Some experiments have shown that some forms of shark cartilage possess a modest ability to slow the growth of new blood vessels in laboratory cell cultures and in animals, but the effects on humans are not known. Interest in shark cartilage grew after a television news magazine aired a segment in 1993 that showed patients with advanced cancer in Cuba who had gone into remission after being treated with shark cartilage. The results of the study were never published in a peer-reviewed medical journal, and the National Cancer Institute (NCI) later concluded the results of the Cuban study were "incomplete and unimpressive."
Mayo Clinic Oncologist Charles L. Loprinzi, M.D., and his colleagues in the North Central Cancer Treatment Group (NCCTG) designed and conducted a randomized, placebo-controlled, double-blind clinical trial to investigate the efficacy associated with shark cartilage as a treatment for breast and colorectal cancer.
Toxicity related to shark cartilage resulted in significant trial drop out after one month. There was no suggestion that shark cartilage caused any improvement in overall survival nor any significant improvement in quality of life. In fact, some quality of life measurements tended to worsen among patients treated with shark cartilage.
The authors conclude, "shark cartilage did not demonstrate any efficacy in patients with advanced breast or colorectal cancers."
Article: "Evaluation of Shark Cartilage in Patients with Advanced Cancer: A North Central Cancer Treatment Group Trial," Charles L. Loprinzi, Ralph Levitt, Debra Barton, Jeff Sloan, Pam Atherton, Denise Smith, Shaker Dakhil, Dennis Moore, Jr., James E. Krook, Kendrith M. Rowland, Jr., Miroslaw Mazurczak, Alan Berg, George Kim, CANCER; Published Online: May 23, 2005 (DOI: 10.1002/cncr.21107); Print Issue Date: July 1, 2005.