A biomarker can predict with 95 percent accuracy the likelihood that a pancreatic cyst will become cancerous, a new study reports.
Pancreatic cancer kills more than 45,000 people in the US each year, mostly because doctors detect cysts too late to surgically remove them and halt cancer’s spread.
Cysts in the pancreas sometimes develop into invasive cancer, but not always. This creates a quandary for physicians who spot them via CT and MRI scans, researchers say. Surgery to remove pancreatic cysts is often complex, so there is a need for tools to identify which ones will develop into cancer.
As reported in Gastroenterology, testing fluid from cysts for the biomarker—an antibody called mAb Das-1—allowed researchers to improve on current clinical guidelines, which are only about 74 percent accurate.
“Some cysts have the potential to become pancreatic cancer, so there’s the thought that we should err on the side of caution and remove the cysts,” says first author Koushik K. Das, an assistant professor of medicine in the gastroenterology division at Washington University.
“But pancreas surgery is complicated. It often requires removal of the spleen, portions of the stomach, small intestine, and bile duct. In an ideal world, we only would do surgery on people whose pancreatic cysts are likely to develop into cancer. As it is, we probably don’t operate on some people who need surgery and sometimes do operate when cancer isn’t present because we’re working with imprecise information.”
Some 2 percent to 4 percent of patients ages 50 to 70 probably have pancreatic cysts, and that percentage increases to 8 percent to 9 percent in people over the age of 80, Das says. The vast majority of those patients have no symptoms, so when doctors detect cysts, they have to decide whether to perform surgery, knowing that a typical patient 70 years of age or older may have other unrelated serious medical problems, such as heart, lung, or kidney disease. Those complications make patients less than ideal candidates for major abdominal surgery.
Although surgery is effective at removing precancerous cysts, 1 percent to 2 percent of patients who have the surgery don’t survive. The rate of complications from surgery can range from 30 percent to 60 percent. Those are high risks for surgery to remove cysts that could turn out to be harmless, Das says.
For the new study, researchers collected fluid from the cysts of 169 patients who had surgery to remove them. They analyzed the fluid, using a test to detect the Das-1 antibody biomarker. In previous research, the biomarker correlated with pancreatic cysts at high risk to become cancerous.
In the new study, the researchers found that the biomarker was more accurate than any current method at predicting cancer risk in these patients with pancreatic cysts.
The next step, Das says, is to see whether the biomarker can identify pancreatic cysts likely to become cancerous before a patient undergoes surgery.
Testing pancreatic cysts
A gastroenterologist, Das uses endoscopic ultrasound to distinguish patients at risk for pancreatic cancer from those whose cysts often pose no threat. While patients are under anesthesia, he inserts a flexible tube with a camera down through the mouth into the abdomen.
“At the end of that scope is an ultrasound probe that allows us to look into the pancreas,” he says. “Then, under ultrasound guidance, we can pass a needle into the cyst to collect fluid that can be tested for Das-1 and assess for cancer risk.”
Das has collected fluid samples for more than two years to begin to amass a large enough number of samples to validate the test.
“Many cysts, if not most, probably should be left alone,” Das says. “But we do that at our peril because we may miss individuals harboring cancer. If we had a better biomarker, we wouldn’t have to rely on imperfect clinical and radiographic information.”
Additional researchers are from Massachusetts General Hospital, Johns Hopkins School of Medicine, Memorial Sloan Kettering Cancer Center, and the Rutgers-Robert Wood Johnson Medical School.
The National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health, the National Cancer Institute, the American Society for Gastrointestinal Endoscopy, and the National Pancreas Foundation funded the work.