Study: Iressa May Also Help Some Prevent Breast Cancer

Gefitinib, a drug marketed as Iressa for treatment of some lung cancers, may also help some women prevent breast cancer, findings from animal studies suggest.

The drug prevented development of estrogen receptor (ER)-negative breast cancer in a mouse study, raising the possibility that it could prevent a type of breast cancer for which currently are no preventive drugs.

While tamoxifen and the newer aromatase agents work to prevent development of ER-positive tumors, ER-negative breast cancers are not dependent on estrogen to grow and do not respond to these drugs.

To test whether gefitinib could inhibit the growth of ER-negative breast cancer cells, Baylor College of Medicine researchers treated ER-negative normal, precancerous, and cancerous breast cells with the drug, and examined its effect on development of ER-negative breast tumors in transgenic mice.

They reported in the Journal of the National Cancer Institute that gefitinib suppressed the growth of ER-negative normal, precancerous and cancerous breast cells, and mice given a placebo took 230 days to develop breast cancer while those treated with gefitinib took 310 days.

In an accompanying editorial, Dr. Dennis J. Slamon of UCLA cautioned that long-term safety data is not available for gefitinib, and noted that some patients taking Iressa for non–small-cell lung cancer have developed interstitial lung disease, a rare but potentially dangerous side effect.

Other Sources: Journal of the National Cancer Institute