Researchers at several medical centers recently concluded a small trial on a new, experimental blood test that may be effective in detecting pancreatic cancer at much earlier stages than the cancer is usually found currently. If larger trials show the same effectiveness for the blood test, a reliable test for pancreatic cancer could be available within the next few years.
Currently, pancreatic cancer is usually diagnosed at very late stages when treatment is not very effective. Only about 15% of patients diagnosed with pancreatic cancer are treated with surgery that can cure the disease or add years to a person's life.
Last year, pancreatic cancer was the fourth most common cause of cancer-related deaths in the U.S. for both men and women, according to the National Cancer Institute (NCI). In 2014, close to 50,000 people were diagnosed with the disease and nearly 40,000 died. Because pancreatic cancer usually is diagnosed at an advanced stage, the survival rate is extremely low compared with that of many other cancers. In addition, the mortality rate from pancreatic cancer has increased an average of 0.4% annually from 2002-2011, according to NCI data.
The blood test uses a new approach by detecting a protein associated with pancreatic cancer called glypican-1 in tiny particles called exosomes. Exosomes are produced by all cells and circulate in the blood. Pancreatic cancer cells produce exosomes with higher concentrations of glypican-1 than normal pancreatic cells.
Increased production of glypican-1 by pancreatic cancer cells has been reported previously, but measuring the protein in the blood by immunoassay is no more useful than using conventional tumor markers such as CA 19-9. However, by concentrating the tiny particles released by cells and looking for the protein in these, the researchers could show a significant difference between patients with pancreatic cancer and healthy volunteers. They also found that the levels of the protein in exosomes increased with severity of the disease and dropped after patients had surgery to remove their tumor. So an effective blood test for glypican-1 might also be used to monitor treatment and disease progression of pancreatic cancer.
"Studies comparing stage of disease with outcome following surgery suggest that death rates for pancreatic cancer would be reduced if the disease were diagnosed at an earlier stage," said Raghu Kalluri, M.D., Ph.D., chair of Cancer Biology at MD Anderson Cancer Center in Houston, Texas and a lead author of a paper about the new blood test published in the journal Nature. "This [new test] presents an unprecedented opportunity for informative early detection of pancreatic cancer and in designing potential curative surgical options," Kalluri said.
Now large scale trials are needed, and are in development, to look at the effectiveness of the blood test in thousands of people whose cancer status isn't known. An editorial in Nature notes that based on this early trial, the test may not be able to detect cancers other than pancreatic cancer. However, given the mortality rate, it would be a considerable accomplishment to develop a reliable test to detect pancreatic cancer in the early stages.