Abstract
Purpose: Thyroglobulin antibody (TgAb) elevation after I-131 ablation may be difficult to evaluate in cases of recurrence, especially in high-risk patients. This study aimed to evaluate factors contributing to TgAb normalization in papillary thyroid cancer patients receiving high-dose I-131 therapy. Methods: From September 2009 to June 2012, 98 papillary thyroid cancer patients treated with 150 mCi radioactive iodine (RAI) were retrospectively enrolled. Early (3 day) and Delayed (7 day) post-RAI neck counts and reduction ratios were measured and correlated with clinical and pathologic findings. Patients with normal neck ultrasound and undetectable level of serum thyroglobulin (<0.1 ng/mL) and TgAb (<10 IU/mL) were defined as having successful ablation.Results: Thirty-five patients (35.7%) had thyroiditis and 28 (28.6%) achieved ablation success. The thyroiditis group had lower neck counts in both Early and Delayed whole-body scans (WBS), and higher reduction rates than the thyroiditis-absent group. In the ablation success group, Early and Delayed neck counts were significantly higher and the reduction rate of RAI was lower than those in the ablation failure group (p < 0.05). In multivariable analysis, Delayed neck count was the only significant factor for predicting ablation failure (odds ratio = 54.37, 95% confidence interval = 1.33-14.32; p = 0.015).Conclusion: I-131 uptake in the remnant thyroid gland and thyroiditis are factors that indicate TgAb normalization and ablation success in thyroid cancer patients receiving high-dose I-131 therapy.
Possible transient adaptive response to mitomycin C in peripheral lymphocytes from thyroid cancer patients after iodine-131 therapy