To investigate the association between induced abortion, miscarriage, and breast cancer risk using a large Finnish registry-based case-control study.
Key Findings:
No increased risk of breast cancer associated with induced abortion or miscarriage in either premenopausal or postmenopausal women.
Odds ratio for breast cancer in women under 50 with a history of induced abortion was 1.00; for those 50 and older, it was 0.95.
No significant variation in breast cancer risk based on the number of abortions or miscarriages or the age at first occurrence.
A potential slight increase in postmenopausal breast cancer risk was noted for women whose first abortion occurred before age 20, but this may be a chance finding.
Interpretation:
The study provides high-quality evidence that induced abortion and miscarriage do not increase breast cancer risk, countering ongoing misinformation.
Limitations:
The subgroup finding regarding early abortion and breast cancer risk may not be conclusive due to the long interval between abortion and diagnosis.
Conclusion:
Induced abortion and miscarriage are not risk factors for breast cancer, which may help reassure patients in clinical counseling settings.
