Role of concurrent chemoradiation on locally advanced unresectable adenoid cystic carcinoma

Background/Aims: Adenoid cystic carcinoma (ACC) is a rare salivary gland tumor characterized by indolence, with a high rate of local recurrence and distant metastasis. This study aimed to investigate the effect of concurrent chemoradiation (CCRT) on locally advanced unresectable ACC. Methods: We retrospectively analyzed clinical data from 10 patients with pathologically confirmed ACC of the head and neck who received CCRT with cisplatin in Seoul National University Hospital between 2013 and 2018. Results: Ten patients with unresectable disease at the time of diagnosis or with positive margins after surgical resection received CCRT with weekly cisplatin. Eight patients (80%) achieved complete remission, of which three later developed distant metastases without local relapse; one patient developed distant metastasis and local relapse. Two patient achieved partial remission without progression. Patients experienced several toxicities, including dry mouth, radiation dermatitis, nausea, and salivary gland inflammation of mostly grade 1 to 2. Only one patient showed grade 3 oral mucositis. Median relapse-free survival was 34.5 months (95% confidence interval, 22.8 months to not reached). Conclusions: CCRT with cisplatin is effective for local control of ACC with manageable toxicity and may be an effective treatment option for locally advanced unresectable ACC.