by To find breast cancer early, there is a mammogram. To find colon cancer early, there is a colonoscopy. But there is no standard test to detect early cases of pancreatic cancer, before cancer cells have spread and when surgery is most likely to help.
Early detection of pancreatic cancer may increase patients’ chances of survival. Although pancreatic accounts for only about 3% of all new cancer cases in the United States, it is the third leading cause of cancer death and is expected to become the second leading cause of cancer death by the end of this decade.
Across the United States, research teams are exploring ways to detect early cases, with many turning to blood-based liquid biopsy tests.
“This term ‘liquid biopsy’ is basically trying to find markers in the blood that show they are present – and there are many different ways to do that. There are many different aspects of blood suction that you could use,” said Dr. Brian Wolpin, director of the Gastrointestinal Cancer Center at the Dana-Farber Cancer Institute., whose laboratory has done work in this area.
But there are still many studies investigating the potential of liquid biopsy tests for early detection of pancreatic cancer in its early stages. And the US Preventive Services Task Force recommends against screening for pancreatic cancer in asymptomatic adults, particularly because there is no established method or test for early detection of this type of disease in the general population. .
Although there is currently no single blood test recommended to detect early pancreatic cancers, “there is a large scientific community working to try to change this and to identify a screening test that we can use in the clinic, but it is quite difficult,” said Wolpin . “There is still more work to be done to achieve it.”
One team presented its research Monday at the annual meeting of the American Association for Cancer Research, detailing the development of a liquid biopsy test found to detect 97% of stage I and stage II pancreatic cancers in hundreds of volunteers. The researchers are from the City of Hope Comprehensive Cancer Center and other institutions around the world.
Their study, which was not published in a peer-reviewed journal, included 984 people, some healthy and others with pancreatic cancer, located in Japan, the United States, South Korea and China.
The researchers collected blood samples from each person and tested the expression of a series of small genes called microRNAs within the blood and contained within exosomes found in the blood. Exosomes are small vesicles produced by both cancer cells and healthy cells in the blood.
“Cancer cells tend to release many, many more exosomes compared to our healthy cells because our healthy cells don’t multiply as fast as cancer cells do,” said Dr. Ajay Goel, senior author of the study and chair of the Department of Molecular Diagnostics and Experimental Therapeutics at City of Hope. “And when the tumor cells release these exosomes, they circulate in our bloodstream.”
Goel and his colleagues identified eight microRNAs found in exosomes shed by cancer cells in the pancreas and five microRNAs in the blood. They used these markers to develop an approach to determine whether a person’s exosomes are associated with pancreatic cancer.
The researchers found that their liquid biopsy approach detected 93% of pancreatic cancers among US volunteers in their study, 91% of pancreatic cancers in a South Korean cohort and 88% of pancreatic cancers in a cohort of China.
The researchers ran their tests again and, this time, they not only used their exosome-based markers but also tested for a key protein called CA19-9, which is known to be associated with pancreatic cancer. When they combined their approach with the CA19-9 test, they were able to accurately detect 97% of stage I and stage II pancreatic cancers in the US volunteers.
“That’s what we’re really excited about: not only did this test work beautifully in all stages, but it’s 97% accurate in finding those with stage I or stage II disease,” Goel said. .
He added that the test showed false positive results for stage I and II pancreatic cancers at a rate of less than 5%, the study data showed.
“It is very important to diagnose the disease at the earliest possible stage, like stage I or II disease, which means there is a higher chance that the cancer is surgically operable,” said Goel. “The best cure for a pancreas patient is not chemotherapy or drugs but to get rid of the cancer.”
Surgeons can be “very reluctant” to operate when someone has stage III or IV pancreatic cancer, he said. This sometimes happens because of the complexity of such a procedure, the long-term complications and the likelihood that surgery at that advanced stage will not be enough to prevent the cancer from coming back.
“That’s why it’s so important that this blood test is so good that, 97% of the time, it can find the cancer at the earliest possible stages when we can intercept the cancer, where which we can intervene, and we can remove this surgically. cancer effectively,” said Goel.
‘We have to do something’
There are blood-based tests for pancreatic cancer that are used in medicine, but they are often used in people who have already been diagnosed with the disease. Doctors may repeat blood tests during and after treatment to see how the cancer is responding. But there is no blood test that can detect pancreatic cancer early.
Goel and his colleagues wrote in their abstract that their approach “can be further validated for clinical use in the near future,” specifically for the early detection of pancreatic cancer.
“We were generally excited about this particular data, because the type of cancer we’re looking at here is extremely lethal,” Goel said.
“The number of people who will be affected by this disease or this cancer is increasing,” he said. “So we have to do something about it, and that’s why we were very excited to have a blood-based liquid biopsy for early detection of pancreatic cancer with this high sensitivity.”
The liquid biopsy test study presented by Goel and his colleagues is “interesting,” Wolpin said, and describes one approach to possibly developing a test for early detection — where the need is great.
A definitive diagnosis of pancreatic cancer may involve a series of scans, blood tests and biopsies, which are usually only done when a person has symptoms, including jaundice or yellowing of the eyes and the skin, weight loss, abdominal or back pain, or fatigue. and weakness. But by that point, the cancer is probably advanced.
“The vast majority of patients who present with pancreatic cancer have advanced disease at diagnosis. So 80% or more of patients have advanced disease and we know at the time of presentation, we’re unlikely to be able to cure the cancer,” said Wolpin.
“That’s very different than many other major types of cancer like breast cancer or colorectal cancer, where the vast majority of patients have early disease,” he said. “Symptoms of pancreatic cancer tend to be less specific, such as abdominal discomfort or occasional weight loss – things that don’t often prompt people to immediately go to their doctor.”
But some experts warn that mass testing of healthy, average-risk people who aren’t showing symptoms could lead to false positives, doing more harm than good.
‘The pancreas is a very strange organ’
City of Hope researchers are not the only scientists hoping to develop a reliable test to diagnose pancreatic cancer patients as soon as possible.
In 2020, a study from the University of Pennsylvania found that a blood test to screen for certain biomarkers associated with pancreatic cancer was 92% accurate in its ability to detect disease.
In 2022, a pilot study by researchers at UC San Diego and other institutions found that a blood test to detect proteins associated with cancer cells was able to identify 95.5% of stage I pancreatic cancers among a sample of more than 300 volunteers , and 139 among them. they were cancer patients and 184 were healthy people.
In general, the field of pancreatic cancer is one that has not made much progress in early- or advanced-stage disease, said Dr. Al Neugut, a medical oncologist at Columbia University’s Herbert Irving Comprehensive Cancer Center and associate professor. epidemiology at Columbia University’s Mailman School of Public Health, who were not involved in any of the liquid biopsy testing research.
“Pancreatic cancer is the poster child for a cancer that we haven’t gotten anywhere with,” Neugut said.
“The pancreas is a very strange organ, and it’s different from every other organ in the body,” he said. “It’s behind the belly, so it’s hard to find. It is not easy for a surgeon. It’s not easy for an oncologist. It makes it very difficult to even approach. You cannot physically examine it. It is difficult to find radiologically. It’s hidden.”
Although pancreatic cancer is rare, people can reduce their risk by eating a healthy diet, maintaining a healthy weight, exercising regularly, avoiding alcohol, limiting exposure to carcinogens and not smoking.
“Smoking is the most important preventable risk factor for pancreatic cancer,” according to the American Cancer Society.
However, some kind of test to detect pancreatic cancer early would “significantly change the landscape” for patients, Wolpin said, adding that he hopes the medical field can develop such a tool. develop that.
“The more patients we can find early, the more likely we are to cure pancreatic cancer patients and begin to reverse the very harsh statistics – almost 90% of pancreatic cancer patients die from their -cancer,” Wolpin said. “We really need to change those numbers, and finding cancer earlier would be a great way to do that.”
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