Abortion and breast cancer: case-control study

Aims and background. The aim of the present study was to examine if certain aspects of a woman's experience of abortion might be associated with the risk of breast cancer. Methods and study design. The case-control study was conducted in Kragujevac (Serbia) during the period 2004-2005. The case group (191 women) consisted of patients with newly diagnosed first primary breast cancer, which was histologically confirmed. The control group (191 women), individually matched by age (+/- 2 years), hospital admittance and place of residence (rural/urban) to the respective cases, was selected from female patients admitted for other diseases. The analysis was restricted to parous women (168 cases and 171 controls). Results. Breast cancer risk was reduced among women who had a history of any abortion (adjusted OR, 0.46; 95% CI, 0.24-0.88). The protective effect was found for both induced abortion (adjusted OR, 0.47; 95% CI, 0.25-0.90) and spontaneous abortion (adjusted OR, 0.31; 95% CI, 0.10-0.98). It seems that these associations did not depend on the number of abortions, age at first abortion, or gestational age at first aborted pregnancy. Conclusions. Our study suggests that even short pregnancies ending in abortion add to the protection against breast cancer.