Prevalence and Significance of Thyroglobulin Antibodies in Pediatric Thyroid Cancer.

CONTEXT

Circulating thyroglobulin antibodies (TgAb) can confound measurement of serum thyroglobulin and impair thyroid cancer surveillance. Few data exist on the significance of TgAb in pediatric thyroid cancer.

OBJECTIVE

To describe the prevalence, natural history, and clinical significance of TgAb in children with thyroid cancer.

DESIGN

Retrospective cohort study.

SETTING

Single academic pediatric center.

PATIENTS

Seventy-three consecutive children (≤18 years) with nonmedullary thyroid cancer who had serum TgAb measured within 6 months after diagnosis.

MAIN OUTCOME MEASURES

Prevalence and natural history of TgAb; association of TgAb status and resolution with patient and disease characteristics.

RESULTS

TgAb were detected in 41% of subjects (30 of 73) and were associated with lymph node metastasis (83% vs 53%, P = 0.01) but not distant metastasis. In patients with TgAb, resolution occurred in 44% (11 of 25) over a median follow-up of 3.8 years. Median time to clear TgAb was 10.7 months, and 10 of 11 patients who cleared (91%) did so within 2 years. Resolution of TgAb was associated with lower initial TgAb level (median 4.5 vs 76 normalized units, P = 0.003). TgAb positivity at diagnosis was not independently associated with persistent or recurrent disease (odds ratio 3.20, 95% confidence interval 0.95 to 10.80, P = 0.06).

CONCLUSIONS

TgAb are common at diagnosis in children with thyroid cancer but resolve in nearly half of patients within 1 to 2 years. TgAb are associated with the presence of lymph node metastasis at diagnosis, but the long-term prognostic significance remains to be determined.