Hormone may protect tumours says research

In collaboration with the Press Association

The hormone oestrogen, which has long been known to fuel the growth of some breast cancers, may also play a second role in protecting cancer cells from the immune system, say scientists.

Under normal conditions immune cells release granules of enzymes, known as granzymes, which enter and kill cancer cells when they are detected.

When oestrogen comes into contact with oestrogen-sensitive breast tissue it encourages the production of a protein called PI-9 which binds to granzymes and prevents them from working.

"It wasn't known that oestrogen could do this in breast cancer cells," said lead researcher Professor David Shapiro. "The amounts of oestrogen required to do this are quite small."

The finding could eventually yield new tests and treatments for breast cancer, said researchers.

The study was conducted by the University of Illinois and is published in the journal Oncogene.