Abstract RF1-07: Cruciferous vegetable intake, dietary glucosinolate and risk of breast cancer in 2 large prospective studies

Abstract Objective: Cruciferous vegetables provide glucosinolate-derived compounds (e.g., isothiocyanates) that have inhibited breast cancer growth in experimental models, but epidemiologic evidence for a protective role remains limited and inconsistent. Therefore, we examined associations of cruciferous vegetable intake and total and subgroup-specific glucosinolates with breast cancer risk in the Nurses’ Health Study (NHS) and NHSII. Methods: We followed 76,713 women from the NHS [1984-2019] and 92,810 from the NHSII [1991-2019]. Diet was assessed by using validated semiquantitative food-frequency questionnaires at baseline and updated every 4 years during follow-up. We used Cox proportional hazards regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for cumulative average cruciferous vegetable intake—including broccoli, cauliflower, cabbage/coleslaw, Brussels sprouts, and kale, mustard greens, or chard—and for energy-adjusted dietary glucosinolate intake in relation to the risk of invasive breast cancer and its subtypes, using the lowest intake category or quintile as the reference. Results: During 4,500,352 person-years of follow-up, 11,181 incident invasive breast cancer cases were identified across the two cohorts. Higher intake of cruciferous vegetables was associated with a statistically significantly lower breast cancer risk (>1 serving/day vs.