Outcomes of Patients in Nasopharyngeal Adenoid Cystic Carcinoma in the IMRT Era: A Single-center Experience

Abstract Objective: Nasopharyngealadenoid cystic carcinoma (NACC) is a rare malignancy with special biological features. Controversies exist regarding the treatment approach and prognosticfactors in the IMRT era. This study aimed to evaluate the long-term outcomes and management approaches in NACC. Methods: Fiftypatients with NACC at our institution between 2010 and 2020 were reviewed. Sixteenpatients received primary radiotherapy (RT), and 34 patients underwent primary surgery. Results: Between January 2010 and October 2020, a total of 50 patients with pathologically proven NACC were included in our analysis. The median follow-up time was58.5 months (range: 6.0–151.0 months). The 5-year overall survival rate (OS) and progression-free survival rate (PFS) were 83.9% and 67.5%, respectively. The 5-year OS ratesof patients whose primary treatment was surgery and RT were 90.0% and 67.3%, respectively (log-rank P =0.028). The 5-year PFS rates of patients whose primary treatment was surgery or RT were 80.8% and 40.7%, respectively(log-rank P= 0.024). Multivariate analyses showed that nerve invasion and the pattern of primary treatment were independent factors associated with PFS. Conclusions: Due to the relative insensitivity to radiation, primary surgery seemed to provide a better chance of disease control and improved survival in NACC. Meanwhile, postoperativeradiotherapy should be performed for advanced stage or residual tumours. Cranial nerveinvasion and treatment pattern might be important factors affecting the prognosis of patients with NACC.