Intrarectal Epinephrine Suspension May Protect Against Radiation Proctitis During Radiation Therapy for Prostate Cancer

Abstract

The aim was to evaluate the safety and efficacy of intrarectal constrictor epinephrine to relieve symptoms of radiation proctitis. A total of 34 patients with prostate cancer (PC) was randomized to receive daily intrarectal epinephrine (4 mg in 40ml, n=16) or placebo (40ml normal saline, n=18) 5 min right before daily radiotherapy. Blood pressure and heart rate were measured at the time of pre-epinephrine, 5 minutes, and 20 minutes after using epinephrine to evaluate the safety. Side effects were graded using Radiation Therapy Oncology Group (RTOG) standard. A two-sided Fish exact test was used for comparing proportions across groups. A Wilcoxon’s rank-sum test was used to compare medians across groups for continuous variables. No patients reported local or systemic toxicity after intrarectal epinephrine or saline. The differences in blood pressure and heart rate (pretreatment, 5 minutes and 20 minutes after using epinephrine) between these two groups were not statistically significant (p=0.792、0.542). At median follow-up of 24 months, the incidence of ≥ Grade 2 rectal toxicity was significantly lower in epinephrine group compared with the placebo group (p=0.016). After 2 years, no ≥ grade 2 toxicity of rectum was observed between these two groups. Results of this trial have demonstrated that intrarectal administration of epinephrine is safe and effective in relieving radiation-induced proctitis in patients with prostate cancer receiving RT.