Cancer of the womb is the fourth most common cancer in women and tends to occur after the menopause.

BBC: Womb cancer deaths 'are rising'

Professor Coombes said switching drugs also seemed to avoid the side-effects of long-term tamoxifen therapy, such as cancer of the womb and deep vein thrombosis.

BBC: Breast cancer drug 'cuts deaths'

The drug does cause side-effects in some patients, including, rarely, cancer of the lining of the womb, but the scientists said that the increased chance of preventing breast cancer returning far outweighed the risk.

BBC: Breast cancer

From the 1970s to 1996 the incidence of womb cancer stayed roughly the same at about 13.7 cases for every 100, 000 women in the UK. It now stands at 19.6 per 100, 000, a 43% increase.

BBC: Womb cancer deaths 'are rising'

In women, the cancer may have spread to the womb, ovaries, and other parts of the reproductive system.

BBC: Bladder cancer