Ablation efficacy in non-high-risk differentiated thyroid carcinoma patients with low-dose and high-dose 131I

Abstract

Objective To investigate the efficacy of low-dose (1.11 GBq) and high-dose (3.70 GBq) radioactive 131I on residual thyroid tissues in patients after a non-high-risk differentiated thyroid carcinoma (DTC) resection. Methods Clinical data of a total of 63 patients with non-high-risk DTC who had experienced 131I therapy were analyzed retrospectively. Binary logistic regression was employed to analyze the effects of age, interval from initial resection to initial 131I ablation, rate of thyroid iodine uptake for 24 h, serum TSH level, and 131I dose on efficacy of thyroid remnant ablation. Out of 63 patients, 27 were given low doses while 36 patients were given high doses of 131I therapy. Pearson's chi-square test was used to differentiate the efficacy of low-dose and high-dose 131I on residual thyroid tissues. P<0.05 was considered statistically significant. Results Among the 63 non-high-risk DTC patients, 46 patients achieved successful thyroid remnant ablation (73.02%, 46/63) but 17 failed (26.98%, 17/63) . Binary logistic regression analysis indicated that the ablation dose of 131I was the main factor for the efficacy of ablation (Wald=6.42, P=0.011) . Among the 27 patients who had low doses of 131I therapy, 15 achieved effective thyroid remnant ablation. However, 31 patients achieved effective thyroid remnant ablation after high doses of 131I therapy among 36 patients. Pearson's chi-square test revealed that the ablation efficacy in patients with high-dose 131I (86.11%, 31/36) was higher than those with low-dose 131I (55.56%,15/27) (χ2=7.311, P=0.007) . Conclusion In clinical practice, high-dose 131I on residual thyroid tissues should be considered for patients after non-high-risk DTC resection to improve the efficacy of 131I ablation at first dose when the volume of thyroid remnant tissues is low. Key words: Iodine radioisotopes; Differentiated thyroid carcinoma; Radiotherapy dosage; Non-high-risk; Thyroid remnant ablation