Breast cancer risk factors in cases and controls.

Cases (n = 353) and controls (n = 730) significantly differed regarding presence of 1st degree relatives with breast cancer. There was also a trend towards increased risk for women with older age at first live birth and late menopause. *numbers do not add up to total numbers due to missing values for the following covariates (numbers of missing values in cases/controls): age at menarche (28/50), age at 1st childbirth (7/26), age at menopause (24/44), BMI at age 20 (12/63), ever breastfed (5/18), ever use of hormone replacement therapy (28/39); ** indicates P-values <0.05; ***adjusted for other variables in table and taking care of missing values by multiple imputation; OR = odds ratio; CI = confidence interval, BMI body mass index.