OP97 – Larger lymph nodes with extranodal extension are associated with aggressive pathologic features of papillary thyroid cancer: Further clues to risk stratification

      Machado, Rosalie A.1,2; Roche, Ansley M.1,2; Urken, Mark L.1,2 1 Thyroid Head and Neck Cancer Foundation, New York, New York, USA 2 Department of Otolaryngology- Head and Neck Surgery, Mount Sinai Downtown, New York, NY, USA   Background: Extranodal extension in metastatic lymph nodes (ENE nodes) is a prognostic indicator of aggressive papillary thyroid cancer (PTC).  We recently reported that small lymph nodes demonstrate ENE as do large lymph nodes. To date, no prior studies have evaluated the relationship between size of ENE nodes and histologic features of the primary tumor and characteristics of nodal metastases. We aim to elucidate this relationship. Methods: A retrospective analysis was performed on patients with PTC who underwent total thyroidectomy and neck dissections and had documented ENE in at least one positive node. Patients were divided into two cohorts based on size of ENE nodes: 1) all nodes ? 1 cm and 2) at least one node  > 1cm. Results: We identified 61 patients between 2004 and 2015 who met inclusion criteria. Mean follow-up was 31 months (range: 1 week-192 months).  There was no statistically significant difference of recurrence (p=0.7) and multiple surgeries (p=1.0) between the two groups.  A statistically significant difference was found between the two groups with group 2 showing larger primary tumors (p <0.005), greater number of ENE nodes (p< 0.0001), greater number of positive nodes (p< 0.003), and aggressive pathologic features, such as hobnail or tall cell variant, angioinvasion, or extrathyroidal extent (p< 0.01). Discussion/Conclusion: Large ENE nodes are associated with larger primary tumors, greater number of positive lymph nodes, greater number of ENE nodes, and aggressive pathologic features. However, size of ENE nodes is not associated with recurrence or need for further surgeries.


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