PC-SPES

Definition

PC-SPES is an herbal mixture of eight botanical compounds adapted from traditional Chinese medicine that is used to treat prostate cancer, particularly the forms that do not respond to anti-androgen (hormone) therapy.

Purpose

PC-SPES is an herbal remedy that has been marketed as an over-the-counter drug for the treatment of prostate cancer. Anecdotal evidence of greatly reduced prostate-specific antigen (PSA) levels in patients taking this preparation prompted more formal testing of its effect. Laboratory studies show that PC-SPES has the ability to slow growth of both hormone-sensitive and hormone-insensitive prostate cancer cell lines in the test tube. Studies done with mice that have been implanted with prostate cancer cells indicate that the treatment triggers apoptosis (programmed cell death) in the artificially created hormone-insensitive tumors.

In three clinical studies, PC-SPES has been shown to reduce the serum prostate-specific antigen (PSA) levels in the overwhelming majority of patients suffering from prostate cancer that is unresponsive to androgen therapy. The treatment also reduces prostate acid phosphatase (PAP) levels, an enzyme often elevated with hormone-resistant disease. Treatment with the mixture has been shown to decrease pain, decrease narcotic use, and increase perceived quality of life. Researchers noted bone scan improvements, indicating a reduction in the size of cancer metastases to the bone. The majority of the work with this treatment has been done with patients having advanced disease, characterized by elevated PSA values and Gleason tumor scores.

Description

PC-SPES is a mixture of eight herbs used in Chinese medicine: Ganoderma lucidum, Scutellaria baicalensis, Rabdosia rubescens, Isatis indigotica, Dendranthema morifolium, Seronoa repens (saw palmetto), Panax pseudoginseng, and Glycyrrhiza uralensis (licorice). The "PC" portion of the name stands for prostate cancer, while SPES is Latin for "hope." It has been commercially available since 1996. Manufacturers claim it stimulates the immune system and has anti-tumor activity. The mixture appears to act like estrogen against the tumors, and the side effects are very similar for the two therapies. Yet an analysis using liquid chromatography shows that diethylstilbestrol (DES), estrone, or estradiol are all absent. Additionally, some patients who did not respond to traditional estrogen therapy and alkylating agents did respond to PCSPES, suggesting the mechanism may be unique from that used by DES or estramustine (nitrogen mustard, an alkylating agent). Researchers plan a clinical trial that will directly compare the action of DES and PC-SPES in an effort to compare and contrast the two treatment methods.

Recommended dosage

In the clinical trials, PC-SPES was given either in a dosage of nine tablets per day, three before each mealtime or six tablets a day, three before breakfast and three before dinner. As there was essentially no difference in the anti-tumor effect for the studies, six tablets a day might be a recommended starting dosage.

With herbal medications, such as PC-SPES, potency of herb per tablet and recommended dosage may vary from manufacturer to manufacturer.

Precautions

As PC-SPES has been used only in relatively small clinical trials, the full spectrum of precautions has yet to be determined. The clinical trials required taking the tablets on an empty stomach. Furthermore, despite the small sample size, experience does suggest that patients with known heart disease or stroke tendencies should take this medicine with caution, as it might aggravate these conditions.

Side effects

The side effects for PC-SPES are relatively mild and include, from most frequent to least frequent, nipple tenderness, nausea and vomiting, diarrhea, fatigue, gynecomastia (swelling of the male breast), leg cramps or swelling, angina, increased hot flashes, and blood clots. The incidence of angina occurred in a patient with preexisting coronary disease and was treated by altered heart medications and a reduction in PC-SPES administered.

Interactions

There have been no studies of drug interactions between PC-SPES and other medications. The lack of information about potential adverse interactions suggests caution in adding PC-SPES to other more traditional treatment methods for prostate cancer.

Michelle Johnson, M.S., J.D.

Alkylating agent

—A chemical that alters the composition of the genetic material of rapidly dividing cells, such as cancer cells, causing selective cell death; used as a chemotherapeutic agent to treat prostate cancer.

Androgen

—Hormones responsible for male characteristics that can be necessary for growth of prostate tumors; blocking the action of androgens can treat prostate cancer.

Apoptosis

—An innate process of a cell that brings about its death at the end of the cell's useful lifetime; when malfunctioning can cause cancer.

Gleason Grading System

—A method of predicting the tendency of a tumor in the prostate to metasta-size based on how similar the tumor is to normal prostate tissue; the higher the number the greater the predicted tendency of the tumor to metastasize.

Prostate-specific antigen

—A protein produced by the cells of the prostate that can be elevated in patients suffering from prostate cancer, abbreviated PSA.