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



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



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).



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.



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.
Berrington de González
Amy
A
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA. aberring@jhsph.edu
Kim
Kwang Pyo
KP
Samet
Jonathan M
JM
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D016016:Proportional Hazards Models; D011829:Radiation Dosage; D018570:Risk Assessment; D012737:Sex Factors; D014057:Tomography, X-Ray Computed / Q000009:adverse effects*