The impact of post-mastectomy radiation timing on overall outcomes of autologous free-flap breast reconstruction

Background: The optimal timing of post-mastectomy radiation therapy (PMRT) in autologous breast reconstruction is controversial. Our study compares overall reconstructive outcomes in patients who received post-mastectomy radiation therapy either before or after the autologous flap. Methods: A single-center retrospective review was performed for patients who underwent free flap breast reconstruction and post-mastectomy radiation from January 2004 through January 2021. Demographic, intraoperative, and postoperative variables were recorded. Results: A total of 452 free flaps were identified, and 82 underwent PMRT. 59.8% were radiated with an expander prior to free flap surgery (PreFlap), and 40.2% flaps underwent PMRT (PostFlap). PostFlap patients were significantly younger (43.0 vs. 47.9 years, p = .016). There were no significant differences in free flap outcomes between the two cohorts including thrombosis, venous congestion, flap loss, takebacks, fat necrosis, seroma, or infection. Mastectomy skin flap necrosis was significantly higher in the PostFlap cohort (9.1% vs. 0%, p = .032), but nipple necrosis rates did not differ. There were no significant differences in number or need for revision surgeries, fat necrosis, or fat grafting between groups. However, there were significantly more total reconstructive complications, including infection and wound breakdown, experienced by the PreFlap cohort (46.9% vs. 24.2%, p = .038). Conclusions: Timing of PMRT did not impact free flap outcomes, but those who had the expander radiated experienced significantly more complications overall. For the 34.7% of patients in the preFlap group who planned for autologous reconstruction form initial consultation, radiation after the flap may have improved their overall outcomes. As added complications cause delays in cancer therapy and final reconstruction, our results suggest that PMRT of the flap when possible may improve the overall experience for breast cancer patients.