A Retrospective Analysis to Demonstrate Achievable Dosimetry for the Left Anterior Descending Artery in Left-sided Breast Cancer Patients Treated with Radiotherapy

Purpose: To demonstrate achievable dose for the left anterior descending artery (LAD) for left-sided breast cancer patients.

Methods: A retrospective analysis was conducted on all left-sided breast cancer patients receiving whole breast or post-mastectomy chest wall irradiation between 2013 and 2018. All patients in this study were treated with tangent-based techniques with the LAD prospectively contoured as routine clinical care. This large patient cohort was used to benchmark achievable mean doses to the LAD in the context of heart dose. The primary cohort of study were patients undergoing treatment with deep-inspiration breath-hold (DIBH), stratified by internal mammary nodes (IMN) inclusion. In all cases, the median (25th-75th percentile) is reported.

Results: A total of 1221 left-sided breast cancer patients were included in this study with 1045 in the DIBH cohort. The median heart mean dose for this cohort is 1.0 Gy (0.8-1.1). For patients treated in DIBH with IMNs included (n = 422), the median of the mean LAD dose is 3.6 Gy (2.9-4.4) and, for patients treated in DIBH with IMNs excluded (n = 623), the median of the mean LAD dose is 3.2 Gy (2.5-3.8).

Conclusions: Appropriate respiratory management can be utilized to achieve low dose to the LAD for the majority of patients without compromising target coverage.