The Relationship of Radiation Therapy Parameters and Perioperative Morbidity and Toxicities on Breast Reconstruction Outcomes.

[BACKGROUND] Postmastectomy radiation therapy (PMRT) is a key component of breast cancer care, reducing locoregional recurrence in appropriately selected patients. Concurrently, use of mastectomy with implant-based breast reconstruction has expanded, heightening attention to how patient, surgical, and radiation factors interact. There is a knowledge gap in how reconstructive strategies and PMRT parameters jointly influence complications, toxicities, and treatment timing across the expander-implant continuum.

[OBJECTIVE] The aim of this study was to determine how reconstructive and radiation therapy (RT) parameters relate to surgical-site complications, delays in PMRT initiation, acute radiation toxicities, delays in expander-to-implant exchange, and capsular contracture.

[METHODS] This study examined a single-center retrospective cohort of women undergoing mastectomy with immediate tissue expander or direct-to-implant reconstruction and PMRT (2017-2022). Complications classified as postmastectomy pre-RT, intra-RT, and post-RT. Associations between clinical and radiation factors and complications, toxicities, and delays were estimated using generalized estimating equation logistic models.

[RESULTS] One hundred forty-six patients underwent 260 mastectomies, and 152 reconstructions received PMRT. The majority underwent dual-stage reconstruction (87.5%). Adverse surgical site outcomes occurred in approximately one-quarter of breasts before PMRT and in a similar proportion after PMRT. Neither pre-RT surgical site outcomes delayed PMRT (P = 0.61) nor did severe dermatitis delay expander-to-implant exchange (P = 0.63). Severe dermatitis was less frequent with intensity-modulated RT (P < 0.01) and proton therapy (P < 0.02) than with three-dimensional conformal RT, whereas bolus use increased the risk of dermatitis (P < 0.01). Severe capsular contracture occurred less frequently after prepectoral versus submuscular reconstruction, but the difference did not reach statistical significance (P = 0.30).

[CONCLUSIONS] In an integrated care setting where PMRT and reconstruction are performed in the same institution, pre-RT complications do not correlate with delaying PMRT, nor do post-RT complications or acute toxicities alter the implant exchange course. Complications were substantial during the pre-RT period, suggesting further opportunities for improvement. These findings emphasize the importance of multidisciplinary planning/communication to optimize patient treatment and outcomes.