Malignant salivary gland tumors are rare and exhibit a broad spectrum of phenotypic heterogeneity. The objective of this study was to investigate prognostic factors in patients with salivary gland carcinomas and review the results in light of other reports. We retrospectively reviewed 40 patients with primary salivary gland carcinomas who were diagnosed and treated at our institution between 1991 and 2014. Of the 40 tumors, 19 (47.5%) were mucoepidermoid carcinomas, 11 (27.5%) were adenoid cystic carcinomas, 7 (17.5%) were acinic cell carcinomas, 2 (5.0%) were myoepithelial carcinomas and 1 (2.5%) was a squamous cell carcinoma. Clinically positive lymph nodes were present in 4 patients (10.0%). As regards clinical stage, 15 cases (37.5%) were stage I, 13 (32.5%) were stage II, 1 (2.5%) was stage III and 11 (27.5%) were stage IVA. The majority of the patients (97.5%) were treated with surgery, of whom 25 (62.5%) received surgery alone and 14 (35.0%) underwent surgery in combination with chemotherapy or chemotherapy and radiotherapy. The median follow-up time for all the patients was 48 months. The disease-specific survival rate at 5 years was 87.1%. We identified a significant correlation between poor survival rate and histological grade (intermediate/high), tumor size (T3/T4), lymph node metastasis (node-positive) and clinical stage (III/IV) using the Kaplan-Meier method (P<0.05 for each). In addition, the Cox proportional hazards regression analysis confirmed that lymph node metastasis and tumor size were independent prognostic factors for disease-specific survival (hazard ratio = 18.7 and 15.1, respectively; P=0.023 and 0.037, respectively). Furthermore, tumor size was found to be a predictive factor regarding recurrence in the multivariate logistic regression analysis (odds ratio = 8.35; P=0.025). Our results suggest that lymph node metastasis and tumor size are significant prognostic factors for patients with salivary gland carcinomas.
Keywords: prognostic factor; retrospective study; salivary gland carcinomas.