[An experimental study on radiotherapy for esophageal cancer using intraluminal administration of radiosensitizer]

This study was undertaken to evaluate the efficacy of intraluminal administration of 5-bromo-2'-deoxyuridine (BUdR) as a radiosensitizer during radiotherapy for esophageal cancer. Lipid-surfactant mixed micelles (MM) was used as an absorption promoter. VX2 carcinoma cells were endoscopically injected into the esophageal wall of rabbits. Two weeks after tumor inoculation, BUdR (100 mg/body) with MM was administered into the esophageal lumen and kept for 3 hours. Subsequently, animals were irradiated with 60Co at dosages of either 5 or 10 Gy. Twelve days after, animals were sacrificed to determine tumor diameter and to evaluate histological effect of radiation. BUdR uptake rates of tumor tissue were determined two weeks after tumor inoculation. Tumor diameters in control animals and those treated with simple irradiation at a dose of 5 Gy were similar. In contrast, irradiation at a dose of 5 Gy significantly reduced tumor diameters when combined with intraluminal administration of BUdR with MM. In cancer bearing animals receiving irradiation under intraluminal injection of BUdR with MM, the histological effect were apparently enhanced as compared to animals receiving simple irradiation. BUdR uptake rates of primary tumors showed a significant increase in animals with the intraluminal administration of the drug as compared the those with intravenous one shot bolus and intravenous drip infusion. Based on those results, we conclude that preoperative radiotherapy combined with intraluminal administration of radiosensitizer could be an effective method.