Radiation therapy in the head and neck area and treatment with high dose chemotherapy entail damage to healthy tissue in the mouth. In order to reduce to a minimum the chances of these side effects of cancer treatment developing, it is necessary to carry out oral foci tests prior to oncological therapy. In addition supplementary oral and dental care measures seem to be important in order to limit the side effects of oncological therapy on the teeth, salivary glands and jaw as much as possible. This supportive oral care is not only necessary during, but also for years after the oncology treatment. Therefore not only dental professionals affiliated to oncology teams will have to take care of cancer patients, but also family dentists and dental hygienists.