The Diverse Distribution of Risk Factors between Breast Cancer Subtypes of ER, PR and HER2: A 10-Year Retrospective Multi-Center Study in China

INTRODUCTION Hormone receptors, human epidermal growth factor receptor 2 and some risk factors determine therapies and prognosis of breast cancer. The risk factors distributed differently between patients with receptors. This study aimed to investigate the distribution of risk factors between subtypes of breast cancer by the 3 receptors in Chinese native women with a large sample size. METHODS The multi-center study analyzed 4211 patient medical records from 1999 to 2008 in 7 regions of China. Data on patients' demographic information, risk factors (menopausal status, parity, body mass index) and receptor statuses were extracted. Breast cancer subtypes included ER (+/-), PR (+/-), HER2 (+/-), 4 ER/PR and 4 molecular subtypes. Wilcoxon and Chi-square tests were used to estimate the difference. The unconditional logistic regression model was used for analysis, and presented p-value after Bonferroni correction in the results. RESULTS Compared to patients with negative progesterone receptor, the positive patients were younger at diagnosis, and reported less likely in postmenopausal status and lower parity (p<0.05). Comparing with the subtype of ER+/PR+, ER+/PR- subtype were 4-year older at diagnosis (OR = 1.02), more likely to be postmenopausal (OR = 1.91) and more likely to have >1 parity (OR = 1.36) (p<0.05); ER-/PR- subtype were more likely to be postmenopausal (OR = 1.33) and have >1 parity (OR = 1.19) (p<0.05). In contrast to the luminal A subtype, triple negative subtype had a lower BMI (OR = 0.96) and ORs of overweight and obesity reduced by >20% (p<0.05). CONCLUSION In this study, it was found that Chinese female patients did have statistically significant differences of age, menopausal status, parity and body mass index between breast cancer subtypes. Studies are warranted to further investigate the risk factors between subtypes, which was meaningful for prevention and treatment among Chinese females.