Is thyroglobulin the stronger indicator for progressive disease than the other conventional factors in same age...

To determine the thyroglobulin cut-off value as an indicator for progressive disease and to research relationships between sex, histological type, extra-capsular invasion and progressive disease in differentiated thyroid cancer.

Four hundred and eight patients were evaluated retrospectively. One hundred and fifty-eight patients (group 1) treated for progressive disease and 166 patients (group 2) that were ablated for thyroid remnant were included in our study. Sex, age, histological type, presence of extra-capsular invasion at the diagnosis and L-thyroxine off thyroglobulin values (6-12 months after the ablation) were obtained. Data were analysed by statistical methods.

There was no statistically significant difference for ages (group 1, 45.3+/-16.1 years; group 2, 47+/-12 years, P>0.05). The chi-squared test revealed statistically significant differences for histological type (P>0.05) and extra-capsular invasion (P<0.001) but not for sex (P>0.05). Feasible cut-off level, sensitivity and specificity were found as a 10 ng.ml thyroglobulin value, 79% and 97%, respectively. However, sensitivity and specificity were 80%, 92% for 5 ng.ml and 82% for 2 ng.ml thyroglobulin levels. Multivariate analysis showed that a 10 ng.ml thyroglobulin cut-off value and extra-capsular invasion were independent prognostic factors.

Increased thyroglobulin level, extra-capsular invasion and follicular type were poor prognostic factors but sex was not, whereas only extra-capsular invasion and increased thyroglobulin level were independent prognostic indicators for our groups. A 10 ng.ml thyroglobulin level was a feasible cut-off and seemed to be a stronger factor than other indicators to predict progressive disease.