To determine if combined [18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) is performant enough with respect to detecting residual lymph node involvement after chemoradiation in order to omit planned neck dissections in patients with locally advanced potentially operable, N2 and N3 head and neck squamous cell carcinoma (HNSCC).

Primary study hypothesis: The lower bound of the 95% confidence interval (CI) of the negative predictive value (NPV) of FDG PET/CT to detect residual malignant lymph node involvement at 12 weeks after completing chemoradiation will exceed 85%.

Patients with locally advanced, N2 and N3 head and neck squamous cell carcinoma (HNSCC) will be recruited. All subjects receiving induction chemotherapy will undergo a baseline integrated [18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) scan before the start of concurrent chemoradiation. This baseline assessment is optional in patients not receiving neo-adjuvant treatment.

All patients will undergo a dedicated FDG PET/CT protocol 12 weeks after the end of chemoradiation (primary endpoint). In PET/CT negative patients, 2 monthly control visits will be performed complemented with additional imaging as required. All patients will undergo PET/CT 1 year after completing chemoradiation unless recurrent/residual disease was already proven pathologically. Patients with a PET/CT suspected for residual nodal disease must have pathological proof of nodal involvement (fine needle aspiration in non-operable patients or neck dissection in the others) before salvage chemotherapy is started.

In a subset of patients receiving induction chemotherapy prior to concurrent chemoradiation, an additional FDG PET/CT scan will be performed at baseline and after 1 cycle of chemotherapy to evaluate the metabolic response to the treatment (secondary endpoint).

Inclusion Criteria:

• Patients with locoregionally advanced HNSCC (clinically and/or radiological N2 or N3 disease, any T stage) with no evidence of distant metastases, scheduled for concurrent chemoradiation and being potential candidates for a subsequent neck dissection.
• Induction chemotherapy is allowed if this approach is followed by concurrent chemo-radiation.

Exclusion Criteria:

• Other head and neck cancer histologies
• Upfront inoperable patients in the neck (eg. carotid invasion)
• Presence of distant metastases
• A history of another primary malignancy, except when disease-free for at least 5 years after radical treatment, or except for treated basaloid skin cancer or in situ carcinoma of the cervix

Patients with locally advanced, N2 and N3 HNSCC