Simple intestinal probe may detect pancreatic cancer
Volume 1, Issue 2, 2012
Michael B. Wallace, M.D.
By simply shining a tiny light within the small intestine, close to its junction with the pancreas, physicians at Mayo Clinic Cancer Center in Florida have been able to detect pancreatic cancer 100 percent of the time in a small study. The light, attached to a probe, measures changes in cells and blood vessels in the small intestine produced by a growing cancer in the adjoining pancreas.
This minimally invasive technique, called polarization gating spectroscopy, will now be tested in a much larger international clinical trial led by the Mayo Clinic Cancer Center researchers. The preliminary study suggests it may one day be possible to use a less invasive endoscope to screen patients for early development of pancreatic cancer. The findings were presented by Mayo Clinic Cancer Center gastroenterologist Michael B. Wallace, M.D., at the International Digestive Disease Week 2012 conference.
The pancreas is notoriously hard to reach and see because it is located deep within the abdomen and surrounded by intestines. The study investigators theorized that there may be changes in the nearby normal-appearing tissue of the small intestine, which is much more accessible.
"No one ever thought you could detect pancreatic cancer in an area that is somewhat remote from the pancreas, but this study suggests it may be possible," Dr. Wallace said. "Although results are still preliminary, the concept of detection-field effects of nearby cancers holds great promise for possible early detection of pancreatic cancer."
Pancreatic cancer is one of the most deadly of human tumors. It is generally only curable in about 5 percent of cases, and even when the cancer is surgically removed, about 70 percent of patients have a recurrence that is fatal, Dr. Wallace said. There are currently no ways to detect pancreatic cancer early enough to cure a substantial number of patients.
Pancreatic cancer is now usually detected through an imaging scan, followed by an invasive biopsy. Tumors found in this way are usually at an advanced stage.
In the spectroscopy study, Mayo Clinic Cancer Center physicians tested a light probe developed by collaborators at Northwestern University. The light probe, attached to a small fiber-optic probe called an endoscope, measures the amount of oxygenated blood and the size of blood vessels in tissue near the duct where the pancreas joins the small intestine. Because a growing tumor requires a heightened supply of blood, normal tissue in the vicinity of the cancer reveals evidence of enlarged blood vessels and changes in the amount of oxygen within the blood.
The probe acts "a bit like a metal detector that beeps faster and louder as you get close to cancer," Dr. Wallace said. The researchers are measuring within 6 to 10 inches of the pancreas in the small intestine immediately next to the pancreas.
Such field effects from cancer can be measured in other areas of the gastrointestinal tract. "With this technology, others studies have shown that cancerous polyps can be detected more than 11 inches from the polyp itself. Early studies are evaluating if esophageal cancers can also be detected remotely," Dr. Wallace said.
Dr. Wallace and his team tested the probe on 10 patients who were later determined to have pancreatic cancer and on nine participants who did not have pancreatic cancer.
They found that testing both measures — blood vessel diameter and blood oxygenation — detected all 10 pancreatic cancers. But the probe was less precise (63 percent accurate) in determining which of the healthy volunteers did not have pancreatic cancer.
"There is room for improvement in this instrument, and our group is working on that," Dr. Wallace said. "If the studies confirm the early results, it would make the pancreas accessible to a much simpler upper endoscope and that would be a real advance in the treatment of pancreatic cancer."
Patients now often undergo an endoscopic examination of the upper intestine to search for the cause of heartburn or stomach pain. An endoscopic probe could be easily outfitted to explore for evidence of pancreatic cancer in patients at heightened risk, Dr. Wallace says.
The study's co-authors include Vadim Backman, Ph.D., a professor in the biomedical engineering department at Northwestern University, and Hemant Roy, M.D., a gastroenterologist at NorthShore University Health System. The study was funded by the National Institutes of Health and Mayo Clinic. For information about cancer clinical trials at Mayo Clinic, call 507-538-7623.
New Study Detects Pancreatic Cancer
Watch a video of Dr. Wallace discussing this study.