Scientists have known for more than 150 years that sharks get cancer. And yet the belief persists that the animals don't suffer from the disease. That misconception is promoted in part by those who sell shark cartilage, who claim that the substance will help cure cancer, said David Shiffman, a shark researcher and doctoral student at the University of Miami. But no studies have shown that shark cartilage is an effective treatment, and the demand for the material has helped decimate shark populations, researchers say: Humans kill about 100 million sharks per year, according to a March 2013 study (although many factors contribute to the killing of sharks, including demand for shark-fin soup).

Recently, researchers in Australia noticed a large tumor protruding from the mouth of a great white shark, as well as another mass on the head of a bronze whaler shark. The great white's tumor measured 1 foot (30 centimeters) long and 1 foot wide, according to a study describing the tumors published online in November in the Journal of Fish Diseases.

"This was a very unusual sight as we have never before seen a white shark with tumors," said Rachel Robbins, a study co-author and shark biologist at the Fox Shark Research Foundation, near Adelaide, in southern Australia.

In total, scientists have now documented tumors in at least 23 species of sharks, including the two in the new study, Robbins said. "The main take-home message from the study is that it adds to the growing evidence of tumor formation in sharks, contrary to popular belief that sharks do not suffer from such anomalies," Robbins told LiveScience.

"Sharks get cancer," said Shiffman, who wasn't involved in the study. "Even if they didn't get cancer, eating shark products won't cure cancer.

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Reference:
http://news.discovery.com/animals/sharks/sharks-do-get-cancer-tumor-found-in-great-white-131205.htm#mkcpgn=fbdsc8

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