The Early Detection of Cancer of the Lung Scotland (ECLS) study is an ongoing, large-scale lung screening trial intended to evaluate the potential benefits of the combination of a blood test, an x-ray exam, and a CT exam in the detection and diagnosis of lung cancer. Results from the first two years of the study showed that the blood test and imaging-based lung screening exams offered a better lung cancer detection rate than standard clinical care recommended by the U.K. National Health Service (NHS).
The intervention helped diagnose a greater proportion of early-stage cancers and could help lower the false-positive rate of lung screening using CT scans alone, presenter Dr. Frank Sullivan from the University of St. Andrews told meeting attendees. The conference was hosted by the International Association for the Study of Lung Cancer (IASLC).
"Both all-cause and lung cancer mortality are ... starting to separate [between the intervention and standard care groups] at two years, and we hope that by following patients up at three [and] five years, we'll be able to come back to the conference and report more on that," he said.
Coupling blood tests with imaging
Widespread implementation of lung cancer screening using CT exams in Europe appears to be on the horizon: Researchers from both the U.K. Lung Cancer Screening Trial and the Dutch-Belgian Randomized Lung Cancer Screening (NELSON) trial reported lower rates of lung cancer mortality among high-risk smokers who underwent CT lung screening, compared with standard care.
In the current study, Sullivan and colleagues set out to evaluate the potential benefits of integrating a blood test, called EarlyCDT-Lung, into CT lung screening. EarlyCDT-Lung is a diagnostic test that can determine an individual's risk of developing lung cancer by measuring levels of autoantibodies for seven tumor-associated antigens (p53, NY-ESO-1, CAGE, GBU4-5, SOX2, HuD, and MAGE A4).
Prior studies have reported that the blood test correctly predicted approximately 41% of lung cancers with a specificity of 90% in individuals at risk of lung cancer, compared with a detection rate of 61% and a specificity of 49% for CT lung screening. The high specificity of the blood test could help boost the cancer detection rate of CT lung screening while also helping to lower the exam's false-positive rate, according to Sullivan and colleagues.
With this aim in mind, the researchers offered the blood test plus imaging-based screening combination or standard NHS clinical care to 12,208 participants ages 50 to 75 who were at high risk for developing lung cancer within the next two years. The average age of the cohort was 60.5 years, and the average pack-years smoked was 38.2.
Participants first received the blood test, and then those who had a positive test underwent a chest x-ray exam followed by a CT exam. Those with a negative CT exam were asked to return for subsequent imaging every six months until the end of the two-year surveillance period.
Earlier lung cancer detection
The researchers found that 9.8% of the participants had a positive EarlyCDT-Lung test and 3.4% ended up with a diagnosis of lung cancer. Physicians diagnosed lung cancer in 56 individuals in the intervention group and 71 individuals in the control group.
Overall, the intervention resulted in a 36% increase in the proportion of early-stage lung cancers detected among all cancers diagnosed in the first two years following baseline screening.
*The difference was statistically significant.
|Blood test + CT lung cancer screening vs. standard clinical care at 2 years
||Standard clinical care
||Blood test + CT lung screening
|Proportion of lung cancers diagnosed in early stages (I, II)*
|Lung cancer mortality
An analysis also revealed a potential association between the combined blood test plus CT lung screening method and decreases in all-cause and lung cancer mortality, though the study was not designed to detect statistically significant differences in mortality rates for the first two years.
"Our results show that the combination of the EarlyCDT-Lung followed by CT imaging in those with a positive blood test, results in a significant decrease in late-stage diagnosis of lung cancer and may decrease all-cause and lung cancer-specific mortality," Sullivan said in a statement. "We shall continue follow-up of all participants' lung cancer and mortality outcomes at five years using Scottish ISD (Information Services Division) data to study these effects further."
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