Retrospective DNA ploidy analysis by image and flow cytometry in head and neck cancer

A retrospective analysis of DNA content (DNA ploidy) was conducted in formalin-fixed specimens from patients with advanced, unresectable head and neck cancer who were treated on a single defined protocol with accelerated fractionation radiation therapy and concomitant cisplatin (Platinol) chemotherapy. Specimens from 31 tumor sites were analyzed by image cytometry using the Feulgen staining method. Fifteen specimens were analyzed by flow cytometry after deparaffinization, nuclear disaggregation, and staining with propidium iodide. By image analysis, 10 (32%) of 31 specimens contained only diploid tumor cells, while 21 (68%) specimens exhibited at least one aneuploid tumor component. Seven of the eight tumors with a single G0/G1 peak by image analysis had a single peak by flow analysis. Five of the seven tumors with multiple peaks by image analysis had multiple peaks by flow analysis. Histology was also reevaluated, and tumor grade was determined, reflecting tumor cell differentiation based on keratinization, mitotic activity and the degree of nuclear polymorphism. For this well-defined patient population managed according to a uniform therapeutic approach, DNA ploidy status and histology provided a suggestion of prognostic separation; however, statistical significance was not obtained, most likely due to the small number of patients.