The US Food and Drug Administration Friday cleared the use of Eli Lilly’s osteoporosis drug Evista (raloxifene) for cutting the risk of breast cancer in postmenopausal women. Evista is only the second drug approved to reduce the risk of breast cancer after tamoxifen and follows a thumbs-up from the drug regulator’s scientific advisory committee towards the end of July.

Specifically, the so-called selective estrogen receptor modulator can now be used in two groups of postmenopausal women, those with osteoporosis and those at high risk of developing invasive breast cancer.

But the agency has also issued a strong warning that "because Evista can cause serious side effects, the benefits and risks should be carefully evaluated for each individual woman." The compound has been linked to blood clots and stroke, and women with a history of blood clots are precluded from treatment. The product's label was updated earlier this year after a trial showed an increase in death due to stroke in patients receiving Evista.

Evista was first approved in 1997 for the prevention of osteoporosis in postmenopausal women and, in 1999, for the treatment of postmenopausal women with osteoporosis. Over the last 10 years Lilly has embarked on a major clinical trial programme involving more than 15,000 postmenopausal women, which showed that Evista cut the risk of invasive breast cancer between 44% and 71%. A fourth clinical trial in 19,750 postmenopausal women at high risk for developing breast cancer compared Evista to tamoxifen and showed the risk of developing invasive breast cancer was similar for the two treatments.

SERMs work by selectively blocking the negative action of estrogen in the breast and the uterus, but permitting its positive impact on the cardiovascular system and in bone. Breast cancer is the second leading cause of cancer death and accounts for 26% of all cancers among women in the USA.

Lilly will be hoping this new indication will give it an edge over rivals in the hard-fought osteoporosis market for its $1 billion a year product; sales have started to slip, growing just 1% during the second quarter of this year to $278 million from $275.5 million in 2006. Other once-daily products include Roche and GlaxoSmithKline’s Boniva (ibandronate) and Novartis’ Reclast (zolendronate), with cheaper medicines in the shape of generic versions of Merck & Co’s top-selling Fosamax (alendronate) expected onto the market next year.