- What is cartilage?
Cartilage is a type of tough, flexible connective tissue that forms parts of the skeleton in many animals. Cartilage contains cells called chondrocytes , which are surrounded by a network of several types of collagen (a fibrous protein ) and proteoglycans , which are combinations of protein and glycosaminoglycans (a type of carbohydrate ).
• What is the history of the discovery and use of cartilage as a complementary or alternative treatment for cancer?
Cartilage from cows (bovine cartilage) and sharks has been studied as a treatment for cancer and other medical conditions for more than 30 years. The mistaken belief that sharks, whose skeletons are made mostly from cartilage, do not develop cancer caused some of the initial interest in cartilage as a possible treatment for cancer. Although malignant tumors are rare in sharks, a variety of cancers have been detected in these animals.
Early studies used extracts of bovine cartilage. The ability of bovine cartilage to reduce inflammation (redness, swelling, pain, and feeling of heat) was first described in the early 1960s. The first report that bovine cartilage contains at least one angiogenesis inhibitor (a substance that blocks the formation of new blood vessels that cancer needs to grow) was published in the mid 1970s. The use of bovine cartilage extracts to treat cancer patients in clinical trials (research studies with people), and the ability of these extracts to kill cancer cells directly and to stimulate animal immune systems, were first described in the mid-to-late 1980s.
The first report that shark cartilage contains at least one angiogenesis inhibitor was published in the early 1980s. There are 2 published reports (1998 and 2005) of clinical trials of shark cartilage as a treatment for cancer (see Question 6 ). The interest in studying shark cartilage results in part from the abundance of cartilage in sharks and from the apparently higher level of antiangiogenic activity in shark cartilage as compared with bovine cartilage.
• What is the theory behind the claim that cartilage is useful in treating cancer?
Three theories have been proposed to explain how cartilage acts against cancer:
• As cartilage is broken down by the body, it releases products that kill cancer cells.
• Cartilage stimulates the body's immune system to kill cancer cells.
• Cartilage produces substances that block angiogenesis .
Based on laboratory and animal studies, there is more support for the third theory than for the first and second theories. Cartilage, a tissue that does not contain blood vessels , is relatively resistant to cancer cells. If the theory that cartilage can prevent angiogenesis is correct, the substances in cartilage that stop the formation of new blood vessels might also help prevent metastasis (the spread of cancer).
• How is cartilage administered?
In animal studies, cartilage products have been administered in a variety of ways: by mouth, in either a liquid or a powdered form; injected into a vein or into the abdomen ; applied to the skin; or placed in slow-release plastic pellets that were surgically implanted .
In studies with people, cartilage products have been given by mouth in liquid, powdered, or pill form; applied to the skin; injected under the skin; or given by enema (injected as a liquid into the rectum ). The dose and duration of cartilage treatment have varied in studies with people, in part because different types of products have been tested.
• Have any clinical trials (research studies with people) been conducted using cartilage?
Since the 1970s, more than a dozen clinical studies of cartilage as a treatment for cancer have been conducted. Results from 5 of these studies have been published in peer-reviewed scientific journals. Although more clinical studies are under way, the evidence to date has not proven the effectiveness of cartilage as a cancer treatment.
One of the 5 published studies compared the use of shark cartilage to a placebo (an inactive substance that looks the same as, and is given the same way as, the substance being tested) in cancer patients. Two of the other published clinical studies evaluated the use of Catrix as a treatment for various cancers. A fourth study looked at Cartilade, a commercially available powdered preparation of shark cartilage, in patients with several types of advanced cancer.
• A randomized clinical trial (a study in which the participants are assigned by chance to separate groups that compare different treatments) studied the use of shark cartilage in patients who had either terminal breast cancer or terminal colorectal cancer . Patients were randomly assigned to receive either shark cartilage or a placebo. There was no difference in the quality of life or survival rate between the two groups.
Other studies have been conducted with Catrix, powdered shark cartilage, and AE¡V941/Neovastat, but the results have not been published in peer-reviewed scientific journals.
Laboratory, animal, and human data provided by the manufacturers have led to several clinical trials of shark cartilage in patients with cancer. People who are interested in taking part in clinical trials should talk with their health care provider.
In addition, the National Cancer Institute (NCI), the National Center for Complementary and Alternative Medicine (NCCAM), and the Office of Cancer Complementary and Alternative Medicine (OCCAM) clinical trials databases offer patients, family members, and health professionals information about research studies that use complementary and alternative medicine . Clinical trials can be found by searching the following:
• The NCI PDQR Clinical Trials Database can be searched using criteria such as cancer type, type of trial, geographic region, trial sponsorship, and/or drug name. This information is also available by calling NCI's Cancer Information Service (1-800-4-CANCER [1-800-422-6237]; TTY: 1-800-332-8615).
• The NCCAM Clinical Trials Web page can be searched by the type of treatment or disease.
• The OCCAM Clinical Trials Web page provides links to the NCI PDQR Clinical Trials Database.
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• Is cartilage approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?
Numerous cartilage products are sold commercially in the United States as dietary supplements . In the United States, dietary supplements are regulated as foods, not drugs. This means that, unless the manufacturer makes specific disease prevention or treatment claims, evaluation and approval by the FDA are not required before the manufacturer can market the product.
Consumers should be aware that dietary supplements may vary a great deal from one batch to another. Dietary supplements are not formally reviewed for manufacturing consistency, and binding agents (substances that make loose mixtures stick together) and fillers may be added during production. Therefore, the result of a particular clinical study may be pertinent only to a particular product from a particular batch made by a specific manufacturer.
In the United States, scientists who plan to conduct clinical research on investigational drugs with humans must file an Investigational New Drug (IND) application with the FDA. To date, IND status has been given to at least 4 groups of investigators to study cartilage as an investigational drug for cancer. Because the existence of an IND application is confidential and can only be disclosed by the applicants, it is not known whether other applications have been made.
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