Prevention of acute radiation-induced rectal toxicity by amifostine: efficacy and evaluation of objective and subjective endpoints for radiation therapy-induced mucositis.

Often the rectum is a dose-limiting organ in curative radiation therapy of pelvic malignancies. It results in serous, mucoid, or more rarely bloody diarrhea. There are few reports on the cytoprotective effect of amifostine in the radioprotection against rectal mucositis. Among 10 studies published in Medline, significant (P < 0.05) grade I-III acute toxicity was reported, and amifostine was used before irradiation in pelvic areas. Although the strength of the evidence is variable, it seems that there is a radioprotective effect, especially with intrarectal administration of amifostine. The cytoprotection seems to be effective in terms of symptomatic and objective (rectosigmoidoscopy) endpoints. However, there is a need for well designed clinical trials with sufficient numbers of participants. Besides, there is a need for accurate endpoints for evaluating acute rectal radiation toxicity. The rectosigmoidoscopy with objective measurements is superior to subjective parameters such as World Health Organization or Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer toxicity grading scales. We propose a system of combining the objective rectosigmoidoscopy with subjective World Health Organization or Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer toxicity scales for grading radiation therapy-induced acute rectal toxicity. This system could be accurate and user-friendly with good clinical reliability and validity.