Pediatric thyroid cancer in Cyprus 1998-2017, incidence, trends,
survival: A population-based study from the Cyprus Pediatric Oncology
Registry
Abstract
Background: Pediatric and adolescent thyroid cancer (PATC) incidence
rates (IR) are increasing in many countries. We determined IRs, temporal
trends and survival from PATC diagnosed in Cyprus during 1998-2017.
Procedure: Patients aged 0-19 years, diagnosed with PATC in the
Pediatric Oncology Registry of Cyprus were included. Crude IR (cIR), age
standardized rates (ASRW), time trends and overall survival were
analysed. Annual IRs and temporal trends were calculated using Microsoft
Excel 2016 and Joinpoint Regression analysis. Results: Eighty-one cases
(76.5% female, 23.5% male) were identified. The cIR (per 100 000
persons) were for both sexes 2.00 (95% CI 1.61, 2.49), females 3.15
(95% CI 2.45, 4.03) and males 0.92 (95% CI 0.58, 1.44). The annual
percentage changes (APC) for cIR and ASRW were 7.5% (p <
0.05) and 7.6% (p < 0.05). The APC of cIR were for females
5.1%, males 8.4% and 15-19-year-olds 7.6%. The female to male RR
(rate ratio) was 3.42 (95% CI 2.06, 5.74). The papillary carcinoma
(PTC) represented 86.4% of all cases. The RR of 2nd (2008-2017) to 1st
(1998-2007) periods for metastatic (regional) stages was 3.76 (95% CI
1.74, 8.31). Survival until 2018 was 100%. Conclusion: This
population-based study demonstrated that IR in 0-19-year-olds was among
the highest reported. Increasing time trends mainly affected both males
and females aged 15-19 years with PTC, the dominant type. Increase of
metastatic cases suggests a true increase of thyroid carcinogenesis
rather than overdiagnosis. Although prognosis is excellent, rising IR is
unexplained, indicating the need to identify causal factors.