Abstract
INTRODUCTION: Thyroid cancer is one of the most common cancers in adolescents and young adults (AYA, 15 to 39 years), with an excellent 5-year survival of 98%. However, treatments for thyroid cancer such as radioactive iodine and thyroid hormone suppression may increase the risk for multiple late effects (LEs). We investigated the incidence of severe LE that clustered in AYA thyroid cancer survivors in a large population-based cohort. METHODS: California and Utah Cancer Registry records identified AYAs diagnosed with first thyroid cancer during 2006-2018 linked to statewide hospitalization, ambulatory surgery, and emergency department data. Cohort entry began 2 years from diagnosis. Severe LE included cardiovascular, respiratory, renal, and liver diseases, diabetes, and second cancers. Cumulative incidence of each LE, accounting for the competing risk of death, was calculated. Latent class analysis (LCA) identified clustering of LE over the study period. The number of LE classes was identified by selecting models with the lowest likelihood-ratio G(2) statistic, Akaike's Information Criterion, and Bayesian Information Criterion. Probabilities of each LE are presented in each class. RESULTS: Of 14,268 survivors, median follow-up time was 7 years. The LCA model identified 3 classes: 88% with low LEs, 9% experiencing moderate LEs with elevated probability of diabetes, liver, and respiratory conditions, and the remaining 3% experiencing the highest probability of all LEs, including cardiovascular disease. Non-Hispanic (nH)-Black and Hispanic survivors, those on public insurance, residing in lower socioeconomic status neighborhoods, or diagnosed with distant stage disease experience greater odds of being in the moderate and cardiovascular classes. CONCLUSION: While most survivors of AYA thyroid cancer have a low incidence of LEs, a small proportion have a high probability of multiple morbidities. Multidisciplinary survivorship care should include identifying and supporting thyroid cancer survivors at higher risk for developing multiple LEs through early screening.