Childhood leukaemias and lymphomas in Greece (1996-2006) : a nationwide registration study

Background: Monitoring time trends in the incidence of childhood leukaemias and lymphomas requires efficient and continuous data collecting systems. In countries without official cancer registries, such as Greece, ad hoc nationwide registration of incident childhood leukaemias and lymphomas could help elucidate the underlying aetiology and monitor socioeconomic differentials in health care delivery. Methods: We registered all cases and produced age, gender, type and immunophenotype specific figures and overall crude and age adjusted annual incidence rates and secular trends for 863 leukaemia and 311 lymphoma incident cases diagnosed in children <15 years of age across Greece during 1996-2006, namely the first 11 years of the Nationwide Registry for Childhood Hematological Malignancies. Results: The epidemiological profiles of leukaemias/lymphomas in Greece are similar to those in industrialised countries. No secular trends are observed for either malignancy during the studied period. However, the calculated incidence for leukaemia (46.60 cases per 1 million children annually) is among the highest in the EU-27 (19% higher than average; p<0.001), whereas that for lymphoma (16.8 cases per 1 million children annually) is around the EU-27 average. Conclusions: Minimal secular changes in childhood leukaemias/lymphomas have been noted recently in the EU-27, which cannot be easily explained in countries with small populations. Therefore, centralised EU databases such as the Automated Childhood Cancer Information System (ACCIS) should be enlarged to generate sufficient statistical power for monitoring time trends. It would be interesting to explore whether different lifestyle patterns across the EU might be responsible for the observed excess leukaemia incidence in countries such as Greece.