Age-dependent prognostic value of body mass index for non-metastatic clear cell renal cell carcinoma: A large multicenter retrospective analysis

Background and Objectives: The prognostic value of obesity is unestablished for renal cell carcinoma. We assessed the age-dependent prognostic value of body mass index (BMI) in a large multicenter cohort of patients with non-metastatic clear cell renal cell carcinoma (nm-cRCC). Methods: This study evaluated 2092 patients with nm-cRCC who underwent surgery with curative intent at five Korean institutions between 2001 and 2014. Results: There was no significant difference in BMI between the young (<45 years) and older patients (≥45 years) (P = 0.398). Among older patients, high BMI (≥25 kg/m²) was associated with better 5-year rates of recurrence-free survival (RFS) and cancer-specific survival (CSS) (P = 0.003 and 0.004, respectively), and multivariate analysis confirmed that high BMI was independently associated with better RFS and CSS (RFS hazard ratio [HR]: 0.617, P = 0.005; CSS HR: 0.588, P = 0.024). However, among young patients, there were no significant BMI-related differences in the 5-year RFS and CSS rates (P = 0.457 and 0.420, respectively), and high BMI was not independently associated with RFS or CSS (P = 0.822 and 0.749, respectively). Conclusions: Among patients with nm-cRCC, high BMI was associated with a favorable prognosis among older patients but not among young patients. Therefore, the relationship between obesity and nm-cRCC prognosis might vary according to age.