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

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. (authors)