[Preablative serum thyroglobulin as predictor of disease-free survival in differentiated thyroid cancer].

Background: Serum thyroglobulin (sTg) is an excellent marker of persistence or recurrence of disease in differentiated thyroid cancer (DTC), however its role as prognostic factor has not been fully established.

Aim: To assess the value of the preablative thyroglobulin (pTg) as predictor of disease-free survival in DTC.

Patients And Methods: Retrospective study of 104 patients with low and intermediate risk DTC subjected to total thyroidectomy and 131iodine ablation. TSH, pTg and thyroglobulin antibodies (AbTg) were determined by chemiluminescence. Patients with distant metastases or presence of AbTg were excluded. Results were analyzed using receiving operating characteristic (ROC) curves.

Results: During the 40 ± 29 months of follow-up (range 6-132), 14 of 104 (13%) patients had recurrence of disease. pTg was an independent indicator to predict disease-free survival. Using a pTg cutoff of < 10 ng/ml the negative predictive value was 99%, sensitivity 93%, specificity 82%, positive likelihood ratio (LR) 5.2 and negative LR 0,087.

Conclusions: pTg value is useful as a prognostic marker in predicting disease-free survival in DTC patients with low or intermediate risk of recurrence.