Clues to Breast Cancer Risk Found in Breast Milk

Preliminary study results out of the University of Massachusetts in Amherst indicate that epithelial cells found in breast milk may be used to assess a woman’s risk of breast cancer, reports the Wall Street Journal. The news was presented by Dr. Kathleen Arcaro, an associate professor of environmental toxicology at the university, on Monday at the American Association of Cancer Research’s annual meeting.

In the study, Dr. Arcaro collected milk samples from both breasts of approximately 250 nursing women who had previously undergone a breast biopsy or were scheduled to have a lump biopsied. In the majority of cases, the lumps were found to be benign, but cancer was detected in 13 women.
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Thus far, Dr. Arcaro and her team have evaluated three (out of an eventual 12) genes, isolating the DNA from epithelial cells (the potentially cancerous cells) in breast milk to look for evidence of methylation, or specific changes that are thought to precede the development of cancer, when substances or chemicals on the body attach themselves to a gene.
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Among the women in the study who had a non-cancerous lump, there were few changes seen in the genes between milk from the biopsied breast and the nonbiopsied breast, as measured by a methylation score. However, for the 13 women who had cancer, there was a significant increase in methylation of one particular gene, RASSF1, a tumor-suppressing gene that normally works to keep healthy cells from turning into cancer, but malfunctions once methylated.
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Because about 80% of women give birth at some point in their lives (and produce milk even just for a few days following the birth, even if they don’t breastfeed longer-term), the study has the potential to lead to a personalized test to help determine a woman’s risk of breast cancer. Dr. Arcaro added that a breast milk test would not replace conventional screening methods like mammograms, but it could provide an early indication of women at the highest risk for later developing cancer (thus allowing them to start screening for it earlier, instead of following new recommendations for mammography beginning at age 50).