Researchers hope to detect the disease while it is still treatable
TUESDAY, Sept. 1 (HealthDay News) -- Texas scientists say they have found small molecules in the blood that can spot pancreatic cancer, a finding that could have diagnostic implications in the future.
Levels of these molecules, called microRNAs, are elevated in patients suffering from pancreatic cancer, the fourth-leading cancer killer in the United States. The disease usually isn't diagnosed until it is in an advanced stage, when treatment is all but ineffective, the researchers say. Less than 5 percent of these patients survive five years past diagnosis.
"We have detected elevated levels of these microRNAs in the blood of pancreatic cancer patients," said lead researcher Subrata Sen, of the University of Texas M.D. Anderson Cancer Center's department of molecular pathology.
"This is an extremely promising finding in terms of developing a blood-based assay for detecting pancreatic cancer," he said.
If such a test could be developed, the question remains: Who should be screened? Sen thinks people with a family history of pancreatic cancer and those with risk factors for the disease, such as smoking, are the first candidates for testing.
However, how early high levels of these biomarkers appear in the development of pancreatic cancer is still unknown, Sen said. "That's the million-dollar question," he said. "That is something that has to be investigated with a bigger patient population."
MicroRNAs are short strands of RNA that regulate what proteins genes make, and they play an important role in both normal cells and cancerous cells. Changes in microRNAs have been seen in different cancers. Because microRNAs can be detected in blood, that may be useful in diagnosing cancer, Sen said.
The report was published in the Sept. 1 online edition of Cancer Prevention Research.
For the study, Sen's team looked at four microRNAs that have been linked to pancreatic cancer: miR-21, miR-210, miR-155 and miR-196a. The researchers looked at levels of these microRNAs in 28 patients with pancreatic cancer and compared them with 19 healthy individuals.
The team found the four biomarkers accurately detect pancreatic cancer 64 percent of the time. In addition, these biomarkers were able to find patients who did not have pancreatic cancer 89 percent of the time.
Toumy Guettouche, manager of the Oncogenomics Core Facility at the Sylvester Comprehensive Cancer Center at the University of Miami Miller School of Medicine, thinks this test shows promise, but is far from being ready for "prime time."
"This is an interesting diagnostic method with a lot of potential," Guettouche said.
However, the sensitivity and specificity of the test is too low, he said. "This would have no chance of getting diagnostic clearance [from the FDA]," he added. It looks for 98 percent accuracy, he noted.
In addition, Guettouche said these same microRNAs have been linked with other cancers. "The problem is to determine pancreatic cancer to begin with," he said.
"What tells you that these upregulated microRNAs are from pancreatic cancer? They could be from another cancer," he said.
For more information on pancreatic cancer, visit the American Cancer Society.
SOURCES: Subrata Sen, Ph.D., department of molecular pathology, University of Texas M.D. Anderson Cancer Center, Houston; Toumy Guettouche, Ph.D., manager, Oncogenomics Core Facility, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine; Sept. 1, 2009, Cancer Prevention Research, online
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