Risks of second primary breast and urogenital cancer following female breast cancer in the south of The Netherlands, 1972-2001.

A cohort of 9919 breast cancer patients from the population-based Eindhoven Cancer Registry was followed for vital status and development of second cancer. Person-year analysis was applied to determine the risk of second primary breast or urogenital cancer among breast cancer patients and to assess its correlation with age, treatment and time since the first breast cancer diagnosis. Women with previous breast cancer have an elevated risk of overall second breast or urogenital cancer. The largest relative risk was observed for second breast cancer (SIR (standardised incidence ratio) 3.5; 95% confidence interval (CI) 3.2-3.8) and second ovarian cancer (SIR 1.7; 95% CI 1.2-2.3). The absolute excess risk was highest for second breast cancer (64/10,000 patients/year). However, breast cancer has an inverse relationship to risk of cervical cancer. Changes in behavioural risk factors are important for lowering the risk of second cancer after breast cancer.