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.