance. All statistical tests were two-sided. RESULTS: Patients in the Decision Board arm were better informed about breast cancer and adjuvant chemotherapy than patients in the control arm (mean knowledge score = 80.2 [on a scale of 0-100], 95% confidence interval [CI] = 77.1 to 83.3, and 71.7, 95% CI = 69.0 to 74.4, respectively; P<.001). Over the entire study period, satisfaction with decision making was higher for patients in the Decision Board arm than for patients in the control arm (P =.032). There was no statistically significant difference between the two groups in the number of patients who chose adjuvant chemotherapy (77% and 70% for patients in the Decision Board arm and those in the control arm, respectively; P =.303). CONCLUSION: When making decisions regarding adjuvant chemotherapy, patients with early breast cancer who had been exposed to the Decision Board had better knowledge of the disease and treatment options and greater satisfaction with their decision making than those who received the standard consultation.