Impact of lymph node metastases identified on central neck dissection (CND) on the recurrence of papillary thyroid cancer: Potential role of BRAFV600E mutation in defining CND

The impact of metastasized cervical lymph nodes (CLN) identified on central neck dissection (CND) on the recurrence/persistence of papillary thyroid cancer (PTC) and the extent of CND needed to reduce recurrence/persistence have not been firmly established. To assess the impact of CLN metastasis and BRAF mutation on the recurrence/persistence of PTC and the potential of BRAF mutation in assisting CND, we analysed data of 379 consecutive patients with PTC who underwent thyroidectomy with (nZ243) or without CND (nZ136) at a tertiary-care academic hospital during the period 2001-2010 for their clinicopathological outcomes and BRAF mutation status. Increasingly aggressive tumor characteristics were found as the extent of CND was advanced following conventional risk criteria from non-CND to limited CND to formal CND. Disease recurrence/ persistence rate also sharply rose from 4.7% to 15.7% and 40.5% in these CND settings respectively (P!0.0001). CLN metastasis rate rose from 18.0 to 77.3% from limited CND to formal CND (P!0.0001). An increasing rate of BRAF mutation was also found from less to more extensive CND. A strong association of CLN metastasis and BRAF mutation with disease recurrence/persistence was revealed on Kaplan- Meier analysis and BRAF mutation strongly predicted CLN metastasis. CLN metastases found on CND are closely associated with disease recurrence/persistence of PTC, which are both strongly predicted by BRAF mutation. Current selection of PTC patients for CND is appropriate but higher extent of the procedure, once selected, is needed to reduce disease recurrence, which may be defined by combination use of preoperative BRAF mutation testing and conventional risk factors of PTC.