2987 - Hypofractionated Adjuvant Radiation for the Treatment of Inflammatory and Other T4 Breast Cancers
Presenter(s)
S. C. Raju-Salicki1, S. J. Jiang2, I. Zoberi1, C. Bergom1, J. C. Yang1, and M. A. Thomas1; 1WashU Medicine, Department of Radiation Oncology, St. Louis, MO, 2Washington University School of Medicine in St. Louis, Department of Radiation Oncology, St. Louis, MO
Purpose/Objective(s): While hypofractionated radiation therapy (hRT) regimens are standard for many breast cancers, they are not routinely used in inflammatory breast cancers (IBC). Further, existing dose fractionation schemas for IBCs are heterogenous, including conventional fractionation over 6 weeks and hyperfractionation. Since the COVID pandemic, some patients with IBCs and other T4 breast cancers were treated with hRT. We sought to evaluate recurrence rates, survival, and toxicity in T4+ breast cancer patients treated with adjuvant hRT at a single institution.
Materials/Methods: Patients with clinical or pathological T4a-T4d breast cancer and no distant metastases were selected for study. All patients were treated with trimodal therapy including systemic therapy, mastectomy, and hRT (40.05–42.56 Gy in 15-16 fractions to the chest wall and regional nodes). The Kaplan-Meier method was used to estimate local, regional, and distant recurrence, as well as disease-free survival and overall survival. Toxicity data (CTCAE v5) during treatment and follow-up were collected.
Results: Twenty-eight patients with T4+ disease, including 17 with T4d IBC, were treated from May 2020 to Nov 2024. Median follow-up was 37.1 months. Local recurrence occurred in 1 patient (4%) at 14.4 months post-diagnosis. Two (7%) in-field recurrences occurred in treated regional nodes at 23.4 and 31.2 months, but only after the development of distant metastases. Eight patients (29%) developed distant metastases, including seven with IBC. Median time to distant metastases was 39.7 months for IBC patients and not reached for other T4 patients. Median disease-free survival was 39.7 months for IBC patients and not reached for other T4 patients. Seven patients (25%) passed away due to disease progression, including six with IBC. Median overall survival was 46.5 months for IBC patients and not reached for other T4 patients. Treatment was well tolerated: eight patients (29%) experienced grade 2 radiation dermatitis, while the remainder experienced grade 1. No acute adverse events beyond grade 2 were noted.
Conclusion: In this small series, adjuvant hRT was well-tolerated and effective for patients with T4+ breast cancer, with low local and regional recurrence rates and favorable toxicity profiles. Further follow-up and a larger sample size is necessary to confirm long-term outcomes in this patient population.