Prostate cancer no worse in African Americans

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

Previous studies used prostate cancer patients who were not matched to each other for similar characteristics and used inconsistent criteria to show that African-American men have more aggressive cancer than Caucasian men do, study leader Dr. Khouri A. Sinha of the Veterans Affairs Medical Center, Minneapolis, Minnesota, noted in comments to Reuters Health.

Cysteine protease cathepsin B is an enyzme necessary for the development of invasive or aggressive prostate cancer, but this enzyme has not been used to assess invasive characteristics of prostate cancer in African-American men compared with Caucasian men, Sinha and colleagues explain in the medical journal Anticancer Research.

Drawing on the resources of the Minneapolis VA Medical Center, which provides equal medical care to all veterans, Sinha and colleagues matched 25 black and 25 white prostate cancer patients by age, tumor grade, clinical tumor stage and blood levels of serum total prostate specific antigen (PSA) levels before the men underwent prostate surgery.

They also measured expression of cathepsin B as well as the cathepsin B inhibitor produced within the body, stefin A. The ratio of cathepsin B and stefin A reaction products, Sinha explained, provides an estimate of how aggressive the tumors may be. The most aggressive tumors have high levels of cathepsin B compared with stefin A.

Results showed that the ratios of cathepsin B to stefin A were similar in tumors of black and white men, all of whom had tumor grades of 6 or 7, indicating moderate risk tumors, the authors report. This shows, 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 protease enzymes (such as cathepsin B) in the invasion and spread of cancer cells," the authors conclude.

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," 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 Sinh

SOURCE: Anticancer Research, September 21, 2007.