Endocrine Abstracts

Background: The short-term follow-up of patients with differentiated thyroid cancer (DTC) after the initial treatment is based on the measurement of stimulated thyroglobulin (s-Tg) and the use of diagnostic whole body scan (WBS).

Objective: To evaluate the clinical utility of WBS performed at 6–12 months after thyroidectomy. Examine the correlation between s-Tg and results of WBS.

Methods: We retrospectively evaluated all patients who were diagnosed with DTC (n=213) at a tertiary hospital center in Cordoba (Spain), between January 2000 and December 2013. The patients who had positive anti-thyroglobulin antibodies microcarcinomas (Tumors < 1 cm) were excluded from the study. Patients were classified according to the new ATA- guideline.

Results: 169 patients were included. Mean age: 40.05±6.20 years; ♀: 76.3%; Papillary subtype: 89.3%.The great majority were classified as Stage I-II (81.1%). At the end of the follow-up, 72.2% had achieved a complete remission. 6 to 12 months after thyroid ablation, s-Tg was negative in 111 patients and WBS control showed negative uptake in 98 of these patients. In 13 patients (13/111), uptake remained in the thyroid bed but no evidence of disease was found. In 4/111 subjects, persistence of disease was detected by ultrasound scan, all of them with negative WBS. Of 58 patients with detectable s-Tg (>0.3 ng/ml), only 22 showed pathological uptake in the thyroid bed (n=16) or in the distance (n=6). In 36 patients with evidence of disease (62.1%) uptake was not observed. In 43 of these 58 patients disease-free status has not been reached. This facts reflect a low correlation between s-Tg level and results of the WBS (I.Kappa=0.226; P=0.001). The diagnostic accuracy of WBS was founded to be low ((Sensitivity=0.36; 95% CI: 0.22–0.49) (Specificity=0.85; 95% CI: 0.79–0.91)).

Conclusions: WBS performed at 6–12 months after initial treatment is out of clinical utility, especially in the presence of a s-Tg <0.3 ng/ml. WBS does not correlate with results of s-Tg determination and its accuracy has turned out to be low.