Tumor Differentiation as a Prognostic Factor for Major Salivary Gland Malignancies

Objective The effect of tumor differentiation on prognosis of major salivary gland malignancies is controversial. The aim of this study was to determine the effect of tumor differentiation on prognosis by stage in patients with major salivary gland malignancies and to analyze which patient factors are associated with tumor differentiation. Study Design and Setting Cross-sectional analysis of Surveillance, Epidemiology, and End Results (SEER) database. Subjects and Methods In total, 9810 patients who had a major salivary gland malignancy from 2004 to 2012 were identified using the SEER database. Patients with no staging information or no information on histologic differentiation were excluded. A total of 5366 patients were included in the study. For analysis, patients were categorized by American Joint Committee on Cancer (AJCC) stage and subdivided by tumor differentiation. Multivariate analysis was used to analyze the impact of tumor differentiation on survival, tumor location (parotid, submandibular, sublingual), and sex within each AJCC stage of disease. Results Data analysis demonstrated a significant difference in histologic differentiation by stage, with P < .0001. Within stages II, III, and IV, tumor differentiation was significantly associated with a decrease in survival. There was no significant difference in tumor differentiation between the parotid and submandibular gland. Conclusion For patients with stage II, III, and IV disease, tumor differentiation was an independent predictor of survival. This information can be useful when discussing prognosis and can potentially influence management of disease.