1. Between 1990 and 1992, a group of 110,792 Japanese men and women completed a self-administered questionnaire that included demographic characteristics, tobacco and alcohol use, coffee consumption, participation in sports or exercise, female reproductive history, hormone use and dietary habits. The women were followed for breast cancer incidence through December 31, 1997. Cox proportional hazards models were used to calculate relative risks and 95% confidence intervals for breast cancer incidence and any association with alcohol consumption.