USPSTF: Earlier Lung Cancer Screening Can Double Eligibility

Neil Osterweil

July 09, 2020

Proposed changes in the eligibility criteria for lung cancer screening with low-dose CT could result in a near doubling of eligibility, and could especially benefit Black persons and women, say lung cancer experts.

The new proposals include lowering the age at which screening starts from 55 to 50 years, and to reduce the smoking history from 30 to 20 pack-years.

The draft recommendation from the United States Preventive Service Task Force (USPSTF) is available for public comment until August 3.

The task force recommends that adults age 50 to 80 who have a 20 pack-year or greater smoking history and currently smoke or have quit within the last 15 years undergo annual screening for lung cancer with low-dose CT,

"In my opinion, the proposed criteria by USPSTF represent a huge step in the right direction," Lecia Sequist, MD, director of innovation at the Mass General Cancer Center in Boston, told Medscape Medical News.

"If these are adopted and implemented, we could see the benefit of screening (measured as reduction in lung cancer mortality) go from 9.8% with current parameters up to 13% with the broader parameters," she said. "In addition, the new criteria should reduce racial disparities in screening eligibility."

The recommendation also earned high marks from the American Lung Association (ALA).

The USPSTF has continued its 'B' recommendation — allowing for coverage of the screening with no cost for many under the Affordable Care Act — and is now proposing to expand the eligibility criteria "so that even more Americans at higher risk for lung cancer can be screened," the ALA commented.

Start Screening at 50  

Lowering the minimum age of screening to 50 would likely mean that more Black individuals and women would be eligible for screening, the recommendation authors contend. The current screening age of 55 is currently recommended under guidelines issued by the American Association for Thoracic Surgery, American Cancer Society, American College of Chest Physicians, and National Comprehensive Cancer Network.

"African Americans have a higher risk of lung cancer compared with whites, and this risk difference is more apparent at lower levels of smoking intensity," they write.

As previously reported by Medscape Medical News, lung cancer screening in an urban, largely black cohort yielded roughly double the rates of positive screens and detected lung cancers compared with results from the National Lung Screening Trial (NLST), which enrolled mostly White individuals.

In addition, although lung cancer risk is greater for men than women who smoke, and women generally accumulate fewer pack-years than men, there is evidence to suggest that women who smoke may develop lung cancer earlier and with lower levels of exposure.

Therefore, "a strategy of screening persons ages 50 to 80 years who have at least a 20 pack-year smoking history and currently smoke or have quit within the past 15 years (A-50-80-20-15) would lead to a relative increase in the percentage of persons eligible for screening by 81% in men and by 96% in women," the proposed recommendation states.

What's the Harm?

One of the major concerns about low-dose CT screening for lung cancer is the relatively high rate of false-positive results reported in two large scale clinical trials, the recommendation authors acknowledged.

For example, in the NLST, which was the basis for an earlier USPSTF recommendation (for annual screening of adults 55 to 80 years of age who have a 30 pack-year smoking history and currently smoke or have quit in the previous 15 years), the false-positive rates were 26.3% at baseline, 27.2% at year 1, and 15.9% at year 2.

Similarly, in the NELSON trial, results of which were published earlier this year, false-positive rates for men were 19.8% at baseline, 7.1% at year 1, 9% at year 3, and 3.9% at year 5.5 of screening, they noted.

"Yes, false-positive results are one of the things we need to think carefully about when embarking on lung screening," Sequist told Medscape Medical News. "The potential harm of a false-positive (unnecessary scans, biopsies or even surgery) can be minimized by having a multidisciplinary team with experience working up lung nodules see patients who have a positive screening test. In fact, the American College of Radiology recommends that all lung screening programs be paired with such a team."

Mass General has a pulmonary nodule clinic to evaluate screen-detected lung nodules, with the goal of minimizing unnecessary procedures, she noted.

Asked about the potential harm from radiation exposure, Sequist said that exposure from low-dose CT screening is fairly minimal, comparable to that from solar radiation at sea level over a 6-month period, or about the level from three cross-country airplane trips.

"While it is not zero radiation, there is very little concern that this low level of radiation would cause a cancer or damage one's lungs," she said.

Albert Rizzo, MD, chief medical officer of the ALA, said that the potential harms of unnecessary interventions are outweighed by the benefits of detecting lung cancer at an early stage.

"I think what has been learned over the last 5 years is that the original recommendations that were put out really allowed the overall rate of positivity well within what's seen with mammography, for example, and the number of patients who have needlessly gone on to procedures remains very low, and the morbidity of those procedures remains low as well," Rizzo told Medscape Medical News.

Not Enough Takers

Despite the clear benefits of low-dose CT screening, however, US screening rates for high-risk individuals are still very low, ranging from 12.3% in Massachusetts to a low of 0.5% in Nevada, according to a 2019 research report on the state of lung cancer from the ALA.

"For screening to be most effective, more of the high-risk population should be screened. Currently, screening rates are very low among those at high risk. This may be because of a lack of access or low awareness and knowledge among patients and providers. As rates vary tremendously between states, it is clear that more can be done to increase screening rates," the report stated.

"I think that there are some mixed messages sent out into the population as to whether or not an individual patient should be screened," Rizzo said.

He noted that some physicians may be reluctant to take on the nuanced risk–benefit discussion required, or may not have the time during a brief patient visit.

"It really boils down to that discussion between the physician and the patient who falls under these risk categories, to say, 'Look, this is what these studies have found, and you fall under a category where if we find a cancer early, it's very likely you're going to be saved,' as compared for waiting for it to present by itself," he said.

Sequist and Rizzo have disclosed no relevant financial relationships.

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