78 scanning methods, gummy jelly as test food, and mixing ability methods.14 One method using the mixing ability method (the Mixing Ability Test (MAT)) has proven to be highly reliable in patients with HNC.15 Objective swallowing performance can be measured with, for example, Fibreoptic Endoscopic Evaluation of Swallowing (FEES), or in a non-invasive and fast manner with minimal equipment using a 100 mL Water Swallow Test (WST).16,17 Measures of objective salivary flow rate from parotid and submandibular glands have been used for years to determine the dose response relationship between RT dose and degree of hyposalivation or sticky saliva.18 Subjective oral functioning can be measured with several validated questionnaires.19 The European Organization for Research and Treatment of Cancer Quality of Life core Questionnaire, Head and Neck module (EORTC QLQ-H&N35) was especially developed to measure HNC specific problems and addresses different items of oral functioning.20 The Dutch version of the Swallow Quality of Life questionnaire (SWAL-QOL-NL) was developed to address swallowing specific problems.21 The Groningen Radiation-Induced Xerostomia (GRIX) questionnaire was developed to observe xerostomia and sticky saliva during day and night.22 Before creating prediction models that show patients at risk for developing mastication, dysphagia or xerostomia related problems after treatment, it is important to get insight in the association between objective and subjective measures to get a total image of oral functioning. Therefore, the aim of this study was to determine the association between the MAT, WST or salivary flow test and the EORTC QLQ-H&N35, SWAL-QOL or GRIX, before treatment, and 3 and 6 months after treatment. Methods Data of the prospective cohort study Netherlands Quality of Life and Biomedical Cohort (NET-QUBIC) Study were used.23 Patients were recruited between 2014 and 2018 and included when they were 18 years or older, diagnosed with oral, oropharyngeal, hypopharyngeal, laryngeal, or unknown primary HNC. Patients with recurrent or residual disease, cognitive impairments, and patients having trouble understanding or reading the Dutch language were excluded. The study protocol was approved by the Medical Ethics Committee (NL45051.029.13). In the present study, the study population consisted of patients with data on MAT, WST and salivary flow test. These tests were only performed in one single center (University Medical Center Utrecht (UMCU)). Sociodemographic and clinical data about age, sex, tumor stage, tumor location, and treatment were collected from medical records. All participants signed informed consent. Data from objective tests and subjective questionnaires were used as collected before primary treatment (baseline,