Prostate Cancer Return Predicted With Biomarker
For the first time, scientists say they have identified an immune molecule that may predict prostate cancer recurrence after surgery, according to a report in Cancer Research.
"We discovered a protein that shows up in prostate cancer cells, and this protein is thought to be involved in shutting down immune responses in the body," says lead researcher Dr. Eugene D. Kwon of the Mayo Clinic.
The molecule, called B7-H3, is found on the surface of prostate cancer cells, and it kills or paralyzes immune cells that are attacking cancer cells, explains Dr. Kwon.
"The most aggressive tumor cells have the highest levels of this protein," he says.
"The other surprising finding was that when we examined 338 men who had had radical prostatectomy and then followed those patients, we found that the patients who had the highest levels of this protein were at highest risk of having recurrence of their prostate cancer."
The researchers found that all tumors and precancerous tissues had B7-H3, but patients with the highest levels were four times more likely to experience cancer recurrence compared to those with lower levels of B7-H3 within their tumors.
Those with moderate levels of B7-H3 had a 35 percent higher risk of recurrence.
Dr. Kwon says that B7-H3 acts as a "crystal ball" to tell whether or not the tumor can come back after surgery.
The researchers also believe that by testing the levels of B7-H3, they might be able to determine which patients are good candidates for surgery.
"Patients at high risk for failing surgery may not be good candidates for surgery alone," notes Dr. Kwon. "In addition, we may be able to sort out, for patients who don't want any treatment, whose cancers are more likely to benefit from 'watchful waiting.'"
In addition, B7-H3 could become a target for therapy, says Dr. Kwon. "We could block this molecule and make the cancer more responsive to the body's immune response.”
One expert suspects B7-H3 might prove very useful in the future.
"The problem in prostate cancer is that we know we diagnose a lot of prostate cancer, but we know that only a small number of them will go on to really cause a man difficulty," says Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society.
The goal is to find markers that sort prostate cancers into aggressive and less aggressive types, says Dr. Lichtenfeld. "This marker may help us in this process.”
He also believes more biomarkers are yet to be identified.
"Ultimately, when someone is diagnosed with prostate cancer we will take a look at their cancer tissue and look at many of these markers and be able to come up with a profile that gives us much more accurate information about prognosis and treatment," explains Dr. Lichtenfeld.
Another expert is not so sure the finding is a great advance.
"What needs to be done is [for the researchers] to show us what this marker tells us that we don't already know from other markers," says Dr. Anthony D'Amico, chief of radiation oncology at Brigham and Women's Hospital in Boston.
"We can't tell from this study whether this marker is providing new information or information that's already contained in other markers," says Dr. D’Amico.
If the marker does add something new it would be important, he says. "Any marker that provides us with additional information about prognosis sets itself up as a target for future therapies,” he notes.
Always consult your physician for more information.
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Prostate cancer is the most common cancer among men, excluding skin cancer.
American Cancer Society estimates for 2007 include 218,890 new cases of prostate cancer in the US.
Year 2007 estimates include 27,050 deaths occurring from prostate cancer in the US alone, making it the second leading cause of cancer death in men.
All men are at risk for prostate cancer. The risk increases with age, and family history also increases the risk.
African-American men have about a 60 percent higher incidence rate of prostate cancer than Caucasian men, and nearly a two-fold higher mortality rate than Caucasian men.
There are usually no specific signs or symptoms of early prostate cancer - which is why prostate screening is so important.
An annual physical examination, prostate-specific antigen (PSA) blood test, and digital rectal exam (DRE) provide the best chance of identifying prostate cancer in its earliest stages.
The following are the most common symptoms of prostate cancer.
However, each individual may experience symptoms differently.
Symptoms may include:
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weak or interrupted flow of urine
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urinating often (especially at night)
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difficulty urinating or holding back urine
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inability to urinate
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pain or burning when urinating
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blood in the urine or semen
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nagging pain in the back, hips, or pelvis
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difficulty having an erection
The symptoms of prostate cancer may resemble other conditions or medical problems. Always consult your physician for a diagnosis.
As a man gets older, his prostate may grow bigger and obstruct the flow of urine, or interfere with sexual function.
An enlarged prostate gland - a condition called benign prostatic hyperplasia, or BPH - may require treatment with medicine or surgery to relieve symptoms.
This common benign prostate condition, which is not cancer, can cause many of the same symptoms as prostate cancer.
Always consult your physician for more information.
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