Breast milk might help determine breast cancer risk -- eventually

Breast milk may do more than sustain an infant; in the future, it could also be used to help assess breast cancer risk.

At least, that’s what a small study hints.

By screening breast milk for cells that can turn into cancer, researchers believe they can develop a way to warn women if they’re at an increased risk of developing breast cancer later in life. Results from the new study were presented Monday at the American Assn. for Cancer Research in Orlando.

Researchers at the University of Massachusetts Amherst collected fresh milk samples from about 250 women, one sample from each breast. The women also underwent a breast biopsy, the most definitive way to tell if a woman has breast cancer.

Within the milk, researchers isolated the epithelial cells. These cells line the inside of the breast and are most likely to turn into tumors. The scientists then examined three of 35 genes within the DNA of those cells that are known to play a role in breast cancer. They looked for epigenetic signals on the genes—signals that tell the body to “turn on” these genes.

Among the women diagnosed via biopsy with a tumor in one breast, researchers found a significant increase in epigenetic signals for the gene RASSF1 in the milk from that breast, compared with milk from the breast that wasn’t biopsied.

The researchers believe that signal is significant enough to warrant screening for women. Further studies should analyze changes in other genes, says Arcaro.

A long-term study is underway with 80% of the women in the original study.

A reliable and inexpensive test for breast cancer risk is needed. But the potential for breast milk to become that test is far from established. It’s difficult to draw conclusions from a couple of hundred women. And it’s unclear how far into a woman’s lifetime such a breast milk test would be accurate. Relatively few women of child-bearing age get breast cancer, after all.