2911 - Is Hypofractionated Radiotherapy with Integrated Boost the New Standard for Patients with Locally Advanced Breast Cancer?
Presenter(s)
S. Allali1, P. Loap2, Y. Gounane1, G. K. Loganadane1, K. I. Cao1, R. Bouaita3, S. Souidi1, J. Vu-Bezin4, and Y. M. Kirova1; 1Institut Curie, Paris, France, 2Department of Radiation Oncology-Institut Curie, Paris, France, 3Institut Curie, Orsay, France, 4Service de Physique Médicale, Département de Radiothérapie, Institut Curie, Paris, France
Purpose/Objective(s): Radiotherapy is a key component in the management of patients with locally advanced breast cancer. Thanks to technological advancements and recent studies, these patients can now benefit from intensity-modulated radiotherapy (IMRT) as well as hypofractionated treatments, which have become the new standard. However, in these studies, the boost was administered sequentially, and there is limited data on the use of an integrated boost in this patient population. In this study, we evaluate the feasibility and tolerability of using a hypofractionated regimen with an integrated boost in patients treated for locally advanced breast cancer.
Materials/Methods: This study included 129 patients. All patients received irradiation to the breast and regional lymph nodes with a dose of 40.05 Gy in 15 fractions, followed by an integrated boost of 48 Gy. All patients received Volumetric Modulated Arc Therapy (VMAT) irradiation. Several toxicity factors were assessed, such as radiodermatitis, pain, lymphoedema, fibrosis etc. Toxicity evaluations were conducted at M0, M1, M4-6, and M12. Toxicities were graded according to the CTCAE v6 scale.
Results: The median age of the patients was 51 years. The majority of patients had hormone receptor-positive (HR+), grade 3, T2N1M0 breast cancer. Fifty-five percent of patients received axillary irradiation, and 70% underwent treatment with breath-hold technique. Fifty-eight percent of patients received left-sided lateral irradiation. The prevalence of immediate toxicities at M1 was low, with most being graded 0 or 1. At M1, radiodermatitis was observed in 61% of patients, while breast fibrosis was present in 16.5% of cases. The evaluation at M4-6 showed a significant reduction in the main toxicities, such as radiodermatitis (2.3% vs 61%), pain (5.5% vs 18%), and fibrosis (11% vs 16.5%). Furthermore, by M12, most toxicities had resolved.
Conclusion: The use of hypofractionated radiotherapy with an integrated boost in patients with locally advanced breast cancer is feasible and well-tolerated. This radiotherapy modality is expected to become the future standard for these patients. It ensures effective and safe treatment while reducing both the treatment time and the overall impact of radiotherapy on these patients.