Protection from Radiation-Induced Oral Mucositis by Misoprostol, a Prostaglandin E(1) Analog: A Placebo-Controlled, Double-Blind Clinical Trial

Abstract

Misoprostol, a prostaglandin E(1) analog, is an effective radioprotector in animal studies. Based on this evidence, a prospective, randomized, placebo-controlled, double-blind study was conducted to determine if misoprostol protected the oral and pharyngeal mucosa of irradiated head and neck cancer patients from radiation mucositis. Postsurgical patients who had no detectable cancer and who were referred for postoperative irradiation were candidates for this study. Thirty-four Hines VA and 35 Loyola University patients were accrued (69 total) over a 2-year period. A misoprostol tablet (200 &mgr;g) or an identical placebo tablet was dissolved in water and administered as an oral rinse daily about 20 min before irradiation. Conventional fractionated radiotherapy, consisting of five weekly doses of 2 Gy day(minus sign1), was delivered. The degree of mucositis was scored on a scale from 0 (no mucositis) to 4. In the 17 patients randomly assigned to the misoprostol arm at the Hines VA, no advantage was seen compared to the 17 placebo-treated patients. However, there was significantly less mucositis (p < 0.01, analysis of variance) from weeks 3--6 in the 17 patients treated with misoprostol at Loyola compared to the 18 placebo-treated patients. Several problems in the study were identified at the VA, including adherence to the protocol design. Other problems such as adequate mucositis scoring, radiation scatter from fillings, and, in particular, adequate timing between misoprostol and irradiation were identified at both locations. Absorption studies in healthy volunteers showed significant plasma levels at 10 min after an oral rinse, suggesting that initial clinical trials should be confined to topical misoprostol until more is known regarding the effect of misoprostol on tumors. The results of this pilot study suggest that misoprotol may protect the oral and pharyngeal mucosa from radiation-induced mocositis if adequate time between topical administration and radiation is allowed.