The independence of intrinsic radiosensitivity as a prognostic factor for patient response to radiotherapy of carcinoma of the cervix

A study was made of the prognostic value of pretreatment measurements of tumour radiosensitivity (surviving fraction at 2 Gy, SF2) in 128 patients with stage I-III carcinomas of the uterine cervix undergoing radiotherapy. The median follow-up time was 47 months. In a univariate analysis stratifying patients according to the median value, radiosensitivity was a significant prognostic factor for overall survival, local control and metastasis-free survival. The 5-year survival rate for tumours with SF2 values below the median was 81% and was significantly greater than the rate of 51% for those with SF2 values above the median. In bivariate analyses, SF2 was shown to be independent of disease stage, tumour grade, patient age, colony-forming efficiency and tumour diameter. In a multivariate analysis, radiosensitivity was the most important variable and, after allowing for this, only stage was a significant independent predictor of treatment outcome. These data indicate that, in carcinoma of the cervix treated with radiotherapy, pretreatment tumour intrinsic radiosensitivity is an important prognostic parameter and contributes to prognosis independently of other established and putative parameters.