Radiosensitization of hypoxic tumour cells with special emphasis on head and neck cancer

The radioresistance of hypoxic tumour cells may be the cause of recurrences in some clinical situations. In nearly all biological systems radiosensitivity is increased by a factor of 2 to 3 in the presence of oxygen. During a course of curative radiotherapy the process of reoxygenation occurs in most tumours. With the use of electron-affinic radiosensitizers of hypoxic cells the possibility exists to eliminate the disadvantage of insufficient reoxygenation of hypoxic cells. The current status of clinical studies using misonidazole in the treatment of head and neck carcinomas is discussed. (Author)