ASTRO 2021: Phase III Trial of Hypofractionated Radiotherapy for Localized Breast Cancer
Posted: Tuesday, November 9, 2021
Findings presented at the 2021 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 10) suggest that extreme hypofractionated radiation therapy (25 Gy in 5 fractions) is as safe and well tolerated as moderate hypofractionation (40 Gy in 15 fractions) in patients with localized breast cancer. In addition, in the early results from the phase III MC1635 trial, Cameron S. Thorpe, MD, of the Mayo Clinic in Phoenix, and colleagues found that extreme hypofractionation may result in fewer skin burns.
The study included 107 patients who were randomly assigned to receive either moderate (arm A; n = 54) or extreme hypofractionation (arm B; n = 53). Optional concurrent integrated boosts of 48 Gy on arm A or 30 Gy on arm B were available and administered to 21% of patients.
At a median follow-up of 20 months, outcomes across both arms were comparable. However, the rate of moderate to severe skin burns was higher in arm A (58.7%) than in arm B (27.9%). Neither arm reported grade 3 toxicities, disease recurrence, or death. Grade 2 toxicities included radiation dermatitis (n = 6), fibrosis (n = 1), and lymphedema (n = 1); they occurred at a nearly identical rate (7.4% in arm A vs. 7.5% in arm B). A total of 1.6% of patients in arm A and 1.7% of those in arm B experienced deterioration in cosmesis at least 3 months after receiving radiation therapy. Quality of life and the average Harvard cosmesis score were similar across arms.
Characteristics of the enrolled patient population included invasive ductal carcinoma (55%), invasive lobular carcinoma (20%), ductal carcinoma in situ (16%). A total of 7% of patients had mixed disease types, while 3% had a type other than those listed. The majority (72%) of patients had stage 1 or 2 disease.
Disclosure: For full disclosures of the study authors, visit astro.org.
