Oral mucositis in morning vs. evening irradiated patients: A randomised prospective study

Purpose: Patients of head and neck cancer undergoing radiotherapy develop oral mucositis. The severity of mucositis may also depend on the time of administration of radiation apart from patient-related factors. The most radiosensitive phase of the cell cycle (G2-M) occurs in the late afternoon and evening in human oral mucosa; therefore, it is more vulnerable to radiation injury in the evening. The present study evaluated prospectively the severity of acute oral mucositis in head and neck carcinoma patients irradiated in the morning (08:00-11:00h) versus late afternoon/evening (15:00-18:00h). Method: A total of 212 patients of head and neck carcinoma were randomised to morning (08:00-11:00h) and evening (15:00-18:00h) groups. The grades of oral mucosa ulceration were compared in the two groups. Results: The grades of mucositis were marginally higher in the evening-irradiated group than in the morning-irradiated group 38% vs. 26% (p=0.08). Conclusion: The observed incidence of grade III/IV mucositis in morning vs. evening irradiated patients may be because of the existence of circadian rhythm in the cell cycle of normal mucosa. This knowledge may provide a possibility of treating the patients with decreased toxicity to oral mucosa.