NARECHEM-BT is an extensive database (~500 variables), pertaining to incident childhood hematological (leukemias, lymphomas) malignancies and central nervous system (CNS) tumors diagnosed all over Greece. Additionally, the database avails for each case an age and gender matched hospital-based control, whereas for the hematological malignancies biological and cytogenetic samples have also been stored.
Historically, registration of descriptive data for newly diagnosed patients with hematological malignancies was initiated in the Department of Hygiene, Epidemiology and Medical Statistics during the 1980s, followed by a concurrent nationwide case control study, during the period 1993-4.
Types of malignancies: Since 1996, the Registry has been actively registering incident hematological malignancies on a nationwide basis without interruption, yielding by the end of 2014 more than 2100 cases and their age and gender matched hospitalized controls. Eventually, NARECHEM became one of the most numerous and wealthiest in qualitative information databases on these type of childhood malignancies, internationally. Since 2009 the database has expanded to the registration of incident cases of childhood (0-14 years) central nervous system tumors.
Coding: Data are coded in ICD-O-3 for all three registered malignancies whereas CNS benign tumors are also registered.
Completeness of coverage: NARECHEM-BT reaches ~100% completeness for both hematological malignancies and CNS tumors. Public and private institutions treating childhood malignancies in Greece are contributing their incident cases and multiple sources of information are used including collaboration with institutions outside Greece to which cases may be referred to (e.g. Stergios Zacharoulis, Consultant Paediatric Oncologist, Harley Street Clinic, London, UK). It is hoped that data certificate only (DCO) cases are minimal in Greece but data linkage with the Hellenic Statistical Services is not currently feasible.
Clinical and follow up data: Treating physicians provide electronically detailed clinical data and long-term follow-up/survival of the registered patients as well as information on previous and subsequent development of second primary tumors. After a certain period of time, it is feasible to compare NARECHEM-BT mortality figures with the tabulated ones provided by the Hellenic Statistics Department (ELSTAT) to ensure completeness of death data.
Ethics approval: The Committee of Bioethics of the Athens Medical School, National and Kapodistrian University of Athens has approved the study along with the participating hospital Ethics Committees.
Dissemination of data: Each participating department has access to their own electronic fileschecked and managed by NARECHEM-BT, whereas standard tables of demographic characteristics by disease subtype as well time trends become available online in the narechem.gr website usually early next year. Basic primary data are also being contributed to European childhood cancer registries, handled by IARC. As the National Cancer Registry in Greece is not fully functional, data of this specialized cancer Registry (NARECHEM-BT) could potentially be used in the future for the evaluation of completeness of the all age Greek Registry.
Further data use and international collaborations: NARECHEM-BT has a rich record of publications of a great range of topics pertaining to descriptive and analytic epidemiology, whereas the recently completed registration of clinical and cytogenetic records open a new research era (please see publication list with >50 articles and ~1000 citations).
Since 2009, NARECHEM-BT has been actively participating in multicenter collaborating projects aiming to overcome statistical power issues in the elucidation of childhood cancer etiology, such as CLIC (leukemia) and MOBIKIDS (brain tumors). Furthermore, collaboration with the Department of Clinical Epidemiology, Karolinska Institutet, Sweden has resulted in one of the first studies showing an increased risk of childhood leukemia among assisted reproduction born children in Greece and Sweden; the scientific interest in the topic is keen with a large on going prospective study in the USA and another one among Nordic countries on the way.
On behalf of the collaborating centers:
Eleni Petridou, M.D.
Professor of Epidemiology and Preventive Medicine
Department of Hygiene, Epidemiology and Medical Statistics
Natiional and Kapodistrian University of Athens