Fractionated radiotherapy of rat prostatic adenocarcinoma (Dunning R3327-PAP) in nonanesthetized animals

BACKGROUND. The dose-response effect of fractionated external beam radiothe rapy on nonanesthetized rats bearing the androgen-sensitive prostatic adeno carcinoma Dunning R3327-PAP was studied. METHODS. The radiation was,given with a photon beam from a 4-MeV linear acc elerator in doses from 4 to 11 Gray per fraction during 5 consecutive days. When the tumors with low and intermediate radiation doses relapsed into re growth, the rats were castrated. Tumor volumes and rat weights were followe d, and at the end of the study a morphometric analysis of the tumors was do ne. RESULTS. Fractionated irradiation induced a dose-dependent delay in tumor g rowth in hormonally intact rats. Castration stopped the tumor regrowth, sho wing that some of the tumor cells were still hormone-sensitive. The study w as facilitated by the nonanesthesia procedure. CONCLUSIONS. The Dunning R3327-PAP hormone-sensitive rat tumor is sensitive to radiotherapy in a dose-dependent way. Regrowing, irradiated tumors cont ain hormone-sensitive cells. This work provided basic knowledge for further experimental studies of the effects of radiation on prostatic adenocarcino ma. (C) 1999 Wiley-Liss, Inc.