Pancreatic Cancer Is Hard to Detect in Early Stages. A New Blood Test Could Help

Pancreatic cancer is one of the deadliest cancer types, largely because it’s difficult to detect in its early stages. Researchers have now developed an experimental blood test that detected 97% of stage 1 and 2 pancreatic cancers in an early clinical trial.

Tumors in the pancreas tend to go undetected until they have already spread to other parts of the body. By some estimates, 80% or more of pancreatic cancers cannot be removed through surgery by the time they are identified.

Despite accounting for just 3% of new cancer diagnoses, pancreatic cancer is the third leading cause of cancer-related deaths in the United States. By 2030, pancreatic cancer is projected to be the second most common cause of cancer death.

“If we can capture all patients in a state where their cancer can still be surgically removed, most of those patients are probably going to live most of their lives without having to worry about it,” Ajay Goel, PhD, senior author of the study and chair of the department of molecular diagnostics and experimental therapeutics at City of Hope, told Verywell.

His team’s experimental liquid biopsy works by detecting genetic markers of pancreatic cancer in the blood. That could alert clinicians to the presence of cancer before it can be seen with traditional imaging tools.

The researchers presented data from their first clinical trial at the American Association for Cancer Research meeting this month. The trial included nearly 1,000 participants from the U.S., Japan, South Korea, and China, about 80% of whom had stage 1 or 2 pancreatic cancer. The U.S. cohort included 139 participants with pancreatic cancer and 193 healthy donors.

The test was almost totally accurate in identifying which study participants had early-stage pancreatic cancers. The test will be studied in larger clinical trials, and researchers will investigate how well the test identifies pancreatic cancer in people with no known disease.

Why It’s Important to Catch Pancreatic Cancer Early

The pancreas is tucked deep within the abdomen, which can make it difficult to sample with a standard needle biopsy or to visualize with standard MRI and CT scans.

The early warning signs, such as abdominal pain and sudden weight loss, can indicate many different conditions. Pancreatic cancer also tends to metastasize early on, when the tumor is still small, said Brian Wolpin, MD, MPH, medical oncologist and clinical investigator in the Center for Gastrointestinal Oncology at Dana Farber Cancer Institute, who was not involved with the research.

“[Pancreatic cancer] has no population screening, which means that you’re not really detecting things at the asymptomatic stage very often,” Wolpin said.

“For a lot of the people who I see in clinic, I already know we won’t be able to cure the cancer because it’s already presented so late,” he added. “Early detection and prevention are really important for this disease, even more so than others.”

The biology of pancreatic cancer is complex, and many of the current treatments don’t work very well, Goel said. Even with advancements in chemotherapy in the last several decades, the prognosis for patients hasn’t much improved, he added.

Catching pancreatic cancer just a few months earlier can significantly increase the possibility of treating the disease.

The five-year survival rate is about 3% for people diagnosed with pancreatic cancer that has metastasized to other organs. The rate is 44% when clinicians catch the cancer before it spreads outside of the pancreas.

“This cancer is already lethal. And if the numbers are going to continue to double in terms of incidence, then we need to do something about it,” Goel said.

How the Liquid Biopsy Works

When cancer cells die, they are released from the tumor into the bloodstream, where they may break down and shed pieces of DNA, proteins, or other cellular parts. A liquid biopsy works by detecting those cellular fragments.

The new pancreatic cancer liquid biopsy identifies small extracellular parts called exosomes, small vesicles that carry genetic information between cells. When they are shed into the blood, they still hold the genetic information from the cell they came from.

The City of Hope researchers identified five genetic markers called microRNAs that float freely in the blood and are unique to people with pancreatic cancer. If the biopsy finds signs of that genetic information, it’s likely that a patient has some cancerous growth.

“Free-floating microRNAs in the blood are very stable and can be easily detected. But the challenge is always: ‘How do we know that the microRNA you’re looking at came from your target organ, whether it is pancreas or breast or colon?’” Goel said.

That’s where the exosomes come in, he said. The test also detects exosomes that contain at least one of eight microRNA unique to pancreatic cancer cells.

This work “appears promising,” said Harry Aslanian, MD, gastroenterologist and pancreatic cancer expert at Yale Cancer Center, who wasn’t involved with the study. Combining the markers found in exosomes and in the blood allows the test to get a fuller “fingerprint” of the cancer, he said.

The only blood test currently available for pancreatic cancer tests for the protein CA 19-9. It’s typically used to monitor how well someone with pancreatic cancer responds to treatments.

Many people have detectable CA 19-9 in their blood and high levels of the protein can be indicative of non-cancer conditions, like gallstones and liver cirrhosis. For that reason, CA 19-9 tests are usually paired with imaging and other tools for pancreatic cancer detection.

When the team used a liquid biopsy with their new genetic signature, they detected 93% of pancreatic cancers in the U.S. cohort. When they combined it with a CA 19-9 test, the accuracy increased to 97%.

Liquid biopsy technology is relatively new and isn’t yet available for most types of cancer besides some options for non-small cell lung cancer.

In 2020, a team of researchers from the University of Pennsylvania published a study in Clinical Cancer Research showing that their liquid biopsy was 92% accurate in detecting early pancreatic cancer. A 2022 pilot study from UC San Diego showed that a blood test to detect exosomes and other proteins associated with pancreatic cancer could detect the disease in stage 1 with nearly 96% accuracy.

Who This Liquid Biopsy Is For

Pancreatic cancer screening is currently reserved for people at high risk of developing the disease. This includes people with certain genetic conditions, chronic pancreatitis, a history of smoking, new-onset diabetes, and a family history of pancreatic cancer.

High-risk individuals are recommended to start screening at age 50 or 10 years before the earliest cancer diagnosis in their family. Screening may involve high-resolution imaging techniques such as MRI scans or endoscopic ultrasounds to check for any precancerous or cancerous growth.

However, this kind of screening can be expensive to perform frequently, Aslanian said.

If the FDA approves a liquid biopsy for pancreatic cancer, the test can tip off clinicians to the presence of the disease, Aslanian said. They might then scan the pancreas to detect the tumor and biopsy the tissue.

Goel said it’s unlikely that blood tests will be made available to screen the general population as is done for colorectal, breast, and other cancers.

“It wouldn’t make financial and practical sense to put everybody on the planet through screening for pancreatic cancer because we’d have to screen probably 10,000 to 15,000 people to find one who has disease,” Goel said.

Goel said the blood test is low cost and easy to use, so people with a family history of pancreatic cancer can, and should, get tested early and often for the disease.

What Comes Next

Researchers are not only working on developing accurate blood tests but also urine- and stool-based liquid biopsies. Those tests are less developed than the blood-based liquid biopsies are, Wolpin said.

Scientists are also using artificial intelligence to try and find signatures of developing pancreatic cancer in MRIs and CT scans that a human radiologist might miss. Developing better imaging tools could also help clinicians notice small tumors hidden deep in the abdomen, Wolpin said.

“There are quite a number of groups now who are really focused on this problem. I am hopeful that in the next several years we’ll see even more advancements, bring these tests to the clinic, and really start to get a handle on whether they can be effective to find cancer earlier,” Wolpin said.

Until then, families with a history of pancreatic cancer who want to access liquid biopsies before they become commercially available can consider participating in clinical trials, Goel said.

“We want to make the pancreas cancer not as a something people should be afraid of when they get diagnosed, but to diagnose them early enough so that they can receive the right treatments and hopefully live a very happy, healthy life much longer,” Goel said.