Complementary and alternative therapies are increasingly used in the United States by
individuals diagnosed with cancer. PC-SPES is a multiherb dietary supplement used by
many patients with prostate cancer (CaP). The wide acceptance of PC-SPES for hormone-
naive and end-stage CaP relates to clinical trials demonstrating significant efficacy and low
toxicity. Although the clinical efficacy of PC-SPES is highly encouraging, its scientific basis
has progressed more slowly. This article describes our understanding of the in vitro …