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Sometimes innovation means adapting existing technology to existing tasks in order to make them more effective. In the medical world, this can save lives. In 2011, the research team from the National Lung Screening Trial, of which the Wake Forest School of Medicine was a member, published a paper in the New England Journal of Medicine. Their research focused on the benefits of using a low radiation dose CT scan, instead of an X-ray, to screen for lung cancer.
For the national lung screening trial, they randomized patients to either chest X-ray or CT Scan, almost like drawing a name out of a hat to pick which patients undergo the low-dose CT scan versus which patients undergo the chest X-ray. Nationally it enrolled over fifty thousand patients, about twenty-five thousand were randomized to a chest X-ray, and twenty-five thousand were randomized to a low-dose CT screening.
That's Dr. Christina Bellinger, Director of Interventional Pulmonology and the Lung Screening Program at Wake Forest Baptist Medical Center. With the X-ray screening method currently used, early detection of lung cancer has been difficult at best. The study suggests, however, that the innovative use of low-dose CT scans can greatly increase the chances of catching it in its earlier stages. So how does a low-dose CT scan differ from an X-ray?
The CT screen gives more detail about the chest, it's thin slices usually around 200 images or so of the chest and the tissue itself, whereas the chest X-ray is a single snapshot of the lung. A CT scan is done with a patient lying flat, and they go through the CT scanner. The low-dose CT is a low radiation risk, it takes about twenty seconds to perform. There's no invasive IVs or medication involved.
Without low-dose screening CT currently in practice, lung cancer is currently diagnosed at a later stage the majority of the time; in advanced stage 3 or stage 4 where the 5-year survival rate is only about 15%. Our hopes with low-dose screening CT is to turn those numbers around, extend the five year survival rate and improve mortality, with low-dose screening CT scans.
What does the “low-dose” in a low-dose CT scan really mean?
A low-dose screening CT is anywhere from 1 to 1.5 milliSierverts of radiation. To put that in perspective, a full dose abdominal CT scan would be around 8. A standard chest CT, not the low-dose, is around 7. Dental X-ray is 0.01. An airline flight is 0.02. We also have knowledge about background radiation exposure. So just on an annual basis we're all exposed to around 3, and sometimes with extra medical dosing we get up to 6 milliSieverts.
The process is not without drawbacks, however.
There will be a high chance of a false positive. And what that means is a nodule that's found that's not necessarily cancer. So out of 100 patients, 15 to 20 will have a nodule found, only one of those will actually be cancer. And the rest of them will need followup CT scans at varying intervals, or an actual biopsy.
The process isn't for everyone. The study finds that benefits are specific to a particular high-risk group of smokers and ex-smokers.
It's actually an annual CT scan. We recommend getting it done at the age of 55 to 75, and the US preventative task-force actually extends that up to age 80. Once you've quit [smoking] up to 15 years, then you're done with your CT scans. So, whichever you reach first. Either age 75 or quit greater than 15 years. We really want the routine part to be just with the high risk smokers. So really just the ages 55 to 75, smoke greater than 30 years, and quit less than 15 years, that's really the only place where the benefit has been shown. To screen outside of that population, the concern is the added radiation risk and false positive being even higher, and not being able to have a mortality benefit.
Are you or a loved one in this high-risk population? This potentially live-saving innovation may be available to you in the near future.
We're advocating to get it on a nationwide basis. Last December, the US preventative task-force came out endorsing low-dose screening CT in high-risk smokers. That population is 55 to 80, smoking greater than 30 years, and quit less than 15 years. They gave it a grade B recommendation, wanting the insurance companies to pay for low-dose screening CT. We think that this year, Medicaid will start paying for low-dose screening CT.
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