Changes in S-phase fraction and micronucleus frequency as prognostic factors in radiotherapy of cervical carcinoma

Twenty-five patients with cervical carcinoma were treated with combined external beam and high dose rate afterloading radiotherapy. Biopsies obtained at different time points in the course of therapy were analysed with respect to cell proliferation and cytogenetic damage. The fraction of cells with an S-phase DNA-content as well as the frequency of micronuclei were determined. These two parameters were then related to treatment outcome, in particular patient survival. Neither S-phase fraction nor the micronucleus frequency before radiotherapy were predictive of treatment outcome in this small group of patients. However, when changes in response to therapy were considered, patients whose S-phase fraction decreased and patients whose micronucleus frequency increased tended to have a better prognosis. Although statistical significance was not achieved with either criterion alone, when applied together the combination predicted patient survival quite reliably; the 5-year survival rate of those patients who showed a decrease in S-phase fraction as well as an increase in micronucleus frequency was about 90% in contrast to less than 30% for the non-responders (p < 0.03).