Studies of metronidazole radiosensitizing effect in radiation treatment of patients with oral cavity cancer.

Clinical observations of 26 patients with tongue, oral cavity and oropharyngeal cancer receiving telegammatherapy by dynamic dose fractionation scheme in combination with metronidazole (MZ) and of 38 patients from control group treated by identical schedule without MZ suggest that MZ favors increasing of the radiation damage in tumors of those sites without changing the character or intensifying early radiation reactions. After oral administration of MZ in single doses of 5-6 g/m2 it reaches its maximum in the blood serum within 2-4 h. When the total dose of 30-60 g of MZ was used, a marked toxic effect manifested by gastrointestinal symptoms was observed in 33.3% of patients. MZ has a negative effect on liver functions, however, changes in biochemical tests illustrating it, are reversible and within the norm. Simultaneous studies of biopsy material from 22 patients (11 from each group) in terms of proliferation activity showed that oral cavity tumors contain a significant portion of proliferating cells which notably decrease in the course of radiation therapy. To a greater extent that decrease is marked after irradiation with MZ.