Does postoperative radiation therapy impact survival in non-metastatic sarcomatoid renal cell carcinoma? A SEER-based study.

Introduction: The effect of adjuvant radiation therapy on survival in sarcomatoid renal cell carcinoma (sRCC) with no evidence of distant metastasis remains unclear.
Methods: Subjects diagnosed with non-metastatic sRCC were identified using the Surveillance Epidemiology and End Results (SEER) (2004-2012) database and divided into groups based on their surgical treatment (ST): no surgery or radiation therapy (NSR); partial nephrectomy (PNE); radical nephrectomy with ureterectomy and bladder cuff resection (RNE + UE + BLAD); and radical nephrectomy (RNE). Certain radical nephrectomy cases also received adjuvant external-beam radiation therapy (RNE + RAD). The Kaplan-Meier method was used to estimate overall survival (OS). A multivariable competing risks regression analysis was used to calculate disease-specific survival (DSS) probability and to determine factors associated with cause-specific mortality (CSM).
Results: A total of 408 patients were included in this study. The 5-year OS and predicted DSS were significantly higher in the patients who underwent STs (i.e., PNE, RNE + UE + BLAD, RNE, and RNE + RAD) (20.1-54.0 and 20.1-59.9 %, respectively) than in the NSR group (9.0 and 11.6 %, respectively) (P < 0.001). ST was independently associated with a decreased CSM (P < 0.0001). No significant differences in OS or the 1-, 3-, or 5-year DSS probabilities between the RNE and RNE + RAD groups were observed. RNE + RAD was not significantly associated with a decrease in 1-year CSM [subhazard ratio (SHR) 0.95; 95 % CI 0.23-3.96; P = 0.947].
Conclusions: Adjuvant external-beam radiation therapy did not increase OS in non-metastatic sRCC patients.