DNA FLOW-CYTOMETRY OF RECLASSIFIED SUBTYPES OF MALIGNANT SALIVARY-GLAND TUMORS

Malignant salivary gland tumors are rare, constitute a heterogeneous g roup and are often difficult to diagnose histologically. This is borne out by the fact that in the present study 43.2% of 118 salivary gland tumors originally diagnosed as mucoepidermoid, acinic cell and adenoi d cystic carcinomas had their original diagnosis altered upon reclassi fication. Patients with confirmed adenoid cystic carcinomas had a much worse prognosis than those with mucoepidermoid and acinic cell carcin omas. DNA flow cytometry showed that very few of the above mentioned t hree types of malignant neoplasms revealed aneuploid DNA stemlines, in dicating that this is not a relevant prognostic tumor marker within th e groups. However, several of the tumors that had their diagnosis chan ged, mostly to undifferentiated adeno- or squamous cell carcinomas, sh owed aneuploid DNA stemlines. The survival lime of patients with aneup loid tumors was considerably reduced compared to those with diploid tu mors. Among confirmed acinic cell, mucoepidermoid and adenoid cystic c arcinomas the S-phase fraction was a significant prognostic factor, as it was among all tumors examined. This indicates that DNA aneuploidy and S-phase fractions are potential prognostic factors for malignant s alivary gland tumors, and that DNA flow cytometry may assist the chara cterization of such tumors.