Association of body mass index (BMI) with survival outcomes in patients with metastatic renal cell carcinoma (mRCC).

e16535 Background: Recent data have reported on obesity as a probable protective factor in metastatic RCC (mRCC). Current knowledge and expanding data suggests a higher BMI (overweight and obese patients) have better survival outcomes. We hypothesize that mRCC patients studied at our institution, Emory’s Winship Cancer Institute, will display similar clinical outcome trends. Methods: We conducted a retrospective analysis of patients with mRCC treated at Winship Cancer Institute between 1/1/2018 and 8/31/23. Overall survival (OS) and progression-free survival (PFS) were defined as months from treatment initiation to death or clinical/radiographic progression, respectively. The correlation between BMI and OS/PFS was studied in 399 patients diagnosed with metastatic RCC under systemic therapy. The groups were divided into overweight and obesity (BMI > 25 kg/m2) and underweight or normal (BMI < 25 kg/m2). Univariate (UVA) and multivariate (MVA) analyses were carried out for OS and PFS using Cox proportional hazard model. Results: A total of 401 eligible patients were included with a median follow up of 60 months. Median age was 66 years (range = 18-95), 71% were male, 29% were female, and 81% had clear cell histology. 36% received checkpoint inhibitor (CPI) monotherapy, 28% received combination CPI, and 26% received CPI in combination with tyrosine kinase inhibitor (TKI). 4% received other therapies. Lower BMI (<25) at initiation of systemic therapy was significantly associated with worse OS and PFS (table). Conclusions: Lower BMI at baseline and during therapy was associated with worse clinical outcomes. This helps validate the association between obesity and improved survival, a potential "obesity paradox." Results should be validated in a larger, prospective study to further understand the complex relationship between BMI, lipid metabolism, and clinical outcomes in mRCC. Table: see text