Event free survival (EFS) is defined as the time from the date of registration to the date of first record of any of the following events:

• Progression.
• Surgery.
• Non-protocol RT, chemotherapy, or biologic therapy (for the current cancer diagnosis) without documentation of the site of failure.
• Death due to any cause. The outcome is reported as the proportion of patients who remain event-free at 2 years.

For patients who have died, overall survival is calculated in months from the day of registration to date of death. Otherwise, overall survival is censored at the last day the patient is known alive (LKA). The outcome is reported as the proportion of patients who remain alive at 2 years.

Local-regional control is defined as the time from the date of registration to the date of any of the following, whichever comes first:

• Surgery of primary tumour at any time performed for clinical or radiological disease persistence/progression/recurrence with tumour present/unknown on final pathology.
• Neck dissection > 20 weeks from the end of radiation therapy performed for clinical or radiological (RECIST 1.1) disease persistence/progression/recurrence within target volumes with tumour present/unknown on final pathology.
• Neck dissection at any time after registration performed for clinical or radiological disease recurrence/progression outside the target volumes or without documentation of the site of failure with tumour present/unknown on final pathology.
• the first record of appearance (radiological or clinical) of local or regional disease progression. The outcome is reported as the proportion of patients who remain local-regional control free at 2 years.

Time to out-of-field regional failure is defined as the time from the date of registration to the date of the first record of appearance of regional progression/recurrence outside the treatment field , or to the date of neck dissection at any time after registration with tumour present/unknown performed for clinical or radiological disease progression outside the target volumes whichever comes first. The outcome is reported as the proportion of patients who remain out-of-field regional control free at 2 years.

Distant metastasis free survival is defined as the time from the date of registration to the date of first record of appearance of distant metastasis or death for any cause. Local-regional failure or second cancers diagnosed before the distant metastases are not considered events of interest for this endpoint. Subjects alive and free of distant metastasis are censored at the date of the most recent follow-up examination. The outcome is reported as the proportion of patients who remain distant metastasis event-free at 2 years.