Risk of cancer incidence before the age of 15 years after exposure to ionising radiation from computed tomography: results from a German cohort study

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 computed 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 general 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 lymphomas. 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 completely and may explain parts of the excess. Furthermore, the CT exposure may have been underestimated as only data from the participating clinics were available. This should be taken into account when interpreting risk estimates.

Medical conditions associated with the use of CT in children and young adults, Great Britain, 1995–2008

“…14 Since the previously published risk analyses, [3][4][5][6][7][8][9][10][11][12][13][14] additional information on CT exposures and scan reports was collected for the period [2003][2004][2005][2006][2007][2008] in half of the participating hospitals and the follow-up (diagnosis of cancer, vital status) was extended up to 31 December 2010. Available information for scans performed before 1995 was sparse and not included in this report.…”

“…Other cohort studies have found comparable results. [4][5][6][7] The interpretation of these results nevertheless requires an understanding of whether the excess risks of later malignancies observed after CT scans were due to the radiation exposure or to the underlying medical condition. 8,9 It is indeed possible that the increased incidence rates observed after receipt of CT scans were, at least in part, attributable to the indication for CT use, whether it was the first symptoms of a tumour, a followup for cancer predisposition or a non-cancer disease associated with an elevated risk of developing cancer.…”

“…In all the previously reported epidemiological studies, the analyses were conducted after excluding cancers occurring within the first 1-10 years after exposures to reduce the possibility that scans were performed to investigate early symptoms of a tumour diagnosed later. [3][4][5][6][7] Ad hoc analyses 7,14,15 showed little to no evidence of an overestimation of radiation-related risks owing to the presence of cancer-predisposing conditions, such as Down syndrome, neurofibromatosis or ataxia telangiectasia, or immune deficiencies known to be associated with an elevated risk of haematopoietic tumours. 16,17 To complement these findings, we aim here to describe medical conditions associated with the use of CT in children or young adults with no previous diagnosis of cancer, among members of the previously reported UK CT cohort.…”

Understanding the problem of a parent’s fear of their child getting cancer from CT scan radiation

“…Claims that children are more sensitive to radiation and are more likely to get cancer from CT scans than adults are found repeatedly in many scientific articles (9,33,40,45,46,51). I do not know if these claims are true or not.…”

The Think A-Head campaign: an introduction to ImageGently 2.0

“…In addition, there is variability in adherence to best practice clinical guidelines [30][31][32][33][34]. The issue of head CT and cancer risk is debated [35][36][37][38][39][40][41]; parental as well as emergency department providers' understanding of medical radiation exposure and cancer risk can vary [42][43][44][45]. Emergent care involves multiple stakeholders, including the patient and family, primary care physicians; nurses; emergency medicine physicians; trauma, pediatric and neurosurgeons; and the imaging team.…”