Clinical efficacy and prognosis of adjuvant radiotherapy for adenoid cystic carcinoma of head and neck salivary gland / 中华放射肿瘤学杂志

ABSTRACT

Objective:To investigate the optimal treatment modalities and prognostic factors of adenoid cystic carcinoma of the head and neck salivary gland.Methods:From January 2016 to December 2018, clinical data of 166 patients with adenoid cystic carcinoma of the head and neck salivary gland who received postoperative radiotherapy at Department of Radiation Oncology of the Ninth People′s Hospital of Shanghai Jiao Tong University School of Medicine were retrospectively analyzed. The survival analysis was performed by Kaplan-Meier method. Univariate prognostic analysis was conducted by log-rank test. Multivariate prognostic analysis was carried out by Cox proportional hazard regression model.Results:Among 166 enrolled patients, 70 cases were male and 96 female with an average age of 53 years (18 to 71 years). The median follow-up time was 31.2 months (8.6-63.1 months). Sixty-six patients underwent radical surgery (extended resection across the anatomical areas outside the tumor bed, pursuing negative margins of various resections), and the remaining 100 patients underwent conservative surgery (only extended resection of lesions, not pursuing negative nerve resection margins). The median dose of postoperative radiotherapy was 66 Gy (54-70 Gy). Seventy-three patients were treated with TP regime due to positive or close margins and 9 cases of cervical lymph node metastasis. The 3-and 5-year overall survival (OS), locoregional recurrence-free survival (LRRFS), distant metastasis-free survival (DMFS), progression-free survival (PFS) rates were 95% and 95%, 93% and 93%, 74% and 66%, 73% and 65%, respectively. Seven patients experienced primary lesion recurrence, 5 cases of regional lymph node recurrence and 38 cases of distant metastasis. T 3-T 4 stage, lymph nodes (+ ), stage IV, solid pathologic subtype, Ki-67≥10% and perineural invasion were associated with worse PFS and DMFS. Multivariate analysis demonstrated that only solid pathologic subtype was the independent prognostic factor of OS, LRRFS, PFS and DMFS. Conclusions:The local control rate of salivary gland adenoid cystic carcinoma can be improved by postoperative intensity-modulated radiotherapy (IMRT) with a recommended dose of ≥66 Gy. Solid pathologic subtype is the most important adverse prognostic factor.