Study Supports Change to Prostate Cancer Biopsy
TUESDAY Oct. 2, 2007 -- Adding an extra step to the standard test for prostate cancer might improve treatment for some men, a new study finds.
Doctors now use what's known as the Gleason test -- named for the physician who developed it -- as a major tool in judging how aggressively a prostate cancer should be treated, explained lead researcher Dr. Abhijit A. Patel, a radiation oncologist at Brigham and Women's Hospital in Boston.
His team published its findings in the Oct. 3 issue of the Journal of the American Medical Association.
In the Gleason test, doctors take a biopsy of the cancer and look at the level of disorder displayed by cells in the two largest sections of the sample -- scoring them from 1 (less disorderly) to 5 (more disorderly).
"The less it looks like normal tissue, the more aggressive [the cancer] is," Patel explained. They then add up the two numbers to arrive at a Gleason score. A score of 7 calls for treatment such as radiation therapy, Patel said, while higher scores indicate an even more dangerous tumor.
In the new study, the Brigham and Women's team looked for a third pattern of disorder from another part of the samples. Such disorderly patterns are found in about 5 percent of cases but usually are ignored. The new report included that third pattern in the diagnostic process.
Tests on 2,370 men with prostate cancer showed that men with Gleason score 7 plus this disorderly third pattern had a more rapid increase in prostate-specific antigen (PSA) levels in the blood. PSA indicates prostate tumor growth of the tumor and is the basis of the common PSA diagnostic blood test.
These men should probably receive more aggressive treatment to fight their disease, Patel said, compared to men without this combination of factors.
The time to what physicians call "PSA failure" averaged five years in these men, compared to 6.7 years in men with a Gleason score of 7 but no disorderly third pattern. In fact, the failure time for men with a Gleason score of 7 and the third pattern of disorderly cells was the same as for men whose cancers had a Gleason score of 8 or greater.
"We think these patients should get more therapy," Patel said. "In addition to surgery, they might need hormonal therapy to suppress the activity of testosterone."
Testosterone, the male sex hormone, spurs the growth of prostate cancer.
It's not known yet whether more aggressive treatment for men with the disorderly third pattern will improve their outcomes, since no such study has been done, Patel said.
But the idea does make sense, said Dr. David Berman, an assistant professor of pathology, urology and oncology at the Johns Hopkins University School of Medicine in Baltimore. "In prostate cancer it's difficult to go with things like survival to measure outcome. Biochemical recurrence is the easiest thing you can measure."
The revised Gleason score tested by Patel's group was first proposed several years ago, and has already been adopted by some specialists, Berman noted.
The Hopkins expert is also the lead author of a new report, published in the October issue of Cancer Research, that indicates that the addition of hormone suppression therapy to prostate cancer treatment might bring dangers of its own.
Laboratory studies indicate that hormone suppression therapy could boost the activity of a protein called nestin, which promotes the movement of prostate cancer cells to other parts of the body.
That danger is far from proven, however. "These are early days to make a whole lot of therapeutic recommendations based on it," Berman said.
You can learn more about prostate cancer from the U.S. National Cancer Institute.
Posted: October 2007