Pak up Your Breast Tumor—and Grow!

Extract

The estrogen receptor (ER) has proved to be an extremely important target for the treatment of breast cancer ( 1 ) . Tamoxifen, a nonsteroidal antiestrogen, blocks estrogen-stimulated breast cancer growth by binding to ER. However, years of adjuvant tamoxifen therapy are required to “smother” estrogen-sensitive micrometastases. Thus, two principles for optimal molecular therapeutics in breast cancer have emerged: tumor targeting and the appropriate duration of treatment that creates optimal survival advantages for patients ( 2 ) . Although these principles have taken two decades to translate from the laboratory ( 3 ) to changes in healthcare ( 4 ) , the widespread use of tamoxifen is credited with contributing substantially to the decline in death rates from breast cancer in the United States ( 5 ) . Most importantly, in these days of meteoric rises in health care costs for targeted therapies, tamoxifen is, by contrast, a cheap and affordable drug that is known to save lives. However, because not all ER-positive breast cancers respond to tamoxifen treatment, the development of ways to improve targeting tamoxifen to treat the “right” tumors would be of value throughout the world.