In patients with squamous cell carcinoma of the oral cavity, the oropharynx and larynx with local advanced tumors (pathologic stage T3 = pT3) and or lymph node involvement (pN+) postoperative radio - or radiochemotherapy is the standard of care. Postoperative radiochemotherapy is indicated in patients with multiple lymph node metastasis, lymph node metastasis with extracapsular spread and / or residual tumor (R1-Status) after resection. Oropharyngeal cancer caused by HPV (human papillomavirus 16) is a distinct subgroup with a known sensitivity to radiotherapy (RTx) or radiochemotherapy (RCTx). Additionally a superior outcome after R(C)Tx over HPV negative patients was shown for patients treated with primary or adjuvant RCTx. To date it is unknown if the total dose of the radiotherapy can be safely reduced with the aim to decrease the therapy associated late effects. Patients with a HPV associated carcinoma that take part in the study will be treated with a reduced radiotherapy dose, chemotherapy will be prescribed based on clinical factors (number of affected lymph node, presence of extracapsular spread or residual tumor). Radiation dose will be reduced in two steps.