Background: Data from the Shanghai Breast Cancer Study were analyzed to evaluate the relationship between benign breast disease (BBD) and breast cancer among Chinese women with a self-report of physician-diagnosed BBD.
Methods: Study participants consisted of 3,452 breast cancer cases and 3,474 population controls recruited by the Shanghai Breast Cancer Study. In-person interviews were conducted to collect information on demographics and suspected risk factors for breast cancer, including a detailed history of BBD. Unconditional logistic regression was used to derive adjusted odds ratios (OR(adj)) and 95% confidence intervals (CI) for the association between self-reported BBD and breast cancer.
Results: Women with breast cancer were significantly more likely to have a self-reported history of BBD including lobular proliferation (OR(adj) = 1.6; 95% CI 1.4-1.8), fibroadenoma (OR(adj) = 1.9; 95% CI 1.6-2.3), and other BBD (OR(adj) = 1.6; 95% CI 1.3-2.1). Breast cancer risk was lower for surgically treated fibroadenoma as compared to non-surgically treated and higher for other BBDs that were surgically treated versus non-surgically treated.
Conclusions: Our results suggest that personal history of BBD is associated with an increased risk of future breast cancer among women in China. Surgical intervention for fibroadenoma may reduce the risk.