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

BACKGROUND. The authors studied a series of 97 consecutive cases of salivar y gland tumors to investigate the correlation between the biologic paramete rs DNA ploidy and S-phase fraction (SPF) and the presumptive behavior of th e neoplasms, as well as their potential clinical utility. METHODS. Histopathologic classification and grading of the tumors were eval uated according to 1991 World Health Organization criteria DNA analysis was performed by flow cytometry in fresh material after propidium iodide stain ing. Clinical data and follow-up information were obtained from the clinica l charts. RESULTS. All the 71 benign salivary tumors showed a DNA diploid pattern. Se ven carcinomas (7.2%) exhibited DNA aneuploidy. Eleven (42.3%) of 26 malign ant tumors were considered low grade carcinomas, all of them being DNA dipl oid. Of the remaining 15 tumors, classified as high grade carcinomas, 7 sho wed DNA aneuploidy. SPF values ranged from 0.6% to 27.7%. A statistically s ignificant difference was found between the mean SPF values of benign and m alignant tumors, diploid and aneuploid tumors, and low grade and high grade carcinomas. When a cutoff Value of 3% was used to discriminate histopathol ogic subgroups with prognostic impact, a significant difference was found b etween benign and malignant salivary tumors, high grade and low grade carci nomas, and high grade and benign tumors (P < 0.001). CONCLUSIONS. The data from this study confirm the low incidence of DNA aneu ploidy in salivary gland tumors and suggest the potential utility of SPF es timation in evaluating the clinical behavior of these neoplasms. (C) 1999 A merican Cancer Society.