Chromophobe renal cell carcinoma (RCC): oncological outcomes and prognostic factors in a large multicentre series

Study Type - Outcomes (cohort) Level of Evidence 2b What's known on the subject? and What does the study add? About 80% of RCCs have clear cell histology, andconsistent data are available about the clinical and histological characteristicsof this histological subtype. Conversely, less attention has been dedicated tothe study of non-clear cell renal tumours Specifically, published data show that chromophobe RCC (ChRCC) have often favourable pathological stages and betternuclear grades as well as a lower risk of metastasizing compared with clear cell RCC (ccRCC). Patients with ChRCC were shown to have significantly highercancer-specific survival (CSS) probabilities compared with ccRCC. However, anindependent prognostic role of RCC histotype was not confirmed in some largemulticenter series and only a few studies have focused on the oncologicaloutcomes of ChRCC. The present study is one of the few to evaluate cancer-relatedoutcomes of ChRCC and represents to our knowledge the largest series of ChRCCs.Consequently, the present findings may assist in elucidating the natural history of surgically treated ChRCC. The present study confirms that ChRCCs have goodprognosis and a low tendency to progress and metastasize. Only 1.3% of patientspresented with distant metastases at diagnosis, and the 5- and 10-year CSS were93% and 88.9%, respectively. However, although ChRCCs are generally characterisedby an excellent prognosis, we observed that patients with locally advanced ormetastatic cancers as well as those with sarcomatoid differentiation have a poor outcome. The study also investigated prognostic factors for recurrence-freesurvival (RFS) and CSS for this RCC histotype. The definition of outcomepredictors can be useful for patient counselling, planning of follow-upstrategies, and patient selection for clinical trials. In the present study,gender, clinical T stage, pathological T stage, and presence of sarcomatoiddifferentiation were significantly associated with RFS and CSS at multivariableanalysis. We also identified N/M stage as an independent predictor of CSS.Notably, as Fuhrman grade was not an independent predictor of cancer-relatedoutcomes, the present study confirms that this histological variable is not areliable prognostic factor for ChRCC.OBJECTIVES: To investigate cancer-relatedoutcomes of chromophobe renal cell carcinoma (ChRCC) in a large multicentredataset. •  To determine prognostic factors for recurrence-free survival (RFS)and cancer-specific survival (CSS) for this RCC histological type.PATIENTS AND METHODS: In all, 291 patients with ChRCC were identified from amulti-institutional retrospective database including 5463 patients who weresurgically treated for RCC at 16 Italian academic centres between 1995 and 2007. Univariable and multivariable Cox regression models were used to identifyprognostic factors predictive of RFS and CSS after surgery for ChRCC.RESULTS: •  At a median follow-up of 44 months, 25 patients (8.6%) had diseaserecurrence and 18 patients (6.2%) died from disease. The 5-year RFS and CSSrates were 89.3% and 93%, respectively. Gender (P= 0.014), clinical T stage(P= 0.017), pathological T stage (P= 0.003), and sarcomatoid differentiation (P= 0.032) were independent predictors of RFS at multivariable analysis. •  For CSS, there was an independent prognostic role for gender (P= 0.032) and T stage (P=0.019) among the clinical variables and for T stage (P= 0.016), N/M stage (P=0.023), and sarcomatoid differentiation (P= 0.015) among the pathologicalvariables.CONCLUSIONS: Patients with ChRCC have a low risk of tumour progression,metastasis, and cancer-specific death. Patient gender, clinical andpathological tumour stage, and sarcomatoid differentiation are significantpredictors of RFS and CSS for ChRCC