This complementary and alternative medicine (CAM) information summary provides an overview of the use of PC-SPES as a treatment for cancer. The summary includes a brief history of PC-SPES research, the results of clinical trials, and possible adverse effects of PC-SPES. Included in this summary is a discussion of the contamination of PC-SPES and its withdrawal from avenues of distribution.

This summary contains the following key information:

• PC-SPES is a patented mixture of eight herbs.
• PC-SPES was sold as a dietary supplement to support and promote healthy prostate function.
• Each herb used in PC-SPES has been reported to have anti-inflammatory, antioxidant, or anticarcinogenic properties.
• PC-SPES was recalled and withdrawn from the market because certain batches were contaminated with Food and Drug Administration–controlled prescription drugs.
• The manufacturer is no longer in operation, and PC-SPES is no longer being made.
• There is evidence from both laboratory and animal studies to suggest that PC-SPES had some effect in inhibiting prostate cancer cell growth and prostate-specific antigen (PSA) expression, but it is not known whether these results were caused by contaminants such as diethylstilbestrol (DES), which is an estrogenic compound, the herbs in PC-SPES, or their combination.
• Evidence from clinical trials has shown that PC-SPES lowers PSA and testosterone levels in humans, but it is not known whether these results were caused by contaminants, the herbs in PC-SPES, or their combination.
• There is some evidence to suggest that PC-SPES has some anticancer effects that are not related to estrogen-like activity.
• Although there are products that claim to be substitutes for PC-SPES, they are not the patented original formulation. Few of these products have been the subject of laboratory or clinical trials reported in the peer-reviewed medical literature.

Glossary Terms

An unwanted side effect of treatment.

Having to do with reducing inflammation.

Having to do with preventing or delaying the development of cancer.

A substance that protects cells from the damage caused by free radicals (unstable molecules made by the process of oxidation during normal metabolism). Free radicals may play a part in cancer, heart disease, stroke, and other diseases of aging. Antioxidants include beta-carotene, lycopene, vitamins A, C, and E, and other natural and manufactured substances.

A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord.

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.

A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called clinical study.

Forms of treatment that are used in addition to (complementary) or instead of (alternative) standard treatments. These practices generally are not considered standard medical approaches. Standard treatments go through a long and careful research process to prove they are safe and effective, but less is known about most types of CAM. CAM may include dietary supplements, megadose vitamins, herbal preparations, special teas, acupuncture, massage therapy, magnet therapy, spiritual healing, and meditation. Also called CAM.

A product that is added to the diet. A dietary supplement is taken by mouth, and usually contains one or more dietary ingredient (such as vitamin, mineral, herb, amino acid, and enzyme). Also called nutritional supplement.

A synthetic form of the hormone estrogen that was prescribed to pregnant women between about 1940 and 1971 because it was thought to prevent miscarriages. Diethylstilbestrol may increase the risk of uterine, ovarian, or breast cancer in women who took it. It also has been linked to an increased risk of clear cell carcinoma of the vagina or cervix in daughters exposed to diethylstilbestrol before birth. Also called DES.

Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition. Also refers to a substance that alters mood or body function, or that can be habit-forming or addictive, especially a narcotic.

A type of hormone made by the body that helps develop and maintain female sex characteristics and the growth of long bones. Estrogens can also be made in the laboratory. They may be used as a type of birth control and to treat symptoms of menopause, menstrual disorders, osteoporosis, and other conditions.

Research done in a laboratory. These studies may use test tubes or animals to find out if a drug, procedure, or treatment is likely to be useful. Laboratory studies take place before any testing is done in humans.

A mixture of eight herbs that has been sold as a dietary supplement and promoted as a way to keep the prostate healthy and to treat prostate cancer. PC-SPES has been studied in the treatment of prostate cancer, but has been taken off the market in the U.S. because of safety concerns.

A doctor's order for medicine or another intervention.

A gland in the male reproductive system. The prostate surrounds the part of the urethra (the tube that empties the bladder) just below the bladder, and produces a fluid that forms part of the semen.

A substance produced by the prostate. It may be found in higher levels in the blood of men who have prostate cancer, benign prostatic hyperplasia, infection or inflammation of the prostate. Also called PSA.

A hormone that promotes the development and maintenance of male sex characteristics.