Risk Factors and Survival Associated with Distant Metastasis in Patients with Carcinoma of the Salivary Gland

Abstract

Background: Salivary gland cancer (SGC) is rare and has various pathologies and metastatic potentials. Because distant metastasis can be observed after treatment, as well as at initial presentation, this study aimed to investigate the rates, risk factors, and survivals associated with distant metastasis in patients with SGC.

Methods: This study involved 454 consecutive patients with previously untreated SGC who were treated at our tertiary referral center. Clinical factors, operative and pathologic findings, and treatment outcomes were carefully reviewed. Univariate and multivariate analyses were performed to identify factors associated with distant metastasis and their associations with distant metastasis-free survival (DMFS), cancer-specific survival (CSS), and overall survival (OS).

Results: Of 454 patients, 95 (20.9 %) presented with distant metastases; of these, 7 (7.4 %) were at the initial stage, while 88 (92.6 %) were detected during a median follow-up of 100 months (range 24-282). Distant metastases to single and multiple organs were found in 64 (67.4 %) and 31 (32.6 %) patients, respectively, with the most common site being the lung (77.9 %). In multivariate analysis, a non-parotid tumor site, high histological grade, perineural invasion, and T3-4 and N2-3 classifications were independent variables of DMFS, while distant metastasis was an independent variable of CSS and OS (p < 0.005 each). The median survival duration after distant metastasis development was 15 months (range 2-103).

Conclusions: Distant metastasis frequently develops after treatment for SGC and is associated with poor survival outcomes; thus, close surveillance may be required for patients with SGC and risk factors.