Percentage of sarcomatoid component as a prognostic indicator for survival in renal cell carcinoma with sarcomatoid dedifferentiation.

Objective: Renal cell carcinoma with sarcomatoid dedifferentiation (sRCC) is associated with higher stage of presentation and worse survival. The objective of this study was to examine the clinicopathologic characteristics associated with overall survival (OS), specifically examining the percentage of sarcomatoid component (PSC).
Methods: We reviewed clinicopathologic data for all nephrectomized patients with confirmed sRCC. Histologic slides were rereviewed by dedicated genitourinary pathologists to ascertain PSC. Patient characteristics were tabulated overall and by disease stage. Cutpoints in the PSC providing a meaningful difference in OS were identified by recursive partitioning analysis (RPA). Factors selected included age group, gender, race, clinical stage, tumor histology, presurgical systemic therapy, lymphovascular invasion, and tumor size. The Kaplan-Meier method and log-rank test were used to assess differences in OS.
Results: Among 186 patients with sRCC, 64 (34%) had localized, and 122 (66%) had metastatic disease at presentation. Patients had primarily clear cell histology (73%). Median follow-up was 12.1 months (range: 0.1-242.2mo). Median OS was 12.6 months (95% CI: 10.7-14.9mo). Univariate RPA identified a PSC cutpoint of 10% as prognostically significant. Patients with PSC>10% were at higher risk of death when compared with patients with PSC≤10% (45% vs. 61% 1-y OS; P = 0.04). Multivariate RPA revealed that tumor size, presence of metastatic disease, and PSC were significantly associated with OS. Among 4 identified groups, patients with localized disease and tumor size≤10cm were most likely to be alive at 1 year (89%), and patients with metastatic disease and PSC>40% were least likely to be alive at 1 year (28%; P<0.001).
Conclusion: PSC appears to be a prognostic factor in patients with sRCC, with larger percentage of involvement portending a worse survival, especially in patients with metastatic disease.
(Copyright © 2015 Elsevier Inc. All rights reserved.)