Impact of body mass index on clinical outcomes in triple-negative breast cancer

BACKGROUND: Obesity is associated with poorer outcomes in patients with hormone receptor-positive breast cancers. This association is not well established for women with triple-negative breast cancers (TNBC). In this study, the prognostic effects of body mass index on clinical outcome were evaluated in patients with TNBC. METHODS: A retrospective study was conducted on 418 patients who were treated between July 1996 and July 2010 for TNBC. Recurrence-free survival (RFS) and overall survival (OS) were evaluated in relation to body mass index (BMI) after controlling for clinically significant variables. RESULTS: One hundred twenty-four patients (29.7%) were normal/underweight (BMI ≤24.9 kg/m), 130 patients (31.1%) were overweight (BMI from 25 to 29.9 kg/m), and 164 patients (39.2%) were obese (BMI ̂¥30 kg/m). At a median follow-up of 37.2 months, there were 105 recurrences (25.1%) and 87 deaths (20.8%). Compared with normal/underweight patients, the multivariate hazard ratio (HR) for RFS was 0.81 (95% confidence interval [CI], 0.49-1.34) for obese patients. Similarly, OS was not associated with BMI category; obese patients had an HR of death of 0.94 (95% CI, 0.54-1.64) compared with normal/underweight patients. A Cox regression analysis identified the receipt of chemotherapy (HR, 0.25; 95% CI, 0.12-0.52), ductal histology (HR, 0.49; 95% CI, 0.25-0.97), stage III disease (HR, 3.5; 95% CI, 1.35-9.06), and increasing tumor size (HR, 1.19; 95% CI, 1.09-1.3) as independent prognostic factors for OS. CONCLUSIONS: No significant relation between obesity and RFS or OS emerged in patients with TNBC after controlling for clinically significant factors.