Doctors may soon be able to use a simple blood test to detect lung cancer in people who are showing no signs or symptoms of the condition, according to a recent study. Currently, low-dose computed tomography (LDCT) scans are recommended for lung cancer screening — which are more costly, invasive, and difficult to administer than a blood test. LDCT scans also expose people to radiation, known to cause cancer.
“Our study demonstrates the potential for developing a sensitive screening tool for the early detection of lung cancer,” said Leo Cheng, associate biophysicist in pathology and radiology and lead researcher, to The Harvard Gazette. “The predictive model we constructed can identify which people may be harboring lung cancer. Individuals with suspicious findings would then be referred for further evaluation by imaging tests, such as low-dose CT, for a definitive diagnosis.”
Lung cancer is the second most common cancer for men and women in the United States, according to the American Cancer Society — and the leading cause of cancer deaths. Most cases are found in the late stages of the disease, because screening is uncommon. Symptoms can also be unnoticeable until the cancer has progressed and spread throughout the lungs and — in some cases — the body.
The U.S. Preventive Services Task Force recommends yearly screening for a subset of people using LDCT scans. Specifically, screening should be done in people who:
This form of screening is recommended only for those who are at a high risk of developing lung cancer, leaving others without a way to detect possible cases. LDCT also exposes otherwise healthy people to additional radiation, which may increase the risk of developing lung cancer.
Additionally, LDCT scans have high false-positive rates, according to a 2019 study from American Family Physician. Researchers found that “of 1,000 high-risk patients who do not have cancer, 250 will have an abnormal low-dose CT result and will require further testing to rule out cancer; 2.5 percent of patients without cancer will undergo invasive procedures (e.g., lung biopsy, bronchoscopy) with a small risk of complication and death.”
With this, researchers are searching for screening methods that can be used by anyone to detect lung cancer. Blood tests, which are less invasive and intensive than CT scans, may be useful in screening for lung cancer.
Cheng and colleagues from Massachusetts General Hospital (MGH) studied blood samples collected at the hospital. Samples came from 25 from people with non-small cell lung cancer (NSCLC) and 25 from people without cancer. The samples from those with NSCLC had been collected at least six months prior to diagnosis and again at the time of diagnosis.
When examining the samples, the researchers identified differences between metabolites in the blood of those with NSCLC (at the time of their diagnosis) and those without cancer. Metabolites are small molecules produced by cells for a variety of reasons. People with lung cancer produce different types of metabolites than people without the condition, meaning metabolites can be used as identifiers for the disease.
The researchers then created and trained a computer program to recognize the presence of metabolites in the blood samples provided by those with and without NSCLC.
Finally, researchers studied the blood samples taken from people who were later found to have NSCLC. When the computer program looked at these blood samples, it found a group of metabolites that resembled a cross between the blood of those with and without NSCLC. The researchers believe that this new “in-between” group of metabolites may be used to identify people who are likely to be diagnosed with NSCLC in the future.
Notably, the researchers found their testing model had a 62 percent accuracy rate in predicting whether a person had lung cancer. Nevertheless, the results of the study are promising, showcasing that a simple blood test may be used in the future to detect lung cancer cases — and even other diseases. Future studies will be needed to verify these findings in larger populations and in different types of cancer.