Sarcomatoid renal cell carcinoma: Does stage impact survival?

Abstract

693 Background: Sarcomatoid differentiation is associated with poor clinical outcomes and is present in approximately 4% of patients with renal cell carcinoma (sRCC). However, limited studies have evaluated the impact of sarcomatoid differentiation among patients, especially with lower stage pT1−2 disease. Methods: This study evaluated 3,850 patients with RCC who underwent partial or radical nephrectomy between 2000−2017. Patients were divided into four groups for analysis: pT1−2NxMx RCC without sarcomatoid features, pT1−2NxMx sRCC, pT3−4 RCC without sarcomatoid features and pT3−4 sRCC. Clinicopathological outcomes including sex, race, age, primary histology, lymph node involvement and margin status were compared between groups using Chi−squared and T-tests. Overall survival rates were analyzed by constructing Kaplan−Meier curves, p−values were calculated using log−rank tests and fitting Cox proportional hazards models for adjusted analyses. Results: Among 3,850 cases, 168 (4.4%) sRCC patients were identified. Of these, 33 (19.6%) were pT1−2. The mean overall follow up time was 59.9 months. When comparing CSS between groups, survival was poorer in patients with sarcomatoid features regardless of pT stage (p < 0.0001). Of note, CSS was worse in sRCC pT1−2 patients compared to non−sarcomatoid pT3−4 patients. Overall survival (OS) results were similar, with sarcomatoid tumors having worse estimates on survival analysis (p < 0.0001). Conclusions: Patients with pT1−2 sRCC demonstrated worse CSS when compared to pT1-2 and pT3−T4 RCC without sarcomatoid features, regardless of primary histology. Sarcomatoid differentiation in low−stage disease may be a marker of poor oncologic outcomes requiring more vigilant surveillance and possible inclusion in adjuvant therapy trials. Our next step, which is currently ongoing, is to pursue a multi−institutional collaborative effort and establish a larger cohort of sRCC for analysis.