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Reviewed By Laura J. Martin, MD
May 26, 2010 -- Hopes that shark cartilage would prove to be a useful treatment for cancer were not borne out in one of the most rigorously designed and executed studies of an alternative therapy ever conducted.
Adding a drug derived from shark cartilage to standard cancer treatments did not improve survival among patients with late-stage lung cancer in the study, funded by the National Cancer Institute (NCI) and the National Center for Complementary and Alternative Medicine (NCCAM).
Shark cartilage has been touted as a potential alternative or complementary cancer treatment for several decades. Dozens of shark cartilage products are sold as dietary supplements, but almost none have been studied in humans.
Testing the Usefulness of Shark Cartilage
The trial examined a carefully formulated and regulated liquid shark cartilage product developed as a drug, rather than one of the commercially available, but unregulated, supplements.
Researchers from multiple academic and community cancer centers in the U.S. and Canada enrolled almost 400 patients with inoperable non-small-cell lung cancer (NSCLC) in the study.
No difference was seen in overall survival, progression-free survival, time-to-disease progression, and tumor response rates between the two groups.
Patients who got the shark cartilage treatment lived for an average of 14.4 months, which was a month less than the average survival of patients who did not take shark cartilage.
The study was published online today and it will appear in the June 16 issue of the Journal of the National Cancer Institute.
"It is clear from these findings that this pharmaceutical-grade shark cartilage extract is not an effective treatment for this cancer," study researcher Charles Lu, MD, tells WebMD.
Shark Cartilage Still Widely Used
Cancer is fueled by the growth of new blood vessels in a process known as angiogenesis. Cartilage contains no blood vessels and has been shown in some lab studies to slow blood vessel growth.
The idea that cartilage may stop or slow the growth of cancer was first proposed in the 1950s by a New York surgeon who also claimed that powdered cow cartilage could speed surgical wound healing.
The 1992 publication of the book Sharks Don't Get Cancer, by nutrition researcher William Lane, PhD, and Lane's appearance on the news magazine show 60 Minutes the next year, led to the wide use of cartilage supplements among cancer patients.
Jeffrey White, MD, director of the NCI's Office of Cancer Complementary and Alternative Medicine, tells WebMD that shark cartilage supplements remain a popular alternative or complementary treatment among cancer patients.
Even though the shark cartilage study proved disappointing, White says other alternative treatments still show promise for the treatment of cancer. Among them, he says, are green tea extract and curcumin, which is derived from the spice turmeric.
"Just as with shark cartilage, there are many challenges involved in studying these treatments," he says. "But I believe these challenges can be met."
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Charles Lu, associate professor, department of thoracic and head and neck medical oncology, University of Texas M.D. Anderson Cancer Center.
Jeffrey White, MD, director, Office of Cancer Complementary and Alternative Medicine, National Cancer Institute, Bethesda, Md.
News release, Journal of the National Cancer Institute.
American Cancer Society: "Shark Cartilage."
National Cancer Institute: "Questions and Answers About Cartilage."
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