Objective:

To evaluate the effectiveness of radioiodine (RAI) therapy in RAI-naïve patients with papillary thyroid carcinoma (PTC) and structurally confirmed cervical lymph node metastases.

Approach:

• Study Design: Retrospective analysis of a prospectively followed cohort of RAI-naïve PTC patients with confirmed cervical nodal metastases post-surgery.
• Patient Selection: Included patients with documented metastatic lymph nodes in recently operated compartments or those declining immediate reoperation.
• Treatment Evaluation: Treatment response assessed at lymph-node and patient levels using serial ultrasonography and biochemical follow-up.

Key Findings:

• 39 out of 146 cervical lymph node metastases (26.7%) were RAI-avid, while 89 (61%) were RAI-non-avid.
• Among RAI-avid nodes, complete and partial responses were observed in 38.5% and 20.5%, respectively.
• Overall, complete and partial responses across all nodes were 10.3% and 6.2%, with no objective response in 83.5%.
• At the patient level, a complete response was achieved in 11% (8/71) of patients, with all responders maintaining an excellent response category at a median follow-up of 77 months.

Interpretation:

RAI-non-avid nodal metastases were common and primarily influenced treatment outcomes. Response rates among RAI-avid lesions were modest, indicating that lesion-level RAI-avidity is important for therapeutic response.

Limitations:

• Retrospective design may introduce bias.
• Limited generalizability due to the specific patient cohort.
• Lack of control group for comparison.

Conclusion:

The findings indicate the complexity of RAI therapy in patients with residual nodal disease.