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National Lung Screening Trial publication yet to impact mortality rates
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CHICAGO — Publication of the National Lung Screening Trial in 2011 has had no impact on lung cancer mortality or incidence rates among the general U.S. population, according to results of a retrospective study presented at ASCO Annual Meeting.
Researchers did, however, observe a favorable increase in the proportion of early-stage vs. late-stage lung cancers detected, depending on median family income, race and location.
“I think it’s a little too early to know what the true impact on mortality will be,” Isabel M. Emmerick, PhD, MS, instructor in the department of surgery at University of Massachusetts Medical School, told HemOnc Today. “For policy implementation in something as big as this, sometimes you have delays in adoption. This work tried to determine if it is already having an effect and what that effect is. What we found is that there was an uptick of early-stage diagnosis for lung cancer.”
The National Lung Screening Trial showed screening with low-dose CT, compared with chest X-ray, reduced lung cancer deaths by 20% among those at high risk for the disease. Results of the trial served as the basis for the U.S. Preventive Services Task Force recommendation in 2013 that individuals who meet certain age and smoking history criteria undergo annual screening with low-dose CT.
Emmerick and colleagues analyzed the impact of the trial’s publication on overall lung cancer incidence and mortality rates using information from the SEER18 database for the years 2008 to 2015. Researchers calculated the ratio of early-stage to late-stage lung cancer diagnoses by dividing the number of stage I and stage II cases by the number of stage III and stage IV cases diagnosed by year. They assessed changes in levels and trends through interrupted time-series analysis, with 2011 considered the intervention. A T-test to determine the average ratios comparing 2007 to 2010 with 2012 to 2015 was performed for the entire lung cancer population and in subgroups by median family, ethnicity, sex, age and SEER registry.
Results showed that overall lung cancer rates remained stable during the study period; however, the ratio of early-stage to late-stage diagnoses increased significantly following the release of the screening trial among the overall lung cancer population (P = .006) and among the screening group (P = .014).
This effect persisted in all subgroups except among patients with a median annual income of less than $40,000, white patients, and patients living in the Detroit metro area, Iowa, greater and rural Georgia, and Louisiana. In some cases, researchers observed a decrease in late-stage detection among these subgroups.
Results showed no impact on lung cancer mortality in the general lung cancer population or in any of the subgroups.
Emmerick noted that researchers will monitor these trends moving forward.
“I didn’t expect to find an effect on mortality based on the screening at this point,” Emmerick said. “The screening will impact the detection first and incidence rates for stage I and stage II disease. We need a lot more time to determine the mortality rates.” – by John DeRosier
Reference:
Emmerick IM, et al. Abstract 1569. Presented at: ASCO Annual Meeting; May 31-June 4, 2019; Chicago.
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Jorge Nieva , MD
I’m not surprised by the results of this trial because we are still very early in this process. We have only been doing lung cancer screening in the U.S. for 4 years, and the uptake has been relatively slow across major centers.
Additionally, we are finding that the people who were best for screening need it the least. Those include the wealthy and those who receive care at academic medical centers. Smokers, former smokers, poor people and people who live in rural communities are less likely to be screened.
Unless we have comprehensive lung cancer screening in the United States, with uptake rates close to what we see with mammography in the 40% to 60% range, I don’t think we will see the mortality benefit. We need to see higher uptakes in recommendations from community centers, community practitioners and particularly in places with high rates of tobacco use.
However, we did see early signs that we’re making a difference. There has been a very nice shift toward the diagnosis of early-stage lung cancer compared with late-stage lung cancer in the United States since 2015, and that seems to be the earliest indicator that we are making a difference.
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