Treatment outcome and survival associated with metastatic renal cell carcinoma of non-clear-cell histology

Purpose: To define outcome data for patients with metastatic renal cell carcinoma (RCC) with histology other than clear-cell type, including collecting duct (or medullary carcinoma), papillary, chromophobe, and unclassified histologies. Patients and Methods: Sixty-four patients with metastatic non-clear-cell RCC histology were the subjects of this retrospective review. Included in the analysis were 22 (8%) of 286 patients from a clinical trials database, 19 of 1,166 patients from a surgery database, and 23 of 357 patients from a pathology database. Results: The prevalent histology was collecting duct, present in 26 (41%) patients. The number of patients with chromophobe and papillary histologies was 12 (19%) and 18 (28%), respectively. Eight (12%) of the patients had tumors that could not be classified for specific tumor histology. Among the 43 patients treated with 86 systemic therapies, including 37 cytokine therapies, two patients (5%) were observed to have a partial response. The median overall survival time was 9.4 months (95% confidence interval, 8 to 14 months). The survival was longer for patients with chromophobe tumors compared with collecting duct or papillary histology, and this group included four patients with survival of greater than 3 years. Conclusion: RCC consists of a heterogeneous group of tumors including clear-cell, papillary, chromophobe, collecting duct, and unclassified cell types. Non-clearcell histologies constitute less than 10% of patients in general populations of patients with advanced RCC treated on clinical trials. Metastatic non-clear-cell RCC is characterized by a resistance to systemic therapy and poor survival, with the survival for patients with chromophobe tumors longer than that for patients with metastatic collecting duct or papillary RCC. Treatment with novel agents on clinical trials is warranted.