What can breastmilk tell us about breast cancer risk? (Part 1)

Written by Tanya Lieberman, IBCLC

This is Part 1 of a 2-part series on the research of Dr. Kathleen Arcaro.  Please check back tomorrow about specific information about how to help your clients become involved in this research.

To the many wonders of breastmilk, add another possible one: Clues to your breast cancer risk.

Are you at high risk for breast cancer? Despite years of breast cancer research,it’s very hard to know. You may have heard that family history puts you at greater risk, but the startling fact is that 8 out of 9 women diagnosed with breast cancer have no close female relative with a history of the disease. Women with “the breast cancer gene” (BRCA) know they’re at higher risk, but they account for only a small number of new cases.

Enter Dr. Kathleen Arcaro of the University of Massachusetts, Amherst. An environmental toxicologist by training, Dr. Arcaro had been studying pollutants in breastmilk for years before she became curious about what breastmilk could tell us about breast cancer risk.

Breast cells are key in breast cancer research, but are notoriously hard to get. You can get a limited number through biopsy or extracting nipple aspirate (ouch!), but neither of these methods sound like much fun to most women. They also have limitations: breast biopsies only yield cells in a very small area of a breast, and nipple aspirate produces very few cells for analysis.

It’s been clear for some time, though, that ductal breast cells naturally slough off into breastmilk. The cells in breastmilk of course come from all ductal areas of the breast, and they’re plentiful – an average of 30,000 per milliliter.

Dr. Kathleen Arcaro

Until very recently the presence of these cells in milk was only an interesting footnote in the literature. But with the advent of DNA analysis, the breast cells in breastmilk suddenly became an extremely valuable resource. Scientists could now extract DNA from these cells and look for patterns of “methylation:” the presence of methyl groups that attach to key parts of our DNA which are thought to regulate its functioning in important ways.

For example, some parts of our DNA are known as “tumor suppressor genes.” As the name implies, these genes tell our cells to stop the growth of tumors – a key way our bodies protect us from cancer.

But if a methyl group attaches to this gene, it can essentially turn it off – kind of like you would a light switch. This leaves us more vulnerable to the growth of tumors. In a cancer prone area of our bodies like the breast, their function is critical.

Taken collectively, these alterations to our DNA are known as our “epigenome,” (yes, you have one) and they have an even bigger influence over our health trajectories than the DNA we were born with. Factors like diet, smoking, exposure to toxins, stress, and exercise all contribute to the functioning of our DNA and our health.

So, how do you get this breastmilk and the elusive cells it contains? Funders and researchers told Dr. Arcaro that getting large numbers of breastmilk samples wouldn’t be worth the effort. Too costly, too time consuming, and too hard to find willing mothers.

Undeterred, Dr. Arcaro began looking for milk. Spreading the word through lactation consultants and La Leche League leaders (and occasionally stopping a mother on the street), she found willing participants. She started driving from mother’s house to mother’s house, occasionally sitting on the floor at a “pumping party” at a pediatrician’s office or a La Leche League meeting. Far from finding it difficult to recruit moms, she found mothers enthusiastic to donate their milk in the name of breast cancer research. Many viewed their milk donation as a way of fighting the disease which had taken the health and sometimes lives of friends and family members.

In 2009, Dr. Arcaro received a federal grant to investigate whether breastmilk could reveal patterns in breast cancer risk, by studying women who had or were planning to have a breast biopsy. These women were at a higher risk (though still relatively small) of developing breast cancer. Would their DNA methylation show it?

Dr. Arcaro indeed found that certain patterns of methylation are correlated with a higher risk of breast cancer. She has since published two papers demonstrating this, and there are more to come.

Two things make this finding important: One is the hope that one day women might be able to get a personalized breast cancer risk profile and not just learn how to get bigger breasts. The second possibility is that once the “target” methylation is revealed by this research, new treatments may actually be able to reverse it. Amazingly, some of the first generation chemotherapy drugs are in fact “anti methylating” agents – drugs which can actually remove methyl groups from your DNA, allowing your DNA to function properly in the fight against cancer. Dr. Arcaro would even like to see if some dietary changes might actually reduce methylation, which she could measure in milk.

Check back tomorrow for Part 2 of this series on the work of Dr. Kathleen Arcaro where we will discuss what she discovered about the mothers who were donating their milk and what is being done to specifically address the needs of high risk groups.

Tanya Lieberman, IBCLC is a lactation consultant who has worked in pediatric and hospital outpatient settings. She writes the Motherwear Breastfeeding Blog, for the Best for Babes Foundation, for Motherlove Herbal Company blog, among other websites. She is co-author of Spanish for Breastfeeding Support (Hale Publishing, 2009). She has been a member of several Dr. Kathleen Arcaro’s study teams, working to recruit mothers to donate milk samples. Before becoming a lactation consultant she was senior education policy staff in the California legislature. She lives in Massachusetts with her husband and two children.

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3 Responses to What can breastmilk tell us about breast cancer risk? (Part 1)

  1. mumsmilk by Naomi Hull 15 June 2012 at 00:56 #

    Reblogged this on mumsmilk and commented:
    The human body is exceptionally amazing!


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