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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Wednesday, December 13, 2023
Complication rates for patients undergoing proton radiotherapy after mastectomy seem to be similar between groups receiving conventionally fractionated and hypofractionated regimens, according to a phase II trial published in The Lancet Oncology. Robert W. Mutter, MD, of the Mayo Clinic, Rochester, Minnesota, and colleagues, could not establish noninferiority of the hypofractionation approach by the 24-month follow-up. And there appeared to be no significant differences in recurrence or complication rates between the two strategies. Studies continue to assess the potential of proton therapy to reduce the risk of cardiac and tissue complications, according to the investigators.
“The study provides the first prospective data supporting the use of shorter-course proton postmastectomy radiotherapy, including in patients with immediate breast reconstruction, and the first mature results of a randomized trial in the field of breast particle therapy,” stated Dr. Mutter in a Mayo Clinic press release.
By the 24-month follow-up, 14 protocol-defined complications occurred in six patients (15%) receiving conventional fractionation and in eight (20%) patients receiving the hypofractionated regimen (P = .27). All eight protocol-defined complications with the hypofractionated regimen were attributable to infections. All 14 complications were in patients with immediate expander or implant-based reconstruction. The investigators specifically noted unplanned surgical interventions for contracture in 5 of 41 patients (12%) and fat necrosis in 1 patient (2%) in the conventional fractionated group but no events in the hypofractionated group.
The study included 82 patients, with 41 assigned to both groups; one received proton radiotherapy after mastectomy with pencil-beam scanning by conventional fractionation (50 Gy in 25 fractions of 2 Gy), and the other, hypofractionation (40.05 Gy in 15 fractions of 2.67 Gy). Patients undergoing immediate reconstruction, a group known to be at high risk of reconstruction complications, were included in both groups. Mean follow-up was 39.3 months.
Disclosure: For full disclosures of the study authors, visit thelancet.com.
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