Study Finds Prostate Cancer Tumors No More Aggressive in Black Men Than White Men
Black men do not necessarily have more aggressive prostate cancer tumors than white men, particularly when tumor characteristics are similar and measurements of a certain enzyme are the same, according to a study published in the journal Anticancer Research, Reuters Health reports.
Previous research has shown that black men have more aggressive forms of cancer than white men, but such studies did not include patients with similar characteristics and used inconsistent data, lead researcher Khouri Sinha of the Veterans Affairs Medical Center in Minneapolis, Minn., said. For the study, Sinha and colleagues studied 25 black and 25 white prostate cancer patients at the VA Medical Center, which provides equal medical care to all veterans. Researchers matched participants by age, tumor grade, clinical tumor stage and blood levels of serum total prostate specific antigen before they underwent prostate surgery.
Researchers also measured the levels of cysteine protease cathepsin B, an enzyme needed for the development of invasive or aggressive prostate cancer, and stefin A, a cathepsin B inhibitor. The ratio of cathepsin B to stefin A indicates how aggressive tumors might be, according to Sinha. According to the study, researchers found that the ratios were similar in tumors of black and white men, which means that the tumors were considered moderate. Sinha said the results show that the "biological basis of prostate cancer cell invasion, its progression and development of aggressiveness is not race-dependent." Thus, 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," Sinha said.
Sinha also noted a "highly significant" difference between black and white men's use of follow-up care, with white men being four times more likely than blacks to receive additional treatment. He said, "Most likely because of their inadequate follow-up appointments, diagnosis of recurrent cancer was delayed in black men who did not receive timely treatment" (Reuters Health, 10/4).