Feulgen microdensitometry and analysis of S-phase cells in cervical tumour biopsies

Tissue specimens from the cervical tumours of 70 patients undergoing radiotherapy were examined by Feulgen microdensitometry. Twenty-five of the 70 specimens were also subjected to in-vitro tritiated thymidine autoradiography to determine the proportion of DNA synthesising cells they contained. A spectrum of frequency distributions of nuclear DNA content was obtained from Feulgen microdensitometry, but by inspecting the data the basic DNA content of malignant cells could be established in most cases. Fifty-nine per cent of the tumours were 'diploid', 10% 'tetraploid', 13% 'diploid to tetraploid', and the remaining 18% 'aneuploid'. Grafical analysis of DNA frequencies from 48 'diploid' or 'tetraploid' tumours enabled the proportion of DNA synthesising (S) cells to be estimated by frequency distribution analysis. Estimates of the S component ranged from nil to 30%, were log normally distributed, and comparable to direct measurements of cells in S determined by autoradiography for 25 cases (range 1.2-28.7%). For all paired data the mean difference was 1.2 +/- 1.45% (confidence limits), suggesting that overall Feulgen microdensitometry analysis may be an equally valid technique in providing cellular kinetic information with human tumour material.