Pulse cytophotometric investigations concerning ploidy and proliferation pattern of invasive squamous cell carcinomas of the cervix uteri.

Tumor cell suspensions from 100 biopsies of squamous cell carcinomas of the cervix uteri were investigated by impulse cytophotometry (ICP) after staining with pepsin-ethidium bromide. We estimated the ploidy pattern by comparing the ICP curves with normal diploid material. The originally linearly classified curves were transformed in a logarithmical manner. We found 48 diploid populations and 42 polyploid populations, among them 19 tetraploid tumors. In these the 4c-peak was the highest. In 10 cases there were aneuploid stem lines, mainly lying between 2c and 4c; 2 curves had a hypertetraploid pattern. Helpful for interpretation of the whole curve is the introduction of an index: the "relative mean DNA-content" (DNA). In 15 diploid tumors we found a low proliferating rate, characterized by low 4c-peaks. For interpretation of polyploid cell cycles a completed nomenclature of cell cycle phases was introduced. Comparing our material with chromosome analyses in laterature we found more polyploid, e.g. tetraploid tumors. It can be assumed that the estimation of ploidy pattern solely by DNA measurements has another meaning than by chromosome analyses. The higher ploid peaks in DNA distribution curves (e.g. ICP-karyograms) represent not only true polyploid nuclei but also nuclei which are in a blocked premitotic resting phase (G2 for 4c; G'2 for 8c and so on). The ICP is a valuable method for estimating biological pecularities of tumor cell suspensions.