Decreased Skeletal Muscle Mass is Associated with an Increased Risk of Mortality after Radical Nephrectomy for Localized Renal Cell Cancer

Purpose We evaluate the association between severe skeletal muscle deficiency or sarcopenia, and disease progression, cancer specific mortality and all cause mortality in patients with localized renal cell carcinoma treated with radical nephrectomy. Materials and Methods The baseline lumbar skeletal muscle index of 387 patients treated with radical nephrectomy for nonmetastatic renal cell carcinoma between 2000 and 2010 was measured on preoperative computerized tomography. Sarcopenia was classified according to gender specific consensus definitions as male - skeletal muscle index less than 55 cm²/m² and female - skeletal muscle index less than 39 cm²/m². Progression-free, cancer specific and overall survival was estimated with the Kaplan-Meier method. Associations with progression, cancer specific mortality and all cause mortality were summarized with hazard ratios. Results Of 387 patients 180 (47%) had sarcopenia. Patients with sarcopenia were older, more likely to be male (77% vs 56%, p <0.001), to have a smoking history (67% vs 55%, p=0.02), and to have nuclear grade 3 or greater disease (67% vs 60%, p=0.05), but were otherwise similar to patients without sarcopenia. Median postoperative followup was 7.2 years. Patients with sarcopenia had inferior 5-year cancer specific survival (79% vs 85%, p=0.05) compared to those without sarcopenia, as well as significantly worse 5-year overall survival (65% vs 74%, p= 0.005). As a continuous variable, increasing skeletal muscle index was linearly associated with a decreased risk of cancer specific mortality and all cause mortality. Moreover, on multivariable analysis sarcopenia was associated with increased cancer specific mortality (HR 1.70, p=0.047) and all cause mortality (HR 1.48, p=0.039). Conclusions Sarcopenia is independently associated with cancer specific mortality and all cause mortality after radical nephrectomy for renal cell carcinoma. These findings underscore the importance of assessing skeletal muscle index for risk stratification, patient counseling and treatment planning.