• A recent study has found that circulating pieces of DNA can be sequenced and analyzed to screen people for lung cancer.
• Using a simple blood test and computational analysis, researchers were able to identify lung cancer cases with high sensitivity and specificity.
• This method may eliminate the need for invasive tests in those who show suspicious signs of lung cancer in X-rays and scans.

A recent study published in Nature Communications found that cell-free DNA (cfDNA) that circulates in the bloodstream can be used in a noninvasive way to test for lung cancer. The method — pioneered by researchers at the Johns Hopkins University School of Medicine and Bispebjerg Hospital in Denmark — can identify cases of lung cancer with 94 percent sensitivity and 80 percent specificity.

“The observations that scalable and cost-effective noninvasive cfDNA fragmentation analysis can discriminate lung cancer patients from non-cancer individuals may ultimately provide an opportunity to evaluate not only high-risk individuals but the general population for lung cancer,” the researchers wrote in the study, titled Detection and Characterization of Lung Cancer Using Cell-Free DNA Fragmentomes.

Screening Methods for Lung Cancer

Currently, the U.S. Preventive Services Task Force recommends using low-dose computed tomography (LDCT) scans to screen people who are at a high risk of developing lung cancer. High-risk individuals are defined as adults who are 50 to 80 years old with a 20 pack-year smoking history who currently smoke or have quit within the past 15 years.

However, LDCT has its drawbacks. Among them, there is a higher risk of false-positive results. Researchers also noted a lack of sufficient imaging facilities and infrastructure to can screen large numbers of people. Additionally, LDCT exposes a person to radiation, which can contribute to the development of cancer. LDCT is also underused, with less than 6 percent of those eligible screened.

The study authors propose another screening method that uses a blood draw to look for DNA from tumors that circulates through the bloodstream. The researchers also developed an analysis of the DNA, known as DELFI — which stands for DNA evaluation of fragments for early interception. This approach can help identify fragments of DNA that belong to a tumor.

DELFI and cfDNA Can Accurately Detect Lung Cancer Cases

The study looked at 365 people who were at a high risk for lung cancer. Ninety percent of the participants had symptoms related to smoking, such as coughing or shortness of breath. The other 10 percent of participants had no symptoms, but had a chest X-ray or CT scan showing possible lung cancer.

After researchers collected blood samples for the study, 129 participants were confirmed to have lung cancer and the other 236 had benign (noncancerous) growths or were not biopsied. Once the blood was collected, the DNA was isolated and sequenced, then analyzed using DELFI.

Overall, the DNA fragmentation profiles in study participants without lung cancer were consistent with one another. On the other hand, those with confirmed cases of lung cancer had large variations in their profiles. This variation is mostly likely due to the different genetic mutations that tumors have in their DNA.

Each participant’s DNA fragment profile was given a DELFI score, which was higher for those with lung cancer. For example, the median score for those without lung cancer was 0.16. The median scores increased to 0.21 for those with benign growths, 0.35 for those with stage 1 lung cancer, and all the way to 0.99 for those with stage 4 lung cancer. Interestingly, DELFI was also able to distinguish between cases of non-small cell lung cancer and small cell lung cancer.

The researchers found that their methods were able to detect cases of lung cancer with 94 percent sensitivity (meaning that the number of lung cancer cases detected was indeed true) and 80 percent specificity (meaning that the number of cases not detected was also true).

The researchers hope that this new method can help limit the need for invasive medical procedures — and expand the number of people who can receive screening — while giving accurate results.