ASTRO 2018: Impact of Dosage on Re-irradiation Rates in Multiple Myeloma
Posted: Tuesday, November 13, 2018
Although patients with multiple myeloma often require more than a single radiation treatment, a new study reported that a treatment dose of 20 to 25 Gy in 8 to 12 fractions using involved-site radiation may be associated with a low re-irradiation rate. Adnan Elhammali, MD, PhD, and colleagues at The University of Texas MD Anderson Cancer Center, Houston, suggested that this dose and fractionation may be beneficial in patients who require additional palliation or local tumor control. These study results were presented at the 2018 American Society for Radiation Oncology (ASTRO) Annual Meeting in San Antonio (Abstract 180).
The authors performed an institutional review of 772 patients with multiple myeloma who received treatment in 1,513 sites, including spinal (n = 597) and nonspinal (n = 916) sites. The most common dose and fractionation were 20 to 25 Gy in 8 to 12 fractions. Most patients received at least five fractions.
After the first course of radiation therapy, the median survival rate was 25.6 months. At a median follow-up of approximately 1 year, 39 sites underwent re-irradiation (12 spinal, 27 nonspinal), corresponding to a cumulative re-irradiation rate of 2.6%. The median time to re-irradiation was 9.6 months for those with spinal sites and 10.2 months for those with nonspinal sites.
No significant association was reported between the biologically effective dose and re-irradiation for spinal targets (P = .20) or nonspinal targets (P = .21). A total of 296 spinal sites were treated with involved-site radiation therapy, and of them, 1 patient required re-irradiation for failure in an adjacent vertebral body.
