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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Wednesday, October 2, 2024
Matthew Poppe, MD, FASTRO, of the University of Utah Huntsman Cancer Institute, Salt Lake City, and colleagues aimed to fill the evidence gap of shorter postmastectomy radiation therapy schedules among patients with intermediate- and high-risk breast cancer. Their results, which concluded that a 16-fraction course was noninferior to a 25-fraction course, were presented during the 2024 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 1).
“Patients after mastectomy who were planning breast reconstruction were the one group where we didn’t have sufficient data to support shorter [radiation] courses,” stated Dr. Poppe in an ASTRO press release. "Now, the results of this trial show we can safely reduce treatment time for these patients to 3 weeks, without compromising their reconstruction.”
A total of 898 patients with unilateral invasive breast cancer who were planning delayed or immediate breast reconstruction and postmastectomy radiation therapy were enrolled from 209 centers in the United States and Canada. Participants were randomly assigned 1:1 to receive 50 Gy in 25 fractions or 42.56 Gy in 16 fractions 5 days per week.
At the median follow-up of 4.5 years, 73 patients discontinued treatment. The median patient age was 49 years, 14% had a known genetic predisposition gene, and 6% had diabetes. Approximately half of patients received neoadjuvant chemotherapy (51%), and 27% underwent adjuvant chemotherapy. Of 572 patients who completed reconstruction, 55% of surgeries were delayed, and 45% were immediate.
Of note, hypofractionation yielded a 24-month incidence of reconstruction complications rate of 14%—an increase of 2.3% compared with conventional postmastectomy radiation therapy (11.7%; P = .0005). Regardless of the treatment arm, the complication rate was significantly decreased with autologous vs implant reconstruction (P = .0059). Further, rates of acute and late toxicity did not seem to differ between the arms, and 36-month recurrences were reported in 2.3% and 1.5% of patients on conventional and hypofractionated treatment, respectively.
Disclosure: For full disclosures of the study authors, visit www.astro.org.
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