Histologic characteristics of residual renal cell carcinoma following interferon-α-based therapy: Correlation with clinical parameters

To compare the histologic characteristics of residual renal cell carcinoma (RCC) following an interferon-α (IFN-α)-based therapy with clinical parameters, we examined 12 metastatic and 6 primary kidney tumors resected from 18 patients with advanced RCC. The histologic parameters including tumor necrosis, nuclear grade, inflammatory response and hemosiderin deposition were assessed. The immunophenotypes of tumor-infiltrating lymphocytes (TILs) were also characterized. The tumors of the 12 patients who had partial clinical response (responders) showed more tumor necrosis than the tumors of the 6 non-responders (patients with minor response or stable disease) (p = 0.0061). A tendency of longer overall survival was observed in the group with tumor necrosis compared to the group without necrosis. Predominance of T-cell TIL was demonstrated in all 9 responders compared to 3 non-responders (p = 0.053). Our findings suggest that tumor necrosis and a high percentage of T-cell TILs in residual RCC may be associated with favorable clinical response following IFN-α-based therapy.