Comparative Outcomes of Proton versus Photon Postmastectomy Radiation Therapy in Prepectoral Implant-Based Breast Reconstruction.

[BACKGROUND] The increasing popularity of prepectoral implant-based breast reconstruction (PP-IBBR) and proton-based radiation (PRT) lacks outcomes data. The authors compared complications in PP-IBBR with photon-based radiation (XRT) versus PRT postmastectomy radiotherapy (PMRT).

[METHODS] A single-institution retrospective cohort study included patients with breast cancer undergoing mastectomy and PP-IBBR with PMRT (January 2020 to October 2022) with 2-year follow-up after surgery. The authors assessed for minor infections (requiring oral antibiotics), major infections (requiring intravenous antibiotics), wound complications, flap necrosis, seromas, reoperations, capsular contracture, and implant failures (requiring implant removal for any of the aforementioned complications, except for rupture), including implant exposure.

[RESULTS] A total of 116 patients with PP-IBBR receiving PMRT were analyzed, divided into 2 cohorts: XRT ( n = 75 [64.7%]) and PRT ( n = 41 [35.3%]). Overall, more complications occurred with XRT compared with PRT. Major infection, minor infection, delayed wound healing, partial flap necrosis, seroma development, reoperations, implant failure, and capsular contracture of all grades as well as grade III or IV capsular contracture were seen more with XRT compared with PRT. Compared with PRT, XRT was significantly associated with higher risk of 2 or more complications in univariable analysis (OR, 3.71 [95% CI, 1.02 to 13.53]; P = 0.047) and in the multivariable model adjusting for stage (OR, 4.84 [95% CI, 1.27 to 18.46]; P = 0.021). Compared with stages 1 and 2, stages 3 and 4 were significantly associated with higher risk of 2 or more complications (OR, 3.40 [95% CI, 1.21 to 9.57]; P = 0.021), adjusting for radiation type.

[CONCLUSIONS] Compared with traditional XRT, PRT was associated with fewer complications in patients with PP-IBBR. PRT is a safer option, warranting larger studies and broader utilization in clinical practice.

[CLINICAL QUESTION/LEVEL OF EVIDENCE] Therapeutic, III.