MIAMI BEACH, Fla.—Conventional radiotherapy (CRT) and stereotactic body radiotherapy (SBRT) provide relief of pain related to spine metastases in patients with advanced renal cell carcinoma (RCC), but CRT provides more rapid relief and SBRT has a more durable effect, according to new data presented at the American Society for Radiation Oncology annual meeting.

“Renal cell carcinoma traditionally has been considered more radio resistant … so stereotactic radiation for spine metastases has essentially been favored over using conventional therapy for renal cell carcinoma,” said lead investigator Grant Hunter, MD, a fifth-year radiation oncology resident at Cleveland Clinic in Ohio.

The study included 110 patients with painful spinal metastases from RCC treated with CRT or SBRT. The investigators defined complete response (CR) as complete resolution of pain without an increase in narcotic use. They defined partial response (PR) as a reduction in pain without an increase in narcotics. The researchers classified patients who experienced CR or PR as having pain relief and those with persistent pain and/or requiring additional narcotics as failures.

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Among the 110 patients, 34 underwent conventional radiation therapy (CRT) and 76 underwent SBRT. The median follow-up was 4.3 months (range 0.2-38 months) and median radiation dose was 20 Gy/5 fractions for CRT and a single 15 Gy fraction for SBRT.

Dr. Hunter’s team found that overall crude pain response rates were 68% for CRT and 62% for SBRT. The CR and PR rates were 12% and 56% for CRT and 33% and 29% for SBRT.  The median time to pain relief was 2.4 weeks for CRT compared with 4.8 weeks for SBRT. For the 79 patients who achieved pain relief, the median duration of relief was 1.7 months for CRT compared with 4.8 months for SBRT.

“We think the significance of the findings is that in the appropriate patient conventional fractionated therapy for renal cell carcinoma to the spine works effectively and is very good at palliating pain,” Dr. Hunter said. “For a patient who is on a systemic therapy and might have longer to live or is doing better, then stereotactic body radiotherapy seems like a very good alternative.”