Objective: Our objective was to evaluate the breast cancer risk associated with body burden levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).Methods: We conducted a hospital-based case-control study among 79 women diagnosed with invasive breast cancer and 52 controls diagnosed with benign breast conditions. We collected breast adipose tissue and analyzed it for all 17 2,3,7,8-substitituted PCDD/PCDFs. We used unconditional logistic regression to calculate age- and race-adjusted exposure-specific odds ratios (ORs) and 95% confidence intervals (CI) for each individual PCDD/PCDF congener as well as for the summary measures (I-TEQ, Adj-TEQ).Results: Dioxin levels were consistent with reports from other small, contemporary studies of body burdens in the U.S. None of the odds ratios for any of the congeners or summary measures differed significantly from one. Especially for the PCDF congeners, point estimates tended to be below one. One notable exception was octachlorodibenzo-p-dioxin (OCDD), for which the odds ratio for the second and third tertiles appeared modestly elevated (OR = 1.22, 95% CI: 0.47:3.16 and OR = 1.62, 95% CI: 0.64:4.12, respectively), though the test for trend was not significant (p = 0.36).Conclusion: Breast cancer risk was not associated with adipose levels of PCDD/PCDFs. More study is suggested among women of color who may have higher body burden levels of these compounds.

Objectives

These analyses were designed to describe characteristics associated with active and passive smoking in a large cohort of women in order to identify possible confounders of the relationship between smoking exposures and breast cancer risk.

Methods

Analyses were based on 1995 data collected from the California Teachers Study (CTS) and were restricted to those with complete and usable tobacco data (n = 128,174). Age-adjusted and race-adjusted odds ratios (OR) were generated by unconditional logistic regression.

Results

Compared with never smokers, both current and former smokers experienced menarche at an earlier age. Current and former smokers also were more likely than their never smoking counterparts to be nulliparous. Among parous women, current, but not former smokers were less likely than never smokers to have had their first child at an older age. Similarly, among never smokers, those exposed to household passive smoking experienced menarche at an earlier age, were more likely to be nulliparous, and among parous women, were less likely to have had their first child at an older age than never smokers not exposed to passive smoking. Greater alcohol consumption was strongly associated with both active and passive smoking exposures. Compared with never smokers, current smokers were less likely to take antioxidant supplements, whereas former smokers were more likely to take antioxidant supplements. Among never smokers, antioxidant use did not differ depending on passive smoking exposure. A number of other dietary correlates of active and passive smoking were identified.

Conclusions

We identified a number of reproductive and dietary correlates to smoking exposures that underscore the need to adjust for such factors in an analysis of smoking and breast cancer and potentially other disease entities. Furthermore, these findings may suggest potential mechanisms underlying an association between breast cancer and smoking.

Background

Especially for cancers with long latency periods, such as breast cancer, the issue of residential mobility hinders ecologic analyses seeking to examine the role of environmental contaminants in chronic disease etiology. This study describes and evaluates characteristics associated with residential mobility in a sub-sample of the California Teachers Study (CTS) cohort.

Methods

In 2000, lifetime residential histories were collected for a sub-sample of 328 women enrolled in the CTS; women's degree of residential mobility and associated factors were analyzed.

Results

While most women moved many times during their lives (average = 8.9), the average number of years at their residence when they enrolled in the study was reasonably long (15.1 years). Age strongly predicted duration at current residence but was not related to the number of lifetime residences. After adjusting for age, California-born women and women living in high socioeconomic status (SES) neighborhoods were significantly more residentially stable. Agreement between self-reported urbanization of recent residences and that based on census data of the geocoded residences was very good (80% concordant). Among women currently living in urban areas, an average of 43.3 years, or 77%, of their lifetimes were spent in urban residences; among women currently living in a rural area, an average of 37.3 years, or 67% of their lifetimes were spent in rural residences.

Conclusions

This suggests that analyses of incidence rates based on current residence, while not capturing a woman's full exposure history, may reasonably reflect some aspect of longer term chronic exposures, especially those related to urbanization, at least in professional women.

We examined the association between residential proximity to agricultural pesticide use and breast cancer incidence among members of the California Teachers Study cohort, a large study of professional school employees with extensive information on breast cancer risk factors, followed for cancer incidence since 1995. We identified 1552 invasive breast cancer cases, diagnosed between 1996 and 1999, among 114,835 cohort members. We used California Pesticide Use Reporting data to select pesticides for analysis based on use volume, carcinogenic potential, and exposure potential; a Geographic Information System was used to estimate pesticide applications within a half-mile radius of subjects' residences. We applied Cox proportional hazard models to estimate hazard rate ratios (HR) for selected pesticides, adjusting for age, race, and socioeconomic status. We saw no association between residential proximity to recent agricultural pesticide use and invasive breast cancer incidence. HR estimates for the highest compared to the lowest exposure categories for groups of agents were as follows: probable or likely carcinogens (1.07, 95% confidence interval (CI): 0.86-1.32), possible or suggestive carcinogens (1.06, 95% CI: 0.87-1.29), mammary carcinogens (1.15, 95% CI: 0.90-1.48), and endocrine disruptors (1.03, 95% CI: 0.86-1.25). HR estimates for other groups and individual pesticides did not differ from unity, nor was there a trend for any groupings of or individual pesticides examined. Stratifying by menopausal status or family history of breast cancer did not substantially affect our results. Our analyses suggest that breast cancer incidence is not elevated in areas of recent, high agricultural pesticide use in California.