OBJECTIVEObesity has been shown to be an indicator of poor prognosis for patients with primary breast cancer. The aim of this study was to clarify the effect of obesity on Chinese women with breast cancer.

METHODSThis is a retrospective analysis of 1699 breast cancer patients. We evaluated the effect of body mass index (BMI) on disease-free survival (DFS) and overall survival (OS) in these patients. BMI was obtained before surgery. Obesity was defined as a BMI ≥ 24. Kaplan-Meier analysis and Log rank test were employed to perform survival analysis. The impact of different characteristics on survival was assessed by using Cox proportional-hazards regression model.

RESULTSIn total 635 (37.4%) patients were obese, while 1 064 (62.6%) were non-obese. Comparing the tumor characteristics in the two groups, the BMI ≥ 24 group showed a higher rate of older age (P < 0.001), postmenopausal status (P < 0.001), increased risk of lymph node metastasis (P = 0.001) and less chances of accepting breast conservation surgery (P = 0.012). The median follow-up time was 16 months, and the estimated 16-months DFS was 98.1% for non-obese and 95.0% for obese patients (P = 0.007), the estimated 16-months OS was 99.4% for non-obese and 98.4% for obese patients (P = 0.004). The multivariate analysis indicated that obesity is an independent prognostic factor for OS and DFS in breast cancer patients.

CONCLUSIONSOur findings suggest that obesity is associated with a poorer outcome in Chinese female patients with breast cancer.