Many former smokers should consider yearly lung cancer screening—even if they quit decades ago, according to updated guidelines from the American Cancer Society (ACS).

Although fewer Americans are dying of lung cancer than in decades past, the disease remains the nation’s top cancer killer by a wide margin. The ACS projects that in 2024, over 125,000 Americans will die of the disease—more than from colon, breast, and prostate cancers combined.

There are, however, treatments for lung cancer, and they are more likely to be successful when it’s caught early. That’s why yearly lung cancer screening, done by low-dose CT scan, has long been recommended for certain current and former smokers. Research shows screening can cut the risk of dying from lung cancer by up to 20 percent.

And in recent years, the number of Americans eligible for that screening has grown, due to guideline changes from various medical groups. The updated ACS guidelines are the latest. The group now says that current and former smokers should consider lung cancer screening if they:

• are between the ages of 50 and 80 (broadened from 55 to 74 under the group’s previous recommendations),
• and have at least a 20 “pack-year” history. A pack-year translates to smoking a pack of cigarettes every day for a year. So people can have a 20 pack-year history if they smoked a pack per day for 20 years, or two packs per day for 10 years, for example. (The old recommendation specified a 30 pack-year history.)

It doesn’t matter how long ago you quit

Those two changes bring the ACS recommendations in line with those from other groups, including the influential U.S. Preventive Services Task Force—an independent panel of medical experts that advises the federal government.

But the ACS advice differs in one important way: It says that former smokers who fit the profile above should consider lung cancer screening no matter how long ago they quit. In contrast, the Task Force and other groups recommend screening only for people who quit within the past 15 years—a requirement the ACS had included in its old guidelines.

Why the change? According to the ACS, the 15-year window was based on the “erroneous assumption” that a former smoker’s lung cancer risk keeps declining over the long haul. But based on recent research, that risk never drops to the level of a lifelong non-smoker—and screening people who quit many years ago could save more lives.

Talk to your doctor

If you fit the ACS guideline profile for screening, your first step should be a discussion with your doctor. That’s because there are risks and downsides to screening, and not everyone is automatically an ideal candidate. Some general points to consider:

• Are you in fairly good health? People with serious health conditions that limit their life expectancy are unlikely to benefit from lung cancer screening.
• CT screening may spot abnormalities that look like cancer but turn out to be false alarms—leading to further tests and sometimes lung biopsies, not to mention anxiety.
• Each scan involves a small dose of radiation; done annually, that increases your cumulative radiation exposure. There’s a “very small” chance that could lead to cancer at some point, the ACS says.
• If you quit smoking more than 15 years ago, you’ll likely have to pay for lung cancer screening yourself. Currently, Medicare does not cover it for those individuals, since it’s not recommended by the Task Force. Private insurers generally follow Task Force guidelines, as well.

Finally, if you still smoke, this is a good time to talk with your doctor about ways to quit. It’s never too late to gain numerous health benefits from kicking the habit.