Cancer: Bovine and Shark Cartilage

by National Cancer Institute

Overview

Cartilage is a type of tough, flexible connective tissue.

Cartilage from cows (bovine cartilage) and sharks has been studied as a treatment for cancer and other medical conditions for more than 30 years.

Laboratory and animal studies have looked at whether of bovine and shark cartilage products can kill cancer cells, make the immune system more active against cancer, and prevent the body from making the new blood vessels that a tumor needs to grow.

Clinical trials (research studies with people) are under way to study cartilage as a cancer treatment for humans).

Studies to date have not proven cartilage to be an effective treatment for cancer in people.

The US Food and Drug Administration (FDA) has not approved cartilage as a treatment for cancer.

Questions and Answers About Cartilage (Bovine and Shark)

1. 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 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.

2. 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. 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 malignant tumors are rare in sharks, cancers have been found in these animals.

Early studies used extracts of bovine cartilage.

• In the 1960s, it was first reported that bovine cartilage decreased inflammation (redness, swelling, pain, and feeling of heat).

• In the 1970s, it was first reported that bovine cartilage contains a substance that blocks angiogenesis (the forming of new blood vessels). If blood vessel growth into a tumor can be blocked, the tumor will stop growing or shrink.

• In the 1980s, researchers first described laboratory and animal studies and clinical trials (research studies in people) testing bovine cartilage as a treatment for cancer.

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.

• In the 1980s, it was first published that shark cartilage contains a substance that blocks blood vessel growth.

• In 1998 and 2005, there were published reports of clinical trials of shark cartilage as a treatment for cancer.

3. What is the theory behind the claim that cartilage is useful in treating cancer?

Three theories have been suggested to explain how cartilage acts against cancer:

• As cartilage is broken down by the body, it releases products that kill cancer cells.

• Cartilage increases the action of the body's immune system to kill cancer cells.

• Cartilage makes substances that block tumor angiogenesis (the growth of new blood vessels that feed a tumor and help it grow).

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.

4. How is cartilage administered?

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.

5. Have any preclinical (laboratory or animal) studies been conducted using cartilage?

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 has been reported from preclinical studies of the effect of cartilage on cancer cells:

In a published laboratory study, a powdered form of bovine cartilage called Catrix slowed the growth of human cancer cells by half or more. It is not clear if Catrix had this effect only on cancer cells, because its effect the growth of normal cells was not tested. It is also not known if the dose used in the laboratory study could safely be used in people.

• In a laboratory study, a liquid form of shark cartilage called AE-941/Neovastat was reported to stop the growth of a number of cancer cell types. The results, however, have not been published in a scientific journal.

• In a published laboratory study of powdered shark cartilage, there was no effect on the growth of human astrocytoma cells (cancer cells that begin in the brain or spinal cord).

• In a published animal study, powdered shark cartilage given by mouth to mice and rats decreased the growth of gliosarcomas, a type of brain cancer.

• In a published animal study, two powdered shark cartilage products (Sharkilage and MIA Shark Powder) did not stop the growth or spread of a type of skin cancer.

The following has been reported from preclinical studies of the effect of cartilage on the immune system:

• One published study reported that Catrix injected into mice caused their immune systems to be more active. This effect did not happen when Catrix was given by mouth.

• Other laboratory and animal studies have been done on the effect of cartilage on the immune system, but they have not been published in scientific journals.

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