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Stimulated postoperative thyroglobulin levels can predict DTC disease status

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March 23, 2017

Stimulated postoperative thyroglobulin levels may be useful for predicting the risk for persistent disease in children and adolescents with differentiated thyroid cancer, study data show.

Ana Luiza Maia, MD, PhD, of the thyroid section, endocrine division, Hospital de Clínicas de Porto Alegre in Brazil, and colleagues evaluated 32 children and adolescents with differentiated thyroid cancer (DTC; mean age at diagnosis, 14.7 years) to determine potential prognostic factors. Participants attended a thyroid outpatient clinic from 2000 to 2015.

Most participants had papillary thyroid carcinoma (96.9%); one had follicular thyroid carcinoma.

At 1 year of follow-up, 51.9% of participants were disease-free, 22.2% had persistent biochemical disease and 25.9% had persistent structural disease. After a median 5 years of follow-up, 55.6% of participants were disease-free, 22.2% had persistent biochemical disease and 22.2% had persistent structural disease.

Lymph node metastasis (P = .003) and distant metastasis (P = .01) were more common in participants with persistent disease, and they had higher stimulated postoperative thyroglobulin (P < .001).

Total thyroidectomy was performed in all participants, and 90.6% received radioactive iodine therapy. Seventeen participants had data available on disease status and stimulated postoperative thyroglobulin; median time between surgery and stimulated postoperative thyroglobulin was 3 months.

Participants who were disease-free had a lower median stimulated postoperative thyroglobulin level compared with participants with persistent disease (P < .001). The optimal cutoff point to predict disease-free status was a stimulated postoperative thyroglobulin level of 31.5 ng/mL with a sensitivity and specificity of 100%.

“We have demonstrated that lymph node metastasis, distant metastasis and [stimulated postoperative thyroglobulin] are useful prognostic factors in young patients with DTC,” the researchers wrote. “Of particular interest, [stimulated postoperative thyroglobulin] seems to have a promising role as a tool for identifying children and adolescents with DTC at high risk of persistent disease.” – by Amber Cox

Disclosure: The researchers report no relevant financial disclosures.

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PERSPECTIVE
Andrew Bauer
Andrew J. Bauer

Zanella and colleagues assess the utility of TSH-stimulated postoperative thyroglobulin (abbreviated as “sPOTg” in the study) to identify a cut-off level to predict persistent disease. The authors retrospectively reviewed 32 patients aged 18 years or younger at diagnosis with the majority undergoing total thyroidectomy with postoperative radioiodine treatment (median activity of 100 mCi) for the treatment of papillary thyroid cancer (PTC). At 5 years, disease status was available for 27 patients with 15 achieving remission and 12 with persistent disease; six had detectable thyroglobulin; four had pulmonary and two had cervical metastasis. The authors ultimately assessed the sPOTg for 10 patients who achieved remission and seven patients with persistent disease. An ROC-generated sPOTg value of 31.5 ng/mL conferred 100% sensitivity and specificity for predicting patients with persistent disease with a suggestion that a value of less than 31.5 ng/mL may afford an opportunity for “less intensive treatment and monitoring.”

The authors are commended for their efforts reporting pediatric-specific data to stratify postoperative surveillance for patients with PTC. However, as the authors admit, the ROC-generated value of 31.5 ng/mL is based on a small number of patients with a very wide range of sPOTg levels (49.5 ng/mL to 4493 ng/mL), several very elevated (1656 ng/mL, 2297 ng/mL and 4493 ng/mL). Thus, while there are no arguments that patients with very elevated sPOTg are likely to have persistent disease, and those with undetectable or very low (< 10 ng/mL) sPOTg are likely to have a low risk for persistent disease (American Thyroid Association pediatric low risk), the conclusions to reduce treatment and monitoring for patients with sPOTg between 10 ng/mL and 31.5 ng/mL must be confirmed with a larger series of pediatric patients. In the meantime, treatment and monitoring for patients with sPOTg greater than 10 ng/mL should continue to be based on PTC variant and TNM malignant tumor classification. 


Andrew J. Bauer, MD

Associate Professor of Pediatrics

Perelman School of Medicine

The University of Pennsylvania

Director of the Thyroid Center

Division of Endocrinology and Diabetes

Disclosure Bauer reports serving on the board of directors of the American Thyroid Association and has previously served on the advisory board for Akrimax Pharmaceuticals, LLC.