Impact of histology on the treatment outcome of metastatic or recurrent renal cell carcinoma.

Among 107 renal cell carcinoma (RCC) patients with histopathologic subtype diagnosis who were treated at Albert Einstein Cancer Center with cytokines over a 10-year period, seven patients had sarcomatoid histology, 63 had clear cell carcinoma, and 10 patients had mixed histology (sarcomatoid and clear cell). Regardless of their histology, patients with a disease free interval of 2 years or more had significantly better survival. None of the patients with sarcomatoid histology responded to therapy. However, several patients with mixed and clear cell histology achieved partial or complete responses following high dose Interleukin-2 (IL-2) therapy. The median survival of patients with sarcomatoid histology was the shortest (13.8 months), whilst that of patients with mixed and clear cell histology was much longer (34.8 months and 39.1 months, respectively). This result was statistically significant in both univariate and multivariate survival analysis (P < 0.001 and P < 0.01, respectively). Patients with mixed and clear cell histology had no significant difference in survival, and their median survival combined was significantly longer than that of patients with sarcomatoid histology (P < 0.0001 in univariate analysis, P < 0.01 in multivariate analysis). This study suggests that survival with a diagnosis of RCC is predicted by tumor histology and disease free interval, and this impacts on the ability to respond to standard therapy. Patients with mixed and clear cell histology respond to cytokine therapy. Other therapies should be sought for patients with sarcomatoid RCC.