The prognostic impact of BMI in patients with HR+/HER2- advanced breast cancer: a study of the SONABRE registry

Abstract

Abstract Purpose This study determines the prognostic impact of body mass index (BMI) in patients with hormone receptor-positive/human epidermal growth factor receptor-2-negative (HR+/HER2-) advanced (i.e. metastatic) breast cancer (ABC). Methods All patients diagnosed with HR+/HER2- ABC who received endocrine therapy with or without a cyclin-dependent kinase (CDK) 4/6 inhibitor as first-given systemic therapy between 2007 and 2020 in the Netherlands were identified from the Southeast Netherlands Advanced Breast Cancer (SONABRE) registry (NCT03577197). Patients with a recorded BMI were categorised as underweight (<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), or obese (≥30 kg/m2). Overall survival (OS) and progression-free survival (PFS) were compared between BMI classes using multivariable Cox regression analyses. Results This study included 1,456 patients, of whom 35 were underweight, 580 normal weight, 479 overweight, and 362 obese. No differences in OS were observed between normal weight patients and respectively overweight (HR=0.99; 95% CI: 0.85-1.16) and obese patients (HR=1.04; 95% CI: 0.88-1.24). However, the OS of underweight patients (HR=1.45; 95% CI: 0.97-2.15) tended to be worse than the OS of normal weight patients. When compared with normal weight patients, the PFS was similar in underweight (HR=1.05; 95% CI: 0.73-1.51), overweight (HR=0.90; 95% CI: 0.79-1.03), and obese patients (HR=0.88; 95% CI: 0.76-1.02). Conclusion In this study among 1,456 patients with HR+/HER2- ABC, overweight and obesity were prevalent, whereas underweight was uncommon. When compared with normal weight, overweight and obesity were not associated with either OS or PFS. However, underweight seemed to be an adverse prognostic factor for OS.