Cytokinetic evaluation in human head and neck cancer by autoradiography and DNA cytofluorometry.

As part of a comprehensive research program on cell proliferation characteristics of squamous cell carcinoma in humans and the relation of these characteristics to treatment, 4 untreated cases of head and neck cancer and 2 recurrences were studied. Previously, cell kinetics following the percent labelled mitoses method were done and the same carcinomas now studied by measuring microfluorometrically the time distribution of the nuclear DNA content. Two cases were characterized by a homogeneous cell population, whereas in 2 other cases, two cycling subpopulations distinguished by their DNA content were encountered. The clinical response was not related to the occurrence of single- or multiple-cell populations. In all cases, a great variability in the mitotic index (MI) and in the proportion of cells in the different cycle phases was found. The heterogencity in the proliferative structure of these tumors stresses the need for a greater accuracy in performing cell kinetics studies in vivo and could account for the difficulties in devising a therapeutic regimen based on cycle or phase-specific agents.