Background — Thyroid carcinoma (TC) is rare in young children, with a sharp increase in incidence among adolescents and young adults (AYA), between 15 and 29 years of age. The incidence of TC is increasing worldwide. Limited prospective population-based data are available to describe diagnostic and treatment practices in this age group. This study undertook a population-based review of TC among 0 to 29-year-old individuals in Ontario, Canada, utilizing linked administrative data to describe the demographic and care patterns over nearly two decades.
Methods — Cases from the Ontario Cancer Registry were identified and linked to administrative data sources at the Institute for Clinical Evaluative Sciences. Cases diagnosed prior to a patient's 30th birthday, between 1992 and 2010 were considered eligible. Billing records identified ultrasonography, fine-needle aspiration biopsy (FNAB), radioiodine therapy and surgical approach.
Results — 2,552 patients 0-29 years, were diagnosed with TC during the study period. There was a 2.1-fold increase in standardized incidence rate over the 19-years of this study. TC was diagnosed subsequent to a prior malignancy in 47/2552 patients at a median interval of 11.6 years after initial cancer diagnosis. Seventeen individuals developed a second malignancy after treatment for TC. Most patients (90.44%) underwent pre-operative ultrasound (ranging from 1-13 pre-operative studies). Pre-operative thyroid scintigraphy was used in 44% of patients, with a significant decline in usage over the study period. FNAB usage rose by 20% over the study period, although 26% of patients had no biopsy prior to surgery. Primary total thyroidectomy, followed by 2-stage thyroidectomy were the most frequently performed procedures and 56% of patients received therapeutic radioiodine.
Conclusions — This study establishes a foundation of diagnostic and practice patterns over nearly two decades. We corroborate, in the Ontario population, the rising incidence of thyroid carcinoma in children, adolescents and young adults. Finally, we have identified the use of multiple pre-operative ultrasound studies, low rates of thyroid biopsy and thyroid scintigraphy as targets to improve efficiencies of care and to reduce unnecessary healthcare expenditures through education, standardization of diagnostic approach and possibly through regionalization of care.