Lymph node ratio of the central compartment is a significant predictor for locoregional recurrence after prophylactic central neck dissection in patients with thyroid papillary carcinoma.

Background: Lymph node ratio (LNR) is an important prognosis factor in many solid cancers, but there have been few reports of LNR in papillary thyroid carcinoma (PTC). This study investigated LNR of the central compartment to determine whether LNR has clinical significance as a prognostic predictor for recurrence after prophylactic central neck dissection (pCND) in patients with PTC.
Methods: The study includes 295 consecutive patients who underwent total thyroidectomy with bilateral pCND, which was pathologically diagnosed as N1a PTC. LNR was calculated as the ratio of positive LN to total LN removed.
Results: LNR of 0.65 was significantly meaningful for recurrence when three or more LNs were collected (P < 0.001). The 10-year estimated recurrence-free survival rates were 98.6 % for patients with LNR ≤0.65 and 75.4 % for patients with LNR >0.65 (P < 0.001). Univariate analysis revealed that increasing tumor size and LNR >0.65 were significantly associated with recurrence (P < 0.05 each). No significant association with recurrence was found for age ≥45 years, male gender, microscopic extrathyroidal extension, coexistent chronic lymphocytic thyroiditis, T classification, multicentricity, number of positive LN, and extranodal extension (P > 0.05 each). The only independent variable for recurrence identified by multivariate analysis was LNR >0.65 (P < 0.001).
Conclusions: LNR may be a useful predictor to stratify the likelihood of recurrence after pCND in patients with pathologic N1a PTC.