Analysis of tumor recurrence factors of the patients with intermediate risk papillary thyroid carcinoma after radioactive iodine treatment

Objective To analyze the recurrence factors of the patients with intermediate risk papillary thyroid carcinoma (PTC) after radioactive iodine treatment (RAIT). Methods A total of 254 intermediate risk PTC patients after RAIT from January 2018 to May 2020 in our hospital were enrolled into this study. Chi square test and multivariate analysis were applied to analyze the main recurrence factors after RAIT. Results Thirty four (13.4%) patients with intermediate risk PTC relapsed after RAIT. The primary tumor size, lymph node metastasis staging, and pre-ablation stimulated thyroglobulin (psTg) were associated with tumor recurrence. According to the receiver operating characteristic （ROC） curve, psTg 25.6 μg/L was the best cutoff value for predicting recurrence. Further multivariate analysis revealed that lymph node metastasis staging and psTg levels were independent factors of predicting PTC recurrence. When the patients with N1b and psTg≥25.6 μg/L, the incidence of tumor recurrence after RAIT was 58.3%. While the patients with N1a and psTg