New Breast Cancer Drugs May Beat Tamoxifen
Cancer Group OK's Arimidex, Aromasin, Femara to Prevent Recurrence
Nov. 15, 2004 - The newest family of breast cancer drugs is ready for prime time, a major cancer organization now says.
The new drugs are Arimidex, Aromasin, and Femara. Doctors call them third-generation aromatase inhibitors. For increasing numbers of postmenopausal breast cancer patients, they're taking the place of tamoxifen for after-surgery treatment.
Until now, the American Society for Clinical Oncology (ASCO) has recommended tamoxifen to reduce the risk of recurrent breast cancer after surgery. Now, an ASCO blue-ribbon panel says doctors may also choose Arimidex, Aromasin, or Femara.
The new breast cancer drugs are for postmenopausal women only. They are used after breast cancer surgery to prevent breast cancer from coming back. The drugs keep the body from making the sex hormone estrogen, which makes many breast cancers grow faster. Therefore, the drugs are useful only in women with hormone-sensitive breast cancers.
ASCO's new guidelines say postmenopausal women should consider after-surgery treatment with aromatase inhibitors:
- If their breast cancers tested positive for hormone receptors
- If they cannot take tamoxifen
- If they already have taken tamoxifen for two to three years, or for five years
The guidelines -- released today -- will appear in the Jan. 20, 2005 issue of the Journal of Clinical Oncology. Breast Cancer Treatment: Learn About Options
Lower Recurrent Breast Cancer, Side Effect Risk
The new breast cancer drugs work better than tamoxifen -- and they have less dangerous side effects, says Aman Buzdar, MD, deputy chair of the department of breast and medical oncology at University of Texas M.D. Anderson Cancer Center.
"All new postmenopausal breast cancer patients should be offered aromatase inhibitors," Buzdar tells WebMD. "The evidence suggests they lower the risk of breast cancer recurrence, and they have lower-risk side effects."
In studies, Arimidex, Aromasin, and Femara carry a lower risk of potentially deadly blood clots and uterine cancer than tamoxifen. However, the breast cancer drugs do increase the risk of bone loss and fracture -- a major concern for women after menopause. Buzdar says this risk can be minimized by bone-loss-preventing drugs.
And risk is the name of the game, says breast cancer specialist Pamela N. Munster, MD, of H. Lee Moffitt Cancer Center, Tampa, Fla.
"Any benefit of [post-surgery] breast cancer chemotherapy is a matter of risk reduction," Munster tells WebMD. "The higher a woman's risk, the more the benefit. First, we need to know if a patient needs chemotherapy. If a woman has a hormone-sensitive tumor, the choice becomes which treatment to use. So since the aromatase inhibitors seem better, most doctors would use them first."Are Arimidex, Aromasin, and Femara interchangeable? Nobody knows yet. It will be years before definitive information is available. Munster says doctors now have to make their decisions based on limited evidence.
"Based on the information that is out there, if a patient came to me to get started, I would use Arimidex," Munster says. "If the patient has been on tamoxifen for two to three years, I would use Aromasin. But if she were on tamoxifen for five years, I would switch her to Femara."