Radiation risks potentially associated with low-dose CT screening of adult smokers for lung cancer

Radiology. 2004 May;231(2):440-5. doi: 10.1148/radiol.2312030880.


Purpose: To estimate the radiation-related lung cancer risks associated with annual low-dose computed tomographic (CT) lung screening in adult smokers and former smokers, and to establish a baseline risk that the potential benefits of such screening should exceed.

Materials and methods: The estimated lung radiation dose from low-dose CT lung examinations corresponds to a dose range for which there is direct evidence of increased cancer risk in atomic bomb survivors. Estimated dose-, sex-, and smoking status-dependent excess relative risks of lung cancer were derived from cancer incidence data for atomic bomb survivors and used to calculate the excess lung cancer risks associated with a single CT lung examination at a given age in a U.S. population. From these, the overall radiation risks associated with annual CT lung screening were estimated.

Results: A 50-year-old female smoker who undergoes annual CT lung screening until age 75 would incur an estimated radiation-related lung cancer risk of 0.85%, in addition to her otherwise expected lung cancer risk of approximately 17%. The radiation-associated cancer risk to other organs would be far lower. If 50% of all current and former smokers in the U.S. population aged 50-75 years received annual CT screening, the estimated number of lung cancers associated with radiation from screening would be approximately 36,000, a 1.8% (95% credibility interval: 0.5%, 5.5%) increase over the otherwise expected number.

Conclusion: Given the estimated upper limit of a 5.5% increase in lung cancer risk attributable to annual CT-related radiation exposure, a mortality benefit of considerably more than 5% may be necessary to outweigh the potential radiation risks.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Female
  • Humans
  • Lung Neoplasms / diagnostic imaging*
  • Lung Neoplasms / etiology
  • Male
  • Middle Aged
  • Radiation Dosage
  • Risk Assessment
  • Risk Factors
  • Smoking / adverse effects*
  • Tomography, X-Ray Computed / adverse effects*