Response Prediction of Altered Thyroglobulin Levels After Radioactive Iodine Therapy Aided by Recombinant Human Thyrotropin in Patients with Differentiated Thyroid Cancer
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Thyroglobulin (Tg) may be released from damaged residual thyroid tissues after radioactive iodine (RAI) therapy in patients with differentiated thyroid carcinoma (DTC). We investigated whether altered levels of serum Tg after recombinant human thyrotropin (rhTSH)-aided RAI therapy could be a prognostic marker in patients with DTC.
We evaluated 68 patients who underwent RAI therapy after total thyroidectomy. Serum Tg levels were measured just before RAI administration (D0Tg) and 7 days after RAI therapy (D7Tg). Patients with a D0Tg level greater than 2.0 ng/mL were excluded to more precisely evaluate the injury effect of RAI in small remnant tissues. The ratioTg was defined as the D7Tg level divided by that on D0Tg. The therapeutic responses were classified as acceptable or non-acceptable. Finally, we investigated which clinicopathologic parameters were associated with therapeutic response.
At the follow-up examination, an acceptable response was observed in 50 patients (73.5%). Univariate analysis revealed significant differences in N stage (P = 0.003) and ratioTg (acceptable vs. non-acceptable responses, 21.9 ± 33.6 vs. 3.8 ± 6.5; P = 0.006). In multivariate analysis, only ratioTg significantly predicted an acceptable response (odds ratio 1.104; 95% confidence interval 1.005–1.213; P = 0.040). A ratioTg above 3.5 predicted an acceptable response with a sensitivity of 66.0%, specificity of 83.3%, and accuracy of 70.6% (area under the curve = 0.718; P = 0.006).
Altered levels of serum Tg after RAI therapy, calculated as the ratioTg (D7Tg/D0Tg), significantly predicted an acceptable response in patients with DTC.
KeywordsDifferentiated thyroid carcinoma Radioactive iodine therapy Recombinant human thyrotropin Thyroglobulin Therapeutic response
This research was supported by the Pioneer Research Center Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (2015M3C1A3056410).
Compliance with Ethical Standards
Conflict of Interest
Authors Minchul Song, Subin Jeon, Sae-Ryung Kang, Zeenat Jabin, Su Woong Yoo, Jung-Joon Min, Hee-Seung Bom, Sang-Geon Cho, Jahae Kim, Ho-Chun Song, and Seong Young Kwon declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
The institutional review board of our institute approved this retrospective study, and the requirement to obtain informed consent was waived.
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