Oncological outcome of patients with salivary gland cancer treated with surgery and postoperative intensity-modulated radiotherapy: a retrospective study

Abstract

Background To investigate the outcomes, prognostic factors, patterns of failure, and adverse events in patients with salivary gland cancer (SGC) treated with surgery and postoperative intensity-modulated radiotherapy (IMRT). Methods We identified 60 patients with major SGC treated with surgery followed by postoperative IMRT. Data for overall survival (OS),progression-free survival (PFS), locoregional relapse-free survival (LRRFS), distant metastasis-free survival (DMFS), prognostic factors, and treatment-related toxicities were analyzed. Survival was calculated with the Kaplan–Meier method. Multivariable analysis (MVA) was used to identify prognostic factors for OS, PFS, LRRFS and DMFS. Results Adenoid cystic carcinoma (ACC) was the most common histology ( n =21; 35%). With a median follow-up of 55.5 months, OS and PFS were 90.7%, 85.1%, and 85.1%; and 80.1%, 72.7%, and 63.1%, at 3, 5, and 10 years, respectively. LRRFS and DMFS at 3, 5, and 10 years were 87.4%, 82.1%, and 82.1%; and 85.3%, 78.4%, and 66.1%, respectively. Five-year OS, PFS, LRRFS, and DMFS for ACC was 100%, 67.7%, 76.2%, and 90.2%, respectively. In MVA, N stage was an independent predictor of PFS ( p =0.047). Positive margin was a significant prognostic factor for PFS, LRRFS, and DMFS ( p =0.036, 0.026, and 0.011, respectively). Major nerve involvement was significantly correlated with PFS and DMFS ( p =0.034 and 0.008, respectively). Interval from surgery to radiotherapy (RT) predicted PFS and DMFS ( p =0.036 and 0.012, respectively). The most common acute toxicities were mucositis and dermatitis, and xerostomia was the most common late adverse event. Lung metastasis was the most common pattern of distant failure. Conclusion Postoperative IMRT leads to improved survival for SGC patients with acceptable toxicities.