Researchers say a protein called AKAP4 is a "highly effective" biomarker for detection of nonsmall cell lung cancer and could form the basis of a blood test for the disease.
Dr. Qihong Huang, associate professor in the Tumor Microenvironment and Metastasis Program at The Wistar Institute - a National Cancer Institute (NCI) Cancer Center based in Philadelphia - and colleagues publish the details of their discovery in the journal Oncotarget.
Nonsmall cell lung cancer (NSCLC) accounts for around 85-90% of lung cancer cases in the US.
As with other cancers, the earlier a patient is diagnosed with lung cancer, the more likely they are to survive. According to the American Cancer Society, the 5-year survival rate of a patient with an early-stage NSCLC diagnosis stands at 49%, while a late-stage diagnosis yields a 5-year survival rate of only 1%.
At present, the only form of lung cancer screening in the US involves a low-dose computed tomography (CT) scan. The US Preventive Services Task Force (USPSTF) recommend that all individuals aged 55-80 who have a history of heavy smoking undergo lung cancer screening annually.
However, Dr. Huang and colleagues note that this screening method is not highly accurate, it exposes the patient to radiation and is expensive to conduct, emphasizing the need for a better diagnostic test.
"There are many people who stand to benefit from a better diagnostic test for lung cancer," notes Dr. Huang. "If we can develop a simple blood test that's more accurate than low-dose CT scans, we can detect the cancer earlier with a less expensive, less invasive and more accurate blood test. Everyone stands to gain from such a test becoming available."
AKAP4 a 'highly effective' biomarker for NSCLC
The team focused on cancer testis antigens (CTAs) for their study, which are frequently found in blood-circulating tumor cells.
By analyzing 116 CTAs from the blood samples of patients with NSCLC, the team identified a protein called AKAP4 as a potential biomarker for the disease.
Next, the researchers set out to validate AKAP4 as an NSCLC biomarker by analyzing the blood samples of 264 patients, of whom 136 had received an early-stage diagnosis. The blood samples of 135 patients without NSCLC were also assessed.
A technique called the receiver operating characteristic (ROC) curve was used to assess the effectiveness of AKAP4 in distinguishing between patients with and without NSCLC. The technique produces an area under the curve (AUC) score, with a score of 1 indicating that the biomarker tested is fully accurate.
On comparing the blood samples of patients with and without NSCLC, the team found AKAP4 produced an AUC score of 0.9714 in distinguishing between the two groups, while a score of 0.9795 was produced when researchers compared only the 136 patients with an early-stage NSCLC with control subjects.
The team notes that AKAP4 levels increased as disease stage increased, though the protein was still present in patients with early-stage NSCLC, suggesting it could be used for early detection.
Dr. Huang says the study results "exceeded their expectations," adding:
"AKAP4 appears to be a highly effective biomarker for the detection of nonsmall cell lung cancer. If we are able to confirm these results in a more robust study, then we have the potential for a new, more accurate screening method that could help save many, many lives."
The team now plans to validate AKAP4 as a biomarker for NSCLC in a larger study involving more than 800 blood samples.
Commenting on Dr. Huang and colleagues' findings, Dr. Dario C. Altieri, president and CEO of The Wistar Institute and director of the Cancer Center at Wistar, says the team may be on the way to creating a "more accurate test than any method that's been used to screen for nonsmall cell lung cancer to date."
"With the government recommending annual screening for high-risk populations, the identification of a promising target like AKAP4 comes at a critical time," he adds. "Early detection is needed in order to have a meaningful impact on this devastating disease."
In April, Medical News Today reported on a study by researchers from the University of California-Los Angeles, which suggests a drug approved to treat melanoma - the deadliest form of skin cancer - may also be effective for treating advanced NSCLC.