Prostate Cancer No More Aggressive In Black Men

Posted: October 4, 2007

NEW YORK (Reuters Health) - A new study refutes the long-held belief that African-American men have more aggressive prostate cancer tumors than Caucasian men.

"Previous studies used unmatched prostate cancer patients and inconsistent criteria to show that African-American men have more aggressive cancer than Caucasian men," study leader Dr. Akhouri A. Sinha of the Veterans Affairs Medical Center, Minneapolis, Minnesota, noted in comments to Reuters Health.

The cysteine protease cathepsin B is critical in the development of invasive prostate cancer, but assessment of this enzyme has not been utilized to characterize prostate cancer in African-American men in comparison to Caucasian men, Dr. Sinha and colleagues explain in the September 21 issue of Anticancer Research.

The team matched 25 black and 25 white prostatectomy patients by age, Gleason grade, clinical tumor stage, and serum total prostate specific antigen (PSA) levels before prostatectomy. The patients received equal care within the VA system.

The researchers also measured expression of cathepsin B as well as the endogenous cathepsin B inhibitor, stefin A. As Dr. Sinha explained, "The ratio of cathepsin B and stefin A reaction products in archival prostate sections gives a measure of how aggressive the tumors may be; the most aggressive ones are characterized by a high ratio of cathepsin B to stefin A."

The ratios of cathepsin B to stefin A were similar in tumors of black and white men, all of whom had Gleason score 6 or 7 tumors, the investigators found.

This shows, Dr. Sinha said, that "the biological basis of prostate cancer cell invasion, its progression, and development of aggressiveness is not race-dependent."

Therefore, "the previous conclusion of race-based differences in prostate cancer requires re-evaluation with respect to the role of proteases (such as cathepsin B, matrix metalloproteinase) in invasion and metastasis of cancer cells," the researchers conclude in their report.

The study also found that black prostate cancer patients were less likely than white patients to attend follow appointments with their physician "and this difference was highly significant," Dr. Sinha noted.

"Most likely because of their inadequate follow-up appointments, diagnosis of recurrent cancer was delayed in black men who did not receive timely treatment. In contrast, white patients were four times more likely to receive additional treatment after prostate surgery than black patients," according to Dr. Sinha.

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