The impact of body mass index on the progression-free survival of CDK 4/6 inhibitors in metastatic breast cancer patients

Aim: Endocrine therapy (ET) plus cyclin-dependent kinase (CDK) 4/6 inhibitors is a standard treatment for hormone receptor (HR) positive HER-2-negative metastatic breast cancer patients. In this study, we aimed to investigate the effect of body mass index (BMI) on progression-free survival (PFS) in patients receiving ET plus CDK 4/6 inhibitors. Materials & methods: Patients with metastatic HR-positive breast cancer receiving CDK 4/6 inhibitors were included in the study. A total of 116 patients were retrospectively evaluated. Patients were divided into three groups according to BMI level: normal weight (group 1) 18.5-24.9 kg/m(2), overweight (group 2) 25-29.9 kg/m(2) and obese (group 3): >= 30 kg/m(2). Median follow-up was 10.83 months. Comparisons of PFS and BMI categories were performed by Kaplan-Meier curve and log-rank test. Results: PFS was 9.3 (5.3-13.4) months in normal weight patients and 11.1 (9.7-12.56) months in obese patients and was not reached in overweight patients. This difference was statistically significant (p = 0.02). Conclusion: Low BMI has been shown to have a negative prognostic effect on survival in patients with metastatic breast cancer and overweight patients had a longer PFS.