How to detect pancreatic cancer early? Scientists seek alternatives

To detect breast cancer early, there are mammograms. To find colon cancer early, there are colonoscopies. But there is no standard test for detecting early cases of pancreatic cancer, before cancer cells have spread and when surgery is most likely to be helpful.

Finding pancreatic cancer early could increase a patient's chances of survival. Although pancreatic cancer represents only about 3% of all new cancer cases in the United States, it is the third leading cause of cancer deaths and is projected to become the second leading cause of cancer deaths by the end of this decade. .

In Brazil, it is the 14th most common type of cancer (without considering non-melanoma skin tumors), according to Inca (National Cancer Institute). Pancreatic tumors are responsible for around 5% of cancer deaths in the country.

Across the United States, research teams are investigating ways to detect early cases, with many turning to liquid biopsy tests blood-based.

“This term 'liquid biopsy', essentially, is trying to find markers in the blood that indicate the presence of a tumor – and there are many different ways to do this. There are many different characteristics of a tumor that can end up in the blood that could be used,” said Brian Wolpin, director of the Gastrointestinal Cancer Center at the Dana-Farber Cancer Institute, whose laboratory has done work in this area.

However, many studies investigating the potential of liquid biopsy tests for early detection of pancreatic cancer are still in the early stages. And the United States Preventive Services Task Force recommends against screening for pancreatic cancer in adults who do not have symptoms, especially because there is no established method or test for detecting this form of the disease early in the general population.

Although there is currently no single blood test recommended for finding early pancreatic cancers, “there is a large scientific community working to try to change that and identify a screening test that we can use in the clinic, but it is quite difficult,” Wolpin said. “There is still more work to be done to get there.”

A team presented its research Monday at an annual meeting of the American Association for Cancer Research, detailing the development of a liquid biopsy test that was found to detect 97% of stage I and II pancreatic cancers in hundreds of cases. of volunteers. The researchers are from the City of Hope Comprehensive Cancer Center and other institutions around the world.

The study, which was not published in a peer-reviewed scientific journal, included 984 people, some healthy and others with pancreatic cancer, based in Japan, the United States, South Korea and China.

The researchers took blood samples from each person and tested the expression of a set of small genes called microRNAs within the blood and encapsulated within exosomes found in the blood. Exosomes are small vesicles that are released by both cancerous and healthy cells into the blood.

“Cancer cells tend to release many, many more exosomes compared to our healthy cells because our healthy cells don't multiply as quickly as cancer cells,” said Ajay Goel, senior author of the study and chair of the Department of Molecular Diagnostics and Therapeutics City of Hope Experimental. “And once these exosomes are released by tumor cells, they circulate in our blood.”

Goel and his colleagues identified eight microRNAs found in exosomes that are released by pancreatic cancer cells 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 U.S. volunteers in their study, 91% of pancreatic cancers in the South Korean cohort, and 88% of pancreatic cancers in the Chinese cohort.

The researchers ran their tests again, and this time they not only used their exosome-based markers, but also tested a key protein called CA19-9, known to be associated with pancreatic cancer. When they combined their approach with CA19-9 testing, they were able to accurately detect 97% of stage I and stage II pancreatic cancers in US volunteers.

“That's what we're excited about: Not only did this test work wonderfully across all stages, but it is 97% accurate in finding those who have stage I or stage II disease,” said Goel.

He added that the test returned false positive results for stage I and II pancreatic cancers at a rate of less than 5%, study data showed.

“It is very important to diagnose the disease at the earliest stage possible, such as stage I or II, which means there is a greater chance that the cancer will be surgically operable,” Goel said. “The best cure for a pancreas patient is not chemotherapy or drugs, but to remove the cancer.”

Surgeons can be “very reluctant” to operate when someone has stage III or IV pancreatic cancer, he said. This is sometimes due to the complexity of such a procedure, the long-term complications, and the likelihood that surgery at this advanced stage may not be enough to prevent the cancer from returning.

“That's why it's very important that this blood test is so good that it can, 97% of the time, find cancers at the earliest stages possible where we can intercept the cancer, where we can intervene and we can surgically remove this cancer effectively. ,” said Goel.

New test development

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 determine 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 potentially be further validated for clinical use in the near future,” specifically for the early detection of pancreatic cancer.

“We were generally excited about this specific data, because the type of cancer we are looking at here is extremely lethal,” said Goel.

“The number of people who will be affected by this disease or this cancer will continue to increase,” he said. “So we need to do something about it, which is why we were extremely excited that we have a blood-based liquid biopsy for the early detection of pancreatic cancer with this high sensitivity.”

The liquid biopsy test study that Goel and his colleagues presented is “interesting,” Wolpin said, and describes an approach to possibly developing a test for early detection — where there is a great need.

Definitively diagnosing someone with pancreatic cancer can involve a series of exams, blood tests and biopsies, which are usually only performed when someone has symptoms, which can include jaundice or yellowing of the eyes and skin, weight loss, abdominal or back pain , or tiredness and weakness. But at this point, the cancer is likely advanced.

“The vast majority of patients who present with pancreatic cancer have advanced disease at the time of diagnosis. So 80% or more of patients present with advanced disease where we know at the time of presentation, it is very unlikely that we can cure the cancer,” Wolpin said.

“This is very different from many other major types of cancer such as breast cancer or colorectal cancer , where the vast majority of patients actually present with early disease,” he said. “Symptoms of pancreatic cancer are often less specific, like some abdominal discomfort or sometimes weight loss — things that often don't immediately trigger people to see a doctor.”

But some experts warn that mass testing of healthy, average-risk people who don't show symptoms could lead to false positive results causing more harm than good.

Reliable Test

City of Hope researchers are not the only scientists hoping to develop a reliable test to diagnose pancreatic cancer patients as early as possible.

In 2020, a University of Pennsylvania study found that a blood test to screen for certain biomarkers associated with pancreatic cancer was 92% accurate in its ability to detect the 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, among which 139 were cancer patients and 184 were healthy people.

In general, the field of pancreatic cancer is an area where there have not been many advances when it comes to early-stage or advanced-stage disease, said Dr. Al Neugut,

Source: CNN Brasil

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