Comparison of oncologic outcomes between sarcomatoid and clear cell renal cell carcinoma

Sarcomatoid renal cell carcinoma (sRCC) is a rare histological subtype that is associated with unfavorable prognosis. We sought to examine the effect of sRCC on cancer-specific mortality (CSM) relative to clear cell renal cell carcinoma (ccRCC), after adjusting for other variables, as well as other-cause mortality (OCM).

We relied on the Surveillance, Epidemiology, and End Results-Medicare database from 2000 to 2009 to identify a cohort of 7916 patients with either sRCC (n = 234) or ccRCC (n = 7682) who received surgery as primary treatment. Patient, tumor, and treatment characteristics were evaluated. Then, 5-year smoothed Poisson regression CSM and OCM estimates were generated for stage-by-stage comparisons between sRCC and ccRCC. A multivariable competing-risks regression model predicting CSM and adjusting for several patient and tumor characteristics, as well as OCM, was finally fitted.

Compared to ccRCC patients, sRCC patients had more advanced and more aggressive disease at diagnosis. Specifically, 48 and 7 % of sRCC and ccRCC patients presented with stage IV disease, respectively (p < 0.001). Overall, 5-year CSM and OCM estimates were 67 and 17 % for sRCC patients and 14 and 19 % for ccRCC patients. In stage-by-stage analyses, sRCC was invariably associated with worse CSM. After adjusting for several characteristics as well as OCM, sRCC was associated with a 3.2 higher risk of CSM compared with ccRCC.

Patients with sRCC are present with more advanced disease. Moreover, sRCC is associated with a higher rate of CSM, even after adjusting for several characteristics and OCM.