Survival in patients with parotid gland carcinoma - Results of a multi-center study

Parotid gland carcinoma is a rare malignancy, comprising only 1-4% of head and neck carcinomas; therefore, it is difficult for a single institution to perform meaningful analysis on its clinical characteristics. The aim of this study was to update the clinical knowledge of this rare disease by a multi-center approach.

The study was conducted by the Kyoto University Hospital and Affiliated Facilities Head and Neck Clinical Oncology Group (Kyoto-HNOG). A total of 195 patients with parotid gland carcinoma who had been surgically treated with curative intent between 2006 and 2015 were retrospectively reviewed. Clinical results including overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS), local control rate (LCR), regional control rate (RCR), and distant metastasis-free survival (DMFS) were estimated. Univariate and multivariate analyses were performed to identify prognostic factors.

The median patient age was 63years old (range 9-93years), and the median observation period was 39months. The OS, DFS, DSS, LCR, RCR, and DMFS at 3years were 85%, 74%, 89%, 92%, 88%, and 87%, respectively. Univariate analysis showed age over 74, T4, N+, preoperative facial palsy, high grade histology, perineural invasion, and vascular invasion were associated with poor OS. N+ and high grade histology were independent factors in multivariate analysis. In subgroup analysis, postoperative radiotherapy was associated with better OS in high risk patients.

Nodal metastases and high grade histology are important negative prognostic factors for OS. Postoperative radiotherapy is recommended in patients with advanced high grade carcinoma.