Association of BMI, body composition and outcomes in Chinese patients with metastatic renal cell carcinoma treated with immunotherapy: A retrospective, multicohort analysis.

Abstract

e16563 Association of BMI, body composition and outcomes in Chinese patients with metastatic renal cell carcinoma treated with immunotherapy: a retrospective, multicohort analysis. Background: Obesity (body-mass index [BMI] ≥30 kg/m) is associated with a higher risk of developing clear cell renal cell carcinoma (RCC) but, paradoxically, obesity is also associated with better outcome in renal cell carcinoma (RCC) patients treated with immunotherapy. Whether BMI associate outcomes in Chinese RCC patients treated with immunotherapy considering Asian population has a lower BMI? In this study, we aimed to investigate the relationship between BMI, body composition and outcomes of Chinese patients with RCC treated with immunotherapy. Methods: We evaluated clinical data of metastatic RCC patients treated with immunotherapy from five major centers in China. Despite using the Chinese standard, only 6 people met the obese standard (BMI ≥28 kg/m, as per WHO's BMI categories), so we divided the patients into high BMI gourps (BMI ≥24.0 kg/m), and normal weight groups (BMI 18.5-23·9 kg/m). We assessed overall survival, defined as the time from treatment initiation to the date of any-cause death or of censoring on the day of the last follow-up, in high BMI patients and in patients with a normal weight. We also investigative the relationship between body composition (skeletal muscle index (SMI = skeletal muscle area/height2), skeletal muscle density (SMD), and subcutaneous adipose distribution index (SADI = subcutaneous adipose tissue area / subcutaneous adipose tissue area + visceral adipose tissue area) of each patient at the third lumbar vertebrae) and overall survival using CT or MRI scan at the treatment initiation. Results: Out of a total of 222 patients, 203 had evaluable CT or MRI radiographs, pretreatment BMI measurements, and overall survival data for analyses, and we excluded 4 (1.7%) underwetight patients, leaving a final cohort of 199 patients from this study for our analyses. There were 79 (39.7%) high BMI patients and 120 (65.3%) normal weight patients. There was no difference in overall survival between the high BMI and normal weight groups (HR:1.36, CI 0.83-2.21). In addition, SMI and SMD were not associated with outcome of patients. Interestingly, although there was no statistical difference, subcutaneous fat was associated with better outcomes, while visceral fat was associated with poor outcomes. Thus, the combination of the two indicators, SADI, showed a significant prognostic correlation after adjustment for International Metastatic RCC Database risk score (aHR:0.314, CI 0.19-0.51). Conclusions: BMI is not a good predictor of the outcome of immunotherapy in Chinese patients with RCC. Evaluation of body composition may be a better tool for predicting prognosis in RCC patients treated with immunotherapy.