Flow cytometric analysis of head and neck carcinoma DNA index and S‐fraction from paraffin‐embedded sections: Comparison with malignancy grading

Abstract

Archival, paraffin-embedded, pathology specimens representing pretreatment tissue biopsies from 73 patients with epidermoid carcinoma of the head and neck were analyzed for DNA Index and %S-phase cells by flow cytometry and were scored for quantitative histomorphology. The DNA fluorescence/light scatter size patterns derived from paraffinembedded specimens were shown to be essentially the same as those from mechanically disaggregated, ethanol-fixed cells obtained from the same tissue specimen. Patterns ranged from lymphocyte-like to highly abnormal DNA Index cytokinetic patterns. The DNA Index values ranged from 0.70 to 3.50 (median 1.42), with an aneuploidy frequency of 63/73 (86%). DNA distribution %S ranged from 4% to 45% (mean 19), with the microscopic malignancy grading showing broad heterogeneity (mean 2.1, range 1.0–3.0, where 1.0–1.7 = well differentiated, 1.8–2.3 = moderately differentiated, 2.4–3.0 = poorly differentiated). Cross-comparison of these data showed that (1) the tumor %S was dependent on DNA Index (higher %S at higher ploidy), (2) low to high malignancy tumors were randomly distributed between diploid/near diploid tumors and high-degree DNA abnormality tumors, and (3) proliferative activity values broadly overlapped between low to high malignancy scored tumors. However, those carcinomas characterized by high DNA Index (≥ 1.50) and high %S-phase fractions (≥ 20) had a five fold higher incidence of high-degree malignancy, invasive tumors than diploid/near diploid (%S ⩽19) tumors.