Early tumor shrinkage as a predictive factor of metastatic renal cell carcinoma in molecular targeted therapy: A single institutional study.

The aim of the present study was to investigate the impact of metastatic sites and early tumor shrinkage (eTS) as prognostic predictive factors of metastatic renal cell carcinoma (mRCC) in molecular targeted therapy. A total of 209 advanced RCC cases treated with sorafenib, sunitinib, axitinib, pazopanib, temsirolimus and everolimus from our single institution were included in the present study. Several known prognostic predictive factors, including metastatic sites and the rate of eTS, were analyzed by Kaplan-Meier survival estimate analysis followed by Cox's proportional hazards model analysis. eTS was measured by three independent physicians. Four metastatic sites in the liver, bone, lymph nodes and brain as well as greater eTS were identified as potential independent predictors of overall survival (OS) in several cohorts: i) Metastatic RCC (n=194); ii) metastatic clear cell RCC (n=119); and iii) mRCC patients with eTS data (n=127). In sub-analyses of patients treated with each 1st line tyrosine kinase inhibitor, eTS was identified as a potentially potent predictor of OS in patients treated with axitinib. The liver, bone, lymph nodes, brain metastases and eTS were identified as independent predictive factors of OS by analyzing a limited Japanese cohort.