Amifostine as radioprotective agent for the rectal mucosa during irradiation of pelvic tumors. A phase II randomized study using various toxicity scales and rectosigmoidoscopy.

AIM

To evaluate the cytoprotective effect of amifostine against radiation-induced acute toxicity to the rectal mucosa.

PATIENTS AND METHODS

36 patients irradiated for prostate or gynecologic cancer were randomized to receive amifostine (n = 18, group A) or not (n = 18, group B). The radiation-induced acute rectal toxicity was evaluated by using three different toxicity scales: WHO scale, EORTC/RTOG toxicity criteria, and a modified toxicity scale based on the LENT-SOMA grading scale and the endoscopic terminology of the World Organization for Digestive Endoscopy. The objective measurements were coming from flexible rectosigmoidoscopy performed at baseline and 1-2 days after completion of the radiotherapy schedule. Anterior-posterior fields were used in the gynecologic patients while 3-D conformal 4-field technique was applied in the prostate cancer patients. The area under the curve (AUC) for dose-volume histograms (DVHs) of the rectum was also assessed during a 3-D treatment planning schedule, and no significant differences were assessed between the two groups, indicating a homogeneous dose-volume effect.

RESULTS

Amifostine was well tolerated. No grade 2 or higher WHO and EORTC/RTOG acute toxicity was noted in group A, while acute rectal toxicity (> or = grade 1) was observed in 16/18 patients of group B versus 2/18 of group A (p < 0.001). The onset as well as the duration of acute rectal toxicity were significantly improved in group A (p = 0.002). Rectosigmoidoscopy revealed more severe rectal mucositis in noncytoprotected patients (group B), and modified LENT-SOMA overall mucositis grading score was significantly lower in group A (p = 0.003).

CONCLUSION

Amifostine seems to have a significant cytoprotective efficacy in acute radiation-induced rectal mucositis in terms of symptomatic and objective endpoints.