143 8 Netherlands between 2014 and 2018. Patients were included when they were 18 years or older, were diagnosed with oral, oropharyngeal, hypopharyngeal, or laryngeal HNC and were treated with curative intent (all treatment modalities). Patients with an unknown primary tumor, recurrent or residual disease, cognitive impairments, lymphoma, skin malignancies or thyroid cancer, and patients having trouble understanding or reading the Dutch language were excluded. All patients signed written informed consent before participation. The study protocol of this prospective observational cohort study was approved by the Medical Ethics Committee of the VUmc (NL45051.029.13) and all local participating centers.32,33 In the present study, patients were included when they had completed the SWAL-QOL questionnaire at any given time point. The SWAL-QOL questionnaire was assessed before primary treatment (baseline, M0), 3 months (M3), 6 months (M6), 12 months (M12), and 24 months after treatment (M24). Demographic factors (age and sex), clinical factors (tumor stage,34 tumor site, HPV status (in oropharynx patients), treatment modality, comorbidity, and weight loss), and lifestyle factors (alcohol use and smoking) were assessed at baseline. The primary outcome measure was the 47-item Swallowing Quality of life Questionnaire (SWAL-QOL).16 This questionnaire comprises of 10 subscales on food selection (2 items), eating duration (2 items), eating desire (3 items), fear of eating (4 items), general burden (2 items), mental health (5 items), social functioning (5 items), communication (2 items), sleep (2 items), and fatigue (3 items). Furthermore, a symptom scale (14 items) is included. Based on the 23 items of the first seven mentioned scales, a total SWAL-QOL score can be calculated. All items refer to the last month. In NET-QUBIC, the subscales communication, sleep, and fatigue were removed, because of the considerable overlap with the Speech Handicap Index and the Multidimensional Fatigue Inventory. The 5-point items are transformed to scales ranging from 0 to 100, where a higher score indicates more swallowing problems. As found in previous research, a cut-off score on the total SWAL-QOL score of ≥14 points indicates a high level of swallowing problems in daily life.26 The SWALQOL has been translated into Dutch and validated for use in patients with HNC.16 Baseline characteristics about age, sex, ACE-27 comorbidity score,35 TNM7 classification (2010), and weight loss prior to treatment were collected from medical files. HPV status was collected for oropharynx tumors. A 13-item study-specific patient-reported questionnaire was used to assess smoking status and nicotine dependence. One item about passive smoking was included, 7 items about smoking behavior, and 5 items about nicotine dependence. For this study, patients were categorized as current smoker, nonsmoker (less than 100 units in their lifetime) or former smoker. A 21-item questionnaire was used to assess alcohol intake and dependence, consisting of questions about current alcohol intake