Raloxifene Continues to Lower Incidence of Invasive Breast Cancer in Postmenopausal Women

June 6, 2004

A study of more than 5,000 postmenopausal women with osteoporosis shows that raloxifene (Evista), a drug used to treat bone loss, also lowers a woman's risk of estrogen receptor (ER) positive invasive breast cancer. These findings mark eight years of follow-up without any new safety concerns.

Raloxifene is a type of drug called a SERM (selective estrogen receptor modulator), which means it acts like a natural estrogen in some ways. It is currently used for the prevention and treatment of osteoporosis. Osteoporosis is a condition marked by a decrease in bone size and strength. Postmenopausal women are at greater risk of developing this condition because their bodies stop producing the estrogen hormone, which helps protect against bone loss.

The CORE (Continuing Outcomes Relevant to Evista) trial is a follow-up to the MORE (Multiple Outcomes Of Raloxifene) trial. In the MORE trial, doctors compared raloxifene with no treatment (a placebo) over a four-year period in a large group of women. They found that the incidence of invasive breast cancer was reduced by 72% in women receiving raloxifene.

In the CORE trial, researchers continued to follow the women who were part of the MORE trial for four more years to learn whether raloxifene continues to lower the incidence of breast cancer in postmenopausal women.

The CORE trial results showed that women who received raloxifene reduced their risk of invasive breast cancer by 59% during years four through eight. The magnitude of the risk reduction during the second four-year period was similar to that seen during the first four years. When the results of the CORE trial are combined with the results of the MORE trial, women taking raloxifene reduced their incidence of ER-positive invasive breast cancer by 66% over the eight-year period.

"These data add to the existing body of information that SERMs are an approach by which breast cancer incidence can be reduced," said Silvana Martino, DO, of the Cancer Institute Medical Group and John Wayne Cancer Institute in Santa Monica, Calif, and lead author of this study.

What This Means For Patients

These data suggest that women can take raloxifene for as long as eight years to reduce their risk of ER-positive breast cancer without serious side effects. These findings also support other data showing that SERMs can reduce the incidence of ER-positive breast cancer.

Although raloxifene is approved for the prevention and treatment of osteoporosis, it is not approved to reduce a woman's risk of breast cancer. At this time, doctors do not recommend that women take raloxifene to reduce their risk of breast cancer outside of a clinical trial setting. Finally, it should be noted that his study was not designed to address the effect of raloxifene on ER-negative breast cancer.