History of benign breast disease and risk of breast cancer among women in China: a case-control study.

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.