BRUSSELS (Reuters) - Cancer patients buying shark cartilage capsules as a treatment for the disease are wasting their money, a cancer expert said on Friday.

Dr Lene Adrian, of Copenhagen University Hospital in Denmark, said that the supplement had no effect when it was tested on Danish breast cancer patients.

"There was no evidence that the therapy had any benefit and I would not advise patients to use it," she told the European Breast Cancer conference on Friday.

Shark cartilage has been sold as an alternative treatment for cancer since the early 1990s when a book entitled "Sharks Don't Get Cancer" by William Lance was published. It suggested that a protein in shark's cartilage kept the fish from getting cancer by blocking the development of small blood vessels that cancer cells need to survive and grow. The idea spawned a market for shark cartilage supplements that is estimated to be worth $50 million a year.

Researchers have since discovered that sharks do get cancer but they have a lower rate of the disease than other fish and humans.

Danish researchers tested the treatment on 17 women with advanced breast cancer that had not responded to other treatments. The patients took 24 shark cartilage capsules a day for three months, but the disease still progressed in 15 and one developed cancer of the brain.

The cancer did stabilize in one women but Adrian said that is not unusual in patients with breast cancer that has spread to another part of the body.

"The evidence that shark cartilage has no place in cancer treatment is growing stronger. I would not recommend it, since is has no convincing effect, it produces gastrointestinal side-effects and it is expensive," she said.