Meta-analysis of risk of occult lymph node metastasis in the irradiated, clinically N0 neck

Background Recurrent head and neck squamous cell carcinoma (HNSCC) after radiation is associated with poor survival, and management of the clinically negative (N0) neck during salvage surgery is controversial. Methods Studies were selected according to preferred reporting items for systematic reviews and meta-analyses guidelines. Inclusion criteria were patients with HNSCC, prior radiation to the lateral neck nodal basin, undergoing salvage surgery for local recurrence, persistence or second primary, and N0 at time of salvage. Eleven studies with a total of 382 patients met inclusion criteria. Results The rate of occult metastasis was 15.4%. The pooled rate of occult nodal metastasis was 16.2% for oral cavity, 12.9% for oropharynx, 23.7% for hypopharynx, and 27.3% for supraglottic or transglottic tumors. There was a significantly higher relative risk of occult metastasis for locally advanced tumors. Conclusion Elective neck dissection at time of salvage surgery should be considered based on subsite, T classification, and prior history of nodal metastasis.