Clinical and biologic activity of an estrogenic herbal combination (PC-SPES) in prostate cancer.
BACKGROUND
Herbal mixtures are popular alternatives to demonstrated therapies. PC-SPES, a commercially available combination of eight herbs, is used as a nonestrogenic treatment for cancer of the prostate. Since other herbal medicines have estrogenic effects in vitro, we tested the estrogenic activity of PC-SPES in yeast and mice and in men with prostate cancer.


METHODS
We measured the estrogenic activity of PC-SPES with transcriptional-activation assays in yeast and a biologic assay in mice. We assessed the clinical activity of PC-SPES in eight patients with hormone-sensitive prostate cancer by measuring serum prostate-specific antigen and testosterone concentrations during and after treatment.


RESULTS
In complementary yeast assays, a 1:200 dilution of an ethanol extract of PC-SPES had estrogenic activity similar to that of 1 nM estradiol, and in ovariectomized CD-1 mice, the herbal mixture increased uterine weights substantially. In six of six men with prostate cancer, PC-SPES decreased serum testosterone concentrations (P<0.05), and in eight of eight patients it decreased serum concentrations of prostate-specific antigen. All eight patients had breast tenderness and loss of libido, and one had venous thrombosis. High-performance liquid chromatography, gas chromatography, and mass spectrometry showed that PC-SPES contains estrogenic organic compounds that are distinct from diethylstilbestrol, estrone, and estradiol.


CONCLUSIONS
PC-SPES has potent estrogenic activity. The use of this unregulated mixture of herbs may confound the results of standard or experimental therapies and may produce clinically significant adverse effects.
DiPaola
R S
RS
Department of Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick 08901, USA.
Zhang
H
H
Lambert
G H
GH
Meeker
R
R
Licitra
E
E
Rafi
M M
MM
Zhu
B T
BT
Spaulding
H
H
Goodin
S
S
Toledano
M B
MB
Hait
W N
WN
Gallo
M A
MA
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology*; D001940:Breast / Q000187:drug effects; D004365:Drugs, Chinese Herbal / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007989:Libido / Q000187:drug effects; D008297:Male; D051379:Mice; D010936:Plant Extracts / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology*; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000503:physiopathology; D011960:Receptors, Estrogen / Q000187:drug effects*; D012441:Saccharomyces cerevisiae / Q000187:drug effects; D013739:Testosterone / Q000097:blood; D013924:Thrombophlebitis / Q000139:chemically induced; D014599:Uterus / Q000187:drug effects; D015003:Yeasts / Q000187:drug effects
D000972:Antineoplastic Agents, Phytogenic; D004365:Drugs, Chinese Herbal; D010936:Plant Extracts; D011960:Receptors, Estrogen; C114209:herbal preparation PC-SPES; D013739:Testosterone; D017430:Prostate-Specific Antigen