Body Composition in Relation to Clinical Outcomes in Renal Cell Cancer: A Systematic Review and Meta-analysis

CONTEXT: Several studies suggest that body composition (ie, body proportions of muscle and fat defined by computed tomography) is associated with clinical outcomes of several cancer types, including renal cell cancer (RCC). OBJECTIVE: To conduct a systematic review and meta-analysis of the evidence on body composition in relation to clinical outcomes in RCC. EVIDENCE ACQUISITION: Literature was reviewed through October 2016 using PubMed and Embase. We included studies investigating computed tomography-measured cross-sectional areas of visceral adipose tissue (VAT), perinephric fat, subcutaneous adipose tissue (SAT), skeletal muscle index (SMI), and skeletal muscle radiodensity (SMD) in relation to perioperative outcomes, treatment toxicity, and survival in RCC patients. EVIDENCE SYNTHESIS: We included 28 studies with a total of 6608 patients. Binary classification of body composition was used in most studies. In metastatic RCC (mRCC) patients treated with antiangiogenic drugs, dose-limiting toxicity was more frequent in patients with low versus high SMI (four studies, risk difference = 16%, 95% confidence interval [CI]: 2-31%, p = 0.03, I(2) = 26%). Low versus high SMI (six studies, hazard ratio = 1.48, 95% CI: 1.08-2.03, p = 0.02, I(2) = 28%) and SMD (four studies, HR = 1.56, 95% CI: 1.20-2.03, p = 0.0008, I(2) = 0%) were associated with an increased risk of overall mortality in mRCC. Low versus high VAT and perinephric fat were not consistently associated with perioperative outcomes and survival. No associations for SAT were found. CONCLUSIONS: Low SMI is associated with increased dose-limiting toxicity, and low SMI and SMD are associated with increased overall mortality in mRCC. The association of VAT, perinephric fat, and SAT with clinical outcomes needs further investigation, also in localized RCC. PATIENT SUMMARY: We reviewed studies assessing the association of body composition with clinical outcomes in renal cell cancer. We demonstrated higher risk of dose-limiting toxicity and overall mortality for metastatic renal cell cancer patients with low versus high skeletal muscle index or skeletal muscle radiodensity, but observed inconsistent associations with visceral adipose tissue and perinephric fat