Outcomes of patients (pts) with renal cell carcinoma and sarcomatoid dedifferentiation (sRCC) treated with nephrectomy (Nx) and systemic therapies (T) over three decades: The MD Anderson Cancer Center (MDACC) experience.

Abstract

534 Background: Pts with sRCC historically have had a poor prognosis. We determined the overall survival (OS) and prognostic factors of pts treated with Nx and T in the cytokine and targeted therapy eras. Methods: This is a retrospective study of pts with sRCC who had Nx and received T at MDACC in the cytokine era (1987-2005) or the targeted therapy era (2006-2015). OS was measured from time of diagnosis until death of any cause or last follow-up. OS times were estimated by Kaplan-Meier plots and were compared using the log-rank test. Cox regression models were used to determine the association of covariables with OS. Results: Among 199 pts with sRCC (80.9% clear-cell) identified, 167 pts (83.9%) have died at a median follow-up of 8.8 years (median OS 16.5 months; 95% CI: 15.2, 20.9). The 1-year, 2-year, and 5-year OS rates were 67%, 38%, and 14%, respectively. There was no significant difference in OS between pts with clear-cell vs. those with non-clear cell histology. Pts with metastatic disease at initial diagnosis had a significantly shorter OS compared with pts with localized disease (median 12.1 months vs. 23.3 months; p=0.0064). Biopsy of the primary tumor or a metastatic site was able to detect the presence of sarcomatoid features in only 7% of cases. The % of sarcomatoid component (<10%, 10-40%, >40%) in the primary tumor did not impact OS. For first-line (1L) therapy, 77 pts (39%) received targeted agents, and 122 pts (61%) received chemotherapy or cytokines. Although a significant improvement in OS rate was observed at 1 year for pts treated in the targeted therapy era (p = 0.011), this effect was attenuated at year 2 and disappeared at years 3-5 after diagnosis. Conclusions: Pts with sRCC still have poor prognosis with no clear long-term benefit of targeted therapy, underscoring the need to develop more effective systemic therapies for these patients.