Who Needs Lung Cancer Screening?
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Who Needs Lung Cancer Screening?

Screening for lung cancer is low risk—and it could end up saving your life.

Lung cancer is a certified killer, and it’s much more common than people realize. In fact, more than one-quarter of cancer deaths are from lung cancer. “Lung cancer is the most common cancer worldwide,” says cardiac and thoracic surgeon Matthew Arneson, MD, of Wesley Medical Center in Wichita, Kansas.

About 90 percent of lung cancer cases are due to smoking, and the five-year survival rate is low. Just over half of people with lung cancer survive past five years if their cancer hadn’t spread by the time it was found. That number drops to about one in five if the cancer had already spread before it was found.

“Only about 15 percent of people get it diagnosed at an early stage,” adds Dr. Arneson. “Our goal is to increase that 15 percent so we can treat them earlier and have a better cure rate.” Lung cancer screening may be the answer. According to the U.S. Preventive Services Task Force (USPSTF), current screening guidelines can catch half of all lung cancer cases at an early stage.

Should I be screened? 
But those guidelines don’t include everyone. The USPSTF says you should get screened annually if you’re between the ages of 55 and 80, you’re a current smoker or you’ve quit within the last 15 years and you’ve smoked at least 30 pack-years. (Pack-years are packs per day times the number of years you smoked. So, if you’ve smoked one pack a day for 30 years, or two packs a day for 15 years, you fit the criteria.) Studies show that you’re still at increased risk for lung cancer even 15 years after you’ve quit smoking.

A low-dose CT scan is the only reliable screening method, says Arneson. Other tests that have been tried include a sputum test, which looks for cancer cells, and a chest X-ray. A 2012 study compared CT scans and X-rays, and CT scans came out the clear winner.

“It’s a lot more specific,” according to Arneson. “With a chest X-ray you often can’t see nodules that are close to the heart or other organs. The other thing is, some nodules are very small and the X-ray is not as sensitive in finding small nodules. The smaller the nodule, the more likely it is to be cured.”  

Some worry that the guidelines are too narrow. A 2015 study suggests that about two-thirds of people with new lung cancer diagnoses wouldn’t fit the USPSTF’s screening guidelines. That means people who would benefit are missing out.

Risks and benefits
The benefits of lung cancer screening are clear: you’re more likely to have small, nodules detected, so you can start the treatment process earlier, than if you wait for symptoms. Symptoms of lung cancer include coughing up blood, pain, shortness of breath and weight loss. “Unfortunately, when symptoms arise, it means the cancer has advanced,” says Arneson.

According to Arneson, the risks of screening are few. It’s called a low-dose CT scan for a reason, and that reason is the amount of radiation you’re exposed to is very low—less than you’d receive just walking around for a year. Still, it’s still not nothing. Some studies suggest starting screening before age 50 can cause more cases of radiation-induced lung cancer.

The other downside, says Arneson, is the risk of a false positive—something shows up on the scan and requires further tests, but turns out not to be cancer. That risk is all too real: 97.5 percent of all positive screening results do not lead to a cancer diagnosis, according to a January 2017 study in JAMA Internal Medicine.

“That’s why before anyone gets a CT scan, there’s a conversation about risks and options and the risks of false positives and negatives,” says Arneson. “No test is 100 percent accurate.” Talk to your doctor if you’re a current or former smoker between ages 55 and 80 to see if screening is right for you.

See more from Dr. Arneson
How should I do breathing exercises after thoracic surgery?
How is video-assisted thoracic surgery used in lung cancer?
What should I expect after having lung surgery for lung cancer?

This article was updated on November 10, 2017.