Patterns and temporal trends in the incidence of childhood and adolescence cancer in Cyprus 1998–2017: A population-based study from the Cyprus Paediatric Oncology Registry

1Introduction

Childhood and adolescence cancer (CAC) is rare. It represents from less than 0.5% (reported in Europe and North America) to 2% (in developing countries) of all cancer cases [1] . Globally, between 360,000 and 400,000 new cases of CAC occur yearly [23] . Within continents and countries, there are large variations in the reported incidence. Cancer registries around the world report incidence rates of cancer in children that vary by a factor of about four, between less than 60 to more than 210 per million per year [4] . The socioeconomic development of a population seems to be associated with the reported incidence of childhood cancer, with a general pattern of highest incidence in countries with the highest positions in the Human Development Index. In Africa, reported age standardised incidence rates (Segi 1960 World Standard Population) per million children and adolescents per year (ASRW) vary from approximately 60 to 173, in Latin America and the Caribbean from 80 to 173, in North America from 93 to 221, in Asia from 72 to 192, in Europe from 122 to 234 and in Oceania from 112 to 199 [4] . Geographical differences in incidence rates may suggest unique genetic or environmental exposures that affect the risk of childhood cancer. However, there is growing evidence that most, if not all of the variations in incidence rates, are due to high levels of underdiagnosis and underreporting in regions with lower observed incidence rates [2] .

Although cancer occurring in children and adolescents is a major health problem, unfortunately, globally, there is a lack of reliable data about incidence and temporal trends [56] . This is because in many low- and middle-income countries – in which 80% of CAC occur [78] – there is a lack of population-based cancer registration [9] . The lack of high-quality CAC registries in these countries but also in some high income countries does not allow the real depiction of the problem and thus hampers the much-needed cancer control activities [25] . The creation of adequate CAC registries everywhere could improve this situation.

Cyprus is a high-income economy as classified by the World Bank [10] . In Cyprus, the epidemiology of childhood cancer was never before studied comprehensively. For this descriptive epidemiological assessment, we first created the national population-based Paediatric Oncology Registry of Cyprus (PORCY). The aims were to analyse incidence patterns and temporal trends for a 20-year period. This important information can be used for improving cancer control activities. As the aetiology of childhood cancers remains poorly understood and preventive measures are lacking, these novel data could also add to the global effort of better managing the burden of CAC.