Pancreatic cancer is one of the deadliest types of malignancies because most individuals are diagnosed too late to substantially benefit from surgery. A new blood test, recently published about in Science Translational Medicine, could change that by detecting pancreatic cancer in its earliest stages.
The test combines a new pancreatic cancer biomarker, thrombospondin-2 (THBS2), a protein released by platelets in the blood, with the CA 19-9 protein, which is already used clinically. The study found that the test detects individuals with stage 1 or 2 pancreatic cancer with 87% sensitivity. The new test will need more study before it becomes clinically available.
New biomarkers to detect pancreatic cancer at its earliest stages are important because the 5-year survival rate after a late diagnosis is only about 5%. The majority of patients—about 80%—receive their diagnosis too late for surgery. The disease spreads quickly and resists chemotherapy.
"If we could detect the disease earlier, it could have a huge impact on survival for patients," said Kenneth Yu, MD, a medical oncologist at Memorial Sloan Kettering Cancer Center in New York City.
Even after decades of research, CA 19-9 was the only biomarker routinely used in pancreatic cancer testing. On its own, CA 19-9 is useful for monitoring disease progression, but CA 19-9 is not sensitive or specific enough for screening. Combining CA 19-9 with THBS2 made the blood test more sensitive in identifying people with pancreatic cancer (87% sensitivity) and more specific in ruling out those who do not have pancreatic cancer (98% specificity).
Over the past 10 years, the search for new pancreatic cancer biomarkers has intensified. "The literature is full of promising candidate biomarkers, but I don't know of any that have been validated," said Randy Haun, PhD, an associate professor at the University of Arkansas for Medical Sciences College of Pharmacy in Little Rock, who has researched pancreatic cancer biomarkers. "It's not that people aren't trying. It's a very tough problem."
The researchers behind the new THBS2 and CA 19-9 test hope to continue studying it with larger groups of pancreatic cancer patients and with those at higher risk. Their ultimate goal is seeing it used clinically to detect pancreatic cancer before it reaches stage 1.