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Background: In a previous exploratory study, we reported lower concentrations of the ovarian reserve biomarker anti-Müllerian hormone (AMH) in adulthood with prenatal farm exposure. We now examine this association as well as childhood farm exposure using enrollment data from the Sister Study, a large US cohort of women.Methods: We collected prenatal and childhood farm exposure data by questionnaire and telephone interview. However, serum AMH data were available only for a nested subset: premenopausal women ages 35-54 subsequently diagnosed with breast cancer (n = 418 cases) and their matched controls (n = 866). To avoid potential bias from restricting analyses to only premenopausal controls, we leveraged the available cohort data. We used data from both premenopausal cases and controls as well as postmenopausal women ages 35-54 (n = 3,526) (all presumed to have undetectable AMH concentrations) and applied weights to produce a sample representative of the cohort ages 35-54 (n = 17,799). The high proportion of undetectable AMH concentrations (41%) was addressed using reverse-scale Cox regression. An adjusted hazard ratio (HR) <1.0 indicates that exposed individuals had lower AMH concentrations than unexposed individuals.Results: Prenatal exposure to maternal residence or work on a farm was associated with lower AMH concentrations (HR 0.66; 95% confidence intervals [CI] = 0.48 to 0.90). Associations between childhood farm residence exposures and AMH were null or weak, except childhood contact with pesticide-treated livestock or buildings (HR 0.69; 95% CI = 0.40 to 1.2).Conclusions: Replication of the prenatal farm exposure and lower adult AMH association raises concern that aspects of prenatal farm exposure may result in reduced adult ovarian reserve. [ABSTRACT FROM AUTHOR]

Background: Detrimental effects of oxidative stress are widely recognized, but induction of apoptosis and senescence may also have benefits for cancer prevention. Recent studies suggest oxidative stress may be associated with lower breast cancer risk before menopause.Methods: We conducted a nested case-control study (N = 457 cases, 910 controls) within the NIEHS Sister Study cohort of 50,884 women. Premenopausal women ages 35-54 were eligible for selection. We matched controls 2:1 to cases on age and enrollment year and were breast cancer-free at the time of the corresponding case's diagnosis. Oxidative stress was measured by urinary F2-isoprostane and metabolite (15-F2t-isoprostane-M) concentrations. Odds ratios (OR) and 95% confidence intervals (CIs) were calculated with multivariable conditional logistic regression.Results: After multivariable adjustment for body mass index (BMI) and other potential confounders, the OR for breast cancer comparing the >90th (≥2.94 ng/mgCr) to <25th percentile (1.01 ng/mgCr) was 1.1 (CI: 0.65, 1.7) for F2-isoprostane and 0.70 (CI: 0.43, 1.1) for the metabolite. Higher metabolite concentrations were associated with lower breast cancer risk among women who were also premenopausal (353 cases, OR: 0.59, CI: 0.34, 1.0) or <46 years (82 cases, OR: 0.15, CI: 0.06, 0.42) at diagnosis. ORs for the metabolite and breast cancer were inverse among women with BMI 18.5-24.9 kg/m (OR: 0.47, CI: 0.18, 1.2, 208 cases) and >30 kg/m (OR: 0.71, CI: 0.30, 1.7, 107 cases), but not among women with BMI 25-29.9 kg/m (OR: 0.98, CI: 0.39, 2.5, 138 cases).Conclusions: Together with other studies, our results support a possible inverse association between oxidative stress and premenopausal breast cancer risk. [ABSTRACT FROM AUTHOR]

Background: To date, epidemiologic studies have not strongly supported an association between pesticide exposure and breast cancer. However, few previous studies had the ability to assess specific time periods of exposure. Studies that relied on adult serum levels of metabolites of organochlorine pesticides may not accurately reflect exposure during developmental periods. Furthermore, exposure assessment often occurred after diagnosis and key tumor characteristics, such as hormone receptor status, have rarely been available to evaluate tumor subtype-specific associations. We examined the association between pesticide exposure during childhood and adolescence and breast cancer risk in the prospective Sister Study cohort (N = 50,884 women) to assess this relation by tumor subtype.Methods: During an average 5-year follow-up, 2,134 incident invasive and in situ breast cancer diagnoses were identified. Residential and farm exposure to pesticides were self-reported at study enrollment during standardized interviews. Multivariable hazard ratios and 95% confidence intervals for breast cancer risk were calculated with Cox proportional hazards regression.Results: HRs were near null for the association between childhood/adolescent pesticide exposure and breast cancer risk overall or among ER+/PR+ invasive tumors. However, among women who were ages 0-18 before the ban of dichlordiphenyltrichloroethane in the US, exposure to fogger trucks or planes was associated with a hazard ratio = 1.3 for premenopausal breast cancer (95% confidence interval: 0.92, 1.7).Conclusion: These findings do not support an overall association between childhood and adolescent pesticide exposure and breast cancer risk. However, modest increases in breast cancer risk were associated with acute events in a subgroup of young women. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study that determined if the premenopausal bilateral oophorectomy's protective effect on breast cancer risk is mitigated by the use of estrogen therapy after surgery. The study showed a 14 percent increase in breast cancer risk among women using estrogens after total abdominal hysterectomy with bilateral salpingo-oophorectomy (TAHBSO). It concludes that unopposed use of estrogen does not negate breast cancer risk reduction associated with oophorectomy.

Background: Early life risk factors for breast cancer have been investigated in relation to hormonal, nutritional, infectious, and genetic hypotheses. Recent studies have also considered potential health effects associated with exposure to environmental contaminants in breastmilk.Methods: We analyzed data from a population-based case-control study of women living in Wisconsin. Cases (n = 2016) had an incident diagnosis of invasive breast cancer in 2002-2006 reported to the statewide tumor registry. Controls (n = 1960) of similar ages were randomly selected from driver's license lists. Risk-factor information was collected during structured telephone interviews. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated from multivariable logistic regression.Results: In multivariable models, maternal age and birth order were not associated with breast cancer risk in the full study population. The odds ratio for breast cancer risk associated with having been breast-fed in infancy was 0.83 (95% CI = 0.72-0.96). In analyses restricted to breast-fed women, maternal age associations with breast cancer were null (P = 0.2). Increasing maternal age was negatively associated with breast cancer risk among women who were not breast-fed; the odds ratio for breast cancer associated with each 5-year increase in maternal age was 0.90 (0.82-1.00). Higher birth order was inversely associated with breast cancer risk among breast-fed women (for women with 3 or more older siblings compared with first-born women, OR = 0.58 [CI = 0.39-0.86]) but not among nonbreast-fed women (1.13 [0.81-1.57]).Conclusion: These findings suggest that early life risk factor associations for breast cancer may differ according to breast-feeding status in infancy. [ABSTRACT FROM AUTHOR]

Although the associations with cigarette smoking have been explored extensively for invasive breast cancer, the relation to in situ cancer has not previously been examined in depth.We analyzed data from a population-based case-control study of women living in Wisconsin, Massachusetts, and New Hampshire. Eligible cases of incident breast carcinoma in situ were reported to statewide registries in 1997-2001 (n = 1878); similarly aged controls (n = 8041) were randomly selected from population lists. Smoking history and other risk factor information were collected through structured telephone interviews. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated from logistic regression models adjusting for potential confounders.In multivariate models, the OR for breast carcinoma in situ among current smokers was 0.8, compared with never-smokers (95% CI = 0.7-1.0). Risk estimates increased towards the null with greater time since smoking cessation. Odds ratios were also less than 1.0 among women who initiated smoking in adolescence (OR = 0.8) or after a full-term birth (OR = 0.7), relative to women who never smoked. The reduced odds ratios associated with current smoking were strongest among women with annual screening mammograms (OR = 0.7; 95% CI = 0.6-0.9). Odds ratios were not less than 1.0 among current smokers without a recent screening mammogram (1.3; 0.9-2.0).Our findings suggest an inverse association between current smoking and risk of breast carcinoma in situ among women undergoing breast cancer screening. [ABSTRACT FROM AUTHOR]