[en] In oral cancer radiotherapy may be used as the sole treatment, or in combination with other modalities of treatment. Irradiation which aims at cure is termed radical radiotherapy. Here the object is local control, i.e. the elimination of tumour from the irradiated site, which requires the killing of all those tumour cells with unlimited capacity for cell division, while at the same time leaving sufficient normal cells viable in the adjacent tissues to maintain the integrity of these tissues. The possibility of achieving this depends on the properties of both tumour and normal tissue