NOTE: The information in this summary is no longer being updated and is provided for reference purposes only.
PC-SPES is a mixture of herbs that was sold as a complementary and alternative medicine (CAM) treatment for people with prostate cancer. The mixture contains these 8 herbs:
PC-SPES was taken off the market because some batches were found to contain prescription medicines in addition to the herbs. Clinical trials of PC-SPES that were underway were stopped. There are products being sold now as substitutes for PC-SPES, but they are not the same mixture. Since the only company licensed to make PC-SPES is no longer in business, PC-SPES is not legally available in the United States.What is the history of the discovery and use of PC-SPES as a complementary and alternative treatment for cancer?
Most of the herbs in PC-SPES have been used in traditional Chinese medicine (TCM) for many health problems, including prostate problems, for hundreds of years. A chemist in New York and a doctor/herbalist in China worked together to create the mixture. In 1997, a company was formed to make PC-SPES and sell it in the United States without a prescription. Interest in PC-SPES grew, and researchers began looking at it. Tests found that some batches of PC-SPES contained one or more of the following drugs, which are not found in nature:
Because these drugs are to be used only by prescription and could be harmful to some people, PC-SPES was taken off the market in 2002.What is the theory behind the claim that PC-SPES is useful in treating cancer?
In lab tests, each herb used in PC-SPES has been reported to help keep cancer cells from growing or to help prevent cell damage that can lead to cancer and other diseases.
PC-SPES was reported to slow the growth of prostate cancer but did not cure it. It is not known how PC-SPES works in the body. Some of the herbs in the mixture contain phytoestrogens, which are estrogen-like substances found in plants. Estrogen can cause the testicles to stop making testosterone, which makes some prostate cancers grow. Patients' responses to PC-SPES were similar to responses to estrogen therapy using DES. The DES found in some batches of PC-SPES, however, may not have been enough to cause all of the estrogen-like effects that were seen in users of the mixture. There is some evidence that the mixture works in a different way than DES does, and that PC-SPES alone (without DES in it) may fight prostate cancer.
PC-SPES has also shown anticancer effects on prostate cancers that do not depend on testosterone and on other types of cancer. This suggests that PC-SPES may have anticancer qualities other than its estrogen-like effects.How is PC-SPES administered?
PC-SPES is taken by mouth in capsules.Have any preclinical (laboratory or animal) studies been conducted using PC-SPES?
Studies of PC-SPES in test tubes and using rats showed that it might keep cancer cells from growing. These studies were done, however, before it became known that some batches of the product contained unlisted prescription medicines. Also, the product was not standardized (different batches of PC-SPES were found to contain different strengths of the herbal ingredients). For these reasons, the results of the lab tests and animal studies are not considered to be good evidence.Have any clinical trials (research studies with people) of PC-SPES been conducted?
Clinical trials of PC-SPES had begun before the product was taken off the market. In these trials, PC-SPES was reported to improve quality of life, reduce pain, and lower PSA (prostate specific antigen) levels in patients with prostate cancer. Rising PSA levels can be a sign that prostate cancer is growing.
After it was learned that some batches of PC-SPES contained prescription medicines, ongoing studies were stopped and previous study results came into question. The responses reported in the studies may have been caused by the prescription medicines that were in the PC-SPES, as well as by the herbal ingredients. Also, since different batches of PC-SPES contained different ingredients, the studies cannot easily be compared.Have any side effects or risks been reported from PC-SPES?
Common side effects were the same as those reported with estrogen therapy:
There were other, less common, side effects:
PC-SPES may also change the way drugs, including anticancer drugs, work in the body. It may cause drugs to be more or less effective, or cause effects on the body that are not expected.Is PC-SPES approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?
The U.S. Food and Drug Administration has not approved PC-SPES for use in cancer treatment. It is not legally sold in the United States.
Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.
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Purpose of This Summary
This PDQ cancer information summary has current information about the use of PC-SPES in the treatment of people with cancer. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.
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Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Updated") is the date of the most recent change.
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A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
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PDQ® Integrative, Alternative, and Complementary Therapies Editorial Board. PDQ PC-SPES. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/about-cancer/treatment/cam/patient/pc-spes-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389430]
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Complementary and alternative medicine (CAM)—also called integrative medicine—includes a broad range of healing philosophies, approaches, and therapies. A therapy is generally called complementary when it is used in addition to conventional treatments; it is often called alternative when it is used instead of conventional treatment. (Conventional treatments are those that are widely accepted and practiced by the mainstream medical community.) Depending on how they are used, some therapies can be considered either complementary or alternative. Complementary and alternative therapies are used in an effort to prevent illness, reduce stress, prevent or reduce side effects and symptoms, or control or cure disease.
Unlike conventional treatments for cancer, complementary and alternative therapies are often not covered by insurance companies. Patients should check with their insurance provider to find out about coverage for complementary and alternative therapies.
Cancer patients considering complementary and alternative therapies should discuss this decision with their doctor, nurse, or pharmacist as they would any type of treatment. Some complementary and alternative therapies may affect their standard treatment or may be harmful when used with conventional treatment.
It is important that the same scientific methods used to test conventional therapies are used to test CAM therapies. The National Cancer Institute and the National Center for Complementary and Integrative Health (NCCIH) are sponsoring a number of clinical trials (research studies) at medical centers to test CAM therapies for use in cancer.
Conventional approaches to cancer treatment have generally been studied for safety and effectiveness through a scientific process that includes clinical trials with large numbers of patients. Less is known about the safety and effectiveness of complementary and alternative methods. Few CAM therapies have been tested using demanding scientific methods. A small number of CAM therapies that were thought to be purely alternative approaches are now being used in cancer treatment—not as cures, but as complementary therapies that may help patients feel better and recover faster. One example is acupuncture. According to a panel of experts at a National Institutes of Health (NIH) meeting in November 1997, acupuncture has been found to help control nausea and vomiting caused by chemotherapy and pain related to surgery. However, some approaches, such as the use of laetrile, have been studied and found not to work and to possibly cause harm.
The NCI Best Case Series Program which was started in 1991, is one way CAM approaches that are being used in practice are being studied. The program is overseen by the NCI's Office of Cancer Complementary and Alternative Medicine (OCCAM). Health care professionals who offer alternative cancer therapies submit their patients' medical records and related materials to OCCAM. OCCAM carefully reviews these materials to see if any seem worth further research.
When considering complementary and alternative therapies, patients should ask their health care provider the following questions:
National Center for Complementary and Integrative Health (NCCIH)
The National Center for Complementary and Integrative Health (NCCIH) at the National Institutes of Health (NIH) facilitates research and evaluation of complementary and alternative practices, and provides information about a variety of approaches to health professionals and the public.
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CAM on PubMed
NCCIH and the NIH National Library of Medicine (NLM) jointly developed CAM on PubMed, a free and easy-to-use search tool for finding CAM-related journal citations. As a subset of the NLM's PubMed bibliographic database, CAM on PubMed features more than 230,000 references and abstracts for CAM-related articles from scientific journals. This database also provides links to the websites of over 1,800 journals, allowing users to view full-text articles. (A subscription or other fee may be required to access full-text articles.)
Office of Cancer Complementary and Alternative Medicine
The NCI Office of Cancer Complementary and Alternative Medicine (OCCAM) coordinates the activities of the NCI in the area of complementary and alternative medicine (CAM). OCCAM supports CAM cancer research and provides information about cancer-related CAM to health providers and the general public via the NCI website.
National Cancer Institute (NCI) Cancer Information Service
U.S. residents may call the Cancer Information Service (CIS), NCI's contact center, toll free at 1-800-4-CANCER (1-800-422-6237) Monday through Friday from 9:00 am to 9:00 pm. A trained Cancer Information Specialist is available to answer your questions.
Food and Drug Administration
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Last Revised: 2015-01-07
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