Katherine Bennett-Wilson has smoked a pack of cigarettes a day for 50 years. So when the 66-year-old had her annual physical last May, as part of the Medicare screening process, her doctor told her she needed a low-dose CT scan of her lungs.

“They saw nodules in the right upper lobe of my lung,” recalled Bennett-Wilson, who lives in South Philly. “I had to do a follow-up around six months later to see if they had gotten any bigger.”

That scan, and a follow-up PET scan, showed that one nodule had grown, and she would need surgery to remove it.

“It was cancer, but [my doctor] got it so early,” she said. “That’s the benefit of the screening. He caught it early at stage 1 so I don’t have to do chemo or radiation. Without that test, I never would have known I had it. It could have grown and been much worse than it was.”

Lung cancer is the leading cancer killer in both men and women in the United States, according to the American Lung Association (ALA), though lung cancer death rates are declining.

Because smoking is the most common risk factor for getting lung cancer, screening those at risk annually is saving lives. Recent studies showed that choosing the right patients — like Bennett-Wilson — and screening them with low-dose CT scans could find cancers earlier, and improve patients’ survival overall, said Nathaniel Evans III, director of thoracic surgery at Jefferson Health, and Bennett-Wilson’s doctor.

According to the American Cancer Association (ACA), lung cancer death rates dropped 51% from 1990 to 2017 among men and 26% from 2002 to 2017 among women.

That decline is a direct result of fewer people smoking, said Anil Vachani, co-director of lung cancer screening at both Penn Medicine and the Philadelphia VA Medical Center. As smoking has declined, so have lung cancer deaths, but former smokers are still at risk.

“Unfortunately, lung cancer frequently presents with nonspecific symptoms. People can have tumors growing in their lungs and not have any symptoms for a long, long time,” he said, because lungs are comprised mostly of air with few pain receptors. By waiting until someone shows symptoms — coughing up blood, losing weight or pain — the cancer is usually late stage. Stage 1 lung cancer is significantly more treatable and potentially curable compared to stage 3 and 4 lung cancer.

About 10% to 15% of smokers develop lung cancer. While to some, that number may seem low, approximately 541,000 Americans living today have been diagnosed with lung cancer at some point in their lives, according to the ALA.

“A quarter of the population in some parts of Philadelphia smoke,” said Evans. “So even if only 10% of them get cancer in their life, that ends up being a huge proportion of people.”

Screening is recommended for smokers age 55 and older who have smoked 30 pack years — a pack a day for 30 years or two packs a day for 15 years, for example. They also need to have smoked sometime over the last 15 years. Insurance will pay for the screening. The initial scan will be covered without co-pay for those meeting the high-risk criteria who are ages 55 to 80 and have private insurance, or are 55 to 77 and have Medicare, according to the ALA.

For patients who don’t have any signs or symptoms of lung cancer, screening identifies early stage cancer “in about 4% or 5% of them,” said Evans.

And if they are still smoking, patients who are screened also get counseling for smoking cessation, Evans said.

That’s a great opportunity to try and help them quit, added Vachani. “At the time they’re getting screening is perhaps when they are worried about their lung health and future cancer risk,” he said. “We get them the necessary resources to think about quitting and help them quit.”

That worked for Bennett-Wilson. “I’ve tried to quit forever and a day,” she said. “But I’ve always said, ‘That can’t happen to me. I’m not going to get lung cancer because the lung cancer patients I see are on oxygen, and they are coughing and lost weight.’ None of that happened to me. I didn’t have any symptoms. I’m a healthy person, and I’ve never had surgery before so it was scary.”

Like any diagnostic screening, there are risks, most notably, a small amount of radiation that comes with any CT scan, Vachani said. The accumulation of radiation over time can increase the risk for new cancers. There is also the risk of false positive results, which lead to more testing.

Evans urges smokers who fit the screening profile to get the scan. “One of the things that prevents people from getting screening is that they’re afraid of what they will find,” he said. “We only find anything on about a quarter of the scans, and 90% of the things we find are benign. You’re much more likely to be able to get peace of mind that everything’s fine than you are to find a lung cancer. And if you have a cancer, it’s better to find out about it than not.”

Though there are causes of lung cancer unrelated to smoking — exposures to radon, secondhand smoke, environmental factors such as air pollution, and occupational exposures like asbestos — currently, the screening is not recommended for nonsmokers.

“We don’t have a way of identifying nonsmokers who are high risk enough, that we could justify screening them,” Evans said.

For patients who don’t have a lung cancer, quitting can decrease their risks of developing one, Evans said. “Much of the damage they’re doing to their lungs can be reversed just by not smoking anymore. For patients who smoke that do have lung cancer, smoking puts them at risk for complications no matter what type of treatment they have.”

Evans said treatment of lung cancer is much different than it was 20 or 30 years ago. “Most patients’ understanding of lung cancer is based on when their parents or grandparents might have lung cancer,” he said. “That’s not the way it is anymore. It’s hard to get people to screen for things if they think, no matter what happens, you can’t do anything about it anyway. The reality is, at all stages of the disease, there are new treatments every day.”