A novel prognostic model for patients with sarcomatoid renal cell carcinoma

Objective To demonstrate sarcomatoid differentiation is an independent prognostic feature for patients with grade 4 renal cell carcinoma (RCC) with or without distant metastases. To identify independent predictors of survival, evaluate the correlation between the amount of sarcomatoid differentiation and cancer-specific survival (CSS), and to design a multivariate prognostic model for patients with sarcomatoid RCC. Patients and Methods We used the Mayo Clinic Nephrectomy Registry to identify 204 post-nephrectomy patients with sarcomatoid-variant RCC, as well as 207 patients with unilateral grade 4 RCC without sarcomatoid features for comparison. All slides were reviewed by one pathologist. CSS was estimated using the Kaplan-Meier method. The associations of clinical and pathological features with death from RCC were evaluated using Cox proportional hazards regression models. Results For all patients with grade 4 RCC, the presence of sarcomatoid differentiation was associated with a 58% increased risk of death from RCC (P < 0.001). For patients with grade 4 non-metastatic (M0) RCC, the presence of sarcomatoid differentiation was associated with an 82% increased risk of death from RCC (P < 0.001). For patients with sarcomatoid RCC, the 2009 primary tumour classifications, presence of regional lymph nodes and distant metastases, coagulative tumour necrosis, and the amount of sarcomatoid differentiation were each significantly associated with death from RCC in a multivariate setting. After adjusting for other prognostic variables, each 10% increase in the amount of sarcomatoid differentiation was associated with a 6% increased risk of death from RCC (P = 0.028). Patients whose tumours contained ≥30% (median amount) sarcomatoid differentiation were 52% more likely to die from RCC compared with patients whose tumours contained <30% sarcomatoid differentiation (hazard ratio 1.52; P = 0.018). Conclusions Among patients with grade 4 RCC, either with or without distant metastases at surgery, sarcomatoid differentiation is significantly associated with adverse survival in a multivariate setting. We also suggest for the first time that the percentage of sarcomatoid differentiation is an independent prognostic feature in a multivariate setting. The 2009 primary tumour classifications, regional lymph node status, the presence of distant metastases classifications, coagulative tumour necrosis, and the amount of sarcomatoid differentiation are independent predictors of survival for patients with sarcomatoid RCC.