Although the widespread use of low dose computed tomography screening for lung cancer has led to improved mortality in recent years, disparities in uptake persist throughout the United States.
New research published in The BMJ indicates the introduction of low dose CT (LDCT) screening in 2013 coincided with improved survival and a shift toward diagnoses of stage I non–small cell lung cancer (NSCLC).
However, data also showed disparities in stage diagnoses persist between patient populations and increased efforts to improve access to the service is warranted.
Although the early detection of lung cancer is the most promising strategy to decrease mortality from the disease, and the use of LDCT can detect the cancer at an earlier stage, “skepticism about the effectiveness of such screening outside of rigorous clinical trial settings continues to exist in the medical community,” the researchers explained.
In an effort to show these benefits in a real-world setting at the population level, investigators carried out a quasi-experimental study using data from the National Cancer Database (NCDB), a hospital-based registry that captures approximately 65% of all newly diagnosed cases of lung cancer in the United States. Data from the Surveillance, Epidemiology, and End Results (SEER) program were also included in the retrospective analysis.
All patients aged 45 to 80 years in the NCDB and 55 to 79 iyears n the SEER Program database who received their NSCLC diagnosis from 2010 to 2018 were evaluated.
Cutoff years of 2010 to 2013 and 2014 to 2018 were employed due to the United States Preventive Services Task Force’s (USPSTF) recommendation for LDCT screening among individuals at high risk of lung cancer, which was issued in December of 2013.
The researchers evaluated annual percent change in percentage of stage I NSCLC diagnoses, trends in median all-cause survival, and whether a lung cancer stage shift between 2010 and 2018 was accompanied by more frequent detections of indolent histologic subtypes.
Analyses showed that between 2010 and 2013, the percentage of stage I NSCLC diagnosed among those aged 55 to 80 years did not significantly increase (27.8% to 29.4%). However, between 2014 and 2018, rates increased 3.9% (95% CI, 3.0%-4.8%) per year (from 30.2% to 35.5%).
Additional multivariable adjusted analyses revealed:
In addition to the introduction of LDCT for lung cancer screening in 2013, the researchers assessed additional factors that could have contributed to the observed stage shift seen in the analysis, concluding overdiagnosis “likely did not contribute significantly to the accelerated increase in the rate of stage I disease identified beginning in 2014.”
When examining the rate of diagnosis of stage I disease between 2010 and 2013, prior to the first recommendation of LDCT screening by the USPSTF, they observed an increase. Although not certain, this finding could be attributed to efforts already underway at this time to increase early detection of the disease using nonscreening diagnostic imaging.
“However, it is unlikely that any one of these possible explanations would result in an inflection point identified in 2013 corresponding to an accelerated increase in the rate of stage I disease diagnosed from 2014 to 2018,” the authors noted.
Percent increases in median overall survival observed in those aged 55 to 20 years from 2014 to 2018 could be due to the increased incidence of stage I disease diagnosed and the decreased incidence of stage III disease.
Racial and socioeconomic disparities seen among those with either early- or late-stage lung cancer are likely a result of screening access disparities, the researchers hypothesized, along with poor adoption of LDCT screening in community settings. The COVID-19 pandemic also likely exacerbated these screening disparities, they said.
However, the “2021 USPSTF lung cancer screening guidelines are estimated to increase eligibility for an additional 6.5 million Americans at high risk, with the greatest increases in eligibility occurring among women and racial minorities,” the researchers wrote.
“This increase in eligibility presents an opportunity to engage communities that have historically been burdened with the highest rates of lung cancer incidence and mortality and to eliminate disparities in the early detection of lung cancer.”
Data included in the study did not specify whether lung cancer was detected using LDCT or incidentally, nor do they offer information on patients’ smoking history, marking limitations to the analysis. Confounding may have also been present while SEER and NCDB samples may not be representative.
Despite slow adoption of lung cancer screening and low national screening rates, the researchers concluded their findings indicate the beneficial effects of even a small amount of screening on a population level.
“Efforts to increase utilization of screening should be prioritized to ensure equitable access to screening and to reduce disparities in the stage of lung cancer diagnosed and in survival among different patient populations with lung cancer,” they concluded.
Potter AL, Rosenstein AL, Kiang MV, et al. Association of computed tomography screening with lung cancer stage shift and survival in the United States: quasi-experimental study. BMJ. 2022;376:e069008. doi:10.1136/bmj-2021-069008