In summary, our study provides a comprehensive assessment of the relationship between alcohol intake and breast cancer risk in terms of timing, frequency, quantity, and types of alcohol in a large prospective cohort with detailed information on breast cancer risk factors. We did find an increased risk at low levels of use, but the risk was quite small. We found independent associations with drinking in early and later adult life with the strongest associations seen with cumulative drinking assessed over multiple decades. Our results highlight the importance of considering lifetime exposure when evaluating the impact of alcohol, and probably other dietary factors, on the carcinogenesis process. However, an individual will need to weigh the modest risks of light to moderate alcohol use on breast cancer development against the beneficial effects on cardiovascular disease44 to make the best personal choice regarding alcohol consumption.
