ESPE Yearbook of Paediatric Endocrinology

J Clin Oncol. 2022 May 1;40(13):1439-1449. doi: 10.1200/JCO.21.01841. Epub 2022 Jan 19. PMID: 35044839

Brief Summary: This retrospective study showed that children and young adults (< 45 years) treated with radioactive iodine (RAI) for primary Differentiated Thyroid Cancer (DTC) have increased risks for leukemia and solid cancers, particularly beyond 20 years after treatment.

This retrospective study provides data on the risks of secondary cancer and leukemia after RAI treatment for DTC in childhood or young adulthood in 36,311 patients diagnosed between 1975-2017. Increased relative risk of solid malignancy after RAI was 1.23. Higher relative risk was observed in patients who were younger at DTC treatment (RR 1.6 in patients with RAI before age 25 years). The cumulative incidence of second solid malignancy at 20 years after DTC was 5.6% with RAI vs. 5.0% without RAI and increased continuously with age. In this large cohort of DTC patients post-RAI, the authors estimated that, 14% of hematological malignancies, 6% of solid tumors and 5% of breast cancer were associated with prior RAI.

These important data provide for the first time a reliable estimate of the relative risk for second malignancies in DTC survivors treated with RAI during a long follow-up period. They further confirm previous data on risk of leukemia [1]. This work as well as a second paper from last year [2] opens the discussion on risk and benefits of RAI, especially in low-risk DTC in young patients.

References: 1. Risk of Hematologic Malignancies After Radioiodine Treatment of Well-Differentiated Thyroid Cancer. Molenaar RJ, Sidana S, Radivoyevitch T, Advani AS, Gerds AT, Carraway HE, Angelini D, Kalaycio M, Nazha A, Adelstein DJ, Nasr C, Maciejewski JP, Majhail NS, Sekeres MA, Mukherjee S. J Clin Oncol. 2018 Jun 20;36(18):1831–1839. doi: 10.1200/JCO.2017.75.0232. Epub 2017 Dec 18. PMID: 29252123. 2. Radioactive Iodine Treatment for Children and Young Adults with Thyroid Cancer in South Korea: A Population-based Study. Seo GH, Kong KA, Kim BS, Kang SY, Moon BS, Yoon HJ, Kim HO. J Clin Endocrinol Metab. 2021 Jun 16;106(7):e2580–e2588. doi: 10.1210/clinem/dgab192. PMID: 33755732.