Prognostic Factors of Flap Complications After Carbon-ion Radiotherapy for Head and Neck Cancer With Reconstruction

The incidence of flap complications after carbon-ion (C-ion) radiotherapy (RT) for head and neck cancer with reconstruction is unknown. This study investigated the incidence and risk factors of flap complications following C-ion RT for head and neck cancer with reconstruction.

We retrospectively analyzed 24 cases, excluding cases of re-irradiation, treated with C-ion RT at QST Hospital for loco-regional recurrence after reconstructive surgery for head and neck cancers from April 1997 to March 2020. We evaluated flap complications as anastomosis-related (flap loss and necrosis) and flap bed-related (wound dehiscence) complications. Wound dehiscence was assessed using Common Terminology Criteria for Adverse Events version 5.0. The correlation between clinical factors, dosimetric parameters, and flap complication was analyzed retrospectively.

The median follow-up period was 42.2 months (range=6.7-155.9 months). None of the 24 enrolled patients experienced flap loss and flap necrosis, and two (8.3%) patients had grade 1 wound dehiscence; grade 2 or greater toxicities were not recorded. The median interval between C-ion RT and wound dehiscence of the flap was 6.8 (6.5 and 7.0) months. Univariate analysis to identify clinical and dose-volume histogram parameters associated with the occurrence of grade 1 wound dehiscence after C-ion RT revealed that the minimum dose (Dmin) ≥5.9 Gy for flap was a statistically significant risk factor (p=0.017).

C-ion RT for head and neck cancers after reconstructive surgery is safe, with no serious flap complications. Dmin was an independent risk factor for the development of wound dehiscence.