Nasopharyngeal adenoid cystic carcinoma: five new cases and a literature review.

Nasopharyngeal adenoid cystic carcinoma (NACC) is a rare tumour, and its mainstay treatment is different from adenoid cystic carcinoma arising from another head and neck region. In this study, we analyzed 20 cases of NACC with complete clinical information, 5 from Chang Gung Memorial Hospital and 15 from the literature review.The time interval between first symptom and treatment ranged from 2 weeks to 8 years, with a median of 24 months. Compared with usual nasopharyngeal carcinoma, NACC has higher incidence of cranial nerve involvement (55%) and lower incidence of cervical adenopathy (15%). All patients were treated by radiotherapy and 6 patients received surgical treatment. The 5- and 10-year overall survival rates were 78% and 49.5%, respectively. Seven patients developed metastasis to lung or bone. After a minimum of 5 years' follow-up, the local control rate was 45.5% in patients receiving radiation dose > 70 Gy, and 28.6% in those receiving dose < or = 70 Gy, suggesting higher radiation dose is necessary to achieve better local control in NACC.