Non-type 1 papillary renal cell carcinoma is associated with a worst oncological outcome in patients treated surgically
Papillary renal cell carcinoma (pRCC) is the second most frequent histologic subtype of kidney cancers. Recent series introduced some conflicting data that did not show differences on survival regarding histological subtyping. Molecular studies suggest that type 2 pRCC is a heterogeneous disease with multiple subgroups which lead pathologists to classify these lesions as “non-type 1” pRCC. The objective of our study was to compare clinicopathologic factors of type 1 pRCC and non-type 1 pRCC, assess clinical outcomes and to determine whether histological subtyping can be considered as a prognostic factor for survival.
A bicentric retrospective study was conducted after approval from each institutional review board. We analyzed data from all patients with pRCC who were treated surgically between 2000 and 2015. Two groups were defined after review by two senior uropathologists : type 1 pRCC in group 1 and non type 1 pRCC in group 2.
We included 362 patients : 164 (45%) in group 1 and 198 (55%) in group 2. Non type 1 tumors were associated with more aggressive histological characteristics (Table 1). Patients with non type 1 pRCC had 91,9% high grade tumors (vs 25% in group 1, p < 0,001). Overall survival (OS), cancer free survival and cancer specific survival were significantly lower in group 2 (Figure 1). High Fuhrman grade was the only histological prognostic factor for OS on multivariate analysis (HR = 2,1 ; p = 0,036).
Histological subtyping of pRCC has an impact on oncological outcome. Non type 1 tumors show higher Fuhrman grade and significantly lower survival. Although in multivariate analysis the histological subtype is not associated with significant differences regarding survival, its strong association with high grade tumors must be considered as a poor prognostic factor for OS.