Phd Ceremony I. Beetz: Prediction of patient-rated radiation-induced xerostomia

In patients with head and neck squamous cell carcinoma, radiotherapy either as primary or postoperative modality, generally includes irradiation of at least some parts of the salivary glands. Irradiation of the salivary glands may result in salivary dysfunction and subsequent xerostomia, which is one of the most frequently reported side effects of radiation treatment in the head and neck area. In addition, salivary dysfunction may lead to a sensation of a dry mouth, altered taste, swallowing problems, and speech problems, and has a significant impact on the more general dimensions of health-related quality of life. The overall aim of this thesis was to develop and validate multivariable normal tissue complication probability models for different aspects of patient-rated complaints related to radiation-induced hyposalivation, taking into account the possible role of dose distributions in different salivary glands as well as other factors. From this thesis we can conclude that hyposalivation, resulting in moderate-to-severe xerostomia and sticky saliva as reported by patients, is still an important and frequently occurring problem after curative radiation for head and neck cancer. The risk of patient-rated xerostomia and sticky saliva depends on several factors, including factors related to radiation dose to the major salivary glands. These findings offer opportunities to select patients for more advanced radiation delivery techniques, such as proton therapy.