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Prostate Cancer Tests Might Miss One In Seven Cases

Traditional screening methods for prostate cancer might overlook the disease in one in seven cases, according to a new study.

In traditional screening for prostate cancer, a physician will take six tissue samples from the prostate. But for this new study, researchers expanded the number of tissue samples to 12.

The additional samples yielded evidence of cancer in 10 of the 74 study subjects.

"That's a substantial portion of cancers that would have been missed if we hadn't done a more extensive set of biopsies," said Robert Bahnson, a study co-author and a professor of surgery and chief of urology at Ohio State University.

This year alone, physicians expect to detect an estimated 198,000 new cases of prostate cancer.

"Somewhere between 10 and 20 percent of the cancers in these men might otherwise be missed by using the traditional biopsy approach."

The study appears in a recent issue of the journal Urologic Oncology.

Bahnson used what's called the extended sector biopsy. Ordinarily, a physician takes six tissue samples from the outer rim of the prostate.

Bahnson took an additional six tissue samples from inside the gland of the 74 subjects. These men underwent biopsies because preliminary tests showed either an elevated level of prostate specific antigen (PSA) and/or a digital rectal exam found a possible abnormality.

"The prostate is like a sphere," Bahnson said. "The area where cancer is most often found is kind of like a horseshoe around the outside." The six additional areas are just inside this horseshoe area.

Forty subjects in the study tested positive for adenocarcinoma -- cancer of the lining or inner surface of an organ. In 10 of these men (13.5 percent of the study group), cancer was found only in one or more of the six additional areas.

Bahnson and his colleagues now use the extended sector biopsy test as a matter of routine, and have reduced the biopsy number to 10 tissue samples.

"Cancer is rarely detected in the inner portion of the prostate," he said.

Detecting prostate cancer in its early stages has gotten easier for doctors and patients alike. The advent of the PSA measurement -- a test used to screen for cancer -- has led to a "tremendous increase in the number of routine biopsies performed each year," Bahnson said.

Also, the age at which cancer is diagnosed has gotten younger, from 71 years in the pre-PSA era to 67 years after the development of the PSA test.

Detecting the number of organ-confined cancers has risen from 13 to 30 percent, also since the advent of the PSA. While using a more extensive biopsy technique won't result in the same kind of jump in detection rates, performing the extended sector biopsy will cut down on a patient's time and cost for treatment.

"One of the reasons for doing a more extensive biopsy is that there is a certain percentage of patients who we bring back for a second biopsy and do find cancer," Bahnson said. "If we can eliminate the need for a second biopsy, all the better for the patient."

Bahnson co-authored the study with Paul Arnold and Theodore Niemann, all of the division of urology at Ohio State.

Support for this research came from The Charles S. & Mary Coen Family Foundation.

[Contact: Robert Bahnson, Holly Wagner ]






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