Yes, these 5 alpha-Reductase Inhibitors did reduce Prostate cancer occurrence,
but in those where it did occur, it seems to be high grade when exposed to these drugs.
That is why the advisory Committee felt that these were not the best as a prevention intervention!
Vitamin E, on the other end, at 400 IU (a high dose), increased the risk of prostate cancer!
When it comes to Saw Palmetto, Wikipedia adds:
"It is also an expectorant, and controls irritation of mucous tissues. It has proved useful in irritative cough, chronic bronchial coughs, whooping-cough, laryngitis, acute and chronic, acute catarrh, asthma, tubercular laryngitis, and in the cough of phthisis pulmonalis. Upon the digestive organs it acts kindly, improving the appetite, digestion, and assimilation. However, its most pronounced effects appear to be those exerted upon the urino-genital tracts of both male and female, and upon all the organs concerned in reproduction. It is said to enlarge wasted organs, as the breasts, ovaries, and testicles, while the paradoxical claim is also made that it reduces hypertrophy of the prostate. Possibly this may be explained by claiming that it tends toward the production of a normal condition, reducing parts when unhealthily enlarged, and increasing them when atrophied.[4]Saw palmetto extract is the most popular herbal treatment for benign prostatic hyperplasia,[5] a common condition in older men. Early research indicated that the extract is well-tolerated and suggested "mild to moderate improvement in urinary symptoms and flow measures."[5][6] Later trials of higher methodological quality indicated no difference from placebo.[7][8] Questions of adequate blinding and delivery of any active ingredients remain.[9] The latest Cochrane Database review (2009) concludes that "Serenoa repens was not more effective than placebo for treatment of urinary symptoms consistent with BPH."[1]
A 2001 study published in JAMA (The Journal of the American Medical Association) reported on a double-blind study study that eleven North American clinics conducted on 369 men. The study found that saw palmetto fruit extract failed to reduce urinary tract symptoms more than placebo.[10] Men in the experimental group experienced a 2.20 point drop in their American Urological Assn. Symptom Index (AUASI) score. However, men in the placebo group saw a 2.99 point drop. The Los Angeles Times reports, “42.6% of the men in the extract group saw their AUASI scores fall by at least three points; 44.2% of the men in the placebo group saw the same degree of benefit.” The study was funded by several offices within the NIH, including the National Center for Complementary and Alternative Medicine.”[11]
Inhibition of both forms of 5-alpha-reductase with no reduction in cellular capacity to secrete prostate-specific antigen is indicated.[12][13][14][15] Other proposals for mechanisms of action include interfering with dihydrotestosterone binding to the androgen receptor, relaxing smooth muscle tissue similarly to alpha antagonist drugs, and acting as a phytoestrogen.[16][17]
Limited in vitro and animal model studies suggest possible anti-tumor activity and potential for use in the treatment of cancer.[12][18][19] These results have not been substantiated with human trials.
Saw palmetto extract has been suggested as a potential treatment for male pattern baldness.[20]" wikipedia
