Better Prostate Cancer Screening Test May Be on Horizon

Dec. 6, 2000 -- A man's PSA level -- how much prostate specific antigen he has in his blood -- has long been considered the best indicator of whether he has, or is likely to get, prostate cancer. But now there is evidence that screening for additional molecules could make the test even more sensitive.

Swedish researchers comparing newly-diagnosed patients with healthy men found that blood levels of certain growth factors were linked to prostate cancer.

Alicja Wolk, PhD, an associate professor in the department of medical epidemiology at Stockholm's Karolinska Institute, was inspired to take a closer look at these growth factors and their connection to prostate cancer when some of her earlier findings contradicted those of another research team.

In her study, published in the Dec. 2, 2000 issue of The Lancet, blood was collected and analyzed from about 200 men with newly-diagnosed, but not yet treated, prostate cancer. Their results were then matched with those from healthy men of the same age.

Wolk and colleagues looked at the effect of growth factors in patients with different PSA levels. They found that certain growth factors were increased while others were decreased in men with prostate cancer. But more importantly, they found that these growth factors were associated with a higher risk of prostate cancer even when PSA levels were normal.

What all this means, says Wolk, is that growth factor screening may better identify high-risk patients before they develop cancer, and before subjecting them to biopsies or other invasive tests. For example if a man has a normal or low PSA level but specific growth factor levels, his doctor may decide to test him further. Also, Wolk says, his doctor may take precautions such as more frequent screening tests.

But according to H. Ballentine Carter, MD, a growth factor researcher not involved in this particular study, "although these are interesting findings and it's worth investigating further, the data are insufficient to suggest that [growth factor] screening would be useful." It could even be argued, he tells WebMD, that having cancer causes the change in growth factor levels, and not the other way around. Carter is professor of urology and oncology at The Johns Hopkins University School of Medicine in Baltimore, Md.

Wolk agrees that it's far too early to consider widespread growth factor screening when the precise relationship to prostate cancer is not very clear. "The message is that maybe this will have important implications, but it's too early to judge. There is some hope that [this will enable] better diagnostic tools, and we are collecting data. But it takes time."

Right now, her team is looking more closely at what the various growth factors levels mean. "There are already drugs available that can influence [growth factor] levels, but do we want to? We need a lot more, specific information," she says.