Study Shows Test for PAM4 Protein Can Reveal Early-Stage Pancreatic Cancer
WebMD Health News
Reviewed By Louise Chang, MD
Latest Cancer News
Jan. 20, 2010 -- Researchers say they have developed a blood test that can spot pancreatic cancer earlier, when it is more curable.
The test uses an antibody that works like a heat-seeking missile, homing in and attaching to cells that carry a protein called PAM4 that is present in the vast majority of pancreatic cancers.
"This protein appears to be very specific for pancreatic cancer. It's [rarely] found in normal tissue or other cancers," says David V. Gold, PhD, of the Garden State Cancer Center in Belleville, N.J.
Importantly, PAM4 is also seldom detected in pancreatitis, a condition marked by inflammation of the pancreas that is initially often difficult to distinguish from pancreatic cancer, he says.
The antibody also shows promise for treating the disease by acting as a carrier for radiation or drugs that can target and kill pancreatic cancer cells, Gold says.
The findings were released today in advance of the 2010 Gastrointestinal Cancers Symposium, being held later this week in Orlando, Fla.
Pancreatic cancer is the fourth leading cause of cancer deaths in men and women in the U.S. More than 42,000 new cases and over 35,000 deaths are expected in 2010 in the U.S., according to the American Cancer Society.
"This disease is a killer," Gold says. "Only 2% to 3% of patients will survive for five years."
The reason, Gold tells WebMD, is that most patients with pancreatic cancer are not diagnosed until the disease has spread throughout the body.
"The goal of the new test is to provide a tool for the detection of early-stage disease," he says. If cancer is detected early, a patient's chance of surviving five years jumps to 20%, according to Gold.
Currently, only 7% of pancreatic cancer cases are detected at an early stage, before the cancer has spread.
The researchers first tried out the test on blood samples taken from nearly 300 people -- some of whom had pancreatic cancer, some of whom had other cancers, including breast and lung, and some of whom were healthy.
"The test was positive in 77% of pancreatic patients, but only 5% of patients with other forms of cancer," Gold says. "Thus we know that if the [test] is positive, there is a large likelihood a patient has pancreatic cancer."
For the new study, the researchers evaluated the PAM4 protein test in 68 people who had pancreatic cancer surgery and 19 healthy people.
The test correctly detected 62% of very early-stage pancreatic cancers that were still confined to the pancreas, 86% of cases that had spread only to nearby tissue, and 91% of later-stage cancers that had spread further throughout the body.
Overall, the test correctly identified 81% of all pancreatic cancers.
Screening for Pancreatic Cancer
If the findings are validated in larger numbers of people, Gold foresees the test being used to screen people at high risk of pancreatic cancer. This includes people with long-term diabetes, those with chronic pancreatitis, people with a history of tobacco or alcohol use, and those with a family history or genetic factors that place them at increased risk, he says.
Also, "if a doctor suspects pancreatic cancer, the test could be used to distinguish between various types of cancer and healthy tissue," he says. The test could also be used to monitor patients who have undergone treatment for signs of recurrence, Gold says.
He predicts the test will be available in two to three years.
In a separate study of 21 people with advanced pancreatic cancer, the researchers also tested whether the antibody could be used as a treatment to bring targeted agents to the cancer.
The antibody is attached to radioactive isotopes and injected into the body. The idea is that once the antibody homes in on tumor cells, radiation is released, killing the tumor cells while sparing healthy tissue.
In the study, tumors shrank in 23% of the patients and stopped growing in an additional 45%, Gold says.
Robert P. Sticca, MD, of North Dakota School of Medicine and Health Sciences, who moderated a news briefing, tells WebMD that he is very enthusiastic about the possibilities.
"If we had a blood test that could detect cancer early, we could better manage our patients and we would have few deaths. The added benefit of using it as a treatment option is also very exciting," he says.
SOURCES: Press Program, Gastrointestinal Cancers Symposium.
David V. Gold, PhD, Garden State Cancer Center, Belleville, N.J.
Robert P. Sticca, MD, University of North Dakota School of Medicine.
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