Baglia ML, et al. - Researchers used conditional logistic regression to assess the link between reproductive and menopausal factors and risk of developing a second primary breast cancer among women with a previous in situ breast cancer in this population-based nested case–control study including 552 cases and 1,032 individually matched controls. They found that, among women with a previous in situ breast cancer, those with older age at menarche were at risk of developing second primary breast cancer, whereas a decreased risk was observed in those who had breastfeeding for > 12 months. For other reproductive or menopausal factors assessed, no associations were found. A role of reproductive factors was suggested in development of a second primary breast cancer after diagnosis of in situ breast carcinoma.