Therapy response summary (Fig. 
tumor
TUMOR, RECURRENCE, INFILTRATION, DISEASE, RECURRENT DISEASE, SECONDARY, PRIMARY TUMOR
For the Radiotherapy arm (Arm 1), the therapy response will be evaluated by the same modality as for staging (CT, MRI or PET-CT) 12–16 weeks after treatment, depending on local institutional standards. All patients must be discussed at the MTB with this imaging and clinical evaluation.In case of negative imaging, the patient will start the follow-up period of 2 years.In case of positive imaging, a panendoscopy with biopsy should be performed to confirm the residual/recurrence disease. Salvage surgery is recommended for residual or recurrent disease. For patients with residual nodes > 1 cm in size (smallest diameter), an ipsilateral neck dissection will be done. For patient with local residual or recurrent disease (at any time subsequent to radiation treatment), surgical salvage will be offered if feasible. The salvage surgery will be done by open (Total Laryngectomy) or transoral approach at the discretion of the treating surgeon and depending of the clinical situation.For the surgical arms (Arms 2 and 3), all patients must be discussed in the MTB with the post-operative histological results. All volumes are drawn based on pre-op imaging.Post-operative adjuvant radiotherapy alone will be performed in the presence of adverse pathological factors [(a) close margins (1-3 mm);(b) peri-neural infiltration or lympho-vascular invasion.(c) pT3 disease.(d) 1 invaded lymph node > 3 cm (pN2a) or more than 2 invaded lymph nodes per side of the neck (pN2b).The therapeutic CTV will consist of the primary tumor bed expanded in function of the quality of the surgical margins, and the eventual positive nodal levels. The elective CTV will be selected according to the international guidelines [Therapeutic/elective doses will be prescribed to the respective PTV’s at 60/54 Gy in 30 fractions of 2/1,8 Gy and planned with SIB-IMRT.Post-operative adjuvant chemo-radiation will be performed in case of [positive surgical margins in the definitive histology (< 1 mm) and no surgical revision possible;extracapsular extension in node(s).Delineation of CTVs and PTVs will follow the same rules. Therapeutic/elective doses will be prescribed to the respective PTVs at 66/56,1 Gy in 33 fractions of 2/1,7 Gy and planned with SIB-IMRT. Concomitant radio-sensitizing chemotherapy with 3-weekly Cisplatin or Carboplatin-5FU will be prescribed following the same rules as for definitive-radiation.In both cases, every reasonable effort should be made to start the post-operative (chemo)radiation within the 6 weeks after surgery.In case of recurrence or secondary primaries, a new panendoscopy with biopsy must be performed and the results should be discussed at the MTB. In case of a very small recurrence of secondary primary, a new trans-oral procedure can be performed. In case of a bigger tumor, salvage radiotherapy should be preferred. In case of contra-indication to radiotherapy (e.g., previous radiation on the neck), a total laryngectomy or total pharyngo-laryngectomy is required.