Detection and Diagnosis

Methods:We followed 220,720 women, ages 30 to 60 years, completing a mailed questionnaire at recruitment to the Nigerian-Ethiopian Cohort Study in 2005/2006, through December 2012. We used Cox proportional hazard regression models to estimate relative risk (RR) of breast cancer associated with different measures of smoking initiation, duration, and intensity adjusting for confounding variables. We conducted analyses on the entire study population, among women who had smoked for at least 30 years, among non-drinkers, and separately for each country.