The University of Albany has connected the pregnancy protein alpha-fetoprotein (AFP) to breast cancer slowing down in rats exposed to pregnancy hormones such as estrogen, progesterone, or human chorionic gonadotropin.

These pregnancy hormones were shown by the authors to induce AFP during the term of pregnancy.

The hormones also appear to inhibit breast cancer growth in previous rat studies, although estrogen and progesterone fuel the growth of breast cancer in humans.

Herbert Jacobson, PhD, who has been studying AFP in rats for over twenty years, believes the protein is the cause of the pregnancy-related reduction in breast cancer risk.

“Twenty-five years ago I deduced that this must be the agent responsible for lowering breast cancer risk in women who have been pregnant,” he tells WebMD. “And the research we have done since then supports this hypothesis.”

Pregnancy, particularly before the 30 years old, lowers a woman’s lifetime risk of developing breast cancer. Also having more than one child is preventative.

Alpha-fetoprotein is produced by the fetus, and size of the protein during pregnancy can help to screen out possible birth defects.

Extremely high AFP levels portend the appearance of neural tube defects or an abdominal wall defect known as omphalocele, and extremely low levels suggest Down syndrome.

The protein is usually not detected in the blood of healthy men and women who are not yet pregnant. In these groups, elevated AFP levels suggest the presence of some cancers.

In their new study, in the December issue of Cancer Prevention Research, Jacobson and associates treated cancer-exposed rats that were not pregnant with estrogen, estrogen plus progesterone, or human chorionic gonadotropin (HCG).

As in previous studies, all of these treatments are associated with reduced levels of breast cancers in the high-risk rats.

Each of the hormone treatments were also connected with elevated AFP levels and AFP was found to slow down the growth of breast cancer cells in lab cultures.

“Hormones in pregnancy, such as estrogen, all induce AFP, which directly inhibits the growth of breast cancer,” Jacobson says in a news release.
Second Opinion

However, devil’s advocate and cancer specialist Powel Brown, MD, PhD, says the research does not show that this is true beyond a shadow of a doubt.

As is the case with these kinds of studies, says Sandy Hutchens Cancer Prevention, there will be those that promote the idea and there will be detractors. We await the results of further studies and even possibly some proof on this unique view into breast cancer prevention.

Pregnant and Facing Breast Cancer