Posterior airway space following mandibular reconstruction using microvascular free flaps in oral cancer patients in relation to radiotherapy: a single-center study.

INTRODUCTION: The posterior airway space (PAS) is of considerable clinical relevance, as airway obstruction in this region may compromise patient well-being, manifesting as symptoms ranging from acute dyspnea to chronic obstructive sleep apnea. Although previous studies have demonstrated significant alterations in the PAS following oral and maxillofacial surgical procedures, changes in the PAS among patients with oral cancer undergoing microvascular reconstruction remain insufficiently investigated. This study aimed to evaluate changes in PAS following mandibular resection and microvascular free flap reconstruction, focusing on the impact of radiotherapy. METHODS: In this retrospective, single-center study, patients with oral cancer treated between January 1, 2020, and January 1, 2025, were assessed. Patients were eligible for inclusion if they had undergone mandibular resection followed by primary microvascular reconstruction and if preoperative and postoperative computed tomography (CT) scans with a maximum slice thickness of 1 mm were available. Imaging data were segmented using 3D Slicer (The Slicer Community, www.slicer.org), and PAS volume was quantified in cubic centimeters (cm³). Intraindividual changes in PAS volume were subsequently analyzed, and potential influencing factors, such as adjuvant radiotherapy, defect type, and reconstruction method, were evaluated. RESULTS: A total of 42 patients (18 females, 24 males; mean age 66 ± 13 years) were included in the analysis. Overall, PAS volume increased by a mean of 11.6% (95% CI: -6.8% to 29.9%) on the first postoperative CT scan. At one-year follow-up (mean 381 days), PAS volume had increased significantly by 58.5% (95% CI: 39.7% to 77.2%) compared with baseline (p = 0.0023). The increase in PAS volume was significantly greater in patients who received adjuvant radiotherapy (p = 0.0266). Furthermore, multiple linear regression identified neck dissection, defect type, reconstruction method, and adjuvant chemotherapy as independent factors significantly associated with changes in PAS volume at the one-year follow-up. DISCUSSION: Mandibular resection followed by microvascular reconstruction is associated with a significant overall increase in PAS volume in patients with oral cancer. However, multiple factors - particularly adjuvant radiotherapy - are significantly associated with the extent of PAS alteration.