The clinical relevance of ploidy and S-phase fraction determination in salivary gland tumors: A flow cytometric study of 97 cases

Abstract

The authors studied a series of 97 consecutive cases of salivary gland tumors to investigate the correlation between the biologic parameters DNA ploidy and S-phase fraction (SPF) and the presumptive behavior of the neoplasms, as well as their potential clinical utility. Histopathologic classification and grading of the tumors were evaluated according to 1991 World Health Organization criteria. DNA analysis was performed by flow cytometry in fresh material after propidium iodide staining. Clinical data and follow-up information were obtained from the clinical charts. All the 71 benign salivary tumors showed a DNA diploid pattern. Seven carcinomas (7.2%) exhibited DNA aneuploidy. Eleven (42.3%) of 26 malignant tumors were considered low grade carcinomas, all of them being DNA diploid. Of the remaining 15 tumors, classified as high grade carcinomas, 7 showed DNA aneuploidy. SPF values ranged from 0.6% to 27.7%. A statistically significant difference was found between the mean SPF values of benign and malignant tumors, diploid and aneuploid tumors, and low grade and high grade carcinomas. When a cutoff value of 3% was used to discriminate histopathologic subgroups with prognostic impact, a significant difference was found between benign and malignant salivary tumors, high grade and low grade carcinomas, and high grade and benign tumors (P < 0.001). The data from this study confirm the low incidence of DNA aneuploidy in salivary gland tumors and suggest the potential utility of SPF estimation in evaluating the clinical behavior of these neoplasms.