CT Scan Screening Of Lung Cancer Decreases Mortality By 20%

by Dr Sam Girgis on July 1, 2011

In the United States, lung cancer kills more people than breast cancer, prostate cancer, and colon cancer combined.  Breast, prostate, and colon cancer screening is routinely performed and recommended as a public health policy standard.  The efficacy and cost effectiveness of the screening for breast, prostate, and colon cancer have been previously debated and yet the recommendation for screening still stands.  Lung cancer is currently not screened for and it is currently not recommended as a standard of care in the United States.  This policy may soon change though, as a result of research that was recently published in the New England Journal of Medicine by the National Lung Screening Trial research team.  The study was funded by the National Cancer Institute and lead by Dr. Christine Berg.  The results of the study showed that screening with low dose CT scans had a relative reduction in mortality from lung cancer of 20% as compared to screening with single view posteroanterior chest radiography.  In the study, the researchers enrolled 53,454 participants that had at least a 30 pack year smoking history.  The participants were randomly assigned to have annual lung cancer screening with either low dose CT scan or singe view posteroanterior chest radiography for three consecutive years.  The participants were followed for an additional three years after the annual screening stopped and data on the occurrence of lung cancer diagnosis and death was collected.  More than 90% of the participants were adherent with the screening schedules.  Positive screening results were obtained at a rate of 24.4% for low dose CT scanning and 6.9% for radiography.  There was a very high rate of false positive results for both screening modalities.  The low dose CT scan group had a false positive rate of 96.4% and the radiography group had a false positive rate of 94.5%.  There were 1060 lung cancers diagnosed in the low dose CT scan group and 941 lung cancers diagnosed in the radiography group.  These results show that there were 247 deaths per 100,000 person years in the low dose CT group and 309 deaths per 100,000 person years in the radiography group.  This represents a relative reduction in mortality from lung cancer with low dose CT scan screening of 20%.  This is a very significant finding and is likely to have future health policy implications.  The authors of the study wrote, “The observation that low-dose CT screening can reduce the rate of death from lung cancer has generated many questions. Will populations with risk profiles that are different from those of the NLST participants benefit? Are less frequent screening regimens equally effective? For how long should screening continue? Would the use of different criteria for a positive screening result, such as a larger nodule diameter, still result in a benefit?”  In addition to these questions, the cost effectiveness of low dose CT screening must be evaluated.  In a nation where the health care system is already overburdened, can an additional expensive screening recommendation be possible?  Smoking cessation and the prevention of smoking initiation should also play a key role in the battle against lung cancer so that the burden on lung cancer screening is lessened.

See the MedPage Today interview on this topic with Dr. Reginald Munden from the MD Anderson Cancer Center below:


Berg CD et al. “Reduced lung-cancer mortality with low-dose computed tomography screeningN Engl J Med published online June 29, 2011

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{ 2 comments… read them below or add one }

Concerned MD September 13, 2011 at 2:39 pm

New study shows a 15% rate of pneumothorax in folks getting lung nodules biopsied … 6% requiring a chest tube.

Multiply times the 95% false positive rate of 25,000 scans (or 50,000,000 if it’s rolled out?) Number needed to screen of 320 in a high-high-risk population, which number will go way higher when lower-risk people are screened as would seem likely.

So, I’m not recommending my ex-heavy smoking family member get a chest CT. At least not till things are more clear. Would you?



Dr Sam Girgis September 13, 2011 at 5:22 pm

Thanks for the comments. You have an excellent point. The false positive rate as well as the invasive procedures that will be needed for the work up of this screening modality place significant barriers to its widespread use.


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