Concurrent chemoradiotherapy versus radiotherapy alone in postoperative high-risk adenoid cystic carcinoma of the head and neck: A propensity score matched analysis

Background: The role of concurrent chemoradiotherapy (CCRT) in postoperative head and neck adenoid cystic carcinoma (ACC) remains controversial due to the limited evidence from randomized trials. This study assessed the effectiveness of CCRT by comparing a prospective CCRT group with a retrospective radiation(RT) alone group using propensity score matching (PSM). Methods and materials: Postoperative head and neck ACC patients with T3-4/N1-3 M0 disease or after R1/R2 resection were enrolled. All patients underwent intensity-modulated radiation therapy (IMRT), and CCRT group received two cycles of concurrent docetaxel and nedaplatin. To ensure comparability, PSM were utilized. Following PSM, survival outcomes were analyzed using Kaplan-Meier curves and compared using the log-rank test. Results: A prospective CCRT group of 55 patients and a retrospective RT alone group of 160 patients were included. The multivariate Cox regression analysis showed no association between CCRT and overall survival (OS) (hazard ratio [HR] = 0.71, 95 %CI: 0.24-2.08, p = 0.537), or other survival outcomes. To mitigate potential confounding factors, a 1: 1 PSM analysis was performed. With a median follow-up of 51 months, post-PSM analysis (including 48 patients in each group) indicated no significant differences in OS (estimated 5-year OS rates: 90.7 % versus 84.3 %, p = 0.331), locoregional recurrence-free survival (LRRFS) (p = 0.261), distant metastasis-free survival (DMFS) (p = 0.425), or disease-free survival (DFS) (p = 0.600) between two groups. The multivariate Cox regression analysis also showed no association between CCRT and OS (HR = 0.29, 95 %CI: 0.06-1.38, p = 0.119), or other survival outcomes. Conclusion: The addition of concurrent chemotherapy to postoperative IMRT did not confer a survival benefit in terms of LRRFS, DMFS, DFS, or OS in patients with head and neck ACC. Upcoming results from randomized studies are anticipated to shed more light on this debated issue. CCRT should be avoided outside of clinical trials.