Silent, long discreet, the
pancreatic cancer is often discovered too late, when surgery is no longer possible. At this stage, treatments only buy a little time and only one in 10 patients survive more than 5 years after diagnosis.
A team from the University of Pennsylvania and the Mayo Clinic described in the journal today Clinical Cancer Research
A pancreatic cancer blood test based on four proteins, able to spot pancreatic ductal adenocarcinoma at an earlier stage. Enough to imagine, in the long term, very different support.
A blood test to track very lethal cancer earlier
In more than 90% of cases, pancreatic cancer is a ductal adenocarcinoma (PDAC), with a poor prognosis: overall 5-year survival remains less than 13%, while it rises to 44% when the tumor is detected at a localized stage. The problem is that only 14% of patients are diagnosed at this early stage. There is currently no routine screening.
Already used, the CA19-9 marker is mainly used to monitor the evolution of an already known cancer. CA19-9 has serious flaws for screening: it can be elevated in pancreatitis or biliary obstruction, and some people don’t produce it at all for genetic reasons. The researchers added thrombospondin 2 (THBS2), another marker already in use. And by analyzing stored blood samples, the team discovered two new biomarker proteins that were elevated in the blood of early-stage pancreatic cancer patients compared to healthy volunteers, aminopeptidase N (ANPEP) and polymeric immunoglobulin receptor (PIGR).
The idea is therefore to evaluate the potential of this association of these four blood proteins, measured in a simple blood sample (CA19-9, thrombospondin-2 (THBS2), aminopeptidase N (ANPEP) and the polymeric immunoglobulin receptor (PIGR)).
Four biomarkers instead of one, for fewer “missed” cancers
The authors tested this panel on 672 people in total, including 197 with PDAC in the Mayo cohort (537 participants) and 59 in the Pennsylvania cohort (135 participants), comparing it to CA19-9 alone. At a specificity of 95% (i.e. only 5% false positives in people without cancer), the four-marker test identified 91.9% of cancers of all stages and 87.5% of early stage cancers (stages I and II). CA19-9 alone detected 82.7% and 76.2% of cases, respectively.
“By adding ANPEP and PIGR to existing markers, we have significantly improved our ability to detect this cancer when it is most treatable.”said the study’s principal investigator, Prof. Kenneth Zaret, of the Perelman School of Medicine at the University of Pennsylvania.
In addition, this combination makes it possible to better distinguish cancer from benign pancreatic diseases such as pancreatitis, a crucial point to avoid unnecessary invasive examinations.
A promising tool for high-risk patients, but not yet for tomorrow
This study remains retrospective, carried out on samples taken at the time of diagnosis, and does not yet say whether the test will detect the disease in people without symptoms. Kenneth Zaret warns: “The results of our retrospective study warrant further testing in broader populations, particularly in people before they show symptoms,” Zaret said.Such ‘predictive’ studies would help determine whether the test could be used as a screening tool for people at high risk.”
Researchers are primarily targeting groups at increased risk of pancreatic cancer, such as people with a family history, BRCA mutations, pancreatic cysts or chronic pancreatitis. If the good results are confirmed in prospective studies, this early detection blood test for pancreatic cancer could then serve as a minimally invasive and relatively inexpensive filter, to decide which patients to send as a priority to imaging and expert centers, and to try to increase the proportion of operable tumors.