Effect of Body Mass Index on Survival in Breast Cancer Patients According to Subtype, Metabolic Syndrome, and Treatment

Effect of body mass index (BMI) on survival in breast cancer patients has not yet been established. We analyzed disease-free survival (DFS) and overall survival (OS) of 5668 patients who underwent curative surgery for breast cancer according to BMI in several subgroups. BMI >= 25 kg/m(2) was an unfavorable factor for DFS and OS, particularly in patients with luminal subtype disease. Purpose: To investigate the effect of body mass index (BMI) on survival in patients with breast cancer according to tumor subtype, metabolic syndrome, and systemic treatment. Patients and Methods: We identified 5668 patients who underwent curative surgery for breast cancer between 1996 and 2013 from the clinical data of a single institution. Disease-free survival (DFS) and overall survival (OS) were calculated and compared between the patients with BMI >= 25 kg/m(2) and < 25 kg/m(2) in all patients and in specific subgroups, including tumor subtype, metabolic syndrome, and systemic treatment. Results: In all patients, BMI >= 25 kg/m(2) was an unfavorable factor for OS (P= .030) but not for DFS. In the HR+ /HER2(-) subgroup, DFS and OS were longer in patients with BMI < 25 kg/m(2) than >= 25 kg/m(2) (P = .012 and .005, respectively). In patients with more than one metabolic syndrome, BMI was an unfavorable factor for OS (hazard ratio, 2.669; P < .001) Conclusion: BMI- 25 kg/m(2) was an unfavorable survival factor, particularly in patients with HR+ /HER2- breast cancer.