Abstract
PURPOSE: To report survival outcomes of patients treated surgically for sarcomatoid-variant renal cell carcinomas (sRCC) and to assess whether the underlying histologic subtype is an independent predictor of outcome. METHODS: One hundred and fifty-one patients underwent surgery at a referral center between 1991 and 2014 and had sRCC in final pathology. Kaplan-Meier curves for metastasis-free survival and cancer-specific survival (CSS) were calculated, and the log-rank test assessed differences between clear cell sRCC and nonclear cell sRCC. Cox regression models were generated to test the prognostic value of histologic subtype. RESULTS: Of 151 patients, 120 (79 %) had clear cell sRCC and 31 (21 %) had nonclear cell sRCC. Ninety-eight (65 %) patients had M0/Mx disease at presentation. Among those M0/Mx patients, metastasis-free survival probabilities were 49 % at 2 years [95 % confidence interval (CI) 38-60] and 39 % at 5 years (95 % CI 28-50), while CSS probabilities were 50 % at 2 years (95 % CI 41-58) and 32 % at 5 years (95 % CI 24-41). There was no significant difference in metastasis-free survival between clear cell and nonclear cell sRCC (p = 0.8). However, patients with nonclear cell sRCC had significantly lower CSS than patients with clear cell sRCC (p = 0.035). In multivariable analyses, nonclear cell sRCC conferred a higher risk of cancer-specific death compared with clear cell sRCC (HR 2.30, 95 % CI 1.38-3.82, p = 0.001). CONCLUSIONS: In a cohort of patients treated surgically, the underlying histologic subtype of sRCC had an impact on CSS. These results present valuable information for individual counseling and patient selection in clinical trials.