Postoperative Radiotherapy or Chemoradiotherapy Versus Surgery Only in Non-Metastatic Head and Neck Adenoid Cystic Carcinoma: A Retrospective Analysis

Background: The optimal postoperative treatment (POT) strategy for non-metastatic head and neck adenoid cystic carcinoma (HNACC) remains controversial. This study aimed to evaluate whether postoperative radiotherapy (PORT) or postoperative chemoradiotherapy (POCRT) provide survival benefits compared with surgery only (SO) in patients with HNACC.

Methods: This retrospective study analyzed patients with non-metastatic HNACC who underwent curative-intent surgery between 2011 and 2023. Patients were categorized into SO, PORT, and POCRT groups. PORT and POCRT were collectively referred to as radiotherapy (RT)-based POT in this study. Survival outcomes, including overall survival (OS), progression-free survival (PFS), local failure–free survival (LFFS), and distant metastasis–free survival (DMFS), were evaluated using Kaplan–Meier analyses and Cox proportional hazards models.

Results: A total of 114 patients were included, comprising 35 treated with SO, 42 with PORT, and 37 with POCRT. With a median follow-up of 51.0 months, no significant differences in OS, PFS, LFFS, or DMFS were observed among the three groups in the overall cohort (all P > 0.05). Perineural Invasion (PNI) independently predicted worse OS (Hazard Ratio, HR 3.425, 95% Confidence Interval, CI 1.316–8.913, P = 0.012) and PFS (HR 2.196, 95% CI 1.060–4.549, P = 0.034). In PNI patients, RT-based POT significantly improved LFFS versus SO (P = 0.032), while POCRT showed no clear advantage over PORT.

Conclusions: Survival outcomes were comparable among SO, PORT, and POCRT in non-metastatic HNACC. Patients with PNI may derive greater local control benefit from RT-based POT, warranting prospective validation.