Survival Probabilities Related to Histology, Grade and Stage in Patients With Salivary Gland Tumors.

Abstract

The diversity of malignant salivary gland tumors challenges the study of survival rates. The current study evaluated patient survival rates using Kaplan-Meier analysis and examined the relative effects of histology, grade and stage on survival. Using the Kaplan-Meier model, cancer-specific (CSS) and disease-free (DFS) survival probabilities were calculated as a function of time. Of 101 patients, 79 survived and 22 died of their disease. The probability of CSS was 0.83, 0.73 and 0.61 at 5, 10 and 15 years, respectively; corresponding probability of DFS was 0.69, 0.59 and 0.54, respectively. CSS and the DFS probabilities in patients with salivary malignancies were quite high at 5 years, although these rates dropped over the long-term; the lethal effect of the malignancy is often delayed and prolonged. Tumor histology, grade and stage are well established factors in predicting prognosis. Although the subgroups of patients with MECA and SCC were too small to allow adequate statistical analysis, clear tendencies for devastating effects of poor differentiation in SCC and higher grade in MECA were shown. That is, 2/4 patients with high-grade MECA died from their disease, while only 1/15 with low-intermediate grade MECA died from their disease. Similarly, 2/4 patients with poorly differentiated SCC died from their disease, while only 1/5 with well-to-moderately-differentiated SCC died from their disease. Factors such as molecular markers should be further studied in an effort to improve prognosis prediction.