An increase in Thyroid Cancer (TC) incidence has been seen in most countries worldwide. The same has also been reported for Cyprus¹. The most fundamental issue is whether this increase is due to increased investigations (opportunistic screening) and overdiagnosis of small incidental TC or due to a true increase in clinically relevant TC.
Data collection in the Cyprus Cancer Registry (CyCR) is guided by the MECC Manual of Coding and Staging for Cancer Registration. In this study, we considered only invasive cancer (ICD-O-3 behavior code=3). From 1998 until 2015 there were 2490 thyroid cancer diagnoses recorded in the CyCR, from which 2309 (92.7%) had histology and staging information recorded. We undertook analysis of the staging of recorded cases in the CyCR and calculated APC (Annual Percent Change) to ascertain whether the increase seen is due to small localized cancers (suggesting opportunistic screening) or also true for locally advanced / Lymph node positive tumours.
The APC for all patients is 11.1% yearly increase. When analyzing by stage, the APC for regional (i.e. locally advanced) TC was 16.3% higher than for localized disease at 11.9%. There was also a statistically significant increase in metastatic cases, but this needs to be interpreted with caution due to the small number of patients with metastatic disease (data not presented).Table: 1826P
|Subgroup||Joinpoints||APC||Lower CI of APC||Upper CI of APC||Significance probability at α = 0.05|
Analysis of the Cyprus Cancer Registry data provide evidence of a large increase in TC in Cyprus, being due to an increase of both localized and also locally advanced tumours. It is therefore likely that the increase in TC is not only due to opportunistic screening, but also due to a true increase of larger, clinically relevant tumours.
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All authors have declared no conflicts of interest.