The subclassification of papillary renal cell carcinoma does not affect oncological outcomes after nephron sparing surgery.

Objectives: To evaluate the oncological outcomes of papillary renal cell carcinoma (pRCC) following nephron sparing surgery (NSS) and to determine whether the subclassification type of pRCC could be a prognostic factor for recurrence, progression, and specific death.
Materials and Methods: An international multicentre retrospective study involving 19 institutions and the French network for research on kidney cancer was conducted after IRB approval. We analyzed data of all patients with pRCC who were treated by NSS between 2004 and 2014.
Results: We included 486 patients. Tumors were type 1 pRCC in 369 (76 %) cases and type 2 pRCC in 117 (24 %) cases. After a mean follow-up of 35 (1-120) months, 8 (1.6 %) patients experienced a local recurrence, 12 (1.5 %) had a metastatic progression, 24 (4.9 %) died, and 7 (1.4 %) died from cancer. Patients with type I pRCC had more grade II (66.3 vs. 46.1 %; p < 0.001) and less grade III (20 vs. 41 %; p < 0.001) tumors. Three-year estimated cancer-free survival (CFS) rate for type 1 pRCC was 96.5 % and for type 2 pRCC was 95.1 % (p = 0.894), respectively. Three-year estimated cancer-specific survival rate for type 1 pRCC was 98.4 % and for type 2 pRCC was 97.3 % (p = 0.947), respectively. Tumor stage superior to pT1 was the only prognostic factor for CFS (HR 3.5; p = 0.03).
Conclusion: Histological subtyping of pRCC has no impact on oncologic outcomes after nephron sparing surgery. In this selected population of pRCC tumors, we found that tumor stage is the only prognostic factor for cancer-free survival.