Protective Progeny: Peptide treats and prevents breast cancer

A synthetic version of a protein present in a woman's body during pregnancy is as effective against breast cancer as the current drug tamoxifen is, according to a study in rodents. The new substance may avoid tamoxifen's side effects.

Epidemiological research has estimated that, over her lifetime, the average woman has a 1-in-8 chance of developing breast cancer. However, among women who've had at least one full-term pregnancy, that risk is only 1 in 16, says James Bennett of the Albany (N.Y.) Medical College.

In earlier work, Bennett's team had determined that alpha-fetoprotein (AFP), a substance secreted by the liver of the fetus, is partially responsible for pregnancy's protective effect. Bennett and his colleagues at Albany Medical College set out to make a synthetic compound with AFP's effect.