If you are at a high risk for lung cancer, experts recommend that you get screened yearly. But only a very small number of cancers are found through screening, and the process itself poses some risks. So should you still get checked?

The American Cancer Society, American Lung Association and the U.S. Preventive Services Task Force say yes — if you’re older and are (or were) a longtime smoker.

Peter Mazzone, MD, MPH, Director of the Lung Cancer Screening Program for Cleveland Clinic’s Respiratory Institute, helps us take a closer look at what you need to know about screening.

Q: What patients do doctors typically refer for screening?

A: Your doctor likely will refer you for screening if you fall into these categories:

• You are between age 55 and 77
• You have smoked at least 30 pack years of cigarettes (figured by multiplying the number of packs you smoked each day by the amount of time you smoked: 30 pack years is one pack a day for 30 years or two packs a day for 15 years)
• You have been a smoker in the past 15 years

It’s also important that you’re healthy enough to benefit from finding and treating early-stage lung cancer.

If someone comes to us in a wheelchair wearing oxygen and couldn’t tolerate treatment, they typically aren’t eligible for screening. However, there are nearly 9 million Americans who are at high risk and should receive screening.

Q: How effective is the screening?

A: Only a small fraction of those who get screened have cancer — about one in every 300 patients. This may sound like a small number, but it’s about the same or better than results from breast and colon cancer screening.

Q: Are there potential harms from screening?

A: There are three main problems that we associate with screening:

1. During a scan, a small spot (nodule) is sometimes found, but 95 percent of these are benign little scars in the lungs we would never have known about without screening. This may cause anxiety for people. And, if a nodule looks concerning, it may lead to extra scans and biopsies, or even surgery to remove it — only to find out it’s not cancer.
2. Scans emit a low dose of radiation. Screening is annual, so if you get scans repeatedly, it adds up. No one knows how much impact that has on your health over time. There is a very small risk of getting cancer years down the road because of having repeated scans.
3. Another possibility is overdiagnosis. This gets a little more complicated. Sometimes these cancers progress quite slowly. We may find and treat cancer that might not have killed a person because they may have another illness (such as emphysema or heart disease) that is more immediately life-threatening. They may go through testing and surgery unnecessarily.

Q: Do the benefits of screening typically outweigh the risks?

A: The only reason we offer screening is because the benefits still outweigh the harms in the right person. And, in a high-quality program, we can minimize the harms and manage the findings effectively.

Lung cancer doesn’t have symptoms in its early stages. So, without screening, most people come in when it’s spread too far and there is no longer a good chance of curing it.

Lung cancer patients have about an 80 percent chance of being alive five years later if we diagnose and treat them when their cancer is at Stage 1.

However, only about 16 percent of people with lung cancer are diagnosed before the cancer spreads. For tumors that have spread, the five-year survival rate is only about 4 percent.

Q: How can you make a good choice on screening?

A: Cleveland Clinic mandates a counseling and shared decision-making visit before doing a scan. Here, we talk to patients about the benefits and potential harms so we can personalize their decision.

People need to understand their specific chances of getting lung cancer as well as the potential benefits of screening. They need to understand the possible harms so they can make a value-based decision.

Many people value the potential benefit of screening so much that they are happy to accept them to avoid the potential harms. Others may have a different perspective. And, because it’s an annual test, we should revisit this information every year.

Your doctor can help you decide whether screening for lung cancer is right for you.