SBRT May Be Effective for Metastatic RCC
Michelle Stinauer, MD
SAN DIEGO—Aggressive stereotactic body radiation therapy (SBRT) is effective for controlling metastatic renal cell carcinoma (RCC), according to findings presented at the 52nd Annual Meeting of the American Society for Radiation Oncology.
In a study, researchers showed that the overall local control rate achieved with SBRT in patients with metastatic RCC was 95% at one year.
“At the higher doses of radiation that are delivered during SBRT we found that our local control with this type of therapy is just as good as it is for colorectal cancer or breast cancer,” said Michelle Stinauer, MD, a radiation oncology resident at the University of Colorado in Denver. “I think it would be especially beneficial for renal cell [carcinoma] patients with a lower level of disease burden, such as one or two metastases. These patients can benefit from more aggressive local control. There are studies showing that in patients with metastatic disease that if you remove the primary cancer then they have better outcomes. Similarly, lowering disease burden with SBRT may help patients live longer.”
Dr. Stinauer, who presented the study findings at the meeting, said RCC and melanoma traditionally have been viewed as “radio-resistant” but study findings show that SBRT—which involves radiation dose intensification through escalation of fraction size—can overcome this resistance.
She and her colleagues retrospectively reviewed all patients with recurrent RCC and melanoma who had metastatic sites treated with SBRT. The patients received a minimum radiation dose of 40 Gy over three to five treatments. The researchers defined local control as radiographic or pathologic evidence of a lack of tumor enlargement and/or increased standardized uptake value (SUV) on positron emission tomography/computed tomography scans. An SUV indicates how “bright” or “hot” a lesion is on a scan.
The researchers analyzed the outcomes of 13 RCC patients with a total of 25 lesions and 17 melanoma patients who had a total of 28 lesions. The mean gross tumor volume was 6 cc (range 1-275 cc). Treated sites included the liver (11 lesions), lung (39 lesions) or bone (three lesions). The median follow-up for patients alive at the time of the analysis was 11.5 months (ranges 2-65 months). At one year, the overall rate of local control was 85%. It was 95% for RCC patients.
The results from this study suggest that an aggressive SBRT regimen is an effective modality for controlling metastatic melanoma and metastatic RCC. The local control rates achieved in this series were comparable to those obtained with SBRT for other tumor histologies, Dr. Stinauer said.