Risk factors for distant metastasis in papillary thyroid carcinoma: Association with lateral lymph node metastasis

This study aimed to clarify the characteristics of distant metastasis in patients with N1a and N1b papillary thyroid carcinoma (PTC) and the significance of lateral lymph node metastasis as a risk factor for distant metastasis.

Of the 537 patients with N1a and N1b PTC who underwent surgical treatment at Hyogo Medical University from January 2013 to December 2020 and Shikoku Cancer Center from January 2007 to December 2018, 283 (79 men and 204 women) with lymph node metastasis were analyzed in this study. The median age was 58 (range, 19-93) years, and the median observation period was 73 (range, 1-152) months after surgery.

The incidence rate of distant metastasis was higher when metastases were detected at levels II or V. Multivariate analysis revealed that the factors that significantly increased the distant metastasis rate were age ≥ 55 years (p = 0.011), tumor size > 4 cm (p = 0.034), and lymph node metastasis at levels II and V (p = 0.034).

For patients with N1b metastasis, specifically at levels II or V, total thyroidectomy with lateral neck dissection should be considered the primary choice for postoperative radioactive iodine therapy.