Radiation-induced cancer risk from annual computed tomography for patients with cystic fibrosis

Am J Respir Crit Care Med. 2007 Nov 15;176(10):970-3. doi: 10.1164/rccm.200704-591OC. Epub 2007 Aug 23.


Rationale: Computed tomography (CT) is being considered as a tool for routine monitoring of lung damage in people with cystic fibrosis. Concern has been raised, however, about the associated risk of radiation-induced cancer.

Objectives: To estimate the risk of radiation-induced cancer from lung CT for patients with cystic fibrosis, assuming annual monitoring starting at age 2 years.

Methods: Radiation risk models (derived primarily from the study of Japanese atomic bomb survivors) were used to estimate the excess risk of radiation-induced cancer for the organs that receive measurable doses from lung CT. Two scenarios were considered: median survival to age 36 years (approximate current median survival) and median survival to age 50 years (projected median survival by 2030).

Measurements and main results: The estimated risk of radiation-induced cancer from annual lung CT was 0.02% for males and 0.07% for females assuming median survival to age 36 years. The estimated risks increased to 0.08% for males and 0.46% for females assuming median survival increases to age 50 years. The risks are higher for females because of the risk of radiation-induced breast cancer (50% of total risk) and higher risk of thyroid cancer.

Conclusions: The cumulative risk of radiation-induced cancer from repeated lung CT scans for patients with cystic fibrosis is relatively small (less than 0.5%). However, routine monitoring should not be recommended until there is a demonstrated benefit that will outweigh these risks.

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Child, Preschool
  • Cystic Fibrosis / diagnostic imaging*
  • Female
  • Humans
  • Lung / diagnostic imaging*
  • Male
  • Middle Aged
  • Neoplasms, Radiation-Induced / etiology*
  • Proportional Hazards Models
  • Radiation Dosage
  • Risk Assessment
  • Sex Factors
  • Tomography, X-Ray Computed / adverse effects*