Shark cancer claims rubbished

Shark cartilage is not fully proven as a cancer treatment

Products made from shark cartilage should not be marketed as a "cancer cure", US experts say.

The market for shark cartilage has been fostered by the myth that sharks do not suffer from cancer, the American Association for Cancer Research conference was told.

In fact, according to scientists, sharks and related fish can develop a wide variety of benign and cancerous tumours.

They can even get cancers in the very cartilage being marketed as a cancer cure.

The research was carried out at the Johns Hopkins University and George Washington Univeristy in the US.

By looking at a register of tumours in animals, they found 40 cases of tumours in sharks and related animals like skates and rays.

Professor Gary Ostrander, Hopkins professor of biology and comparative medicine, said: "People are out there slaughtering sharks and taking shark cartilage pills based on very faulty data and no preventative studies to show that it works.

"That's not only giving desperate patients false hope based on misinterpreted data, it's also taking a top level predator out of an ecosystem, which could cause major disruptions."

Growing blood vessels

Advocates of shark cartilage say that it can hold back angiogenesis - which is a tumour's ability to help its growth by encouraging new blood vessels to form.

Cartilage naturally has few blood vessels, so scientists looking for natural chemicals in tissue which might hamper angiogenesis looked here.

And there is some evidence that shark cartilage can indeed slow down tumour growth.

However, Professor Ostrander said: "Chicken cartilage , human cartilage and all other kinds of tissue have anti-angiogenic factors in them.

"Yes, there may be some others in shark, but to suggest they will be a cure-all for cancer based on the available data is bogus."

The myth that sharks are not susceptible to cancer probably developed, he said, from the likelihood that sharks with tumours were far less likely to be caught.