The Role of Body Mass Index in Determining the Efficacy of Nivolumab for Patients with Advanced Non-Small Cell Lung Cancer.

BACKGROUND Non-small cell lung cancer (NSCLC) comprises 85% of lung cancers with poor prognosis. Immune checkpoint inhibitors (ICIs), particularly nivolumab, show survival benefits in advanced NSCLC. The effect of body mass index (BMI) on immunotherapy outcomes remains controversial. This study investigated the relationship between BMI and treatment outcomes in advanced NSCLC patients treated with nivolumab monotherapy. MATERIAL AND METHODS A retrospective analysis at Aydın Adnan Menderes University included 300 metastatic NSCLC patients treated with nivolumab between January 2020 and March 2025. Patients under age 18 years, lacking pathology confirmation, receiving combination therapies, or with BMI <18.5, were excluded. The primary endpoint was overall survival (OS). Secondary endpoints were progression-free survival (PFS), treatment response, and toxicity. BMI was categorized as <25 kg/m² and ≥25 kg/m². Survival outcomes were analyzed using Kaplan-Meier and Cox regression analyses. RESULTS Of 300 patients, 53.3% had BMI <25 and 46.7% had BMI ³25. Median OS and PFS were 8.76 and 3.63 months, respectively, with no significant differences between BMI groups (p>0.05). PD-L1 expression≥50% was associated with reduced progression risk. ECOG PS ≥2, age >65, and liver metastases negatively impacted survival. An increased number of nivolumab cycles improved OS and PFS. The objective response rate was 31.6%. Common adverse events were fatigue (25%), nausea (23.7%), and hypothyroidism (18%), without BMI-related variation. CONCLUSIONS The study found no evidence supporting BMI as a prognostic factor for OS or PFS in advanced NSCLC patients treated with nivolumab. ECOG PS ≥2 and older age were poor prognosis indicators. BMI should be evaluated as a continuous variable. Further studies are needed to clarify obesity's role in immunotherapy responses.