Prognostic value of postoperative stimulated thyroglobulin in differentiated thyroid cancer.

[BACKGROUND] Thyroglobulin (Tg) level is used for long-term follow-up of differentiated thyroid cancer (DTC). However, the prognostic value of the postoperative level and the level which can be considered risky are not clear in literature.

[PURPOSE] To evaluate the prognostic value of postoperative Tg in DTC for subsequent disease-free status. Also, to determine the cutoff with the highest sensitivity and specificity.

[METHODS] A retrospective analysis was performed of 62 patients with non-metastatic DTC presenting to our department from January 2018 to December 2019. Three groups were formed according to postoperative stimulated thyroglobulin (sTg) level: <1ng/ml, 1-5ng/ml, and >5ng/ml. Outcomes were compared at 12 months. ROC curve analysis determined the cutoff with the highest sensitivity and specificity.

[RESULTS] Seven the 62 patients showed persistent or recurrent disease at 12 months after diagnosis. Comparing outcomes in the 3 sTg groups showed thyroglobulin to be a significant prognostic variable. A cut-off of 3.15ng/ml had the highest sensitivity and specificity on ROC curve analysis.

[CONCLUSION] Postoperative stimulated thyroglobulin is a useful prognostic tool in the postoperative categorization of patients and can subsequently be tested for its value to guide radioactive iodine therapy.