Purpose: Nephrectomy before immunotherapy in patients with metastatic renal cell cancer (RCC) will improve patient outcome. In addition, the primary tumor is known to be refractory to cytokines. Sunitinib is now approved for treatment of advanced RCC, but its effect on the primary tumor has yet to be reported.
Experimental design: All patients treated with sunitinib for advanced RCC without prior nephrectomy were reviewed and sequential computed tomography scans were evaluated for response in the primary tumor as well as metastases according to Response Evaluation Criteria in Solid Tumors. Volumes of primary tumors and central necrotic areas were measured with the perimeter method.
Results: Computed tomography scans were available for evaluation of response in 17 of 22 patients with a primary tumor in situ (1 patient with two primaries). According to Response Evaluation Criteria in Solid Tumors, 4 patients had a partial response, 12 had stable disease, and 1 had progressive disease. The one-dimensional longest diameter of the primary tumor correlated with the volumetric measurements both at baseline and at the time of evaluation of response. Excluding the patient with progressive disease, the median volume reduction was 31% associated with a median increase in the volume of necrosis of 39%. Three patients underwent nephrectomy and tumors showed extensive necrotic areas next to small fields of vital tumor cells.
Conclusions: Sunitinib can induce a significant reduction in volume of primary renal cell tumors. Further trials need to address the role of nephrectomy in advanced RCC patients on sunitinib treatment.