Clinicopathological Features of Papillary Renal Cell Carcinoma With Venous Tumor Thrombus: Case Series from a Large Chinese Center

BACKGROUND: Few studies have reported the influence of the histological classification of type-2 papillary renal cell carcinoma (PRCC), which may differ from that of clear cell renal carcinoma (ccRCC), on the prognosis of renal cell carcinoma with tumor thrombus. We investigated the clinicopathological features and prognosis of type-2 PRCC associated with venous tumor thrombi (PRCC-TT). METHODS: We retrospectively analyzed 163 patients with renal cell carcinoma with venous tumor thrombus (RCC-TT) admitted to Peking University Third Hospital between June 2016 and June 2020. Twenty-five patients had type-2 PRCC-TT and 138 had ccRCC combined with tumor thrombus; there were 125 males and 38 females. All the included patients underwent radical nephrectomy and thrombectomy under either complete laparoscopic surgery or open surgery. Univariate and multivariate Cox regression analysis were performed to evaluate the prognostic significance of each variable on cancer-specific survival (CSS). Cancer-specific survival was calculated from the date of surgery to death or the last follow-up using the Kaplan-Meier method. RESULTS: The blood vessels of type-2 PRCC-TT presented on CT images were not as abundant as those of ccRCC-TT. Slight enhancement was observed in the corticomedullary phase. While wash-out symptoms were observed, contrast agent extinction was not obvious in the nephrographic and excretory phases. We compared the macroscopic and microscopic appearances of the 2 cohorts. Compared to the ccRCC TT cohort, lymph node invasion was more prevalent in the PRCC-TT cohort (88.0% vs. 60.9%, P= .009). Multivariate analysis revealed that sarcomatoid differentiation, distant metastasis. and pathological type were the independent predictors of poor CSS. The Kaplan-Meier analysis showed that the CSS of type-2 PRCC TT and ccRCC-TT were 23.5 and 38.4 months, respectively, with statistical significance (P= .002). CONCLUSION: Type-2 PRCC-TT varies with common ccRCC-TT in imaging manifestation and pathological characteristics. The prognosis of type-2 PRCC-TT patients was worse than that of ccRCC-TT patients.