Breast Cancer: Hormone Therapy

By , Caring.com senior editor
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Hormone therapy for breast cancer treatment

One of the most important test results doctors look at when treating a woman with breast cancer is whether her tumor cells contain receptors for the hormones estrogen and progesterone. If present, these hormones can fuel cancer cell growth, and hormone therapy -- which stops them -- can be a very effective weapon in the treatment arsenal.

The presence of receptors

ER positive means tumor cells have receptors for estrogen, and PR-positive means the tumor has progesterone receptors. About 75 percent of breast cancers are estrogen-receptor positive and of those, about 65 percent are also PR-positive. These hormones can fuel rapid cancer cell growth, so the goal is to "turn off" this action by blocking the receptors.

Despite the similar names, hormone therapy is not the same as Hormonal Replacement Therapy, or HRT, which many women take during and after menopause. In fact, HRT isn't considered safe for women with breast cancer.

Which hormone therapy drugs are best?

For years, tamoxifen (brand name Nolvadex, though it's now a generic) was the standard drug of choice for women with hormone-receptor-positive breast cancer. Tamoxifen is a type of drug known as a SERM, which stands for selective estrogen-receptor modulator.

There are newer SERMs being studied and introduced for breast cancer. Raloxifene (brand name Evista) was developed to treat osteoporosis but has been shown to work well for invasive breast cancer. Another SERM, Toremifene (brand name Fareston), is similar to tamoxifen but is rarely used in the U.S., though it's popular in Europe. But tamoxifen is by far the most widely used and prescribed.