A panel of the US Food and Drug Administration (FDA) said on Wednesday that the drug could reduce the chance of contracting the disease in the short-term for those women at high risk of developing the disease.

But it said it could not fully prevent cancer.

The panel said there may be risks attached to long-term use of the drug, manufactured by British firm Zeneca and already widely used to treat breast cancer cases.

Richard Schilsky of the University of Chicago Medical Center said: "As yet, there is not compelling evidence for prevention.

"There is compelling evidence for reduction of short-term incidence of breast cancer."

Controversy

The FDA is likely to follow the panel's recommendation, meaning Tamoxifen could win a licence as a cancer prevention treatment - the first such against breast cancer - within months.

The issue is not without controversy. A US cancer prevention study was stopped in April when it was not yet finished after scientists said data showed it could halve the chance of healthy women developing the disease.