Circulating levels of 25-hydroxyvitamin D and risk of breast cancer: a nested case-control study.

INTRODUCTION: Experimental evidence suggests a protective role for circulating 25-hydroxyvitamin D (25(OH)D) in breast cancer development, but the results of epidemiological studies have been inconsistent. METHODS: We conducted a case-control study nested within two prospective cohorts, the New York University Women's Health Study and the Northern Sweden Mammary Screening Cohort. Blood samples were collected at enrollment, and women were followed up for breast cancer ascertainment. In total, 1,585 incident breast cancer cases were individually-matched to 2,940 controls. Of these subjects, 678 cases and 1,208 controls contributed two repeat blood samples, at least one year apart. Circulating levels of 25(OH)D were measured, and multivariate odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression. RESULTS: No association was observed between circulating levels of 25(OH)D and overall breast cancer risk (multivariate-adjusted model OR = 0.94, 95% CI = 0.76-1.16 for the highest vs. lowest quintile, ptrend = 0.30). The temporal reliability of 25(OH)D measured in repeat blood samples was high (intraclass correlation coefficients for season-adjusted 25(OH)D > 0.70). An inverse association between 25(OH)D levels and breast cancer risk was observed among women who were ≤ 45 years of age (ORQ5-Q1 = 0.48, 95% CI = 0.30-0.79, ptrend = 0.01) or premenopausal at enrollment (ORQ5-Q1 = 0.67, 95% CI = 0.48-0.92, ptrend = 0.03). CONCLUSIONS: Circulating 25(OH)D levels were not associated with breast cancer risk overall, although we could not exclude the possibility of a protective effect in younger women. Recommendations regarding vitamin D supplementation should be based on considerations other than breast cancer prevention.

Consumption of filtered and boiled coffee and the risk of incident cancer: a prospective cohort study.

BACKGROUND: Despite potentially relevant chemical differences between filtered and boiled coffee, this study is the first to investigate consumption in relation to the risk of incident cancer. METHODS: Subjects were from the Västerbotten Intervention Project (64,603 participants, including 3,034 cases), with up to 15 years of follow-up. Hazard ratios (HR) were calculated by multivariate Cox regression. RESULTS: No associations were found for all cancer sites combined, or for prostate or colorectal cancer. For breast cancer, boiled coffee ≥4 versus <1 occasions/day was associated with a reduced risk (HR = 0.52, CI = 0.30-0.88, p (trend) = 0.247). An increased risk of premenopausal and a reduced risk of postmenopausal breast cancer were found for both total (HR(premenopausal) = 1.69, CI = 0.96-2.98, p (trend) = 0.015, HR(postmenopausal) = 0.60, CI = 0.39-0.93, p (trend) = 0.006) and filtered coffee (HR(premenopausal) = 1.76, CI = 1.04-3.00, p (trend) = 0.045, HR(postmenopausal) = 0.52, CI = 0.30-0.88, p (trend) = 0.045). Boiled coffee was positively associated with the risk of respiratory tract cancer (HR = 1.81, CI = 1.06-3.08, p (trend) = 0.084), a finding limited to men. Main results for less common cancer types included total coffee in renal cell cancer (HR = 0.30, CI = 0.11-0.79, p (trend) = 0.009) and boiled coffee in pancreas cancer (HR = 2.51 CI = 1.15-5.50, p (trend) = 0.006). CONCLUSION: These findings demonstrate, for the first time, the potential relevance of brewing method in investigations of coffee consumption and cancer risk, but they must be confirmed in future studies.