Predictors of thyroglobulin in the lymph nodes recurrence of papillary thyroid carcinoma undergoing total thyroidectomy

Abstract Purpose: To investigate serum thyroglobulin (Tg) levels in recurrent papillary thyroid carcinoma (PTC) patients, thereby evaluating possible risk factors and structural features of lymph nodes (LNs) recurrence.Patients and Methods: All the patients with primary PTC who underwent total thyroidectomy (TT) with central or lateral neck dissection and then re-operated due to LNs recurrence between January 2013 and June 2018 were included. Patients were subdivided groups by different Tg levels. Results: This study included 60 patients with LNs recurrence. Of all, 49 patients underwent radioactive iodine (RAI) treatment. Maximum unstimulated Tg (uTg) ≥ 0.2 ng/mL were associated with larger diameter of recurrent LNs (P = 0.027), higher possibility of diameters of recurrent LNs ≥ 25mm (P = 0.023) and higher ratio of metastatic LNs (P < 0.001). Pre-RAI ablation serum-stimulated Tg (off-Tg) ≥ 1ng/mL and unstimulated Tg detected at 1 week after RAI ablation (on-Tg) ≥ 0.2 ng/mL were associated with larger diameter of recurrent LNs and higher possibility of diameters of recurrent LNs ≥ 25mm. Number of metastatic LNs ≥ 8 was an independent predictor for maximum uTg ≥ 0.2 ng/mL (OR = 8.767; 95% CI =1.392-55.216; P = 0.021). Ratio of metastatic LNs ≥ 25% was an independent predictor for off-Tg ≥ 1 ng/mL (OR = 20.997; 95% CI =1.649-267.384; P = 0.019). Conclusion: Tg-positive was associated with larger size of recurrent LNs. Number of metastatic LNs ≥8 could independently predict maximum uTg-positive. Ratio of metastatic LNs ≥ 25% was an independent predicator for off-Tg-positive.