Quantitation by flow cytofluorometry of response of tumours of the uterine cervix to radiotherapy.

We are presently involved in a project to investigate the use of flow cytofluorometry in assessing, by means of serial biopsies, the response to radiotherapy of tumours of the uterine cervix. This technique enables changes in the DNA content profiles and content of proliferating cells in the tumour biopsies to be determined at intervals as therapy progresses. A means has been devised to quantitate the content of hyperdiploid cells, hypertetraploid cells, and dead and dying cells, by computer analysis of DNA vs. RNA scattergrams obtained by flow cytofluorometric analysis. Plotting of these parameters for the serial biopsies vs. time since start of tumour irradiation presents a graphical indication of the response of the tumour to irradiation. Over 100 patients (stage Ib and IIa) have been followed during intracavitary (Cathetron) therapy with parallel flow cytofluorometric analysis and histopathological assessment of serial biopsies. Patterns are beginning to emerge from these analyses which promise to indicate within 14-21 days and sometimes earlier the extent of radioresponsiveness of the tumour. These patterns may also be of assistance in planning modified dose fractionation schedules to obtain improved therapeutic ratios.