Lung cancer screening: What you should know

By Neena Satija, Globe Correspondent

Yesterday, researchers at the National Cancer Institute published some of the first comprehensive data suggesting that getting screened for lung cancer – specifically, getting a low-dose radiation CT scan – might actually reduce your chances of dying from the disease. The results could be a game-changer for doctors and high-risk patients like heavy smokers, according to medical providers. But that doesn’t necessarily mean you should go out and get screened yourself, even if you have a history of smoking. Here’s what you need to know about whether the test is right for you.

What were the primary results of the study?

The study, known as the National Lung Screening Trial (NLST), compared the effects of two different lung-cancer screening methods on lung cancer deaths in a high-risk population. Over a 3-yeard period, the study screened over 50,000 current and former heavy smokers ages 55-74 using either a low-dose radiation CT scan or a chest X-ray. Researchers found 20 percent fewer deaths due to lung cancer in the population screened with CT scans compared to those who got chest X-rays. (A CT scan gives a three-dimensional picture of the area being observed, so it’s much more detailed than a normal two-dimensional X-ray.)

Most previous studies, which used chest X-rays to screen subjects, didn’t show any benefit to lung cancer mortality as a result of screening. The NLST is the first study to show that “we may be able to save lives by screening for lung cancer,” says Dr. Lecia Sequist, an oncologist at Massachusetts General Hospital

Does this mean everyone should get screened for lung cancer?

There’s no evidence that screening for lung cancer in the general population would produce the same results as the NLST, which looked at a very specific group – current and former heavy smokers between the ages of 55 and 74, who showed no symptoms for lung cancer at the time of screening. Given the NLST’s results, Sequist said she thinks it’s “probably a good idea” for people who fit that profile to get a screening CT scan. But, she cautioned, “I probably would not rush to recommend it to everybody in the public or even everybody who’s ever smoked.”

The Lung Cancer Alliance suggests that if you haven’t stopped smoking by the time you turn 45, your risk level for lung cancer will remain high enough that screening for at least 15 years after quitting is still beneficial.

Should I be worried about the risk of radiation exposure if I get a CT screen for lung cancer?

If you are or were a heavy smoker, the benefits of getting screened for lung cancer go far beyond the risks. It’s true that according to some studies, increased radiation exposure can increase the risk of cancer, but that risk is incredibly small - especially in older populations like the one examined in this study.

To give you a sense of how much radiation we’re talking about, people who live in the United States are exposed to an average of 3 mSv of naturally occurring radiation a year (mSv stands for millisieverts, a measure of radiation exposure). A lung CT screen gives your body an effective dose of about half that, and a mammogram gives you slightly less (.7 mSv).

Are there other risks associated with lung cancer screening?

Screening tests look for abnormalities in your organs. Even if they find them, that doesn’t mean they’re cancerous. In fact, a majority of the NLST subjects with positive test results did not actually have lung cancer – and CT scans, which are more detailed, were slightly more likely to deliver false positive results than chest X-rays. If you get a positive test result, you’ll most likely have to get more scans. In rare cases, you may have to get an invasive and potentially dangerous procedure, like a biopsy.

In short, “these tests are expensive, and they can lead to negative consequences for people,” says Sequist. Her advice: If you get screened, make sure you’re going to doctors you can trust. It’s not all about the machine: It’s about the experience and skill of the human being interpreting what’s on the machine.

Will my insurance cover a CT screen for lung cancer?

Right now most insurers, including Medicare, don’t cover CT screens for lung cancer. They’re also expensive, costing at least 4-5x more than a chest X-ray, said Sequist. Insurance coverage could change as agencies that issue screening recommendations, like the U.S. Preventive Services Task Force, take note of this study. But even the study’s authors say we’ll need a lot more data before that can happen.

For more information, check out this web site put together by the Lung Cancer Alliance: http://screenforlungcancer.org/.