A new study published by Hannan et al in European Urology Oncology showed that highly focused radiation to isolated metastases that progress despite drug therapy may prolong drug efficacy in patients with kidney cancer. Together with a Canadian report recently published by Cheung et al in European Urology, the two studies support an expanded role for radiation therapy in renal cancer.
“[The] current standard of care for metastatic progression [in kidney cancer] is to change systemic drug therapy,” said lead study author Raquibul Hannan, MD, PhD, Associate Professor of Radiation Oncology and Radiation Oncology Co-Leader in the Kidney Cancer Program (KCP) at UT Southwestern’s Harold C. Simmons Comprehensive Cancer Center, “but there’s no guarantee the next line of therapy will be effective.”
Results From Both Studies on the Role of SABR
The study by Hannan et al found that highly focused stereotactic ablative radiation (SABR) was an effective strategy for controlling metastatic disease when it progressed at just a few sites, known as oligoprogression. The phase II clinical trial showed that SABR extended ongoing systemic therapy by a median of 11.1 months. Involving multiple institutions across the country, the Canadian study, also a phase II trial, showed similar results with SABR extending systemic therapy by 12.6 months.
Both studies deployed sequential SABR over time while disease remained oligoprogressive, which is a new approach, and both showed that SABR successfully controlled radiated lesions (> 90% local control rates). Additionally, the study by Hannan et al showed that SABR did not undermine patients’ quality of life.
Localized therapies such as SABR, which are generally associated with minimal toxicity, are an attractive option to complement systemic therapies that are otherwise working and well tolerated. For those who respond to systemic therapy, the development of a few “rogue” drug-resistant metastases may not demand a change of treatment. Eradicating progressing sites with high-dose, pinpointed radiation may extend the window where drugs can provide effective cancer control.
“While both clinical trials involved a small number of patients, the concordant positive results suggest that the approach has merit. These studies support larger trials that may introduce SABR in routine patient care,” said co–corresponding author for the study by Hannan et al, James Brugarolas, MD, PhD, Professor of Internal Medicine, Division of Hematology and Oncology, and Director of the KCP.
Disclosure: This work was supported by grants from the National Institutes of Health and the American Cancer Society. The clinical trial was funded by the UTSW Department of Radiation Oncology and UTSW. For full disclosures of the study authors, visit euoncology.europeanurology.com and sciencedirect.com.
