Contrary to the claims of people who market shark cartilage as a cure for cancer, sharks
contract a wide variety of cancers -- including chondromas [cancers of the cartilage] -- according
to a Johns Hopkins researcher, biologist Gary Ostrander. He told a San Francisco meeting of the
American Association for Cancer Research on April 5th that more than 40 types of tumors have
been documented in sharks and related fishes (like skates and rays). "People are out there
slaughtering sharks and taking their cartilage to make pills based on faulty data, while no studies
have been done to show that it works," Ostrander said.
-- Thomas H. Maugh, II,
LA Times Medical Writer
Sharks Do Get Cancer
Daniel Q. Haney,
AP Medical Editor
2:47 PM EDT; April 5, 2000; San Francisco, CA (AP) -- Actually, sharks do get cancer. The discovery challenges a small industry based on the belief that shark cartilage contains some cancer-fighting substance. Dozens of brands of shark cartilage supplements are sold in drugstores, promoted as treatments for cancer, arthritis, and aging. The stuff is even put in dog biscuits. One of the chief arguments behind this is the idea that sharks don't get cancer.
"That idea is wrong. Sharks do get cancer," said John C. Harshbarger of George Washington University. Harshbarger, who heads the federally-sponsored Registry of Tumors in Lower Animals, described 40 cases of tumors that have been found in sharks and their close cousins -- the skates, rays, and chimerids. Harshbarger presented the data Wednesday at a meeting in San Francisco of the American Association for Cancer Research. He said that most of the cases have long been known to scientists, although he added two new ones -- kidney cancer in a dogfish shark and lymphoma blood cancer in a sandbar shark.
"This is good science that shows us that sharks can get cancer," commented biologist John Coffey of Johns Hopkins University. "I don't think there is any benefit to buying shark cartilage and eating it, any more than I think that eating a rabbit will make me run faster."
Shark cartilage proponents dismissed the latest work as nothing new. "It's true that some sharks get cancer. I said this in my book," said William Lane, author of the 1992 book Sharks Don't Get Cancer. "My publisher thought it would be bad to call it, Almost No Sharks Get Cancer." Still, Lane said, cancer is far less common in sharks that in other ocean creatures.
Harshbarger questions that assertion, too. He said that all of the shark cases reported so far are anecdotal discoveries made mostly by sharp-eyed biologists. No one has ever done a systematic survey of sharks to see how often they get cancer or whether they are less prone to the disease than other fish. In theory, shark cartilage might stop cancer by blocking the growth of new blood vessels, a necessary step in tumor spread. However, biologist Gary K. Ostrander of Johns Hopkins said there is no animal or human research to support its anti-cancer properties. A study published in November 1998 concluded that shark cartilage pills were ineffective in 47 patients with advanced breast, colon, lung, and prostate cancer.
A much larger study will begin later this year at the Mayo Clinic to test shark cartilage on 600 terminally-ill patients with breast and colon cancer. The study will be sponsored by the National Institutes of Health and Lane Labs, a company founded by Lane's son Andrew that sells shark cartilage. Harshbarger said that 23 of the 40 tumors in the registry are in sharks, while the rest are in their close relatives. The bodies of all these creatures contain cartilage but no bone. He said 12 or 13 of the 40 tumors were malignant, while the rest were benign, and six of the malignant tumors were in sharks.
Hank Porterfield, head of Us Too, a prostate cancer support group, said he thinks the latest information is useful for people with cancer who are considering taking supplements. "I've never heard of a case where our patients were helped by it," Porterfield said. "Shark cartilage just doesn't work."
On the Web:
American Association for Cancer Research: www.aacr.org
National Cancer Institute: cancernet.nci.nih.gov/index.html