Adopting helical CT screening for lung cancer: potential health consequences during a 15-year period.
BACKGROUND
Simulation modeling can synthesize data from single-arm studies of lung cancer screening and tumor registries to investigate computed tomography (CT) screening. This study estimated changes in lung cancer outcomes through 2005, had chest CT screening been introduced in 1990.


METHODS
Hypothetical individuals with smoking histories representative of 6 US cohorts (white males and females aged 50, 60, and 70 years in 1990) were simulated in the Lung Cancer Policy Model, a comprehensive patient-level simulation model of lung cancer development, screening, and treatment. A no screening scenario corresponded to observed outcomes. We simulated 3 screening scenarios in current or former smokers with > or =20 pack-years as follows: 1-time screen in 1990; and annual, and twice-annually screenings beginning in 1990 and ending in 2005. Main outcomes were days of life between 1990 and 2005 and life expectancy in 1990 (estimated by simulating life histories past 2005).


RESULTS
All screening scenarios yielded reductions (compared with no screening) in lung cancer-specific mortality by 2005, with larger reductions predicted for more frequent screening. Compared with no screening, annual screening of ever-smokers with at least 20 pack-years of cigarette exposure provided ever-smokers with an additional 11 to 33 days of life by 2005, or an additional 3-10 weeks of (undiscounted) life expectancy. In sensitivity analyses, the largest effects on gains from annual screening were due to reductions in screening adherence and increased smoking cessation.


CONCLUSIONS
The adoption of CT screening, had it been available in 1990, might have resulted in a modest gain in life expectancy.
McMahon
Pamela M
PM
Department of Radiology, Massachusetts General Hospital, Boston, MA, USA. pamela@mgh-ita.org
Kong
Chung Yin
CY
Weinstein
Milton C
MC
Tramontano
Angela C
AC
Cipriano
Lauren E
LE
Johnson
Bruce E
BE
Weeks
Jane C
JC
Gazelle
G Scott
GS
D000368:Aged; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000401:mortality; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013997:Time Factors; D036542:Tomography, Spiral Computed