Change of Therapeutic Response Classification According to Recombinant Human Thyrotropin‑Stimulated Thyroglobulin Measured at Different Time Points in Papillary Thyroid Carcinoma
10.1007/s13139-021-00699-2
- Author:
Jang Bae MOON
1
;
Subin JEON
;
Ki Seong PARK
;
Su Woong YOO
;
Sae‑Ryung KANG
;
Sang‑Geon CHO
;
Jahae KIM
;
Changho LEE
;
Ho‑Chun SONG
;
Jung‑Joon MIN
;
Hee‑Seung BOM
;
Seong Young KWON
Author Information
1. Department of Nuclear Medicine, Chonnam National University Hwasun Hospital, 322 Seoyang‑ro, Hwasun‑gun, Jeollanam‑do 58128, Republic of Korea
- Publication Type:ORIGINAL ARTICLE
- From:Korean Journal of Nuclear Medicine
2021;55(3):116-122
- CountryRepublic of Korea
- Language:English
-
Abstract:
Purpose:We investigated whether response classification after total thyroidectomy and radioactive iodine (RAI) therapy could be affected by serum levels of recombinant human thyrotropin (rhTSH)-stimulated thyroglobulin (Tg) measured at different time points in a follow-up of patients with papillary thyroid carcinoma (PTC).
Methods:A total of 147 PTC patients underwent serum Tg measurement for response assessment 6 to 24 months after the first RAI therapy. Serum Tg levels were measured at 24 h (D1Tg) and 48–72 h (D2-3Tg) after the 2nd injection of rhTSH. Responses were classified into three categories based on serum Tg corresponding to the excellent response (ER-Tg), indeterminate response (IR-Tg), and biochemical incomplete response (BIR-Tg). The distribution pattern of response classification based on serum Tg at different time points (D1Tg vs. D2-3Tg) was compared.
Results:Serum D2-3Tg level was higher than D1Tg level (0.339 ng/mL vs. 0.239 ng/mL, P < 0.001). The distribution of response categories was not significantly different between D1Tg-based and D2-3Tg-based classification. However, 8 of 103 (7.8%) patients and 3 of 40 (7.5%) patients initially categorized as ER-Tg and IR-Tg based on D1Tg, respectively, were reclassified to IR-Tg and BIR-Tg based on D2-3Tg, respectively. The optimal cutoff values of D1Tg for the change of response categories were 0.557 ng/mL (from ER-Tg to IR-Tg) and 6.845 ng/mL (from IR-Tg to BIR-Tg).
Conclusion:D1Tg measurement was sufficient to assess the therapeutic response in most patients with low level of D1Tg. Nevertheless, D2-3Tg measurement was still necessary in the patients with D1Tg higher than a certain level as response classification based on D2-3Tg could change.
