Impact of Body Mass Index on Survival Outcome Among Women With Early Stage Triple-Negative Breast Cancer

The aim of this retrospective study was to investigate the prognostic impact of obesity among women with early stage triple receptor-negative breast cancer (TN), a subtype of breast cancer known to be associated with poor prognosis. The results of our study indicate that women with TN disease have a poor prognostic outcome regardless of body mass index (BMI; computed by dividing the weight in kilograms by the square of the height in meters) category. As such, the results of this study indicate that obesity does not function as a prognostic indicator among patients with TN disease. Background: The aim of this retrospective study was to examine the prognostic impact of obesity among women with early stage triple receptor-negative breast cancer (TN), a subtype of breast cancer known to be associated with poor prognosis. Patients and Methods: Women with stage I-III TN breast cancer diagnosed between 1990 and 2010 were identified. The cohort was divided into 3 groups according to BMI: normal or underweight (BMI < 25), overweight (BMI 25-29.9), and obese (BMI >= 30). Distant disease-free survival (DDFS) was estimated using the Kaplan-Meier product limit method and compared across groups using log rank statistic. Cox proportional hazards models were then used to determine the association of DDFS and BMI after adjusting for patient and tumor characteristics. Results: Of 2311 patients, we identified 794(34.3%), 692 (30%), and 825 (35.7%), who had BMI of < 25, 25 to 29.9, and >= 30, respectively. Median follow-up was 39 months (range, 1-233 months). Five-year DDFS was 61%, 62%, and 62% among patients with BMI of <25, 25 to 29.9, and >= 30, respectively. On multivariate analysis, compared with patients with BMI <25, patients with BMI 25-29.9 (hazard ratio [HR] = 1.04; 95% confidence interval [CI], 87-1.25; P = .66) and those with BMI >= 30 (HR = 0.99; 95% CI, 83-1.18; P = .89) did not have a significant increase in risk of distant metastases. When the models were stratified by menopausal status similar results were obtained. Conclusions: Patients with TN disease have a poor prognostic outcome regardless of BMI category. As such, the results of this study indicate that obesity does not function as a prognostic indicator among patients with TN disease.