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 collagen (a fibrous protein) and proteoglycans, which are made of protein and carbohydrate.
Products containing cartilage are sold in the United States as dietary supplements. Companies that make cartilage products may not have a process in place to check that all batches they make are exactly the same. This means different batches of a cartilage product may contain different amounts or strengths of ingredients. Different binding agents (substances that make loose mixtures stick together) and fillers may be used in different batches. Therefore, the results of a particular clinical trial may be true only for the batch that was used in the study.
Cartilage from cows (bovine cartilage) and sharks has been studied as a treatment for cancer and other medical conditions for more than 30 years. It was once believed that sharks, whose skeletons are made mostly from cartilage, do not develop cancer. This caused interest in cartilage as a possible treatment for cancer. Although malignanttumors are rare in sharks, cancers have been found in these animals.
Early studies used extracts of bovine cartilage.
Interest in using shark cartilage grew because it was believed that shark cartilage may be more active than bovine cartilage in preventing new blood vessels from being formed. Since a shark's skeleton is made mostly of cartilage, shark cartilage is more plentiful than bovine cartilage.
(See Question 5 for more information about the laboratory and animal studies. See Question 6 for more information about the clinical trials.)
Three theories have been suggested to explain how cartilage acts against cancer:
Based on laboratory and animal studies, the third theory may be most likely. Cartilage does not contain blood vessels, so cancer cannot easily grow in it. It is suggested that a cancer treatment using cartilage may keep blood vessels from forming in a tumor, causing the tumor to stop growing or shrink.
In animal studies, cartilage products have been given by mouth; injected into a vein or the abdomen; applied to the skin; or placed in slow-release plastic pellets that were surgically implanted (put into the body).
In studies with people, cartilage products have been given by mouth; applied to the skin; injected under the skin; or given by enema (injected as a liquid into the rectum). The dose and length of time the cartilage treatment was given was different for each study, in part because different types of products were used.
A number of preclinical studies have been done with cartilage. Preclinical studies in a laboratory or using animals are done to find out if a drug, procedure, or treatment is likely to be safe and useful in humans. These preclinical studies are done before testing in humans is begun. Some research studies are published in scientific journals. Most scientific journals have experts who review research reports before they are published, to make sure that the evidence and conclusions are sound.
Preclinical studies of cartilage looked at whether bovine and shark cartilage products can kill cancer cells in the laboratory, make the immune system more active against cancer, and prevent blood vessels from forming.
The following have been reported from preclinical studies of the effect of powdered cartilage on cancer cells in vitro (outside of the body):
The following have been reported from preclinical studies of the effect of powdered cartilage on the immune system:
A large number of laboratory and animal studies on the effect of powdered cartilage on angiogenesis have been published. The following have been reported from these studies:
The following have been reported from preclinical studies of liquid cartilage products:
Clinical trials are a type of research study that tests how well new drugs or other treatments work in people. Since the 1970s, there have been at least a dozen clinical studies of cartilage as a treatment for cancer.
There has been one randomized clinical trial of cartilage as cancer treatment published in a peer-reviewed scientific journal. This trial compared treatment using a form of shark cartilage to treatment using a placebo (an inactive substance that looks the same as, and is given the same way as, the substance being tested). Patients also received standard care. In 83 patients having either advanced breast or advanced colon cancer, there was no difference in the quality of life or survival rate between the group that received the shark cartilage product and the group that received the placebo.
The following have been reported from clinical trials of powdered cartilage products:
The cancer went into remission (signs and symptoms of cancer went away) in 19 patients and then recurred (came back) in about half of them. Some of these patients also received standard cancer treatment and there was no control group (a group of patients who do not receive the treatment being studied, to show if the treatment being studied makes a difference). For these reasons, the effectiveness of cartilage as a cancer treatment is not proven by this case series.
All but 1 patient had been treated with standard therapy before the trial. The cancer stopped growing in 10 of the patients for 12 weeks or more and then began to grow again. The cancer did not shrink or go into remission in any of the patients.
The following have been reported from clinical trials of liquid cartilage products:
Catrix was given by injection. One patient's cancer went into remission for more than 39 weeks and the other 8 patients did not respond to treatment with Catrix.
For more detailed information about these clinical trials and others that are ongoing or have not fully reported, see the health professional version.
People who are interested in taking part in clinical trials should talk with their health care provider. Information on clinical trials can also be found by searching the following online databases:
The side effects of cartilage treatment are usually mild or moderate.
Nausea, vomiting, and upset stomach are the side effects reported most often from treatment with the shark cartilage product AE–941/Neovastat.
There has been one report of hepatitis occurring in a person who used shark cartilage.
The US Food and Drug Administration (FDA) has not approved cartilage as a treatment for cancer. A number of cartilage products are sold in the United States as dietary supplements. Dietary supplements are products meant to be added to the diet. They are not drugs and are not meant to treat, prevent, or cure diseases. The manufacturer is responsible for ensuring that the product is safe and that the label claims are truthful and not misleading. The FDA does not approve dietary supplements as safe or effective before they are sold.
