In December 2010, a Food and Drug Administration (FDA) advisory panel overwhelmingly agreed that the drugs finasteride (Proscar, generic) and dutasteride (Avodart) should not be prescribed to prevent prostate cancer. GlaxoSmithKline, the maker of Avodart, is seeking FDA approval to label its product as a prostate cancer-prevention drug.
Clinical trials conducted over the past several years concluded that both drugs could reduce the overall risk of prostate cancer by about 25% compared with a placebo. But the same studies also found slightly increased rates of high-grade cancers in men who took the drugs compared with those who took a placebo.
In subsequent analyses, investigators and the drugs' manufacturers tried to demonstrate that the drugs didn't actually cause more aggressive tumors. Rather, they concluded that because the drugs shrink the prostate, the biopsy needle was more likely to strike cancerous tissue if it was there. In short, they said, the drugs weren't causing the cancers but making them more likely to be found.
Panel members weren't convinced. Concerned that otherwise healthy men might develop aggressive prostate cancers, they voted that the drugs' risks outweighed their prevention potential.