Introduction: Several clinical and molecular markers can be used to establish risk at the time of diagnosis in DTC. Thyroglobulin (Tg), which is essential in follow up, could be an early marker to identify risk patients. Around 25% of patients require 18 months or longer to have indetectable Tg. The presence of Tg antibodies (TgAb) invalidate the follow up of DTC via Tg and this is usually associated with a poor prognosis.
Aim: To evaluate the role of Tg after surgery and before radioiodine treatment, and the presence of TgAb as markers of persistent/recurrent disease in DTC.
Patients and methods: Retrospective study of 165 patients with DTC (19972010): women 78,2%, age at diagnosis 47.9+/- 16,26, medium follow up 4.8+/-3.74 years.
We performed a multivariate (logistic regression) analysis including Tg after surgery and before radioiodine treatment and other known prognostic variables. We divided Tg into tertile (cut-off: 1.7 ug/l, 13.6 ug/l) excluding TgAb positive at first before adding it later. We performed a ROC curve to identify cut-off level of Tg. Statistical analysis was performed with SPSS 19.0.
Results: In the multivariate analysis excluding TgAb positive, Tg in higher tertil is the unique predictive variable of persistent/recurrent disease at 1824 months (RR 21.67). Adding positive TgAb, the predictive variables are Tg (RR 21, 04) and presence of TgAb (RR 112). The ROC curve shows a cut-off of Tg after surgery and before radioiodine treatment of 5,55 ug/l that identifies persistent/recurrent disease (S 81, E 57,5, NPV 92,5 and PPV 31,5% (AUC 0.809)).
Conclusions: In this serie, Tg value after surgery and before radioiodine treatment and the presence of TgAb are predictive variables of recurrent/persistent disease at 1824 months. Tg has a predictive value and could be a useful marker to stratify risk at the time of diagnosis.
27 Apr - 01 May 2013
European Society of Endocrinology