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A New Weapon to Fight Prostate Cancer

November 2005

By Dale Kiefer

Colored urogram of the pelvis of a 60-year-old man with prostate gland cancer. The prostate is below the bladder and should be clear, but due to the presence of a tumor it appears cloudy. The urethra shows narrowing caused by the pressure from the tumor. [click to enlarge]

More Research Needed

Despite the impressive findings showing that isosilybin B inhibited prostate cancer cell growth by 69%, no human studies have been conducted to validate whether prostate cancer patients would see these same kinds of benefits.

Scientists have shown that milk thistle extracts possess anti-cancer actions on human prostate carcinoma in vitro and in vivo. Many of the mechanisms by which silymarin compounds interfere with prostate cancer progression have been identified. The scientists who conducted the most recent study stated that, in addition to isosilybin B, there might be other silymarin compounds that are effective as well. These scientists concluded their presentation of this study by noting that:

“these findings are suggestive that (silymarin) extracts enriched for isosilybin B, or isosilybin B alone, might possess improved potency in prostate cancer prevention and treatment.”

Since silymarin compounds cannot be patented, the National Cancer Institute should sponsor clinical studies in prostate cancer patients to clarify whether these compounds are clinically important in humans. An ideal study would be to evaluate PSA progression (using PSA doubling time values and PSA velocity values) and then institute isosilybin B to see the effect on these biologic parameters. Patients undergoing radical prostatectomy could also be treated prior to surgery with isosilybin B to see the effect on PSA, free PSA, and the histological findings on specimens obtained from tissues removed during the radical prostatectomy procedure.


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