Survival of patients with papillary type II renal cell carcinoma treated with tyrosine-kinase inhibitors: A comparison with clear cell histologies.

Abstract

511 Background: The sequential use of Tyrosine-kinase inhibitors leads to a longer survival in patients with clear-cell renal cell carcinoma (ccRCC). However to-date there is little data available on the survival of patients with non-clear-cell RCC treated with TKI. We focused on papillary type II renal cell carcinoma (papIIRCC) and assessed the outcome of our patients with metastatic disease on systemic treatment. The outcome was compared with our patients with clear cell histology. Methods: Patients with histologic evidence of papillary type II renal cell carcinoma or clear cell renal cell carcinoma were treated with single agent sunitinib or sorafenib. Progression free survival (PFS) and overall survival (OS) were analyzed with Kaplan-Meier curves. Patients were identified from an institutional database and had to have a follow up of ≥2 years. Subgroup analyses were performed to determine the influence of primary tumor stage and cell differentiation on PFS and OS. Results: 18 patients with papIIRCC received sunitinib (16) or sorafenib (2) while 166 patients with ccRCC were treated with sunitinib (78%) or sorafenib (22%). Median PFS for papIIRCC is 8.9 mos, for ccRCC it is 11 mos. OS for papIIRCC is 15 mos, while ccRCC show an OS of 32 mos. The same tendency for longer PFS and OS is seen in ccRCC patients with low primary tumor grade and highly differentiated carcinomas, whereas large tumors and low differentiation determine a poor prognosis in both groups. Conclusions: Most papIIRCC patients have a poor outcome and shorter PFS than ccRCC on the same therapy. They benefit from the TKI therapy, but the survival is clearly reduced compared with ccRCC patients. This may be due to the poor prognosis of the papillary type II histology, but the assumption is that the administered therapy is not conceived for this type of RCC. Future studies are required to determine the optimal therapy for papillary type II renal cell cancer.