Multifocality and total tumor diameter predict central neck lymph node metastases in papillary thyroid microcarcinoma

Area of Science:

• Endocrinology
• Oncology
• Surgical Pathology

Background:

• Papillary thyroid microcarcinoma (PTMC) is defined as a thyroid cancer measuring ≤1 cm.
• Lymph node metastasis (LNM) is a critical factor in thyroid cancer management.
• Identifying high-risk PTMC subgroups prone to LNM is essential for tailored treatment strategies.

Purpose of the Study:

• To pinpoint specific high-risk subgroups within papillary thyroid microcarcinoma (PTMC) that exhibit a higher propensity for lymph node metastasis (LNM).

Main Methods:

• Retrospective analysis of 1,586 PTMC cases undergoing total thyroidectomy and central neck dissection (2003-2010).
• Evaluation of LNM frequency based on clinicopathological features, including tumor size, multifocality, and total tumor diameter (TTD).
• Meta-analysis of multifocality and LNM risk in PTMC, incorporating nine external studies.

Main Results:

• Multifocal PTMC with TTD > 1 cm showed a significantly higher LNM frequency (60.4%) compared to unifocal tumors ≤ 1 cm (30%, P < 0.001).
• A meta-analysis confirmed that multifocality is a significant independent risk factor for LNM in PTMC (OR 1.9, 95% CI 1.5-2.4).
• No significant difference in LNM was observed between multifocal PTMC (TTD ≤ 1 cm) and unifocal tumors (≤ 1 cm).

Conclusions:

• Multifocal PTMC with a total tumor diameter exceeding 1 cm demonstrates a comparable LNM risk to larger clinical papillary cancers.
• Routine central neck dissection is recommended for multifocal PTMC patients with TTD > 1 cm to manage LNM risk effectively.