SUMMARY: The American Cancer Society estimates that for 2022, about 236,740 new cases of lung cancer will be diagnosed and 135,360 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non-Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers and Adenocarcinoma now is the most frequent histologic subtype of lung cancer.
In the National Lung Screening Trial (NLST) with Low Dose CT (LDCT) screening for lung cancer, there was a 20% reduction in mortality. Following the publication of the results of NLST, and NCCN issued guideline in 2011, the United States Preventive Services Task Force (USPSTF) recommended Lung Cancer screening with Low Dose CT scan in high risk patients. The CMS in 2015 determined that there was sufficient evidence to reimburse for this preventive service. The USPSTF expanded the criteria for Lung Cancer screening in 2021 and recommended annual screening with Low-Dose CT for adults aged 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years. The new USPSTF 2021 criteria were given a B recommendation, as there was additional research needed, to improve uptake of LDCT screening and to develop biomarkers to more accurately identify individuals, who would benefit from screening.
Approximately 15% of patients present with early stage (T1-2 N0) disease, and these numbers are likely to increase with the implementation of Lung Cancer screening programs. Surgical resection is the primary treatment for approximately 30% of patients with NSCLC who present with early Stage (I–IIIA) disease. In spite of the favorable stage shift as a result of lung cancer screening, low Health Care Provider knowledge of the lung cancer screening guidelines represents a potential barrier to implementation, and no clinical trials have shown these favorable benefits in a real world setting.
The authors in this study evaluated whether the introduction of Low Dose CT screening in 2013 resulted in an increase in the percentage of Stage I NSCLC diagnosed among patients potentially eligible for screening, along with an increase in median all cause survival among these patients, and whether any effects on stage extend to the entire study population or only select population groups. The researchers analyzed data from two large comprehensive US cancer registries-the National Cancer Database and the Surveillance Epidemiology End Results (SEER) program database using a quasi-experimental observational design. A total of 763 474 patients were identified for analysis in this study. They included those who were diagnosed as having NSCLC between 2010 and 2018 and who would have been eligible for screening by age criteria (age 55-79 years) and a comparator NSCLC patient cohort who would have been ineligible for screening (age 45-55). The authors then compared the rate of change in the percentage of patients with Stage I cancer at diagnosis between 2010 and 2018.
It was noted that among the screen eligible cohort of NSCLC patients, the percentage of patients with Stage I disease at diagnosis increased by 3.9% each year from 2014, following a minor change from 2010 to 2013. The rate of increase in Stage I diagnoses was more rapid in high lung cancer screening states. These findings however were not seen in the younger, screening ineligible patients. These results consistently noted across multiple analyses.
The median all cause survival of screening eligible patients aged 55-80 years increased at 11.9% per year from 2014 to 2018 (from 19.7 to 28.2 months). In multivariable adjusted analysis, the hazard of death decreased significantly faster after 2014 compared with before 2014 (P<0.001).
Disparities were however noted, and the benefits from this significant shift in the stage of the disease was not realized in racial or ethnic minority groups and those living in lower income or less educated regions. By 2018, Stage I NSCLC was the predominant diagnosis among non-Hispanic white people, whereas the economically deprived group of patients, were more likely to have Stage IV disease at diagnosis. Increases in the detection of early stage lung cancer in the US from 2014 to 2018 led to an estimated 10,100 averted deaths.
It was concluded from this study that although the adoption of lung cancer screening has been slow nationwide, this study indicated the beneficial effect of lung cancer screening and a recent stage shift toward Stage I NSCLC, with improved survival, following the introduction of lung cancer screening. This study also highlighted the disparities in the stage of lung cancer diagnosed between patient populations, reinforcing the need for equitable access to screening in the US.
Association of computed tomography screening with lung cancer stage shift and survival in the United States: quasi-experimental study. Potter AL, Rosenstein AL, Kiang MV, et al. BMJ 2022; 376 doi: https://doi.org/10.1136/bmj-2021-069008 (Published 30 March 2022)
