Endocrine Abstracts

Introduction: Most recent ATA thyroid nodule/DTC guidelines recommend thyroidectomy without prophylactic CND for small (T1 or T2), non-invasive, clinically node-negative PTC (cN0). However, some studies have suggested an association between the BRAFV600E mutation and the risk of nodal disease. Moreover, BRAF V600E mutation have recently showed significant association with recurrence in solitary intrathyroidal PTC between 2 and 4 cm (pT2) making suitable a more aggressive treatment (doi:10.1093/jnci/djx227).

Objective: Assess the influence of BRAFV600E mutation status in nodal disease in central compartment in a series of patients with PTC smaller than 4 cm operated on in one tertiary center.

Methods: We select patients with pathological diagnosis of PTC without clinical lymph node metastasis, no surgical evidence of extrathyroidal invasion and no distant metastasis at the time of surgery, who underwent total thyroidectomy and CND between 2005 and 2017. Microscopic extension beyond thyroid capsule, multifocality and BRAF mutation status were included as variables to predict nodal disease. Results were evaluated in all patients and after excluding microcarcinomas, and considering the extent of nodal disease (relevant if 5 or more affected nodes or foci in affected nodes bigger than 2 mm). BRAF V600E mutation was detected by RT_PCR (Cobas 4800 BRAF V600 mutation test, Roche).

Results: 210 patients were included, 158 of them with tumors larger than 10 mm. Multifocality was present in 80 cases. From 158 PTC over 10 mm, 104 had unifocal disease. Microscopic extrathyroid extension appeared in 42 cases, 34 of them larger than 10 mm. Prophylactic CND obtained 2479 nodes (mean: 11.8/patient), without differences between both groups of BRAF mutation. BRAFV600E was evaluated in 148 of 210 cases (109 of 158 PTC>10 mm). BRAFV600E mutation was significantly associated with the rate of nodal disease in CND in all groups (global, monofocal tumors, intrathyroidal tumors and both, monofocal and intrathyroidal tumors) independently of size. Moreover, BRAFV600E mutated PTC also showed more number of affected nodes than non-mutated PTC in all the groups studied. Significant association of the BRAF V600E mutation with relevant nodal disease in CND was present when evaluated throughout the group and among PTC greater than 10 mm, but there were no significant differences in their incidence between mutated and non-mutated monofocal PTC, intrathyroidal PTC or tumors with both characteristics.

Conclusion: BRAFV600E mutation increase the risk of central nodal disease, including intermediate-risk nodal disease. Prophylactic central neck dissection may be considered in the presence of PTC with BRAFV600E mutation.