Changes in nuclear size and DNA content of carcinoma of cervix after fractionated irradiation

ABSTRACT

The effect of conventional fractioned irradiation [5 Fr of 2.00 Gy/week] on the nuclear size and DNA content of squamous cell carcinoma of the cervix was evaluated in 6 patients. Three consecutive biopsies were taken from each patient; prior to irradiation, after 20.00 Gy and after 40.00 Gy. The nuclear diameter was measured using eyepiece micrometer. Cytophotometric DNA analysis was made on Feulgen-stained sections. A total of 1800 tumor nuclei and 1200 normal epithelium nuclei were examined; 100 nuclei per sample. Progressive increase in the nuclear size was observed in tumor cells with increase of the dose. In normal cells, however, this increase was only observed after the high dose. Prior to irradiation, the distribution of DNA content in tumor nuclei showed a primary mode between the diploid and tetraploid range. After irradiation, however, an irregular DNA distribution was observed with disappearance of primary mode, a wide scatter over the extreme values and a relative increase of the mean value. Normal nuclei showed only a slight increase of DNA mode after irradiation. The radiobiologic explanations of these changes are presented together with their possible clinical implications, particularly in predicting tumor responsiveness to radiotherapy