Circadian variation in radiation-induced intestinal mucositis in patients with cervical carcinoma

Mucositis, a radiotherapy-associated toxicity, is an important factor determining morbidity and treatment compliance. Gastrointestinal mucositis in patients undergoing radiotherapy may also depend on time of administration of radiation in addition to several other factors. The presence of any correlation between the severity of acute gastrointestinal mucositis in cervical carcinoma patients and the time of irradiation was prospectively evaluated.

A total of 229 patients with cervical carcinoma were randomized to morning (8:00-10:00 AM) and evening (6:00-8:00 PM) arms. The incidence of mucositis in the 2 arms was assessed and reported in terms of various grades of diarrhea.

Overall (grade I-IV) as well as higher grade (III and IV) diarrhea was found to be significantly increased in the morning arm as compared with the evening arm (overall: 87.39 % vs 68.18 %, P < .01; higher grade: 14.29% vs 5.45%, P < .05). Other radiation-induced toxicity was also higher in the morning arm, but its occurrence in the 2 arms did not differ significantly (13.45% vs 12.73%, P > .05). After completion of treatment, patients' response to radiation in the 2 arms was similar (P > .05).

The significant difference in the incidence of higher grade diarrhea between the morning and evening arms is indirect evidence of the influence of circadian rhythm on the intestinal mucosa of the human intestine. This knowledge may facilitate treating patients with decreased toxicity to the intestinal mucosa.