Abstract
The aim of this study was to investigate the potential survival advantages associated with chemoradiotherapy (CRT) compared to radiotherapy (RT) as standalone modalities in the treatment of adenoid cystic carcinoma (ACC) of the salivary glands. Patients diagnosed with resected salivary gland ACC were retrospectively enrolled and categorized into two groups based on the type of adjuvant therapy received. The overall survival outcomes between the CRT and RT cohorts were evaluated using a multivariable Cox model. Post propensity score-matching, a total of 114 patients (57 in each treatment group) were included in the analysis. In the general patient population, CRT did not confer an additional survival benefit compared to RT alone. High-grade tumors, positive surgical margins, and the presence of five or more positive lymph nodes were identified as independent prognostic factors associated with poorer overall survival. Specifically, for patients with positive surgical margins, CRT was significantly associated with improved overall survival relative to RT, displaying a hazard ratio of 0.93 (95% CI: 0.81-0.99). Furthermore, in patients with more than four metastatic lymph nodes, CRT significantly reduced the risk of mortality by 6% (95% CI: 1-24%) when compared to RT alone. Conversely, in patients with high-grade tumors, the addition of adjuvant chemotherapy to RT did not yield significant alterations in survival outcomes compared to RT alone (p = 0.437, HR: 0.95, 95% CI: 0.75-2.07). CRT may offer an overall survival benefit for patients with salivary gland ACC, particularly those characterized by positive margin or the presence of five or more metastatic lymph nodes.