Raloxifene following tamoxifen may not offer further risk reduction.(Brief Article)

1902 MAR 28 - (NewsRx.com & NewsRx.net) -- A new study done in mice suggests that taking raloxifene after 5 years of tamoxifen therapy may not further prevent the growth of breast cancers. What's more, raloxifene may stimulate the growth of endometrial tumors, concluded Ruth M. O'Regan, MD, and V. Craig Jordan, PhD, DSc, of Northwestern University Medical School, Chicago, and their colleagues in the February 20, 2002, issue of the Journal of the National Cancer Institute.

Adjuvant therapy with the selective estrogen receptor modulator tamoxifen helps some women with early stage breast cancer reduce their risk of recurrence. But some studies have suggested this benefit levels off after 5 years, and further treatment with tamoxifen not only doesn't help, it may increase a woman's risk of endometrial cancer.

To get around this, researchers have suggested following a 5-year tamoxifen treatment with the SERM raloxifene, a drug used to prevent osteoporosis in postmenopausal women. Results from a large randomized clinical trial of raloxifene suggested that the drug may decrease a woman's risk of breast cancer without increasing her risk of endometrial cancer.

However, the new study suggests that raloxifene after tamoxifen may not be beneficial. O'Regan and her colleagues exposed breast and endometrial tumors in mice to combinations of estrogen, tamoxifen, and raloxifene or nothing at all. The authors found that raloxifene did not further prevent the growth of breast tumors previously ...