162 NET-QUBIC objectives This PhD project was part of the NET-QUBIC research: the NETherlands QUality of life and BIomedical Cohort studies in Head and Neck Cancer. In this research, the VUmc, Radboudumc, UMCG, UMC Utrecht, Erasmus MC, Noordwest Ziekenhuisgroep Alkmaar and the Medisch Centrum Leeuwarden worked together to create a large database (n=739) and gained information about many quality of life (QoL) aspects in patients with head and neck cancer (HNC). In the UMC Utrecht, the primary objective was to build models to predict the burden of masticatory, swallowing and salivary dysfunction. The goal of these models was to identify patients at risk for developing masticatory, swallowing and salivary dysfunction. It was hypothesized that a prediction model using both objective function outcomes and patient-reported outcomes (PROs) will have a significantly better predictive accuracy in comparison to a model based on patient-reported outcomes alone. The secondary objectives were to establish the interaction between saliva, swallowing and masticatory function up to 2 years after treatment, and to investigate the course in time of saliva, swallowing and masticatory function and PROs during the first two years after treatment. The ultimate goal of the NET-QUBIC research was to build an optimal model for patients with HNC, to predict the longitudinal QoL effects on saliva, swallowing and masticatory function after treatment. When various treatment options have the same expected survival rates, this model will facilitate a balanced trade-off between the treatment options based on expected QoL. This will result in personalized care for each patient. In addition, it may be used to better inform patients about their options. Overview This thesis addresses main complications that may occur after treatment for head and neck cancer; xerostomia, dysphagia and masticatory deficits. As stated in the introduction of this thesis, there are many different steps and processes that need to work in a timely and often simultaneous or consecutive manner in order for food processing to be successful. Due to head and neck cancer or its treatment, many of these processes can deteriorate, which results in deficits in food processing. In chapter 2, a review is reported that describes the current literature regarding masticatory ability as measured with the UW-QoL (University of Washington Quality of Life) questionnaire in patients with oral cancer. This review shows a large variety in methodology, tumor subsite in the oral cavity, treatment modality, and timing of assessment between the different reported studies, to such a degree that outcome scores are difficult to compare. These results highlight the necessity for more comparable outcome measures.