Pediatric Thyroid Cancer, not a rare entity
Siobhan T. Pittock, MD
Mayo Clinic
Rochester, MN
July 15, 2021
Increasing incidence of thyroid cancer
The incidence of thyroid cancer in all ages has increased significantly over the past 4 decades while the mortality rate has remained relatively unchanged. In adults, the increased incidence has largely been attributed to increased use of diagnostic imaging and fine needle biopsies and has resulted in diagnosis of earlier staged cancers. This change has resulted in a significant change in recommendation for management of smaller papillary carcinomas (measuring <1-1.5cm) where active observation may be the best course. (1)
Has this increase in incidence been mirrored in pediatrics?
Yes. The increase in diagnosis of pediatric thyroid cancer (predominantly papillary thyroid cancer) has been dramatic over the past 40 years but especially over the last 15 years. The incidence of thyroid cancer has increased from 0.48 to 1.33 per 100,000 person years from 1973 to 2018 (2). Recent studies suggest that the rate of increasing incidence has changed significantly over time. Bernier et al show an annual percent change (APC) in incidence of 4.43% per year between 1998 and 2013 (3). Qian et al report the increase has been far more recent with a dramatic increase in the APC from 1.1% per year between 1973 and 2006 to 9.5% per year between 2006 and 2013 (4).
Both groups show the increase as mainly occurring in the 10-19-year-old age group, in both sexes and all racial groups. The fact that both groups found similar increases in incidence for large and small tumors and for those with local or regional disease argues against this simply representing over diagnosis or diagnosis of smaller less clinically relevant tumors.
What should I tell my patients?
Since most known risk factors for thyroid cancer are not modifiable (e.g. age, female sex, family history), we have limited opportunities for counselling our patients. However, one thing we can do is to avoid overuse of imaging studies including CT scans since exposure to ionizing radiation especially at a young age is a known risk factor for thyroid (and other) cancers. Increased risk for thyroid cancer may be yet another reason to avoid excessive weight gain because obesity has been linked to an increased risk of thyroid cancer (5). The fact that the increasing incidence of thyroid cancer has mirrored the obesity epidemic experienced in the developed world lends further credence to this evidence (6).
What should we do?
Thyroid cancer in pediatric patients is not a rare entity, in fact it is the most common non-CNS solid tumor in childhood (2). The most important thing we can do is raise awareness of its existence with patients and primary care providers. Palpation of the neck for the presence of nodules needs to be part of every routine physical exam in childhood. While raising awareness, we also need to avoid excessive intervention for a condition which continues to have an excellent prognosis (7).
References:
1. The changing incidence of thyroid cancer. Kitahara CM, Sosa JA.Kitahara CM, et al. Nat Rev Endocrinol. 2016 Nov;12(11):646-653. doi: 10.1038/nrendo.2016.110.
2. https://seer.cancer.gov/ accessed June 15 2021
3. Trends in pediatric thyroid cancer incidence in the United States, 1998-2013. Marie-Odile Bernier , Diana R Withrow , Amy Berrington de Gonzalez , Clara J K Lam , Martha S Linet , Cari M Kitahara , Meredith S Shiels. Cancer. 2019 Jul 15;125(14):2497-2505. doi: 10.1002/cncr.32125. Epub 2019 Apr 23
4. Pediatric Thyroid Cancer Incidence and Mortality Trends in the United States, 1973-2013. Z Jason Qian , Michael C Jin , Kara D Meister , Uchechukwu C Megwalu. JAMA Otolaryngol Head Neck Surg . 2019 Jul 1;145(7):617-623. doi: 10.1001/jamaoto.2019.0898.
5. Schmid, D., Ricci, C., Behrens, G. & Leitzmann, M. F. Adiposity and risk of thyroid cancer: a systematic review and meta-analysis. Obes. Rev. 16, 1042–1054 (2015)
6. Ng, M. et al. Global, regional, and national prevalence of overweight and obesity in children and adults during 1980–2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet 384, 766–781 (2014).
7. Papillary Thyroid Carcinoma (PTC) in Children and Adults: Comparison of Initial Presentation and Long-Term Postoperative Outcome in 4432 Patients Consecutively Treated at the Mayo Clinic During Eight Decades (1936-2015). Hay ID, Johnson TR, Kaggal S, Reinalda MS, Iniguez-Ariza NM, Grant CS, Pittock ST, Thompson GB.Hay ID, et al. World J Surg. 2018 Feb;42(2):329-342. doi: 10.1007/s00268-017-4279-x.World J Surg. 2018. PMID: 29030676
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