title: Radiation-related cancer risks from CT colonography screening: a risk-benefit analysis.
abstract: OBJECTIVE
  The purpose of this study was to estimate the ratio of cancers prevented to induced (benefit-risk ratio) for CT colonography (CTC) screening every 5 years from the age of 50 to 80 years.
  
  
  METHODS
  Radiation-related cancer risk was estimated using risk projection models based on the National Research Council's Biological Effects of Ionizing Radiation (BEIR) VII Committee's report and screening protocols from the American College of Radiology Imaging Network's National CT Colonography Trial. Uncertainty intervals were estimated using Monte Carlo simulation methods. Comparative modeling with three colorectal cancer microsimulation models was used to estimate the potential reduction in colorectal cancer cases and deaths.
  
  
  RESULTS
  The estimated mean effective dose per CTC screening study was 8 mSv for women and 7 mSv for men. The estimated number of radiation-related cancers resulting from CTC screening every 5 years from the age of 50 to 80 years was 150 cases/100,000 individuals screened (95% uncertainty interval, 80-280) for men and women. The estimated number of colorectal cancers prevented by CTC every 5 years from age 50 to 80 ranged across the three microsimulation models from 3580 to 5190 cases/100,000 individuals screened, yielding a benefit-risk ratio that varied from 24:1 (95% uncertainty interval, 13:1-45:1) to 35:1 (19:1-65:1). The benefit-risk ratio for cancer deaths was even higher than the ratio for cancer cases. Inclusion of radiation-related cancer risks from CT examinations performed to follow up extracolonic findings did not materially alter the results.
  
  
  CONCLUSIONS
  Concerns have been raised about recommending CTC as a routine screening tool because of potential harms including the radiation risks. Based on these models, the benefits from CTC screening every 5 years from the age of 50 to 80 years clearly outweigh the radiation risks.
authors.affiliation: Division of Cancer Epidemiology & Genetics, National Cancer Institute, 6120 Executive Blvd, Bethesda, MD 20892, USA. berringtona@mail.nih.gov
authors.forename: Amy
authors.initials: A
authors.lastname: Berrington de González
authors.forename: Kwang Pyo
authors.initials: KP
authors.lastname: Kim
authors.forename: Amy B
authors.initials: AB
authors.lastname: Knudsen
authors.forename: Iris
authors.initials: I
authors.lastname: Lansdorp-Vogelaar
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Rutter
authors.forename: Rebecca
authors.initials: R
authors.lastname: Smith-Bindman
authors.forename: Judy
authors.initials: J
authors.lastname: Yee
authors.forename: Karen M
authors.initials: KM
authors.lastname: Kuntz
authors.forename: Marjolein
authors.initials: M
authors.lastname: van Ballegooijen
authors.forename: Ann G
authors.initials: AG
authors.lastname: Zauber
authors.forename: Christine D
authors.initials: CD
authors.lastname: Berg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D023881:Colonography, Computed Tomographic / Q000009:adverse effects*; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009010:Monte Carlo Method; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology / Q000209:etiology*; D011829:Radiation Dosage; D018570:Risk Assessment