Objectives: To determine whether nodal necrosis and node size of 3 cm or larger are risk factors for recurrent neck disease and whether negative computed tomography-positron emission tomography (CT-PET) results 8 weeks or more after therapy indicate complete response in the neck in patients with N2 disease.

Design: Retrospective study.

Setting: State university hospital.

Patients: Fifty-six patients with head and neck squamous cell cancer and N2 disease treated with chemoradiotherapy were evaluated for persistent or recurrent neck disease. Tumor characteristics analyzed were primary site, T category, nodal size (<3 cm or > or =3 cm), nodal necrosis based on hypodensity of one-third or more of the node, and type of N2 disease (N2a, N2b, or N2c). Forty-eight of the 56 patients underwent CT-PET to determine treatment response after chemoradiotherapy. Clinical examination, imaging, and pathologic specimens were used to confirm disease recurrence.

Main outcome measures: The number of recurrence events, disease-free interval, and positive posttreatment CT-PET result in the neck.

Results: Most patients had oropharyngeal tumors (n = 37; 66%), T2 tumors (n = 21; 38%), nodes 3 cm or larger (n = 43; 77%), positive necrosis (n = 40; 71%), and N2c disease (n = 28; 50%). Multivariate analysis determined that no factors were significant predictors of recurrence, except for positive posttreatment PET results (P < .001). Comparison of CT-PET with nodal recurrence demonstrated a sensitivity of 82%, a specificity of 97%, a negative predictive value of 95%, and a positive predictive value of 90%.

Conclusion: Posttreatment neck dissections may not be indicated for patients with N2 disease and a negative CT-PET result, even in patients with nodal necrosis and nodes 3 cm or larger.