Prophylactic Lymph Node Dissection for Papillary Thyroid Cancer Less Than 2 cm: Implications for Radioiodine Treatment

Abstract

Objective: Prophylactic neck dissection for small papillary carcinoma remains controversial. Radioiodine ablation is not recommended for tumors less than 10 mm and depends on various factors for tumors between 10 and 20 mm. The aim was to determine the effect of lymph node (LN) staging on the indication for treatment with radioiodine. Patients and Methods: We conducted a retrospective study of 115 patients presenting with papillary thyroid carcinoma less than 2 cm without ultrasonographically detectable cervical LN treated by total thyroidectomy and complete selective dissection of the central and lateral compartment. Radioiodine treatment was based on definitive pathology (tumor and LN). Follow-up was based on neck ultrasound and thyroglobulin levels. Results: LN were found for 41.7% of cases. Radioiodine was not used for 42% of patients with tumors less than 20 mm and no metastatic LN. Fifty-eight percent of patients were treated with radioiodine due to LN metastasis, extracapsular thyroid invasion, or unfavorable histological subtype. LN status affected the indication for radioiodine in 30.5% of cases classified as T1, 12 cases with tumors less than 10 mm but with LN metastases (who received radioiodine), and 13 cases with tumors between 10 and 20 mm but without LN metastases (who did not receive radioiodine). Definitive vocal fold paralysis and hypoparathyroidism each occurred in 0.9% of cases. At 1 yr, ultrasound was normal in all patients, and recombinant human TSH-stimulated thyroglobulin was undetectable for 97% of the patients. Conclusion: Precise LN staging by prophylactic neck dissection for tumors initially staged T1N0 modified the indication for radioiodine ablation for 30% of patients.