Lymph-node ratio for micropapillary and nonmicropapillary differentiated thyroid cancers: a comprehensive analysis.

Area of Science:

• Oncology
• Surgical Pathology
• Cancer Prognostics

Background:

• Regional lymph-node metastasis is crucial for predicting differentiated thyroid cancer (DTC) recurrence.
• The lymph-node ratio (LNR) has emerged as a significant prognostic indicator in DTC.
• Comparing LNR in micropapillary DTC versus nonmicropapillary DTC is essential for risk stratification.

Purpose of the Study:

• To compare the lymph-node ratio (LNR) between patients with papillary thyroid microcarcinoma (PTMC) and nonmicropapillary differentiated thyroid cancer (DTC).
• To evaluate the prognostic significance of LNR irrespective of tumor size in DTC.
• To analyze LNR in the context of neck dissection outcomes for different DTC subtypes.

Main Methods:

• Retrospective review of DTC patients undergoing central lymph-node dissection (CND) across three Istanbul tertiary centers (2013-2023).
• Data collection included patient demographics, tumor characteristics (multifocality, DTC subtype), and surgical details (type of CND).
• Comparison of total lymph nodes (LN) harvested, metastatic LN count, and calculated LNR between PTMC and non-PTMC groups.

Main Results:

• The study included 220 patients with non-PTMC (60%) and 145 with PTMC (40%).
• Mean LNR was 0.14 ± 0.2 for PTMC and 0.17 ± 0.2 for non-PTMC (p=0.286), showing no statistically significant difference.
• LNR was found to be independent of the main tumor size in clinical assessments of DTC.

Conclusions:

• Regional lymph-node metastases in PTMC can result in LNR values similar to those in non-PTMC.
• The LNR is a valuable prognostic tool in differentiated thyroid cancer, independent of primary tumor size.
• These findings support the use of LNR for risk stratification in both micropapillary and nonmicropapillary DTC.