Radiotherapy of head-neck cancer is associated with significant side effects. Using daily online adaptive radiotherapy to account for the changing anatomy, radiation to organs at risk can be lowered. We will investigate whether this is feasible and associated with a reduction in the risk of toxicity.

Inclusion Criteria:

• Patients with histologically proven squamous cell carcinoma of the pharynx or larynx planned for primary radiotherapy with curative intent No current or earlier malignancies, which may influence treatment, evaluation or outcome of the head-neck cancer Informed consent as required by law The patient cannot participate in conflicting protocols Stage I-IV (excluding T1-T2N0 carcinoma of the glottic larynx) ECOG/WHO performance status 0-2

Exclusion Criteria:

Patient with cancers of the glottic larynx (stage I/II), skull base, sino-nasal area and unknown primary tumor.

Inability to attend full course of radiotherapy or follow-up visits in the outpatient clinic Distant metastasis Previous radiotherapy of the head and neck Previous surgery for the primary cancer with curative intent

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Not allowed