Flap Complications Following Maxillectomy, Reconstructive Surgery, and Postoperative Proton Radiotherapy: A Cohort Study and Considerations for Risk Mitigation.

Background: Flap complications following maxillectomy, reconstruction, and adjuvant proton beam therapy (PBT) for primary maxillary and sinonasal malignancies are not well described.

Methods: This retrospective cohort study included consecutive patients treated between 2016 and 2023 from a single-institutional database.

Results: Thirteen patients were identified with a median follow-up of 26 months. No immediate post-operative complications occurred, with a median time between surgery and PBT of 61 days. Nine patients (69.2%) had high-risk postoperative pathology and required 66+ Gy(RBE), including five (38.5%) with gross disease receiving 70 Gy(RBE). Flap necrosis and fistulization occurred in three patients (23.1%) following PBT (median time from PBT to complication, 112 days). Higher flap mean and minimum dose, flap volume receiving at least 66 Gy[RBE], and minimum dose to 50% flap volume were associated with complications.

Conclusions: Careful patient selection and planning strategies should be considered to mitigate flap complication risk following adjuvant PBT for high-risk post-operative pathology.