Updates in Lung Cancer Screening Represent Substantial Progress, but Multiple Barriers to Access Remain

Recent updates in lung cancer screening recommendations have addressed disparities in certain populations, but these changes are not enough to reduce disparities. In addition to expanding eligibility criteria, barriers to accessing screening need to be addressed, according to panelists at CHEST 2022, held October 16-19, 2022, in Nashville, Tennessee.

Guideline recommendations used to be a simple “who do we screen,” but now they have evolved to “what do we screen” and “how do we screen,” explained Peter Mazzone, MD, MPH, FCCP, director of the Lung Cancer Program for the Respiratory Institute and the Lung Cancer Screening Program and Nodule Management Program, Cleveland Clinic, as well as editor in chief of CHEST journal.

When considering screening recommendations, it’s important to establish a balance between the benefits and harms of screening. The obvious benefit is that fewer people die because more are screened, but that benefit has to be balanced against the harms that may result from the test results, he said.

These screens are not diagnostic tests, Mazzone reminded. During screening, someone who is well and asymptomatic is being tested. “In that light, only a slim minority of everybody who's screened ever will see the benefit, but all are exposed to the potential harms,” he said.

Evidence of the benefit of screening comes from 2 major studies: the National Lung Screening Trial (NSLT) and NELSON. In addition, there have been meta-analyses of other controlled trials. In general, these show a positive result of lung cancer mortality reduction.

However, many harms come from finding lung nodules during screening. In NLST, 39.1% of people at least 1 nodule that was 4 mm or larger in size, for instance.¹ In that study, 4.2% of people underwent an invasive procedure, 0.9% had a procedure-related complication, and 0.3% had a serious complication. Overall, 22% of surgeries were performed for benign disease and 37% of nonsurgical procedures were for benign disease.

Other harms include overdiagnosis and overtreatment. There are estimates, according to Mazzone, that 1 lung cancer is overdiagnosed and treated for every cancer death averted. “This means you've either found a very indolent cancer that didn't need to be found, or—maybe more often in our population—you screen somebody who's got a lot of comorbidities…and they die of something else before that cancer would have affected them,” Mazzone said.

For every 1000 people screened, there would be 3 fewer deaths, but 18 people still died from lung cancer. In addition, there would be 365 people with false alarms. Of those people with false alarms, 25 would undergo a biopsy and 3 of those people would develop a serious complication. Finally, 4 people would be needlessly treated for “cancer.”

CHEST guidelines recommend the following:

• For asymptomatic individuals between the ages of 55 and 77 years who smoked 30 pack-years and continue to smoke, an annual screening is recommended.
• For asymptomatic individuals between the ages of 50 and 80 years with 20 pack-years who either continue to smoke or quit within the last 15 years, an annual screening is suggested.
• For asymptomatic individuals who do not meet the first 2 criteria but who have a high net benefit from lung cancer screening based on the results of validated risk predication calculations and life expectancy estimates, an annual screening is suggested.

These guidelines, if followed, will lead to greater equity across race and gender, Mazzone said. However, in addition to these guidelines sometimes being difficult to implement in practice, they may not be covered by private insurance or Medicaid.

In 2021, the United States Preventive Services Task Force (USPSTF) updated its lung cancer screening guidelines with a shift in benefit of life-years gained instead of simply finding and treating cancers. The recommendation is annual screening for people aged 50 to 80 years who have a 20 pack-year history, but to stop screening when they haven’t smoked for 15 years or if they have another health problem that limits life expectancy. In 2013, the recommendation was annual screening for individuals who were 55 to 80 years with 30 pack-years who quit within 15 years.

The change increased lung cancer mortality reduction from 9.8% to 13% and increased how many people will be screened by 87%.

While the change means a greater percentage increase for those individuals who are not currently receiving equitable access to screening, it also means more harm with 2.2 false positive results per person screened compared with 1.9.

“While there has been substantial progress in cancer prevention, screening, diagnosis, and treatment over the past several decades, addressing cancer health disparities in certain populations is an area in which progress has not kept pace,” said Louise Henderson, PhD, professor, radiology, University of North Carolina, Chapel Hill, and program leader, cancer epidemiology, UNC Lineberger Comprehensive Cancer Center.

While White and Black populations have similar incidence of lung cancer (56.7% vs 56.2%), Black individuals have a slightly higher mortality (44.3% vs 42.7%).² Black individuals have the highest lung cancer mortality compared with all races and ethnicities. The reason is because Black individuals develop lung cancer earlier and are more likely to present with advanced-stage cancer.

Henderson noted that Black individuals are more likely to start smoking later, they smoke fewer cigarettes per day, and they are less likely to quit.

The 2013 USPSTF guidelines did not consider racial, ethnic, socioeconomic, or sex-based differences in smoking behaviors and lung cancer risk, but the recent update will increase the percentage of people eligible for screening, the percentage of preventable deaths, and the percentage of life-years gained across all racial and ethnic groups.

However, Henderson noted, “this change in eligibility is not likely to eliminate disparities.” The White population will continue to see the greatest benefit, she pointed out.

Prediction models on the impact of changes to lung cancer screening eligibility³ showed that augmenting the USPSTF 2020 guidelines with high-benefit individuals selected by the Life-Years From Screening with CT (LYFS-CT) model nearly eliminated the disparities between White and Black individuals. However, the USPSTF does not endorse the use of risk prediction models because of insufficient evidence, Henderson said.

Without the augmentation, the disparity between Black and White individuals for cumulative percentage of deaths prevented is 13% on the 2020 guidelines, compared with 15% on the 2013 guidelines. Interestingly, for both Hispanics and Asians, the disparity will increase: 24% in 2013 to 27% in 2020 for Hispanics compared with Whites and 15% in 2013 to 19% in 2020 for Asians compared with Whites.³

Overall, uptake of lung cancer screening is low, Henderson said. Some of the barriers to implementing lung cancer screening include identification of the eligible population, which requires knowledge of smoking history, geographical access to screening programs, and insurance coverage. Medicaid enrollees have an increased risk of lung cancer because of higher cigarette smoking rates, but Medicaid programs across the country do not all cover lung cancer screening.

Another speaker added that 13 states did not accept Medicaid expansion, which is affecting lung cancer screening access. In addition to low-income individuals on Medicaid using the highest amounts of tobacco, racial/ethnic minority populations are more likely to be uninsured or underinsured, said Nichole Tanner, MD, MS, FCCP, professor of medicine and codirector of the Lung Cancer Screening Program at the Hollings Cancer Center, Medical University of South Carolina.

Tanner also spent more time looking at the impact geographic location has on access to screening. Research has shown that, compared with urban counties, the prevalence of cigarette smoking is higher in rural counties, adolescents in these counties start smoking earlier, and lung cancer incidence is 20% higher.² Rural areas are also less likely to have accredited comprehensive screening programs.

“There's a high prevalence and a need, but the resources are not there,” Tanner said. In the Southern and Western states, less than 4% of eligible adults were screened compared with 8% to 10% in the Northeastern states.²

The changes in lung cancer screening eligibility have the potential to reduce morbidity and decrease disparities, but there are aspects of screening that go beyond age, pack-years, and time since quitting, Henderson said.

“Expanding the eligibility criteria alone is not enough to reduce the disparities; we must address disparities and implementation challenges to get lung cancer screening to areas in need,” she concluded.

References

1. Iaccarino JM, Silvestri GA, Soylemez Wiener R. Patient-level trajectories and outcomes after low-dose CT screening in the National Lung Screening Trial. Chest. 2019;156(5):965-971. doi:10.1016/j.chest.2019.06.016

2. Haddad DN, Sandler KL, Henderson LM, Rivera MP, Aldrich MC. Disparities in lung cancer screening: a review. Ann Am Thorac Soc. 2020;17(4):399-405. doi:10.1513/AnnalsATS.201907-556CME

3. Landy R, Young CD, Skarzynski M, et al. Using prediction models to reduce persistent racial and ethnic disparities in the draft 2020 USPSTF lung cancer screening guidelines. J Natl Cancer Inst. 2021;113(11):1590-1594. doi:10.1093/jnci/djaa211