Lung cancer screening

A yearly low-dose CT scan can find lung cancer early in some people who smoke now or smoked in the past.

Rosa: Hi, I'm Rosa. If you smoke now or smoked in the past, a yearly scan may find lung cancer early. Let's see if it's right for you.

Lung cancer screening uses a low-dose CT scan. CT stands for computed tomography. It is a special X-ray that takes detailed pictures of your lungs. Low-dose means it uses much less radiation than a regular CT scan. The scan takes only a few minutes. You lie on a table, hold your breath for a short time, and there are no needles.

Screening is for people at higher risk because of smoking. Doctors measure smoking with pack-years. One pack-year means smoking one pack of cigarettes a day for one year. So one pack a day for 20 years is 20 pack-years. Two packs a day for 10 years is also 20 pack-years.

Two expert groups give slightly different advice. The U.S. Preventive Services Task Force (2021) says adults 50 to 80 years old with at least 20 pack-years should get a scan every year if they smoke now or quit within the past 15 years. The American Cancer Society (2023) uses the same ages and pack-years, but it does not matter how long ago you quit. If you quit more than 15 years ago, ask your doctor whether screening is right for you. Some insurance plans follow the first group's rules.

Most scans are normal or show small spots called nodules. Most nodules are not cancer. They can be scars from old infections. Often the next step is simply another scan in a few months to see if the spot changes. Sometimes you may need a different scan, a visit with a lung specialist, or a biopsy.

Screening works best as a yearly habit, not a one-time test. Screening is not a good reason to keep smoking. Quitting is still the most important thing you can do for your lungs, at any age. Ask about free help to quit at your screening visit.

Screening may not be right for everyone. If you have serious health problems that would keep you from having surgery or other treatment, talk with your doctor about whether screening makes sense for you.

Who should ask (Task Force)

Adults 50 to 80, with 20 or more pack-years, who smoke now or quit in the past 15 years.

Who should ask (American Cancer Society)

Adults 50 to 80, with 20 or more pack-years, who smoke now or ever smoked, no matter when they quit.

How often

One low-dose CT scan every year, as long as you still qualify and are healthy enough for treatment.

Before your first scan

Most people have a shared decision visit with their doctor to talk about the benefits and possible harms.

Nodule

A small spot on the lung. Most are not cancer. Your report will say if you need a follow-up scan.

Follow-up

Depending on the size and look of a spot, the next step may be a repeat scan, another type of scan, or a biopsy.

Other findings

The scan can also show things like heart artery calcium or emphysema. Ask your doctor what these mean for you.

• Count your pack-years and bring that number to your doctor.
• Ask: Do I qualify for lung screening, and will my insurance cover it?
• Ask: Who will call me with my results, and when?
• Ask: If you see a spot, what is the plan?
• Ask for free help to quit smoking. Call 1-800-QUIT-NOW (1-800-784-8669).
• Put a reminder in your phone to get your scan again next year.

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.