The Chinese herbal preparation denoted PC SPES, a mixture consisting of ext
racts from eight herbs, is being used with increasing frequency by prostate
cancer patients worldwide. Evidence has emerged that PC SPES is an effecti
ve modality that alleviates some symptoms in advanced prostate cancer in a
significant proportion of patients including the cases that failed conventi
onal therapy. This evidence as well as published data that show the effects
of PC SPES in suppressing growth of prostate cancer in animal model studie
s, is reviewed together with the available data on the possible side effect
s of PC SPES. The review also covers in vitro studies that reveal the cell
cycle specificity, induction of apoptosis, effects on androgen receptor and
other molecular and metabolic changes induced by PC SPES that may explain
its anticancer activity. Individual chemical components that are present in
herbs of which PC SPES is composed, known to have antiproliferative, antit
umor, antimutagenic, analgesic and/or differentiation inducing activity, ar
e listed and discussed. The effectiveness of PC SPES in prostate cancer is
explained as due to its complex composition which may target many signal tr
ansduction and metabolic pathways simultaneously thereby eliminating the ba
ck-up or redundant mechanisms that otherwise promote cell survival when sin
gle-target agents are used.