RATIONALE: Head and neck squamous cell carcinoma (HNSCC) has variable rates of neck metastasis that vary with subsite and tumor size. Irradiation of the neck at the time of treatment can be done electively in tumors with high risk of metastasis or therapeutically for nodal metastasis. Radiation ablates lymphatic channels and reduces risk of nodal metastasis. Therefore, performing selective neck dissection at the time of salvage surgery in the clinical N0 patient has remained controversial and studies have been limited to case series.
METHODS: EMBASE and Pubmed were queried for the term “salvage OR selective OR elective neck dissection.” Inclusion criteria were defined as: HNSCC, radiation to the lateral neck at time of primary treatment, undergoing salvage surgery for recurrence (>6 months after treatment) or second primary, clinically and radiographically N0 at time of salvage. Eleven studies with a total of 378 patients undergoing selective neck dissection at time of surgical salvage met inclusion criteria for meta-analysis. A fixed effects model was used to generate a pooled weighted average and 95% confidence intervals (CI) for risk of occult metastasis. The Surveillance, Epidemiology, and End Results Program (SEER) database was queried for survival in patients undergoing neck dissection after radiation therapy.
RESULTS: The rate of occult metastasis was 12.6% (CI 9.1% – 16.2%). Seven studies had reliable data for subsite and rate of occult neck metastasis. For oral cavity primaries (n = 39), the rate was 17.9% (CI 7.6% - 28.3%); for oropharynx primaries (n = 64), the rate was 12.4% (5.6% - 19.1%); for hypopharynx primaries (n = 24), the rate was 22.6% (CI 3.6% - 41.7%); for supraglottic primaries (n = 112), the rate was 27.2% (CI 22.8 – 31.8%); for glottic primaries (n = 49), the rate was 11.5% (CI 3.8% - 19.1%). SEER showed decreased rates of survival in salvage selective neck dissection in patients with hypopharyngeal and supraglottic primaries relative to oral cavity and oropharynx primaries.
CONCLUSION: The rate of occult neck metastasis at time of salvage surgery after irradiation to the neck is relatively low (12.6%). Hypopharyngeal and supraglottic subsites have increased rates of occult metastatic disease with decreased survival and selective neck dissection should be considered in these patients at the time of salvage surgery.