Lung Cancer Screening Recommendation Questioned

Patients with a history of heavy smoking who test negative on an initial low-dose CT scan may not need annual screening for lung cancer—the current recommendation of the U.S. Preventive Services Task Force (USPSTF)—according to a study published in The Lancet Oncology. The findings suggest that these patients could work with their doctors to devise an appropriate screening schedule based on individual risk factors, instead of adhering to a one-size-fits-all approach.

An annual screening interval is easy for patients and providers to remember, but “there's not necessarily any biology which dictates annual is the optimal time,” says co-author Edward Patz Jr., MD, a professor of radiology at the Duke University School of Medicine in Durham, NC.

The USPSTF developed its recommendation based on results from the National Lung Screening Trial (NLST), which Patz helped design. The NLST looked at high-risk individuals between ages 55 and 74 who had smoked the equivalent of at least one cigarette pack per day for 30 years and had not quit more than 15 years earlier. It concluded that participants randomized to receive three annual low-dose CT screens had a lower risk of dying from lung cancer than those who received three annual chest X-rays.

When Patz and his colleagues performed a retrospective analysis of NLST data, they found that among 19,066 participants whose baseline CT scan was negative for significant abnormalities suggestive of lung cancer, less than 1% were diagnosed with the disease at their first annual screen or during the subsequent year. Over the course of the 7-year trial, 215 of 441 participants with negative baseline CT results who were diagnosed with lung cancer died from their disease. By the team's estimation, that number would rise to no more than 243 in the absence of the first annual screen.

As such, Patz says, “not everybody may need” a yearly screen—longer intervals may be warranted for some individuals. He notes that disadvantages of frequent screening include false-positive results that prompt unnecessary interventions like biopsies, and substantial costs. Besides CT results, factors such as the presence of emphysema and chronic obstructive pulmonary disease should be considered when determining screening frequency.

Martin Tammemägi, PhD, an NLST co-investigator and professor of epidemiology at Brock University in Ontario, Canada, who was not involved in the current analysis, agrees that CT scan results should be considered. However, he's “a little concerned about oversimplification” of the findings—in other words, public health officials concluding that all individuals with an initially negative test can forgo annual assessments. Instead, because some individuals with a normal baseline screen will still be at high risk for lung cancer, Tammemägi advocates a personalized medicine approach in which multiple risk factors are weighed to devise each person's screening schedule.

In an accompanying commentary, John Field, PhD, of the University of Liverpool, UK, and Stephen Duffy, MSc, of Queen Mary University of London, UK, note that international lung cancer screening guidelines are not yet firmly established, thus offering opportunities for refinement before they become entrenched. “Once annual screening is embedded into a national policy, reducing the frequency of screening will be much more difficult,” they write. –Roberta Kwok