Body Mass Index and Prognosis of Metastatic Breast Cancer Patients Receiving First-Line Chemotherapy

Abstract

The effect of body mass index (BMI) on the prognosis of metastatic breast cancer (MBC) has not been explored so far. The relationship between BMI (kg/m(2)) and progression-free survival (PFS) or overall survival (OS) was assessed in 489 patients with MBC enrolled in three clinical trials of first-line chemotherapy. World Health Organization BMI categories were used: normal, 18.5-24.9 kg/m(2); overweight, 25-29.9 kg/m(2); and obese, 30+ kg/m(2). Univariate PFS and OS curves were estimated; multivariate Cox analysis was conducted adjusting for age, menopausal status, performance status (PS), hormonal status and site, and number of metastases. Overall, 39.9% of the patients were normal or underweight, 37.8% were overweight, and 22.3% were obese. Median age was 57 years (range 25-73); median PS was 0. Median PFS was 10.9 months [interquartile range (IQR) 5.5 to 19.9] in normal weight women, 13.0 months (IQR 7.8 to 23.7) in overweight, and 12.2 (IQR 7.1 to 23.0) in obese women, P = 0.17. Median OS was 32.0 months [95% confidence interval (CI), 14.5-88.3] versus 33.2 months (95% CI, 19.4-81.1) and 30.7 (95% CI, 17.6-50.8), respectively. In multivariate analyses, no statistically significant association between BMI category and PFS or OS was observed. In this study, BMI was not associated with the outcome of patients with MBC treated with first-line chemotherapy. In the absence of any evidence in support of a prognostic role of obesity in patients with MBC treated with chemotherapy, dietary restrictions, medical interventions aimed at reducing BMI/insulin resistance, or specific anticancer treatment strategies do not seem to be appropriate.