Lymph Node Ratio Predicts Recurrence in Patients with Papillary Thyroid Carcinoma with Low Lymph Node Yield

Area of Science:

• Oncology
• Endocrinology
• Surgical Pathology

Background:

• The American Thyroid Association system identifies >5 metastatic lymph nodes (LNs) as a recurrence risk factor in papillary thyroid carcinoma (PTC).
• Limited data exists on recurrence risk stratification for PTC patients with fewer than 5 harvested LNs (low-LN-yield or low-LNY).

Purpose of the Study:

• To stratify recurrence risk in low-LN-yield PTC patients using lymph node ratios (LNRs).
• To identify prognostic factors for tumor recurrence in this patient subgroup.

Main Methods:

• Retrospective analysis of 909 low-LNY PTC patients who underwent thyroidectomy (2007-2017).
• Comparison of tumor recurrence rates based on LNR, with cutoff determined by ROC curve analysis.
• Multivariate Cox regression analysis to identify independent prognostic factors.

Main Results:

• A LNR cutoff of 0.29 was established (AUC=0.676, p<0.001).
• The high-LNR group (≥0.29, n=234) had a significantly higher recurrence rate (12.4%) than the low-LNR group (<0.29, n=675; 2.5%, p<0.001).
• Tumor size and LNR ≥ 0.29 were independent prognostic factors for recurrence.

Conclusions:

• Lymph node ratio (LNR) is a valuable tool for stratifying recurrence risk in papillary thyroid carcinoma patients with low lymph node yield.
• An LNR of 0.29 or higher identifies patients with significantly increased risk of tumor recurrence.