More to Consider When Screening for Lung Cancer

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lung cancer screening

According to a British researcher, the U.S. Preventive Services Task Force (USPSTF) erred in its lung cancer screening suggestions by marking higher risk patients solely based on age and how many years they’ve been smoking.

“Incorporation of predictive models with a more nuanced approach would cut down on false positives that lead to harm and improve cost effectiveness,” said John K. Field, PhD, of the University of Liverpool, England.

"Maybe the Americans need to go back and re-look at the NLST [National Lung Screening Trial] screening criteria for future screening programs. I really feel the USPSTF need to rethink, and that's what we told them,” he said.

That defining trial presented a 20 percent reduction in the mortality rate amongst a screened group of 55- to 74-year-olds with a 30 year track record of smoking, either current or those who quit in the past 15 years, contributing to the overall framework for recommendations from several national organizations.

The USPSTF depended almost fully on the trial entry criteria when it approved annual low-dose CT screening in July, yet contrary only in extending the age for screening through 79.

However, Field was more inclined to approve of the National Comprehensive Cancer Network's 2013 guidelines, which recommended screening patients as young as 50 or those with a 20 year history of smoking if they had further risk factors, such as chronic obstructive pulmonary disease, history of cancer, and occupational exposure to carcinogens like asbestos.

“The high rate of false positives and near universal need for further follow-up in screened individuals, with their resultant harms, means that it's not ethical to screen low risk people. But not all who develop lung cancer are smokers. It's very important that we find a way to include the very high-risk nonsmoker,” said Field.

Field served as the lead investigator on the Liverpool Lung Project, a project where it applied his recommendations on lung cancer screening.

Its risk model distinguished patients with a 5 percent risk of developing lung cancer over a span of 5 years using smoking history along with family history, pneumonia as a substitute for respiratory disease, prior malignancy, and asbestos exposure.

Screening only patients who met that criteria (about 30 percent of the population) would develop about two-thirds of lung cancers. In validation sets, it discriminated lung cancer risk a level similar to the Framingham model for cardiovascular disease and better than the Gail model for breast cancer.

The U.K. Lung Cancer Screening Trial, for which Field was lead investigator, took on that approach, sending patients a questionnaire and admitting only those who met the 5 percent risk factor of contracting lung cancer for CT screening.

For no the trial has completed recruitment and is in follow-up; results have yet to be reported.

Another risk model, a modified version of that used in the Prostate, Lung, Colorectal, and Ovarian (PLCO) trial, was shown to have considerably better positive predictive value for lung cancer than the NLST criteria without losing specificity, as reported earlier this year in the New England Journal of Medicine.

“National lung screening recommendations need to take that evidence into account,” Field voiced.

"The European trials will also provide a far greater insight into risk stratification of the general population who need to be screened, and a robust radiological protocol that will reduce the number of false positives and help with management decisions about indeterminate nodules," he wrote in a clinical series article in the Aug. 24 issue of The Lancet.

An accompanying unsigned editorial that concurred with Field said, “The results of European trials of CT screening, such as the Dutch trial NELSON, which notably includes routine care and not chest radiography for the control group, are much awaited. Questions around cost-effectiveness, assessment of nodules to reduce false positives, and selection of high-risk groups remain divisive.”

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