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New Ways to Treat Breast Cancer

A new generation of drugs and treatment options gives patients new hope in the fight against breast cancer.

Hormone-Positive Cancers

As research into tumor biology continued, doctors soon discovered the hormone-positive breast cancer malignant cells that rely on the female sex hormones, predominantly estrogen, to flourish and grow.

And again, target-specific drugs seemed to be the answer. The first in this category was tamoxifen, which Smith says works by blocking the tumor's ability to use estrogen. While it worked well against hormone-positive cancers, side effects were troubling -- including the risk of blood clots and even other cancers.

More recently, the STAR trial, led by researchers at the University of Texas M.D. Anderson Cancer Center, found an alternative -- the osteoporosisosteoporosis drug Evista. Although this trial focused on prevention of breast cancer, it appears that Evista accomplishes results similar to tamoxifen, with fewer side effects. Experts say it may become another treatment option for some women with hormone-positive breast cancer.

Today, excitement is growing over an even newer approach: drugs known as aromatase inhibitors.

"Aromatase is an enzyme that helps convert steroids to estradiol -- a form of estrogen that makes some breast cancers grow," says Smith. Aromatase inhibitors, she says, are drugs that knock out that enzyme so estradiol can't be made at all, thus inhibiting tumor growth.

The one caveat, says Smith, is that these drugs only work in postmenopausal women, whose estrogen supply comes from this steroid conversion process.

"In premenopausal women ovaries are the prime producers of estrogen, and they are not affected by aromatase inhibitors," says Smith.

In a number of clinical breast cancer trials, newer aromatase inhibitors (such as Femara, Aromasin, and Arimidex) have been compared with tamoxifen and found to be more effective, show greater survival rates, and in many cases have more tolerable side effects overall.

A 2006 analysis of 23 studies showed women with advanced breast cancer lived longer if they took aromatase inhibitors instead of tamoxifen. Researchers found women with advanced breast cancer who had an expected survival rate of 2.5 years lived an additional four months when treated with newer aromatase inhibitors. The analysis was published in the Journal of the National Cancer Institute.

The American Society of Clinical Oncology now recommends the use of aromatase inhibitors for the treatment of hormone-positive breast cancer in postmenopausal women.

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