Gene Discovery May Improve Pancreatic Cancer Diagnosis, Treatment

MicroRNA holds promise, but bedside applications still years away, experts say

TUESDAY, May 1, 2007 (HealthDay News) -- Scientists say they can use small bits of genetic material called microRNA to spot key differences between chronic pancreatitis and pancreatic cancer, aiding in earlier diagnosis for the lethal malignancy.

The researchers say doctors might also someday use microRNA to help predict the survival of patients with pancreatic cancer.

The report is especially important, because pancreatic cancer is one of the most lethal cancers known, eventually killing almost all of the 33,000 Americans it affects each year.

The problem is that pancreatic tumors often grow very large without outward symptoms, leading to late diagnoses and poor patient outcomes.

But "microRNA can help in the diagnosis," said lead researcher Dr. Mark Bloomston, a professor of surgery at Ohio State University, Columbus. "It could also, potentially have some prognostic implications," he added.

His team published its findings in the May 2 Journal of the American Medical Association.

"MicroRNA are small genes that regulate other genes and cells," Bloomston explained. "The role of microRNA has already been explored in other cancers, such as leukemia, breast and lung cancer, and stomach and colon cancer. MicroRNAs are important in normal physiology in the development of the human body, so it is only fitting that they have a role in cancer," he said.

The Ohio expert noted that in the pancreas, microRNA takes on a different form in normal versus cancerous tissue. It is also altered in inflammatory conditions, such as chronic pancreatitis.

According to Bloomston, diagnosing pancreatic cancer is never simple, even when doctors have a biopsy tissue sample to evaluate. "However, looking at how microRNA differs between cancer and normal tissue could help in making an accurate diagnosis," he said.

In the study, the Ohio team performed experiments to identify the patterns of microRNA in pancreatic cancer, attempting to differentiate pancreatic cancer from benign pancreatic tissue.

The researchers also looked at pancreatic cancer cells from 65 patients and compared them with cells from 42 patients with pancreatitis.

"We found a group of microRNAs that distinguish between pancreatic cancers and the normal pancreas and also distinguish them from chronic pancreatitis," Bloomston said.

The researchers looked at cancer tissue from patients who survived for more than 24 months and compared it to those who died in less than 24 months.

"A two-year cut-off in pancreatic cancer is a milestone, because most patients recur or die within two years of their diagnosis," Bloomston said. "We were able to get a small subset of these microRNA genes that could differentiate long-term from short-term survivors," he said.

Bloomston believes that once they better understand how microRNA works in cancers, it might even be possible to target these tiny genes to treat the disease.

One expert cautioned that, although this discovery is exciting in terms of its potential application to diagnosis and treatment, it will be years before it reaches clinical application.

"It's a really long path from discovering something to translating that into something that happens to you in the doctor's office," said Dr. Scott A. Waldman, professor and chairman of pharmacology and experimental therapeutics at Thomas Jefferson University, Philadelphia, and the co-author of an accompanying journal editorial.

However, Waldman does believe the finding will have broad implications for treating many cancers.

"This is a multilevel discovery," he said. "This discovery reveals an underappreciated level of biological regulation. The researchers also identify how these microRNAs can be used for potential diagnostics and indication of survival," he said.

"Knowing who is less likely to survive will enable us to direct treatment to those patients and hopefully improve their survival," Waldman said. "In addition, when we find out what those microRNAs are regulating, they become targets for intervention," he added.

More information

For more information on pancreatic cancer, visit the American Cancer Society.

SOURCES: Mark Bloomston, M.D., professor, surgery, Ohio State University, Columbus; Scott A. Waldman, M.D., Ph.D., professor and chairman, Pharmacology & Experimental Therapeutics, Thomas Jefferson University, Philadelphia; May 2, 2007, Journal of the American Medical Association
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