Lymph node yield in the initial central neck dissection (CND) associated with the risk of recurrence in papillary thyroid cancer: A reoperative CND cohort study

Background: To evaluate the relationship between lymph node yield (LNY) from the initial central neck dissection (CND) and the risk of recurrence in patients undergoing reoperative CND for papillary thyroid cancer (PTC). Method: We reviewed clinical data from all patients with pathologically proven PTC who underwent central neck and/or lateral neck dissection reoperations at Nanfang Hospital between 2012 and 2020. Patient demographics, tumor characteristics, clinical data and follow-up information were obtained. In the initial CND, the total number of lymph nodes removed (LNY), total positive nodes removed, and the percentage of positive lymph nodes to the number of lymph nodes removed (PLN%) were determined. Results: A total of 162 patients were included in the study, with a median follow-up of 44 months. 62 had central neck disease recurrence. The optimal LNY and PLN% cut-off values for recurrence were 11 and 65%, respectively. Group 2 (LNY >= 11, PLN% < 65%) showed a significantly higher RFS rate than group 1 (LNY < 11 and PLN% < 65%; P < 0.001), group 3 (LNY < 11, PLN% >= 65%; P < 0.001), and group 4 (LNY >= 11, PLN% >= 65%; P = 0.038). Furthermore, group 4 had a higher RFS rate than group 1 (P = 0.008) and group 3 (P = 0.001). Multivariate analysis revealed that LNY < 11 in the central neck was an independent risk factor for recurrence/ persistence in the initial surgery (P < 0.001). Conclusion: Higher LNY in central and neck dissections is associated with lower papillary thyroid cancer recurrence rates, which was confirmed by a reoperative CND procedure. To minimize the risk of recurrence and the need for secondary therapy, surgeons should perform compartment-oriented CNDs when indicated.