Purpose: Differentiated thyroid cancer (DTC) has an increasing incidence in childhood and adolescence but long-term outcome data are limited. We aimed to identify possible risk factors associated with disease persistence, with special focus on the usefulness of ATA risk stratification system and pre-ablation stimulated thyroglobulin (Tg) levels.
Methods: We retrospectively studied 103 patients, 79 females (76.7%), aged 15.6 ± 3.2 years (range 5-21 years) who underwent total thyroidectomy for DTC. Patients were classified by ATA risk stratification criteria as low, intermediate, and high risk for recurrence. All, except five with papillary microcarcinoma, received radioactive iodine (RAI) treatment.
Results: At diagnosis, 44.7% of patients had cervical lymph node and 7.8% pulmonary metastases. Amongst the 72 patients with long-term follow-up data, 31.9% had persistent disease. Lymph node as well as pulmonary metastases and increased pre-ablation stimulated thyroglobulin (Tg) levels were associated with persistent disease. The risk of persistent disease was significantly higher in both the intermediate- (OR 17.95; 95% CI 2.66-120.94, p < 0.01) and high-risk (OR 17.65; 95% CI 4.47-69.74, p < 0.001) groups. ROC curve analysis showed that a pre-ablation Tg level higher than 14 ng/ml had a sensitivity of 94.7% to predict persistence, corresponding to a positive (PPV) and negative predictive values (NPV) of 66.7% and 93.8%, respectively.
Conclusions: ATA risk stratification was validated in our population of children and young adults with DTC. Moreover, pre-ablation stimulated Tg levels of <14 ng/ml were associated with a low risk of long-term persistence and may therefore serve as a marker to identify patients who may need less intensive surveillance.
Keywords: Children; Differentiated thyroid cancer; Persistence; Thyroglobulin; Young adults.