Projected Cancer Risks from Computed Tomographic Scans Performed in the United States in 2007

Arch Intern Med.. 2009; 169(22):2071-2077

Berrington de González A, Mahesh M, Kim KP, Bhargavan M, Lewis R, Mettler F, Land C

OBJECTIVES: The use of computed tomographic (CT) scans in the United States (US) has increased more than 3-fold since 1993 to approximately 70 million scans annually. Despite the great medical benefits, there is concern about the potential radiation-related cancer risk. We conducted detailed estimates of the future cancer risks from current CT scan use in the US according to age, sex, and scan type.

METHODS: Risk models based on the National Research Council’s “Biological Effects of Ionizing Radiation” report and organ-specific radiation doses derived from a national survey were used to estimate age-specific cancer risks for each scan type. These models were combined with age- and sex-specific scan frequencies for the US in 2007 obtained from survey and insurance claims data. We estimated the mean number of radiation-related incident cancers with 95% uncertainty limits (UL) using Monte Carlo simulations.

RESULTS: Overall, we estimated that approximately 29, 000 (95% UL, 15 000-45 000) future cancers could be related to CT scans performed in the US in 2007. The largest contributions were from scans of the abdomen and pelvis (n = 14 000) (95% UL, 6900-25 000), chest (n = 4100) (95% UL, 1900-8100), and head (n = 4000) (95% UL, 1100-8700), as well as from chest CT angiography (n = 2700) (95% UL, 1300-5000). One-third of the projected cancers were due to scans performed at the ages of 35 to 54 years compared with 15% due to scans performed at ages younger than 18 years, and 66% were in females.

CONCLUSIONS: These detailed estimates highlight several areas of CT scan use that make large contributions to the total cancer risk, including several scan types and age groups with a high frequency of use or scans involving relatively high doses, in which risk-reduction efforts may be warranted.

PMID: 20008689

2 Responses

  1. Paul Schoenhagen, MD  on December 22nd, 2009

    Read also in the same issue:

    -Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer.
    Smith-Bindman R, Lipson J, Marcus R, Kim KP, Mahesh M, Gould R, Berrington de González A, Miglioretti DL.
    Arch Intern Med. 2009 Dec 14;169(22):2078-86.
    PMID: 20008690

    Recent technologic advances in multi-detector row cardiac CT
    Halliburton SS.
    Cardiol Clin. 2009 Nov;27(4):655-64.
    PMID: 19766922

  2. Eric M. Dandes  on December 22nd, 2009

    I think it’s worth noting some of the statistics used in this study; I am referring to the 95% uncertainty limits (UL). The Uncertainty Principle, ascertains, the more precisely one property is known, the less precisely the other can be known.

    As it relates to the study, it’s a 95% chance a patient with cancer, DID NOT receive cancer from CT (the cancer patient is the known variable); or in other words, only a 5% chance that they DID. Meanwhile, that 5% does not take into account the patients radiation exposure due to outside elements (i.e. sun).

    Not to mention, the benefits of early diagnosis and better prognosis.


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