Non–clear cell histology in patients with metastatic RCC as a prognostic indicator in the targeted therapy era.

Abstract

454 Background: The role of targeted therapy (TT) in metastatic renal cell carcinoma (mRCC) having non-clear cell histology (non-ccRCC) is still being defined. We sought to examine the factors associated with survival outcomes in patients presenting with various histological subtypes in the TT era. Methods: The UCLA Kidney Cancer Program database containing records of over 2000 patients was queried. The clinicopathologic factors between patients with clear cell subtype (ccRCC) and those with non-clear cell histology were compared using the Student’s T-test and the chi-square test for continuous and categorical variables, where appropriate. Survival outcomes were estimated using Kaplan-Meier (log rank). Univariate and multivariate Cox regression models were used to identify independent associations with survival. Results: Of 157 patients treated with FDA-approved TT, 132 (84%) had ccRCC while 25 (16%) had non-ccRCC. The two groups were balanced for baseline demographic variables, including gender, race, BMI, pack-years of smoking, T-stage, Fuhrman grade, performance status and UCLA Integrated Staging System (UISS) risk category. Median survival of patients with ccRCC and non-ccRCC was 41.6 and 18.1 months (p<0.001). In univariate analysis, non-ccRCC was associated with a 2.7-fold risk of cancer specific death compared to ccRCC patients. Among patients receiving TT-only, median survival of patients with ccRCC and non-ccRCC was 35 and 15.4 months (p=0.007). A subset of ccRCC patients treated sequentially with IMT followed by TT had a median survival of 73 months. Worsening UISS risk class and non-ccRCC histology, but not age, gender, race, tobacco exposure history, or tumor size, were independently associated with the risk of cancer death. Conclusions: Non-clear cell histology remains a significant and independent risk factor for cancer specific death for mRCC patients treated by TT even after controlling for UISS risk category. [Table: see text]