Percentage of sarcomatoid histology is associated with survival in renal cell carcinoma: Stratification and implications by clinical metastatic stage.

ABSTRACT

PURPOSE: Sarcomatoid dedifferentiation in renal cell carcinoma (RCC) represents an aggressive histology where degree of sarcomatoid histology (SH) may impact prognosis for cM0 and cM1 patients. We aimed to evaluate the association of percentage of SH with survival. MATERIALS AND METHODS: Patients ≥18 years old diagnosed with RCC with any degree of SH after nephrectomy were included (2005-2020) from a single-center. Associations of degree of SH and cM stage with overall survival (OS) and recurrence-free survival (RFS) were evaluated by Kaplan-Meier curves and Cox proportional hazards regression. RESULTS: One hundred twenty-eight patients were included with 80 (62.5%) cM0 and 48 (37.5%) cM1. cM1 patients were more likely to be male with higher clinical T stage (P = 0.001) than cM0, but a similar proportion had ≥20% SH (47.9% vs. 42.5%, P = 0.55). With median 19.4 months follow-up, SH was associated with worse OS per 10% increase (hazard ratio [HR] 1.12 [95% confidence interval {CI} 1.03-1.23], P = 0.009) and a ≥20% cutoff (HR 2.87 [95% CI 1.27-6.47], P = 0.01). Patients with cM0 disease and <20% SH had better 2-year OS (81.4%) compared to cM0 and ≥20% SH (44.8%) or cM1 patients who received nephrectomy (54.8%). Tumor size was also an independent predictor. Sites of distant metastasis and lines of therapy were similar for metachronous and synchronous patients. SH stratified 2-year RFS (cM0 70.2% for <20% SH vs. 32.1% for ≥20% SH). CONCLUSIONS: SH in RCC is independently associated with OS and RFS. Patients who are cM0 with any SH may be candidates for adjuvant immunotherapy while those with ≥20% SH likely carry micrometastatic disease and should receive closer surveillance.