ORIGINAL PAPER Risk of cancer incidence before the age of 15 years after exposure to ionising radiation from computed tomography: results from a German cohort study L. Krille • S. Dreger • R. Schindel • T. Albrecht • M. Asmussen • J. Barkhausen • J. D. Berthold • A. Chavan • C. Claussen • M. Forsting • E. A. L. Gianicolo • K. Jablonka • A. Jahnen • M. Langer • M. Laniado • J. Lotz • H. J. Mentzel • A. Queißer-Wahrendorf • O. Rompel • I. Schlick • K. Schneider • M. Schumacher • M. Seidenbusch • C. Spix • B. Spors • G. Staatz • T. Vogl • J. Wagner • G. Weisser • H. Zeeb • M. Blettner Received: 12 August 2014 / Accepted: 12 December 2014 / Published online: 8 January 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract The aim of this cohort study was to assess the risk of developing cancer, specifically leukaemia, tumours of the central nervous system and lymphoma, before the age of 15 years in children previously exposed to com- puted tomography (CT) in Germany. Data for children with at least one CT between 1980 and 2010 were abstracted from 20 hospitals. Cancer cases occurring between 1980 and 2010 were identified by stochastic linkage with the German Childhood Cancer Registry (GCCR). For all cases and a sample of non-cases, radiology reports were reviewed to assess the underlying medical conditions at time of the CT. Cases were only included if diagnosis occurred at least 2 years after the first CT and no signs of cancer were recorded in the radiology reports. Standardised incidence ratios (SIR) using incidence rates from the gen- eral population were estimated. The cohort included information on 71,073 CT examinations in 44,584 children contributing 161,407 person-years at risk with 46 cases initially identified through linkage with the GCCR. Seven cases had to be excluded due to signs possibly suggestive of cancer at the time of first CT. Overall, more cancer cases were observed (O) than expected (E), but this was mainly driven by unexpected and possibly biased results for lym- phomas. For leukaemia, the SIR (SIR = O/E) was 1.72 (95 % CI 0.89–3.01, O = 12), and for CNS tumours, the SIR was 1.35 (95 % CI 0.54–2.78, O = 7). Despite careful examination of the medical information, confounding by indication or reverse causation cannot be ruled out L. Krille Á R. Schindel Á E. A. L. Gianicolo Á M. Blettner (&) Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Center Mainz, Obere Zahlbacher Straße 69, 55131 Mainz, Germany e-mail: blettner@uni-mainz.de L. Krille e-mail: KICTSubmission@gmail.com L. Krille International Agency for Research on Cancer, 69372 Lyon, France S. Dreger Á H. Zeeb Leibniz - Institute for Prevention Research and Epidemiology – BIPS, Research Focus Health Sciences Bremen, University of Bremen, 28359 Bremen, Germany T. Albrecht Institut fu¨r Radiologie und Interventionelle Therapie, Vivantes, Klinikum Neuko¨lln, 12351 Berlin, Germany M. Asmussen Sta¨dtisches Klinikum Karlsruhe, Zentralinstitut fu¨r Bildgebende Diagnostik, 76133 Karlsruhe, Germany J. Barkhausen Klinik fu¨r Radiologie und Nuklearmedizin, Campus Lu¨beck, Universita¨tsklinikum Schleswig Holstein, 23538 Lu¨beck, Germany J. D. Berthold Institut fu¨r Diagnostische und Interventionelle Radiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany A. Chavan Institut fu¨r Diagnostische & Interventionelle Radiologie, Klinikum Oldenburg GmbH, 26133 Oldenburg, Germany C. Claussen Abt. fu¨r Diagnostische und Interventionelle Radiologie, Universita¨tsklinikum Tu¨bingen, 72076 Tu¨bingen, Germany M. Forsting Institut fu¨r Diagnostische und Interventionelle Radiologie und Neuroradiologie, Universita¨tsklinikum Essen, 45147 Essen, Germany 123 Radiat Environ Biophys (2015) 54:1–12 DOI 10.1007/s00411-014-0580-3