Komen: Benefits, Drawbacks Of Evista & Tamoxifen

MIAMI (CBS4) -- Breast cancer is diagnosed in about 200,000 women annually in the U.S. In the majority of these cases the cancer is estrogen receptor positive, which means it is stimulated to grow by the hormone estrogen.

Some women who are at high risk of getting breast cancer can be treated with drugs such as tamoxifen to stop the growth.

Recently scientists discovered that Evista, a drug which was being used to treat osteoporosis, also decreased the incidence of breast cancer. But not everyone can take Evista.

Who can take Tamoxifen and who can take Evista can be confusing.

Sheri Siegal has known for some time that breast cancer ran in her family

"My grandmother died of breast cancer when she was in her 30's many years ago. And my mother was diagnosed with breast cancer 20 years ago for the first time and her sister was also diagnosed with breast cancer," said Siegal.

Doctors have monitored Siegal very closely because of her family history.

"Taking the genetic test it came back positive that I would get breast cancer it was an 87% chance that I would get breast cancer," said Siegal. "That's pretty high."

Siegal met with an oncologist and a breast surgeon to determine which preventive measures she could take.

In addition to having her ovaries removed, they considered whether she should take an estrogen blocking drug. Two drugs approved to prevent breast cancer are Tamoxifen and Evista.

Tamoxifen can be used in both pre and post menopausal women for the prevention of breast cancer and also for the prevention of a recurrence of cancer, but it has possible side effects, including uterine cancer.

Evista is comparatively new to cancer treatment.

"Evista was originally developed to treat osteoporosis," said Dr. Donna Kleban, a breast surgeon. "It has been studied and has been shown to be effective at preventing the development of invasive breast cancer in high risk women."

Evista is approved only for post menopausal women who are at high risk of developing invasive breast cancer and is not approved for the prevention of a recurrence of breast cancer.

"Evista and Tamoxifen were studied in a trial called STAR to see if Evista was as effective as Tamoxifen at reducing the incidence of breast cancer in women who are at high risk, said Dr. Kleban. "And it has been shown that it reduces the risk of invasive breast cancer equally as effectively as Tamoxifen with less side effects. But this is for prevention of women who are at high risk women of getting breast cancer, not for women who had already had breast cancer."

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