Localized non‐conventional renal cell carcinoma: Prediction of clinical outcome according to histology

OBJECTIVE: A wide variety of parameters have been investigated in the prognostic significance of non-conventional clear cell renal cell carcinoma. Aim of the present study was to compare its clinical outcome and to determine the independent prognostic factors according to the histology. METHODS: This retrospective study enrolled localized non-conventional clear cell renal cell carcinomas (T1a-T4N0M0), including Xp11.2 translocation (Xp11.2t), all surgically treated in a single institution between 1988 and 2011. The study statistically analyzed the clinicopathological parameters to compare the prognostic outcomes among the different histological subtypes of non-conventional clear cell renal cell carcinoma and to define any independent prognostic factors. RESULTS: A total of 374 cases were examined, including 126 papillary (33.7%), 164 chromophobe (43.9%), eight collecting duct (2.1%), 40 unclassified (10.7%), 16 Xp11.2t (4.3%), seven mucinous tubular and spindle cell (1.8%) renal cell carcinomas and 13 oncocytomas (3.5%). The mean follow up was 56.4 months, with s mean tumor size of 4.9 ± 3.4 cm. The 4-year recurrence-free survival, overall survival and cancer-specific survival were inversely related to the increase of pathological T stages (P < 0.001). For histological type other than 13 oncocytomas and seven mucinous tubular and spindle cell renal cell carcinomas, the chromophobe showed the best prognosis of survival, followed by papillary, Xp11.2t, unclassified and collecting duct renal cell carcinomas, in this order. All survival rates were significantly different, as according to the histology (P = 0.009). The significant prognostic factors were preoperative body mass index (hazard ratio 0.76), serum albumin (hazard ratio 0.64), T stage (hazard ratio 2.28), the sarcomatoid differentiation (hazard ratio 33.45) and lymphovascular invasion (hazard ratio 12.40) in pathology (P < 0.05). CONCLUSIONS: Different non-conventional clear cell renal cell carcinoma subtypes have significantly different clinical characteristics of prognosis with many suggestive predictive factors of survival.