Risk Factors of Breast Cancer in China: A Case-Control Study

  Objective  To screen the risk factors associated with breast cancer among Chinese women, with an attempt to provide evidence for the evaluation of breast cancer risks among Chinese women on an individual level.

  Methods  A case-control study on 416 breast cancer patients and 1156 age-and region-matched controls was conducted in 14 hospitals in 8 provinces/municipalities of China.Conditional logistic regression was applied to analyze the association between risk factors and breast cancer.

  Results  The risk factors of breast cancer among Chinese women included higher body mass index(BMI ≥ 24)(OR=4.07, 95%CI:2.98-5.55), history of benign breast disease biopsy(OR=1.68, 95%CI:1.19-2.38), age of menarche ≥ 14 years(OR=1.41, 95%CI:1.07-1.87), psychological depression(for grade 1-4, OR=2.15, 95% CI:1.26-3.66;for grade 5-9, OR=3.48, 95% CI:2.03-5.95), menostasia(OR=2.22, 95% CI:1.50-3.28), family history of breast cancer(OR=1.72, 95%CI:1.15-2.58), and family history of cancer other than breast cancer(OR=1.55, 95%CI:1.22~1.98)(all P < 0.05 when compared between the 416 breast cancer patients and 1156 controls).Although use of oral contraceptives(OC)(OR=1.59, 95% CI:0.83-3.05)was associated with an increased risk of breast cancer, the difference was not statistically significant(P > 0.05).

  Conclusions  Many risk factors including BMI ≥ 24, history of benign breast disease biopsy, age of menarche ≥ 14 years, psychological depression, menostasia, family history of breast cancer, and family history of cancer other than breast cancer may contribute to breast cancer among Chinese women.This research provides a basis for the individualized evaluation of risks of breast cancer and the population-based interventions in China.