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.