142 24 or as cross-sectional study to investigate swallowing at one point in time,10,21,22,25,26 for example at baseline.21 In these studies, different patients were assessed. Some studies only included patients that received RT or CRT,7,10,20,22,23,25,26 other studies only patients that received surgery,24 and others included patients with all curative treatment options.21,27 In addition, tumor site differed from one tumor site (e.g. laryngeal 27) to all tumors in the head and neck region. The number of patients included in the various studies assessing the SWAL-QOL, varied as well, from 2220 to 1083 patients.22 Most studies found that swallowing function was impaired across most domains for the majority of patients,23,24,27 especially 6 to 12 months after treatment.10 To reduce the risk for persistent patient reported swallowing problems after treatment for HNC, it is important to identify factors associated with these swallowing problems. Information can be provided about possible problems that may occur after treatment and the possibility of rehabilitation during and after treatment can be discussed. This will lead to a better evaluation of possible treatment options and more patient centered care. As mentioned, previous research about the SWAL-QOL mainly focused on one type of treatment modality, or one type of tumor site.28,29 In addition, most studies investigating swallowing problems in patients with HNC were too small to allow subgroup analyses.30 One study included all patients with HNC and assessed a large cohort, but only assessed the subscales swallowing and eating duration of the EORTC QLQ-H7N35.19 Factors that were found to be associated with poor patient reported swallowing problems included patientrelated factors such as smoking, alcohol use, higher age, low socio-economic status, and being female, and tumor-related factors such as advanced tumor stage, multi-modality treatment, and tumor site.10,19,31 However, to our knowledge, there are no studies that assessed the SWAL-QOL questionnaire and included the majority of these factors, included all treatment modalities and tumor sites, and assessed swallowing problems prospectively up to 2 years after treatment. The primary aim of this study was to investigate the course over time in the first two years after HNC diagnosis of various aspects of patient reported swallowing problems as measured with the SWAL-QOL. The secondary aim was to identify demographic, clinical, and lifestyle factors associated with patient reported swallowing problems in patients with HNC. Materials and methods Data were used of 739 patients with HNC participating in the prospective NETherlands Quality of Life and Biomedical Cohort study in HNC cancer (NET-QUBIC), of which details were published previously.32,33 Recruitment took place in 7 HNC centers throughout the