A mushroom widely used in oriental medicine may help fight breast cancer by slowing the growth of tumors and starving them of blood, a study has shown.

Extracts of the fungus, Phellinus linteus, have been used for centuries by Eastern healers, who believe it has the power to rejuvenate and extend life.

Recent research has indicated the mushroom can hold back the growth of skin, lung and prostate cancer cells.

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It is also believed to increase the number of prostate cancer cells killed by the chemotherapy drug doxorubicin.

Working with breast cancer cells, scientists at Indianapolis' Methodist Research Institute found evidence that the mushroom blocks the activity of an enzyme called AKT.

The enzyme, a biological catalyst, is known to control signals that lead to cell growth and the development of new blood vessels feeding tumors.

Cancers need a good blood supply to survive, and send out chemical messages which promote the construction of new blood vessels; scientists are actively looking at ways to block this process.

"We saw a number of positive results from our investigation on aggressive human breast cancer cells,” said Dr. Daniel Sliva, who led the research.

"Those included a lower rate of uncontrolled growth of new cancer cells, suppression of their aggressive behavior and the formation of fewer blood vessels that feed cancer cells essential nutrients.

"We're not yet able to apply this knowledge to modern medicine, but we're excited that we can begin to explain how this ancient medicine works by acting on specific molecules.

"We hope our study will encourage more researchers to explore the use of medicinal mushrooms for the treatment of cancer."

However, Dr. Lesley Walker of Cancer Research in the United Kingdom gave a note of caution.

"Although natural products have been used to develop many important drugs, there is no guarantee that they are all safe or will be effective in the clinic,” she said.

"The results from this study are interesting, but it's certainly too early to advise people to stock up on mushrooms. Further research will be needed before we will know if mushroom extracts can be used to treat cancer patients."