Two new modeling studies suggest that expanding lung cancer screening — to include more smokers or even lifelong nonsmokers — would save thousands more lives in the US every year. But not everyone is convinced the projected benefits would outweigh the harms.

In one study, published in JAMA, researchers at the American Cancer Society (ACS) found that only about 19% of currently eligible Americans underwent lung cancer screening in 2024.

That, the study projected, could translate to roughly 15,000 lung cancer deaths averted over 5 years. But 100% screening uptake would save three times as many lives.

“We estimated that about 62,000 deaths from lung cancer can be prevented [over 5 years] if everybody eligible for screening were to take it up,” said lead author Priti Bandi, PhD, scientific director of risk factors and screening research at the ACS.

She and her colleagues then took their projections a step farther, modeling what could happen if screening were expanded to everyone aged 50-80 years with a smoking history — or about 28 million Americans. Their conclusion: nearly 30,000 additional lung cancer deaths averted over 5 years.

According to Bandi, the findings underscore the importance of boosting the screening rate among Americans who meet current eligibility criteria — and argue for broadening eligibility.

Benefit-Risk Balance

Right now, the US Preventive Services Task Force (USPSTF) recommendsannual low-dose CT screening for adults aged 50-80 years who have a 20 pack-year smoking history and either currently smoke or quit within the past 15 years.

Those criteria are stricter than guidelines from the ACS, which dropped the 15-year rule in 2023. Earlier this year, the National Comprehensive Cancer Network did the same.

However, more screening is not necessarily better, cautioned H. Gilbert Welch, MD, of the Center for Surgery and Public Health at Brigham and Women’s Hospital in Boston.

Clinical trials, including the NLST in the US and NELSON trial in Europe, have proven that low-dose CT screening can reduce lung cancer mortality by about 20%. But those trials focused on people with a heavy smoking history.

Proof of a mortality benefit in lower-risk smokers is lacking, Welch pointed out, while the potential for harm is real.

“All of a sudden expanding to a whole new group of people — it’s just going to lead to a whole new set of procedures, a lot more false alarms, a lot more complications, and more overdiagnosis,” Welch told Medscape Medical News.

“I would say screening is not efficacious in the lowest-risk categories,” he said.

Screening Nonsmokers?

At the same time, interest in expanding lung cancer screening to patient populations other than heavy smokers is growing. That includes even lifelong nonsmokers, who account for between 10% and 20% of lung cancer cases in the US — partly due to other exposures such as secondhand smoke, air pollution, and radon.

The second modeling study, published on November 20 in JAMA Network Open, asked what could happen if lung cancer screening were strictly age-based. A team at Northwestern University in Chicago used data from published studies and 997 patients with lung cancer at their center — 65% of whom did not meet USPSTF screening criteria — to model the expanded scenario.

They calculated that universal screening of Americans aged 40-85 years would detect 94% of all lung cancers and prevent upward of 26,000 deaths annually.

“We moved to universal age-based screening for breast and colon cancer with tremendous success, and we need to move to the same approach for lung cancer,” study author Ankit Bharat, MBBS, professor of thoracic surgery at Northwestern, said in a press release.

However, the study also modeled the risks associated with age-based lung cancer screening: At 70% uptake (comparable to breast and colorectal cancer screening rates), there would be an estimated 16 million false positive results each year, leading to 1.2 million invasive procedures, with complications in 4900.

For context, breast cancer screening was estimated to yield 3.3 million false-positives, 33,000 biopsies, and 500 complications, while colorectal cancer screening yielded 2.1 million false positives, 420,000 polypectomies, and 3200 complications.

Real-World Issues

Welch pointed to the challenges of translating clinical trial findings to the real world, even to higher-risk smokers and former smokers. The NLST researchers “worked hard,” he said, to limit the harms of screening, including overdiagnosis.

“They had growth assessment protocols. They were careful about who they biopsied,” Welch said.

He believes those standards are too high a bar to be expected in routine clinical practice — meaning the benefits of screening may be less and the harms greater. And expanding eligibility to people who are at lower risk vs NLST participants would further shift the risk-benefit equation, according to Welch.

Bandi agreed that the potential for harm is a concern and said that clinicians need to provide patients with information about the risks of screening, in addition to the benefits.

As for why lung cancer screening rates remain low a decade on, Welch and Bandi agreed that heavy smokers often face barriers: They are disproportionately low-income and have less access to healthcare — and may be dealing with daily life issues that push lung cancer screening down on the priority list.

It’s possible, Welch said, that expanding screening eligibility to lower-risk groups would boost the screening adherence rate. But whether screening would be efficacious for those groups is another matter.

Better Data Needed

An editorial published with the ACS study said that as it stands, “lung cancer screening has realized only a fraction of its life-saving potential” — in part because of “overly restrictive” eligibility criteria.

However, worries about the harms of expanding screening — especially to nonsmokers — are valid, stressed Chi-Fu Jeffrey Yang, MD, and colleagues at Massachusetts General Hospital in Boston.

“It is unlikely,” they wrote, “that screening recommendations in the US will be expanded to include populations who have never used tobacco without high-quality randomized trial data.”

And while such trials have long been seen as prohibitively expensive, they noted, new risk-stratification tools may make them feasible by enabling researchers to enroll the highest-risk never-smokers.

The study was funded by the ACS Intramural Research Department. The authors disclosed having no conflicts of interest. Welch reported receiving royalties from books including Should I Be Tested For Cancer?

Ernie Mundell is a freelance medical journalist based in Los Angeles. He has more than 30 years of experience, including editorial positions at Reuters Health and HealthDay.