A pilot study of topical intrarectal application of amifostine for prevention of late radiation rectal injury.

Purpose: Clinical symptomatic late injury to the rectal wall occurs in about one-third of patients with prostate cancer treated with external beam irradiation. Reducing the physical dose to the anterior rectal wall without a similar reduction in the posterior peripheral zone is difficult because of the proximity of the prostate to the anterior rectal wall. On the basis of our previous observations in an animal model that intrarectal application of amifostine resulted in very high concentrations of amifostine and its active metabolite WR-1065 in the rectal wall, a Phase I dose-escalation clinical trial was undertaken.

Intrarectal application of amifostine for the prevention of radiation-induced rectal injury.

Clinically symptomatic late injury to the rectal wall occurs in about one third of patients with prostate cancer treated with external beam irradiation. Reducing the physical dose to the anterior rectal wall without a similar reduction in the posterior peripheral zone is difficult because of the proximity of these structures. Based on our previous observations that intrarectal application of amifostine resulted in very high concentrations of amifostine and its active metabolite WR-1065 in the rectal wall of Copenhagen rats, the authors initiated a phase I clinical trial in 1998.