62: Body composition radiodensities at diagnosis may be non-invasive proxies for tumor aggressiveness and poor prognosis in non-metastatic clear cell renal cell carcinoma (ccRCC): The Resolve Study.

Background: Pre-surgical body composition may be related to tumor characteristics and prognosis in non-metastatic ccRCC, but has not been comprehensively explored.

Methods: The Resolve Cohort includes 1239 non-metastatic ccRCC patients who underwent nephrectomy at Memorial Sloan Kettering Cancer Center between 2000-2020. Skeletal muscle, visceral adipose, and subcutaneous adipose tissue cross-sectional area indices (SMI, VATI, SATI respectively; cm2/m2), and radiodensities (SMD, VATD, SATD respectively; Hounsfield Units [HU]) were assessed from pre-surgical computed tomography (CT) scans at the third lumbar vertebrae. Tumor stage and grade, and patient characteristics were assessed at nephrectomy. Overall (OS) and disease-free survival (DFS) were determined through March 2023. Age and sex-adjusted odds ratios (OR) and 95% confidence intervals between body composition and tumor characteristics were estimated with logistic regression. Adjusted hazard ratios (HR) between body composition and survival outcomes were estimated with Cox regression.

Results: The cohort was predominantly male (69%), white (89%), and had a median age of 58. The proportion of patients presenting with advanced stage and high-grade disease were 31% and 51%, respectively. Lower SMD (i.e. fat infiltration; OR per 8.4 HU decrease: 1.61 [1.34-1.93]) but greater VATD (i.e. lipid depletion; OR per 7.22 HU increase: 1.45 [1.22-1.74]) were associated with advanced stage. The same patterns were found for high grade. Lower SMD was also associated with OS, but only among early-stage (HR: 1.42 [1.06-1.90]), not late-stage patients (HR: 0.90 [0.67-1.20]; p-interaction: 0.03). SMD was similarly related to DFS, as was greater SATD (i.e., lipid depletion; early stage, per 7.2 HU increase HR: 1.40 [1.08-1.80]; late-stage HR: 0.92 [0.71-1.18]; p-interaction: 0.02).

Conclusions: Non-metastatic ccRCC patients presenting with lipid infiltrated skeletal muscle or lipid depleted adipose tissue harbored higher stage and grade tumors, and experienced worse survival. Body composition may be a non-invasive pre-surgical marker of tumor aggressiveness and prognosis in ccRCC patients.