Study Suggests Lung Cancer Screening Criteria May Not Capture All Smokers Who Need It

A study published today in JAMA suggests that former long-term smokers who have quit for more than 15 years would benefit from access to the lung cancer screening recently approved for coverage by Medicare; however, these smokers no longer meet the criteria.

CMS gained attention earlier this month when officials announced Medicare would cover lung cancer screening for high-risk individuals meeting certain criteria, which were largely spelled out in by the US Preventive Services Task Force (USPSTF).

However, a study published today in the Journal of the American Medical Association (JAMA) suggests the criteria may exclude many potential lung cancer patients would benefit from screening. Ironically, based on the data uncovered by the JAMA study, efforts to get long-term smokers to quit in recent decades makes some former long-term smokers ineligible for screening with low-dose computed tomography (LDCT), because they have not smoked for more than 15 years.

The study, by Ping Yang MD, PhD, and colleagues at the Mayo Clinic in Rochester, Minnesota, evaluated trends in the proportion of patients with lung cancer meeting the USPSTF criteria. Researchers looks at 140,000 residents in Olmstead County, Minnesota, age 20 or older, from 1984 through 2011. All confirmed cases of lung cancer were identified using the Rochester Epidemiology Project database, adjusting for age and gender distribution in the US population in 2000.

The proportion of cases meeting USPSTF criteria were identified. Those eligible are asymptomatic adults 55 to 80 years of age, who have a 30 pack-year smoking history. This means the person smoked the equivalent of a pack a day for 30 years; a person could also have smoked 2 packs a day for 15 years. To be screened, a person must be a current smoker or have quit within the past 15 years. (Medicare eligibility criteria are similar; the age cutoff for LDCT coverage is 77 years.)

Researchers identified 1351 patients with a new diagnosis of primary lung cancer between 1984 and 2011. However, the proportion of patients with lung cancer who smoked more than 30 pack-years declined, and proportion of former smokers, especially those who quit more than 15 years ago, increased.

Of note, the share of lung cancer patients meeting the USPSTF criteria declined over time, with 57% of patients eligible for screening from 1984 to 1990 and only 43% eligible from 2005 to 2011. The drop-off in eligibility was greater among women—from 52% to 37%; for men the drop-off was 60% to 50%.

“Our findings may reflect a temporal change in smoking patterns in which the proportion of adults with a 30 pack-year smoking history and having quit within 15 years declined,” the authors write. “The decline in the proportion of patients meeting USPSTF high-risk criteria indicates that an increasing number of patients with lung cancer would not have been candidates for screening. More sensitive screening criteria may need to be identified while balancing the potential harm from computed tomography.”

CMS’ decision to screen current and former smokers for lung cancers was based on the results of the National Lung Screening Protocol Trial Protocol, which found that patients who received screening had a 15% to 20% lower risk of dying from lung cancer; results published in 2013 showed that targeting screening toward those at greatest risk produced the most effective results.

However, the decision to pay for widespread screening is not without controversy. In a paper published in JAMA Internal Medicine in December 2014, authors SH Woolf et al expressly discouraged CMS from paying for screening. This is difficult to do under the Affordable Care Act, since the law requires commercial insurers to pay for tests that receive a B recommendation or better from USPSTF. The authors argued, however, that screening in the general population may not be limited to high-risk smokers outside the clinical trial and may cause unnecessary harm due to radiation and false positives.

Lung cancer is the leading cause of cancer death in the United States; according to CDC, 156,953 people in the United States died from lung cancer in 2011. The vast majority of deaths from lung cancer are caused by tobacco use.

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