Nodal Yield and Topography of Nodal Metastases from Oral Cavity Squamous Cell Carcinoma - An Audit of 1004 Cases Undergoing Primary Surgical Resection

Objectives: Nodal metastasis is an important prognostic factor in oral squamous cell carcinoma (OSCC). Detailed topographic study of metastasis can guide surgical and adjuvant radiation treatment protocols.

Methods: Retrospective analysis of distribution of nodal spread was done by auditing pathology records of 1004 patients who underwent primary surgical management at our center.

Results: The median nodal yield was 41 (range of 9-166) nodes, per patient. Metastasis was present in 42.9% patients, of which 52.3% demonstrated extranodal extension. Reclassification by AJCC8 criteria resulted in up-staging in 35.6% patients (pN1, pN2a, pN2b, pN2c, pN3a and pN3b in 13.1%, 3.7%, 6.9%, 0.9%, 0%, 18.1% respectively). Ipsilateral levels Ib and IIa were involved in a quarter of patients each, while IIb, IV and V were involved in < 4%, 3% and 1% of patients, respectively. Contralateral nodal metastasis was present in 5.4%. Skip metastases to level IV were 2.2% and 1.2% for tongue and gingivobuccal primaries. Tongue primaries had a lower likelihood of involving level Ib, but higher of level IIa and III, compared to gingivobuccal primaries, and a lower likelihood of extranodal extension. Primary site did not influence nodal metastasis to levels IIb, IV or V, but other factors like lymphovascular invasion, pT stage and margin status had an influence.

Conclusion: This large series with high nodal yield, shows low level of metastasis to level IIb, IV and V, which can help modify future guidelines for extent of surgery and avoid targeted adjuvant radiation to specific levels.