Objective biologic parameters and their clinical relevance in assessing salivary gland neoplasms

This review summarizes research advances of cytometric, proliferation, cytogenetic, and molecular "objective" measurable parameters, as additional aids to prognostic information of salivary gland tumors provided by classical clinicopathologic indicators. Flow cytometric DNA ploidy and S-phase fraction seem to be of value as predictors of tumor behavior, aneuploidy, and high S-phase identifying an unfavorable clinical evolution of salivary gland neoplasms. Cell proliferation markers assessed by immunohistochemistry (e.g., PCNA, Ki-67) also appear to have predictive significance, but some conflicting results, in part related to technical procedures, limit their routine clinical application. Silver-stained methods (AgNORs) show a scarce value in estimating prognosis of salivary gland malignancies. p53 and c-erbB-2 as well as karyotyping, are of disputable benefit for clinical use, but the biologic information they provide give a better understanding on the molecular mechanisms involved in the development and progression of tumors. Further studies, with large databases, long follow-up information, uniformized histologic classification, and standardized methodologies, are needed to establish how these "objective" parameters would be of truly beneficial for the treatment of patients with salivary gland tumors.