Many family physicians don't believe lung cancer screening can reduce deaths from these tumors, and some don't offer tests even to longtime smokers, a U.S. survey suggests.
Nearly all agreed that early cancer detection is more likely with low-dose computed tomography (CT) than with traditional x-rays.
But only 41 percent believe low-dose CT scans in asymptomatic individuals can reduce deaths from lung cancer, the survey found.
Even for a 60-year-old patient with a long history of smoking, 12% of family physicians said they would not recommend any screening and another 9% said they would suggest only an x-ray.
Study author Jan Eberth, a public health researcher at the University of South Carolina in Columbia, and colleagues note in the journal Cancer that the American Academy of Family Physicians has said there isn't enough evidence yet to recommend or discourage these tests.
But the government-backed U.S. Preventive Services Task Force (USPSTF), along with the Centers for Medicare and Medicaid services and "multiple professional societies and organizations," do support the use of CT scans for high-risk patients including some current and former smokers, the authors note.
The researchers analyzed data from surveys completed by 101 family physicians in South Carolina in 2015.
Most of the doctors were white, male and had graduated from medical school at least a decade ago.
When asked about the risks of low-dose CT scans, 88% expressed concern about unnecessary diagnostic procedures, and about half said they worried about exposing patients to stress and anxiety or radiation.
About half would screen a 70-year-old former smoker who quit more than 20 years ago - a situation when groups like the USPSTF and Medicare recommend against it.
In another situation where screening isn't recommended - a 50-year-old nonsmoker with 30 years married to a smoker - 22% of family physicians said they would offer screening.
The survey was started in 2015 before Medicare changed its payment polices to cover CT scans for lung cancer screening and counseling sessions discuss test with patients, Eberth noted.
One limitation of the survey was that researchers changed it later in the year to follow up with participants and ask about how Medicare coverage might influence screening decisions, the authors note.
"Primary care physicians may be overwhelmed with the amount of new information required to understand the data regarding lung cancer screening, potential benefits, and with discussing risks," Dr. Ticiana Leal, a researcher at the University of Wisconsin School of Medicine and Public Health who wasn't involved in the study, said by email.
"Chest x-rays for screening is a failed strategy," said Dr. Vinay Prasad, a researcher at Oregon Health and Science University who wasn't involved in the study.
"Low-dose CT screening for lung cancer showed a strong benefit in one randomized trial, though there are a number of caveats and nuances there that may give one pause," Prasad added in an email. "At a minimum, the potential benefits and potential limitations should be discussed with appropriate patients as part of shared decision making."