Presence of Tissue Expanders Does Not Affect Radiotherapy Dose Distribution to Heart and Lungs

Breast cancer treatment often involves mastectomy and postmastectomy radiotherapy (PMRT). PMRT rates are increasing and can improve outcomes in node-positive cases. Although the risks of PMRT to reconstructed breasts are known, the influence of tissue expanders (TEs) on radiation to nearby organs such as the heart and lungs remains unclear.

Patients who underwent total mastectomy and completed a full course of PMRT with 3-dimensional computer tomography planning between January 2014 and August 2022 at Loyola University Medical Center were included. Patient dose statistics for ipsilateral lung, heart, and clinical target volume, as well as demographics, clinical characteristics, PRMT boost, and bolus were collected. Dose statistics for ipsilateral lung and heart were compared between mastectomy versus mastectomy + TE, and dose statistics were compared between dichotomized TE intraoperative fill volumes. Correlations between dose statistics and BMI were analyzed.

A total of 124 patients were included in the study. There were no significant differences in lung or heart radiotherapy across all dose metrics between patients who underwent mastectomy versus mastectomy + TE, or between patients with TE fill volume 60 mL or less versus 60 mL or more. Correlations between BMI and heart maximum dose (P = 0.03) were significantly different and showed a positive, monoclonal correlation (correlation: 0.20, 95% confidence interval: 0.02-0.37).

The presence of TE and intraoperative expander fill volume did not affect dose distribution or complications to the organs at risk. Increased BMI correlated with an increased maximum dose to the heart.