Significance of Metastatic Lymph Node Ratio on Stimulated Thyroglobulin Levels in Papillary Thyroid Carcinoma after Prophylactic Unilateral Central Neck Dissection

Abstract

BackgroundPrognostic significance of metastatic central lymph node ratio (CLNR) in papillary thyroid carcinoma (PTC) remains unknown. Because postsurgical detectable stimulated thyroglobulin (DsTg) after radioiodine ablation may imply persistent or recurrent disease, we evaluated the association between CLNR and rate of DsTg in patients with PTC who underwent unilateral prophylactic central neck dissection.MethodsTo be eligible for analysis, the prophylactic central neck dissection specimen had to contain ≥3 central lymph nodes (CLNs) with ≥1 harboring metastasis. Of 129 specimens, 51 (39.5%) were eligible. CLNR was calculated as follows: (number of metastatic CLNs/number of CLNs retrieved) × 100. They were categorized into group 1 (CLNR <33.34%) (n = 14), group 2 (CLNR 33.34–66.67%) (n = 15), and group 3 (CLNR >66.67%) (n = 22). Postablation sTg level was measured 6 months after radioiodine ablation. A multivariate analysis was conducted to identify factors for postablation DsTg.ResultsYoung age, palpable neck swelling, large tumor size, advanced tumor, node, metastasis system (TNM) stage, and large number of metastatic CLNs were significantly associated with high CLNR (P < 0.05). Compared to groups 1 and 2, group 3 had significantly higher DsTg rate (P = 0.018). Those who developed subsequent recurrence had significantly higher DsTg rate than those who did not (100% vs. 39.1%, P = 0.013). In the multivariate analysis for postablative DsTg, after adjusting for age, palpable neck swelling, tumor size, TNM stage, and number of metastatic CLNs, CLNR was the only independent factor (odds ratio 1.15, 95% confidence interval 1.01–1.31, P = 0.036).ConclusionsA higher CLNR was associated with a higher rate of postablative DsTg; this may imply higher future recurrence rate.

The prognostic value of the metastatic lymph node ratio and maximal metastatic tumor size in pathological N1a papillary thyroid carcinoma

“…Recurrence-free survival rate according to pathological T stage was 96.7% in T1, 76.5% in T2, and 84.6% in T3, and it seems that pathological T staging is not enough to predict prognosis (hazard ratio 1.53, 95% CI 0.94 to 2.51, PZ0.090). This is not consistent with the previous data (1,10,11,12) and we think that patient selection bias might have led to this conclusion, as only those with tumor size O1 cm were analyzed. Patients with tumor size !1 cm showed overall excellent prognosis and it was not meaningful to analyze the impact of central neck LN metastases.…”

“…Several studies also suggested that larger size or higher number of metastatic LNs in PTC is associated with poorer outcomes (1,10,11,12,13). A recent review suggested new risk factors that modify standard N1 risk of recurrence such as clinical status, size, number, or presence of extranodal extension of metastatic lesions in LNs (14).…”

Lateral Neck Lymph Node Characteristics Prognostic of Outcome in Patients with Clinically Evident N1b Papillary Thyroid Cancer

“…4,11 Recent data suggest that in addition to LN location, LN characteristics such as maximal size, number, ratio, and ENS are also prognostic. 5–10 Age at diagnosis is uniquely critical in the staging of differentiated thyroid cancer, and in this series of 438 PTC patients with lateral neck disease, we report LN characteristics that are predictive of outcome in two age cohorts of patients, those <45 years old and those ≥45 years old. In both age groups, both number of positive LNs >10 and LN burden >17 % (which equated to 1 positive node per 6 removed) were predictive for recurrence.…”

“…Others have observed central compartment LN burden to be predictive of postoperative thyroglobulin levels as well as recurrence. 5,6 Our study specifically focuses on the prognostic significance of lateral compartment LN characteristics. Our data show that younger patients with LN burden >17 % were 4.8 times ( p < 0.001) and older patients 2.7 times ( p < 0.02) more likely to develop disease recurrence.…”

“…Several recent publications have suggested that increasing number, size, and ratio of positive LNs in the neck predicts poorer outcome in patients with PTC. 5–10 The objective of this study was to define which lateral LN characteristics have prognostic significance in patients with clinical or radiologic evidence of metastatic LNs in the lateral neck.…”