ESPE Yearbook of Paediatric Endocrinology

Brief Summary: This retrospective study assessed the outcome of thyroid ultrasound (US) surveillance in childhood cancer survivors (CCS) exposed to radiotherapy (RT). 306 CCS were monitored with thyroid US. Patients received TBI (45%) and/or RT to craniospinal (44%), chest (11%), and neck regions (6%). Thyroid US surveillance was started at a median interval of 9.1 years after RT; 150 patients (49%) had thyroid nodule(s); 44 patients underwent surgery, and 28 had a final diagnosis of differentiated thyroid cancer (DTC).

There was no difference in the median radiation dose between CCS with or without thyroid nodules. Eight patients with intermediate- or high-risk disease received RT at age ≤10 years but only 1 in those who recived RT at age >10 years. RT at age ≤3 years old conferred a 2.87-fold increased risk for nodule presentation compared to RT at >10 years old. Female sex and longer duration between RT and first US were additional independent risk factors for thyroid nodule(s).

Thyroid nodules and DTC are among the most common late effects of RT. Estimated lifetime risk for developing DTC among CCS who received radiotherapy (RT) varies greatly, with standardized incidence ratios between 5 and 69-fold higher, compared to controls. Screening recommendations for secondary DTC remain controversial: the current Children’s Oncology Group Follow-Up Guidelines recommend annual neck palpation and conservative US use, only for palpable nodules. On the contrary, endocrine professional societies advocate for more precise monitoring by thyroid US, regardless of neck palpation findings.

This study suggests that thyroid US surveillance is particularly useful in CCS exposed to RT in early childhood. Prospective studies are needed to further define the latency between RT exposure and nodule development and to produce tailored thyroid surveillance guidelines for CCS, avoiding delayed diagnosis without an increase in aggressive and unnecessary interventions.

References: 1. Clement SC, Kremer LCM, Verburg FA, Simmons JH, Goldfarb M, Peeters RP, et al. Balancing the benefits and harms of thyroid cancer surveillance in survivors of Childhood, adolescent and young adult cancer: recommendations from the international Late Effects of Childhood Cancer Guideline Harmonization Group in collaboration with the PanCareSurFup Consortium. Cancer Treat Rev. 2018; 63: 28–39.2. Gharib H, Papini E, Garber JR, Duick DS, Harrell RM, Hegedus L, et al. American association of clinical endocrinologists, American college of endocrinology, and associazione medici endocrinologi medical guidelines for clinical practice for the diagnosis and management of thyroid nodules - 2016 update. Endocr Pract. 2016;22(5): 622–39