Chasing Diabetes' Connection to Pancreatic Cancer

Stephanie Watson

November 22, 2017

Diabetes and pancreatic cancer affect the same organ, but they have more in common than just their location. People who have one of these conditions are also more likely to have the other one.

About 30 million Americans have diabetes. Pancreatic cancer is diagnosed in nearly 54,000 people each year, and it's the third-leading cause of cancer-related death. Most people aren't diagnosed until their cancer has already spread and is harder to treat.

Researchers have been looking at the link between diabetes and pancreatic cancer for many years. Now they're trying to use this connection to diagnose pancreatic cancer earlier, when treatment is more likely to improve survival.

The Diabetes-Pancreatic Cancer Link

Diabetes is both a risk for, and a warning sign of, pancreatic cancer. "The relationship goes both ways," says Lynn Matrisian, PhD, chief science officer of the Pancreatic Cancer Action Network.

Researchers don't know exactly why, but people who have had diabetes for several years are slightly more likely to get pancreatic cancer than those without diabetes.

Pancreatic cancer can also cause diabetes. About half of people with pancreatic cancer have high blood sugar. When the cancer is surgically removed, blood sugar levels often go back to normal.

"In longstanding diabetes, the diabetes came first. In new-onset diabetes that's followed by pancreatic cancer after a year or two, diabetes may be a symptom of the pancreatic cancer. Which is why there's an opportunity to intervene," says Richard Frank, MD, a medical oncologist and director of cancer research at Western Connecticut Health Network.

Frank and other researchers are looking for ways to spot pancreatic cancer early in people with newly diagnosed diabetes.

How to Screen for Pancreatic Cancer in People With Diabetes

Pancreatic cancer often has vague symptoms, or no symptoms in its early stages. "It's back pain and indigestion. So a lot of times people think of other things first, before they finally say, 'Maybe we should check for pancreatic cancer,' " Matrisian says. As a result, most pancreatic cancers aren't diagnosed until they've already spread.

Doctors usually find pancreatic cancer using imaging tests like CT and MRI scans, and endoscopic ultrasound. Testing everyone with diabetes using these methods would be too expensive and impractical, Matrisian says. What doctors need is a way to identify and screen only people who have the highest chances of getting pancreatic cancer.

Suresh Chari, MD, a professor of medicine at the Mayo Clinic College of Medicine, has studied the link between pancreatic cancer and diabetes for many years. He's found that people who are newly diagnosed with diabetes after age 50 have about a 1% chance of having pancreatic cancer -- a rate that's eight times higher than in the general population.

Now he's working with the National Cancer Institute (NCI) on a 5-year study to identify people with new-onset diabetes who are have a higher-than-normal chance of getting pancreatic cancer. The study will include about 10,000 people with high blood sugar, who will have blood tests every 6 months.

"We're looking at finding ways to screen for pancreatic cancer, either in all of them or a subset of them," he says.

The study will also identify biomarkers -- signs of pancreatic cancer in the blood -- that could be used to come up with new screening tests.

Frank is doing a similar study with about 800 diabetes patients.

"The goal is ultimately to be able to identify, though a blood test, those individuals with diabetes who are at the highest risk of pancreatic cancer, and then to put those individuals into a screening program such as an annual MRI," he says.

Eventually, it might even be possible to screen people with prediabetes. "It makes sense that the further back you go, the earlier you'll catch the tumor," Chari says.

Warning Signs for People With Diabetes

People with diabetes don't need to panic about getting cancer, but they should be more aware. "The chance is that less than 1% will have pancreatic cancer," Frank says. "And the greatest risk of pancreatic cancer is in the first 1 to 2 years after the diagnosis."

During that time, he suggests staying alert for any symptoms that could be pancreatic cancer, like unexplained weight loss, changes in bowel habits, or bloating. "If they have those mild symptoms and they have new-onset diabetes, they should talk to their doctor. They should also know their family history. If there's cancer in the family, they should talk to a genetic counselor," he says.

"In essence, being your own advocate is what we can recommend right now, while we do the research and see if we can get a test that can help diagnose pancreatic cancer earlier," Matrisian says.

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