Locoregional breast cancer hypofractionated radiotherapy: How should doses to organs at risk (OAR) be evaluated?

Abstract

Purpose: Patients with locally advanced breast cancer with lymph node involvement may be eligible for hypofractionated locoregional treatment. However, studies conducted thus far have not provided constraints for hypofractionated locoregional radiotherapy with an integrated boost. We propose a framework that allows healthcare professionals to perform extended hypofractionated radiotherapy to include lymph node areas, with an integrated boost.

Methods: We reviewed and analyzed published studies on hypofractionation, focusing on the proposed constraints and dose equivalencies for critical organs during breast irradiation. The feasibility of the proposed constraints was assessed both in real-life clinical practice and dosimetrically on 70 patients treated with hypofractionated radiotherapy to the breast and associated lymph node areas, along with an integrated boost.

Results: A thorough analysis of the literature and dose equivalencies allowed us to propose constraints for organs at risk during hypofractionated locoregional breast irradiation. Seventy patients were evaluated dosimetrically, ensuring that the proposed constraints were met. The various doses received by the organs at risk were reported individually and analyzed based on the different radiotherapy modalities and treatment volumes.

Conclusions: Hypofractionated radiotherapy extended to lymph node areas, has become the standard of care for patients with locally advanced breast cancer. This article provides constraints based on the literature and dose equivalencies for healthcare professionals wishing to implement this type of protocol.

Advance in knowledge: there are no established dose constraints for locoregional breast irradiation with an integrated boost. This study offers an initial framework, based on clinical practice, for managing organs at risk in this form of irradiation.