Do prostate biopsies always tell the full story about prostate cancer?

May 31, 2012 | by City of Hope Staff

Men diagnosed with seemingly slow-growing, non-aggressive prostate cancer are often given the option to avoid treatment — what’s called “watchful waiting” or “active surveillance.” The thinking is that older men are more likely to die from other causes before cancer progresses, and the side effects of treating prostate cancer may outweigh its benefits.

Photomicrograph of invasive prostate adenocarcinoma Photomicrograph of invasive prostate adenocarcinoma. (Photo courtesy of National Institutes of Health)

But Michael Nazmy, M.D., a surgical fellow in the Division of Urology and Urologic Oncology, discovered that many of prostate cancers categorized at “very low risk” are more aggressive than the initial biopsy indicates. He presented his study findings recently at the annual meeting of the American Urological Association.

Nazmy and his colleagues studied nearly 1,300 prostate cancer patients. When they compared the pathology of each removed prostate gland to the pathology of tissues tested through biopsy, their final examination showed that many of the men had cancer that was more aggressive than shown in their initial testing.

The researchers analyzed what’s known as a Gleason score, a way to describe the aggressiveness and abnormality of prostate cancer tissue. Gleason scores range from 2 (least abnormal and aggressive) to 10 (most abnormal and aggressive.) Physicians use Gleason score to recommend treatment strategies.

Men in the study had initial biopsies with a Gleason score of 6. With that score, which is considered low risk, men may choose treatment or watchful waiting. Men in the study chose surgery. But when pathologists tested the cancers after they were removed, more than 36 percent of the men actually had a Gleason score of 7 or higher. A score of 7 would push the patients into a higher-risk category that could suggest choosing treatment over watchful waiting.

Nazmy is cautious about what these results mean for prostate cancer patients. Despite the upgrade in cancer risk of a substantial number of men in the study, he said, more than 90 percent are living five years after surgery.

Only men who had their prostates removed were part of the study, which enabled the researchers to do a complete pathological examination of the gland. Nazmy said, “Further studies and longer follow-up are needed to compare survival rates of patients who chose surgery versus those who did not, and whether diagnostic guidelines or treatment recommendations need to be revised if there is a disparity.”

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