Margin mapping in transoral surgery for head and neck cancer.

OBJECTIVES/HYPOTHESIS: To evaluate the results of patients treated by transoral laser microsurgery and margin mapping with attention to deep margin dimensions in the lateral pharyngeal wall. STUDY
DESIGN: A microscopic margin analysis of multiblock surgical specimens applied to a prospectively accrued case series of squamous cell carcinoma of the palatine tonsils.
METHODS: There were 128 tonsil cancers analyzed that were removed transorally, using microscopic margin mapping by surgeon and pathologist. The closest deep and peripheral margins were assessed. The results were then related to a study of the normal dimensions of the lateral pharyngeal wall in 20 healthy patients using magnetic resonance imaging. Outcome measures included number of positive margins, narrowest margin, local control, and disease-free and overall survival.
RESULTS: The average closest margin was 1.98 mm (range, 0.30-6.50 mm) deep and 2.82 mm (range, 1.00-5.00 mm) peripheral. There was one positive margin encountered in the previously untreated group (1%), and one local recurrence ultimately developed. Radiographic measures revealed a mean minimal thickness of the lateral pharyngeal wall musculature of 2.4 mm. With mean follow-up of 4.3 years (range, 2-14 years), the 5-year estimate for local control is 99%, disease-free survival is 94.5%, and overall survival is 76%.
CONCLUSIONS: Margin mapping achieves a low rate of positive margins and is associated with good local control. Based on lateral pharyngeal wall anatomy, wide margins are often unobtainable and may be unnecessary so long as the final inked margin is clear. LEVEL OF EVIDENCE: 4.