Clinical significance of radiation therapy combined with chemotherapy

With the aim of reducing the side-effects in the surrounding healthy tissues, and/or improving the local control rate, radiotherapy combined with chemotherapy has been used to treat carcinoma of the esophagus, of the tongue, and of the paranasal sinuses. In the treatment of esophageal cancer, a dose of bleomycin too small to demonstrate clinical activity on its own is shown to potentiate the action of radiation with an enhancement ratio lying between 1.3 and 1.7 (Table 1). From the concept of 'therapeutic ratio' a 'two-phase' treatment modality (Table 2) was proposed, because many anticancer drugs or radiosensitizers available today influence not only the tumor tissue but also the surrounding healthy tissues. 'Two-phase' treatment was applied to cancer of the tongue (Table 3) and to cancer of the paranasal sinuses (Table 4). The appearance of the chronical complications such as the osteoradionecrosis of the mandible and the cataract of the lens could be prevented by the use of bleomycin or BUdR combined with radiotherapy.