Prostate cancer dose-response, fractionation sensitivity and repopulation parameters evaluation from 25 international radiotherapy outcome data sets.

This study was undertaken to model the biochemical free survival at 5 years and to evaluate the parameters defining dose-response curve, dose-fractionation radiosensitivity and repopulation. It was carried out a literature search on Pubmed to retrieve data sets of patients treated with external beam radiation therapy of 1.8-4.0 Gy per fraction and overall treatment time of 3 to 10 weeks. 10 groups were identified, based on risk class and androgen deprivation therapy (ADT). Dose-response curve 25 data sets, including 20,310 patients, were considered. The median (95% CI) Dose-response curve resulted dependent on risk class and ADT, with higher steepness for no-ADT patients. Low values of dose-fractionation radiosensitivity were found, supporting the use of moderate hypofractionated radiotherapy in each risk class. A limited dependence on repopulation was observed. Prostate cancer response to moderate hypofractionated radiotherapy was reliably quantified considering risk class and androgen deprivation therapy.