Casting a Broader Net
Can a new combination of blood tests for pancreatic cancer improve detection rates for a disease in which early diagnosis is notoriously difficult?
Luke Turner | | Quick Read
Outcomes for patients with pancreatic ductal adenocarcinoma (PDAC) are poor – only 8.5 percent of patients diagnosed with the most common form of pancreatic cancer survive past five years. That’s approximately the same chance of survival as those diagnosed with the same disease 30 years ago… so why haven’t we seen any improvement?
The disease lacks early symptoms, hindering early diagnosis, and to make matters even more difficult, PDAC typically spreads aggressively before detection. So, to improve the odds of successful diagnosis and treatment, a team at the Van Andel Research Institute developed a new blood test to catch PDAC in high-risk individuals before it can spread. The test’s goal? To improve upon the existing blood test, which isn’t a reliable indicator of the disease.
“[CA-19-9 glycan testing] is not accurate enough as a single marker because, at a cutoff giving 5 percent false positives, it only detects around 40 percent of cancers,” explains Brian Haab, senior author of the study. After realizing that glycans with a similar structure to CA-19-9 could also represent pancreatic cancer biomarkers, the team screened numerous others to identify the sialylated tumor-related antigen (sTRA). Is it a replacement for CA-19-9? Not necessarily; by combining the two, the researchers observed improvements in PDAC detection rate.
“The sTRA glycan is produced and secreted by a different subset of pancreatic cancers than those that produce CA19-9,” Haab explains. When combining the two tests and applying a cutoff to give less than 5 percent false positives, the new approach detected around 70 percent of PDAC cases in people with benign conditions of the pancreas (1). This means that labs could spot pancreatic cancer subtypes that might have been missed by the CA-19-9 test alone, casting a broader net on PDAC.
Haab hopes that the new combined panels can improve diagnosis and surveillance for patients with suspected pancreatic cancer. “The aim is to be able to monitor for incipient cancer in people at high risk, such as those with chronic pancreatitis, pancreatic cysts, family history, or new-onset type 2 diabetes.” The team are currently working toward real-time prospective studies in a clinical lab before collaborating with clinical partners to offer it as a lab-developed test. If successful, they envisage the test being rolled out widely as a screening tool for high-risk individuals.
- B Staal et al., “The sTRA Plasma Biomarker: Blinded Validation of Improved Accuracy Over CA19-9 in Pancreatic Cancer Diagnosis”, Clin Cancer Res, [Epub ahead of print] (2019). PMID: 30617132.