Nov. 13, 2006 A panel of 10 blood biomarkers performed almost perfectly in picking out people who had pancreatic cancer from those who didn't, according to researchers at the University of Pittsburgh. The advance raises hopes that a test can be developed to screen for the aggressive cancer in time to treat it, they say.
"Early detection of pancreatic cancer is crucial to survival, but there has been no way to diagnose it early before symptoms occur," said the lead investigator, Anna E. Lokshin, Ph.D., an associate professor of medicine and pathology at the University of Pittsburgh School of Medicine. "This assay represents a new way to screen for disease that appears to be applicable to pancreatic cancer, and potentially, to other cancer types."
The assay contains the largest panel of blood-based biomarkers to be examined simultaneously in pancreatic cancer. It consists of proteins known to be secreted by pancreatic tumors as well as proteins that represent the body's response to that tumor growth, Lokshin said.
"Tumors are located in the context of certain tissues, and those tissues react in their own individual ways to the cancer," she said. "For example, tissue-specific proteins try to fight the cancer, and each tumor type grows blood vessels in tissue uniquely, so we believe the body responds differently to each kind of cancer."
The researchers initially evaluated a panel of 44 protein biomarkers, including cytokines, chemokines, adhesion molecules and hormones, and used blood from 100 pancreatic cancer patients and a control group of 400 healthy people to find those associated with the cancer. They used a microbead array, which can sample up to 100 different proteins simultaneously, and found 10 biomarkers that offered the highest diagnostic power, Lokshin said. Two of those biomarkers are CA125, which can detect a number of cancers but which is not very specific, and CA19-9, which has been known to correlate weakly with pancreatic cancer.
They found that this panel of markers correctly identified pancreatic cancers 97 percent of the time, with a sensitivity of 95 percent (meaning it could correctly identify cancerous lesions) and with a 98 percent specificity (the ability to detect truly negative cases).
The researchers are continuing to study, validate, and perfect the assay, and test its ability to identify pancreatic cancer at early, treatable stages. Although pancreatic cancer is relatively rare, survival is poor compared to most other forms of cancer - it is the fourth leading cause of cancer-related deaths in males and the fifth-leading cause of cancer-related deaths in females.
A diagnostic screen for pancreatic cancer would likely first be used in smokers, because use of tobacco is a known risk factor for developing pancreatic cancer, Lokshin said.
The researchers also are developing similar assays for ovarian, breast, lung, endometrial, head and neck, and esophageal cancers. "So far, every panel is different for each cancer to the point where we can say with greater than 97 percent certainty which cancer it is," she said.
"Surprisingly, although in theory body response could be similar for several cancers, in practice it is very different."
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The above story is based on materials provided by American Association For Cancer Research.
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