Endocrine Abstracts

Purpose: Papillary thyroid cancer (PTC) has a strong propensity for lymph node metastasis, which is related with local recurrence, and disease-specific survival in the elderly. We evaluated the association between lymph node metastasis and disease multifocality, bilaterality, and other clinicopathological variables to identify risk factors and aid surgical decision-making. The relationship between the number of foci and metastasis to cervical lymph node was also evaluated.

Methods: Patients with PTC (n =819) undergoing thyroidectomy at our institution were included. The study population was segregated into four groups based on PTC multifocality and bilaterality.

Results: Cervical lymph node metastasis, tumor size, and tumor extent were significantly different between the study groups. The frequency of central and lateral cervical lymph node metastasis was the highest in the bilateral multifocal disease group, followed by the bilateral solitary group, unilateral multifocal group, and the unilateral solitary group. One PTC focus per thyroid lobe was associated with increased metastasis (53.8%). Moreover, lymph node positivity doubled with 5–7 foci (71.4%), and tripled with >8 foci (100%). Bilateral solitary and bilateral multifocal PTC were identified as independent predictors of cervical lymph node metastasis.

Conclusions: Bilateral PTC was associated with lymph node positivity, which increased proportionally with the number of PTC foci. Bilateral solitary or multifocal PTC were associated with more aggressive features such as larger primary tumor size, more frequent extrathyroidal extensions, and regional lymph node metastasis. The presence of multiple bilateral foci or more than 3 foci are independent risk factors of lymph node metastases.