Screening for lung cancer with CT scans

Peter Wehrwein

Contributor, Harvard Health

Lung cancer is usually discovered late when it’s difficult to treat and has often spread outside the lung. A reliable screening test to find it at an earlier, more treatable stage would be a legitimate breakthrough—and could potentially save thousands of lives. About 160,000 Americans die each year from lung cancer, which is more than who die from breast, prostate, and colon cancer combined.

Chest x-rays do a good job of finding small lung cancers that can be removed surgically. Why not use them to screen for lung cancer? Because at least a half-dozen studies have been done and for reasons that aren’t entirely clear, early detection with chest x-rays hasn’t translated into prevention of fewer deaths from lung cancer. And in screening, early detection is a means to an end. The real goal is preventing deaths from the disease that is being screened for (and deaths in general).

So it was big news today when the National Cancer Institute (NCI) announced today that a large study sponsored by the institute showed that screening current and former heavy smokers with computed tomography (CT) scans did, in fact, reduce the risk of dying from lung cancer by 20% compared with screening them with chest x-rays. Moreover, those who were screened with CT scans were 7% less likely to die from any cause during the study’s five-year follow-up period.

Good news, and a long time coming for those who have watched disappointing findings from the chest x-ray studies pile up.

But if today was first time that most of us heard about the National Lung Screening Trial, it probably wouldn’t be the last. It’s almost certainly going to stir up more than its fair share of controversy.

Here are a few of the hot buttons:

  • The NCI says there are more than 94 million current and former smokers in the United States (mind you, not all of them are heavy smokers, so the population to be screened may be smaller). It will be very expensive to screen them all with CT scans. How much a screening CT of the lung will cost is hard to say, especially if they become routine, but the NCI says the current Medicare reimbursement rate for a diagnostic CT scan of the lung is $300.
  • Some may argue that smokers shouldn’t be entitled to such an expensive test—or should have to shoulder a large share of the cost. The counterargument is why single out smokers when other bad health habits result in expensive tests and treatments.
  • The NCI itself showed that there’s concern that some people may see an effective screening test as a reason to tune out the dire health warnings about tobacco and cigarettes. In a Q&A about the study posted on its Web site today (which is well worth reading if you want more detail about the study), the third question is, “Is it OK to keep smoking because there is a screening test that has benefit?” The answer begins with an emphatic, “No.” It’s hard to imagine that people would actually ask such question, but the NCI apparently was worried enough to pose it.
  • Radiation exposure and the cancer risk from medical imaging (and CT scans in particular) has become a major issue. Will the radiation from CT screening for lung cancers add to the problem? The NCI position: the radiation from a screening CT is far less than the dose from a diagnostic one and that benefit of finding and treating early lung cancer will likely outweigh the risk from a low dose of radiation from CT scanning.
  • In the Q&A about the study, the NCI says that between 20% and 60% of  screening CT scans of current and former smokers show some kind of abnormality and that most are not lung cancer. CT scanning for lung cancer could generate a large number of false positives: results that indicate the possibility of cancer but turn out not to be. False positives result in worry and additional tests, which in the case of lung cancer would include invasive biopsies.

Of course many of our current screening tests for cancer have shortcomings, cost plenty, and are controversial. The debates about the value of mammography never seem to end. Yet we get behind screening tests for a whole variety of reasons, not the least of which is that cancer caught late is so lethal and, these days, astronomically expensive to treat.


  1. Ryan

    I think any means there is to reduce deaths from lung cancer is a good thing. What annoys me is that I constantly hear how important getting an early diagnosis is, but I rarely hear anyone saying what the early symptoms are to watch out for. I know 3 people who have died from lung cancer. All 3 of them went in to their doctors complaining of various symptoms almost a year before their doctors finally checked them for lung cancer. By then their cancers were already advanced. If they had been checked for lung cancer when they first went to their doctors, they might still be alive today. Plus, two of these people had never smoked cigarettes in there lives. There’s is still very much to be done when it comes to diagnosing lung cancer early. And much more needs to be done to inform people that lung cancer patients are just as deserving as any cancer patients.

  2. Restrictive Lung Disease

    This section deals with restrictive lung disease. He speaks of diagnostic tests are needed to make the distinction between different diseases, and acute and chronic administration of various diseases and many more.

  3. Matt Hoffman

    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 55,000 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.

    Not recommending my ex-heavy smoking mom get a chest CT. At least not till things are more clear. Would you?


  4. Azman Banting

    How do we prepare ourselves if we were to get a CT scan?

  5. Avent LaForge

    Anything that helps the discovery of cancers has to be a good thing. The biggest problem, in my opinion is people’s lack of self preservation. i.e. smoking, excessive alcohol intake, obesity, poor quality nutritional intake and excessive UV exposure.
    Skin cancer is on the increase and people should be aware of the risk moles represent and the availability of mole removal surgery.
    [URL removed by moderator]

  6. James Larson

    As a dentist, I see many pre-cancerous and cancerous lesions due to smoking and chewing tobacco. Your statistic is staggering and yet we still have smokers and chewers. I was a baseball player in high school and college and picked up the habit of chewing back then. I learned to stop after 30 years, using A fellow dentist stopped the same way and I recommend it to patients a few times a week now. It seems to work well for smokers, too.

    CT scans are remarkable and help dentists who send patients for scanning simple lesions we find in the mouth. Unfortunately, not all we find are Pre-cancerous.
    James Larson, DDS

  7. Dr. Philip Morsey

    I have seen a few CT scans in my life and it would not surprise me if more and more patients wanted to have CT scans done.

    I focus mostly on dermatology and Cancerous Moles so I don’t see many CT Scans. Glad we keep getting more information though!

  8. Michael Kirsch, M.D.

    I wouldn’t ‘hold my breath’ over this study. Lots of press hype which confuse and mislead the public. Many of us are skeptics. See

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