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

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 (08:00-11:00 h) versus late afternoon/evening (15:00-18:00 h).A total of 212 patients of head and neck carcinoma were randomised to morning (08:00-11:00 h) and evening (15:00-18:00 h) groups. The grades of oral mucosa ulceration were compared in the two groups.The grades of mucositis were marginally higher in the evening-irradiated group than in the morning-irradiated group 38% vs. 26% (p = 0.08).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.