Researchers Find why Having Children Protects Women from Breast Cancer

There are several risk factors that make some women more vulnerable to breast cancer, and one of them is not having any children or having the first child after age 35. But, how pregnancy affects a woman's chances of breast cancer wasn't known. Now, a team of researchers have found that it depends on the Wnt/Notch signaling ratio which is decreased in mice models that give birth, when compared with mice that didn't have any children.

Researchers found that after pregnancy, activity of genes required in the immune system were upregulated, while there was a reduction in the activity of genes that affect growth.

One gene, called Wnt, was downregulated after pregnancy, while the activity of Notch - an opposing component of a signaling pathway (Wnt/Notch) that controls the fate of a cell - was increased.

Wnt and Notch signaling has been previously studied for its role in prostate cancer.

"The down-regulation of Wnt is the opposite of that seen in many cancers, and this tightened control of Wnt/Notch after pregnancy may be preventing the runaway growth present in cancer," said Mohamed Bentires-Alj from the Friedrich Miescher Institute for Biomedical Research, lead author of the study, according to a news release.

The study is published in BioMed Central's open access journal Breast Cancer Research.

Breast cancer is one of the most common cancers diagnosed in women in the U.S. Despite its high prevalence, researchers aren't sure why normal breast cells turn cancerous. According to most experts, breast cancer is caused by a combination of genetic, hormonal and environmental factors.

According to estimates by the National Cancer Institute, 232,340 new cases of female breast cancer will be diagnosed in 2013 in the U.S., and nearly 40,000 women will die due to breast cancer.