164 Future perspectives The ultimate goal of the NET-QUBIC research was to create one prediction model, taking into account both objective and subjective measures, and exploring the interaction between mastication, salivary flow and swallowing. However, because of the low correlation between objective and subjective measures, as described in chapter 5, it was impossible to create a prediction model taking into account both objective and subjective measures. Because of the low correlation between objective and subjective measures, it was expected that different items than the items described in chapter 6 and 7 will have an effect on the patient-reported outcomes, which are shown in chapter 8 for the SWAL-QOL questionnaire. In addition, because of the high correlation between chewing, swallowing and salivary flow as described in the introduction, it would be preferred to combine all tests and create one outcome that includes the whole food process. There is a huge amount of data in the NET-QUBIC research to elaborate on. For example, nowadays swallowing structures and salivary glands are delineated in patients that received radiotherapy and marked as organs at risk (OAR). Correlating the dose on the OARs to the measured complications will result in normal tissue complication models (NTCP), which can be used to further optimize radiotherapy treatment. However, masticatory muscles are not delineated yet. It is expected that marking the masticatory muscles as OAR and subsequently sparing these organs in the radiotherapy plan can reduce masticatory problems after treatment. In addition, because of the high correlation between mastication and swallowing, sparing the masticatory muscles can result in less swallowing problems as well. The discrepancy between clinical measures and patients’ own evaluations of their health has been described since the 1980s.8,9 PROs are increasingly used in daily practice, because these measures are easy and fast to perform.10 Their use reflects a growing appreciation of the importance of patient’s feelings and satisfaction with treatment.10 Objective measures are based on performance, irrespective of experience. They are thus an accurate and unbiased representation, recording only what is observed.9,11 PROs depend on individual values and priorities, which may differ between persons and even within persons.9 Internal standards, values, and the conceptualization of quality of life can change over the course of a disease trajectory.8 A PRO is based on what people actually experience and how a person evaluates his or her functioning, rather than his or her performance as measured with objective tests.12 Individuals differ in what they find important, and expectation about one’s progress after treatment may change over time and in response to personal circumstances. Patients may develop a degree of adaptation over time, in which their PRO improves, but their objective measure stays the same or worsens, which is also known as