Women with high oestrogen levels have a reduced rate of breast cancer if they take an osteoporosis drug.

We already know that high oestrogen levels can increase the risk of breast cancer, by encouraging the growth of tumour tissue. Now researchers have found that raloxifene, a drug for osteoporosis, reduces the risk of cancer in these at-risk women.

They studied 7290 postmenopausal women aged 80 or younger who had osteoporosis and no history of breast cancer. One group was given the usual daily dose of raloxifene, another a higher dose, while a third group took a placebo. The women also had their oestrogen levels measured.

The women with the highest oestrogen levels were the most at risk of breast cancer and benefitted the most from raloxifene. This is probably because the drug works by blocking oestrogen levels. So women with high oestrogen levels will benefit, while those with lower levels will not. Raloxifene is not, however, currently licensed to protect against breast cancer. But the researchers suggest that measuring oestrogen levels might be helpful to pinpoint the women who could benefit from raloxifene in the future.

Source

Journal of the American Medical Association January 9 2002