Adenoid cystic carcinoma – insights from a national database
Reviewed by Christopher Burgess

Adenoid cystic carcinoma (AdCC) is a rare cancer of the salivary glands that accounts for approximately 1% of all head and neck malignancies. Hallmarks of this cancer type include a predilection for perineural infiltration, a prolonged clinical course with late recurrences and the frequent development of pulmonary metastases. AdCC exhibits three distinct growth patterns – cribriform, tubular and solid, with cribriform being the commonest and solid the most aggressive. In this study, the US Surveillance, Epidemiology and End Results (SEER) database was interrogated to review factors associated with the outcomes of cases of AdCC identified from 2000 to 2018. A total of 1978 patients were included, of whom 59.9% were female, with most patients presenting in the age range 50-59 years (21.4%). The outcomes recorded confirmed the relatively good prognosis from this disease in the short term with a five-year disease-specific survival (DSS) of 78.6%. The longer-term outlook was, however, less favourable with a 10-year DSS of 22.0% and 15-year DSS of 14.0%. The best five-year overall survival was recorded for patients treated with surgery and radiotherapy (76.8%). When outcomes were analysed by stage though, no difference in survival was observed between patients who underwent surgery alone compared to surgery and radiotherapy in stage I and II disease. Multivariate analysis showed that grade of disease was the strongest single predictor of worse survival, which was particularly true for grades III (poorly differentiated) and IV (undifferentiated). Patients with metastatic disease confined to the lungs had much better survival than patients with disease in other sites such as the bones and liver. The results of this study benefit from the inclusion of a large number of cases. The data presented will aid the counselling of patients newly diagnosed with this disease, as well as helping to decide which patients would benefit most from adjuvant radiotherapy following surgical resection of localised disease.

Salivary gland adenoid cystic carcinoma in the U.S population: Importance of grade, site of metastases, and adjuvant radiation for survival.
Ullah A, Ahmed A, Lee KT, et al.
AM J OTOLARYNGOL
2024;45(3):104266.