Pediatric thyroid cancer: key considerations based on the 2024 Korean Thyroid Association Differentiated Thyroid Cancer Management Guidelines

1. Preoperative evaluation

In pediatric patients with confirmed extrathyroidal extension (ETE) or lymph node (LN) metastasis, imaging studies including lateral neck and mediastinal LNs should be performed to determine the extent of surgery.

2. Children at high risk for DTC

Genetic testing is recommended when hereditary tumor syndrome [5,6] is suspected (Table 1) [4]. A careful assessment of past or family history (multinodular goiter, and thyroid or other tumors of embryonal origin), skin findings, and head circumference is required.

Table 1.

Hereditary tumor syndrome associated with thyroid tumor

For childhood cancer survivors who have undergone total body or neck irradiation, total thyroidectomy is recommended, and treatment decisions should consider related complications.

3. Surgery

Total thyroidectomy by a high-volume thyroid surgeon is the treatment of choice for pediatric patients, while lobectomy may be considered for low-risk papillary microcarcinomas [7]. In patients with advanced stage, prophylactic central neck dissection (ND) may be performed. If central or lateral LN metastasis is confirmed, therapeutic central and lateral ND should be performed.

4. Initial treatment plan and follow-up strategy (Fig. 1)

Fig. 1.

Initial treatment and follow-up strategy based on the postoperative 3-tier Pediatric Risk Classification. TSH, thyroid-stimulating hormone; US, ultrasound; SPECT, single-photon emission computed tomography; CT, computed tomography; Tg, thyroglobulin.

Postoperatively, it is recommended to establish an initial treatment and follow-up plan based on a 3-tier Pediatric Risk Classification (low-, intermediate-, and high-risk) according to tumor size, ETE, and extent of metastasis [6]. Details of the initial treatment plan and follow-up strategy based on the 3-tier Pediatric Risk Classification are described in Fig. 1 [4]. In intermediate- and high-risk groups, the measurements of thyroid-stimulating hormone (TSH)-stimulated thyroglobulin (Tg) level and diagnostic scan are recommended to determine the need for RAI therapy.

5. RAI therapy

The decision for RAI therapy should be based on a multidisciplinary evaluation of its benefits and risks. RAI therapy is recommended for iodine-avid pulmonary metastasis and inoperable locoregional lesions. The dose of RAI therapy is determined by weight-based empirical dosing or the calculated maximum tolerable radiation dose, depending on therapeutic goals.

6. Recurrent or persistent disease

In pediatric patients with elevated serum Tg or Tg antibodies during follow-up, neck ultrasound should be performed first. Surgery is the primary option for resectable lesions, while RAI therapy can be performed for inoperable recurrent or persistent lesions if RAI uptake is confirmed.

Iodine-avid pulmonary metastasis should be monitored at appropriate intervals to assess treatment response after RAI therapy. Considering that the majority of pulmonary metastasis does not show a complete remission or it may require years to show a complete remission [8], undetectable Tg levels should not be the goal, and longer intervals between RAI therapy are considered in nonprogressive disease. For progressive iodine-avid pulmonary metastasis, additional RAI therapy is considered, balancing risks and benefits.

7. RAI-refractory thyroid cancer

Pediatric patients with asymptomatic, nonprogressive RAI-refractory disease should be monitored with continued TSH-suppression therapy. For inoperable and progressive RAI-refractory disease, somatic mutations need to be identified because systemic therapy based on genetic mutation (e.g., fusion-directed therapy) can be an effective treatment option [2].

The 2024 KTA pediatric guideline will be helpful in real-world clinical practice and will be updated to suit the domestic situation as needed.