Cardiac dosimetry in patients with breast cancer treated with hypofractioned and ultrahypofractionated radiotherapy: a 4-year retrospective analysis.

Abstract

Introduction: Radiation-induced cardiac disease (RICD) affects breast cancer patients (BCP) and is associated with the dose absorbed by the heart and the left anterior descending artery (LAD). It is important to meet tolerance doses to limit cardiotoxicity when using the recent hypofractionated radiotherapy (HFRT) and ultrahypofractionated radiotherapy (UHFRT) schemes, as their impact on cardiovascular health is unknown. Objective: The objective of this observational, analytical, retrospective, and longitudinal study was to estimate the risk of RICD by dosimetric assessment of the heart and LAD in BCP treated with HFRT and UHFRT (2019-2023). Methods: 440 medical records were reviewed, risk factors for RICD were evaluated, and the techniques used were considered considering the dose when using HFRT and UHFRT. Results: A sample of 51 women aged 41-88 years was formed, 52.94% received HFRT and 47.06% received UHFRT; using 3DCRT:84.31%, IMRT:7.74%, and VMAT:7.74%, with a median follow-up of 18.96 months. In HFRT for the heart, 100% met V16≤5%, for the LAD, 92.59% met V13.4≤10%. In UHFRT for the heart, two restrictions were applied, 87.50% met V6.5≤5% and 62.50% met V1.3≤25%; for the LAD, 83.33% met V9.2≤10%; compliance with tolerances was higher with 3DCRT, followed by IMRT and VMAT. No patient presented cardiovascular complications and all are alive without relapse. Conclusion: It is necessary to delimit the LAD from the beginning of treatment planning in BCP for adequate compliance with tolerance doses, with the aim of reducing the risk of RICD.