Scientists Have made a discovery that shark cartilage contains some cancer-fighting substance.
Dozens of brands of shark cartilage are sold in drugstores, used as treatments for cancer, arthritis and aging. The stuff is even put in dog biscuits.
Some People believe that sharks don't get cancer, "That idea is wrong. Sharks do get cancer," said John Harshbarger of George Washington University.
Harshbarger, who heads the federally sponsored Registry of growths in Lower Animals. he has described 40 cases of growths that have been found in sharks and their close cousins, the skates, rays and chimerids.
Harshbarger presented the data April 7th 2000 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.
For Many years the scientific community has believed that that sharks don't get cancer. Recent studies show on rare occasion sharks do get cancer. Regardless believers in shark cartilage therapy still believe.
"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 to see if sharks are less prone to cancer than other fish.