Phase II Evaluation of Ultra-Hypofractionated Postoperative Radiation Therapy for Breast Cancer: Toxicity and Efficacy in a Single-Center Nonrandomized Prospective Study.

Purpose: To evaluate the toxicity profile and efficacy of postoperative ultra-hypofractionated radiation therapy in elderly patients with breast cancer.

Materials and methods: This is a nonrandomized, single-center, prospective Phase II trial. Patients with breast cancer older than 65 years were treated with ultra-hypofractionated radiation therapy in 5 fractions of 5.7 Gy on alternate days in the breast or chest wall, or regional lymph nodes. The primary end point was acute toxicity.

Results: A total of 60 patients were analyzed, with a median follow-up of 42.5 months (range, 13.8-66.2). Most patients presented pathologic stage I (56.6%, n = 34) or stage II (33.3%, n = 20) disease. Regional lymph node irradiation was performed in 22% (n = 13) of patients. During treatment, 51% (n = 31) of patients experienced grade 1 or 2 acute toxicity, with no cases of grade 3 acute toxicity reported. Late toxicity included 1.7% (n = 1) of patients developing grade 3 fibrosis and 1.7% (n = 1) developing grade 3 pneumonitis. Regional lymph node irradiation was not associated with a statistically significant increase in toxicity risk (P = .194). Cosmesis evaluations revealed no significant changes when comparing pretreatment assessments with evaluations at 10 weeks (P = .223) and 26 weeks (P = .615) post-treatment. Quality of life was not adversely affected, regardless of whether regional lymph nodes were irradiated. Recurrence rates included two patients with both locoregional and distant recurrence and five patients with distant recurrence. The 3-year disease-free survival probability was 81.7%, and the 3-year overall survival probability was 86.7%.

Conclusion: This study demonstrates the safety of ultra-hypofractionated radiation therapy in terms of toxicity in patients with breast cancer. The findings for side effects, cosmesis, quality of life, and survival outcomes are consistent with those observed in moderately hypofractionated radiation therapy regimens, suggesting its use as a viable treatment option in this demographic.