Abortions and breast cancer risk in premenopausal and postmenopausal women in Jiangsu Province of China.

To evaluate the relationship between abortions and risk of breast cancer, we conducted a case-control study with 669 cases and 682 population-based controls in Jiangsu Province of China. A structured questionnaire was used to elicit detailed information. Unconditional logistic regression analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs). The results have revealed that induced abortion was related to increased risk of breast cancer. Premenopausal women who had ≥ 3 times of induced abortion were at increased crude OR (2.41, 95%CI: 1.09-5.42) and adjusted-OR (1.55, 95%CI: 1.15-5.68). Postmenopausal women with a previous induced abortion were at increased crude OR (2.04, 95%CI: 1.48-2.81) and adjusted-OR (1.82, 95%CI: 1.30-2.54), and there was a significant increase trend in OR with number of induced abortions (p for trend: 0.0001). Overall, spontaneous abortion did not significantly alter the risk of breast cancer, but postmenopausal women who had history of spontaneous abortion were at increased OR. These results suggested that relationship between breast cancer and abortions may depend on menopausal status and induced abortion may played an important role in the development of breast cancer in Jiangsu' women of China.