Kathleen Arcaro

Kathleen Arcaro

As a pioneer in studying breast cancer risk using breast milk, Kathleen Arcaro initially encountered a lot of discouragement.

“For the first five years, when I applied for grant funding, most people thought this was not a good idea. They thought there were other reasons to study breast milk, such as for the health of the infant, but not for breast cancer,” recalled Arcaro, professor in the UMass Amherst Department of Veterinary and Animal Sciences (VASCI). The breakthrough, she said, was when the Avon Foundation for Women recognized the value of this work and funded her first major study.  

Arcaro describes breast milk as a “liquid biopsy,” offering unparalleled insights into breast health and future cancer risk. As she explains it, human milk contains multiple cell types, including epithelial cells from the lining of the ducts and lobules. Cancer-related DNA methylation—or changes to epigenetics affecting tumor-suppressing genes—may occur decades before cancer is ever diagnosed. Arcaro’s lab is interested in determining how DNA methylation patterns in sloughed epithelial cells can inform future breast cancer risk.

“Ultimately, I hope that this research leads to breast milk being used to accurately assess a person’s individual risk of breast cancer, allowing them to make informed decisions and modify their risk through lifestyle changes, diet, drugs, or other medical interventions,” she said.

Today, Arcaro is a leading researcher in this field. Her breast milk research program has received over $10 million dollars in external funding from sources including the National Institutes of Health (NIH), the U.S. Department of Defense (DoD), and the Avon Foundation for Women. Nearly half of her 78 peer-reviewed publications present results from her breast milk research, and she has enrolled nearly 2,000 women in her breast milk studies.

Ultimately, I hope that this research leads to breast milk being used to accurately assess a person’s individual risk of breast cancer, allowing them to make informed decisions and modify their risk.

Kathleen Arcaro

Yet Arcaro’s path here was winding. Originally from New Jersey, she earned her BS in biology and psychology, and her PhD in behavior genetics from Rutgers University. Her doctoral work focused on animal behavior, and she went on to receive training in environmental toxicology at the New York State Department of Health’s Wadsworth Laboratories. She worked on a Superfund Project studying the health effects of environmental pollutants on the people of the Mohawk Akwesasne Nation. From there, she became interested in the relationship between environmental pollutants and breast cancer. In 2001, she joined the UMass Amherst faculty.  

At UMass, Arcaro collaborates on research with colleagues from VASCI as well as the UMass Department of Polymer Science and Engineering and the School of Public Health and Health Sciences, and with associates at other institutions, including Baystate Health, the National Cancer Institute (NCI). Arcaro is also the graduate program director for the UMass Animal Biotechnology and Biomedical Sciences Program. Every semester, about a dozen undergraduates, as well as master’s and PhD students, contribute to her research program.  

Despite the initial skepticism Arcaro encountered, her research has shown that exfoliated cells in breast milk provide valuable information on breast health and can help predict breast cancer risk. Moreover, from a public health perspective, studying breast milk makes a lot of sense. According to Arcaro, about 80 percent of all women give birth at some point in their lives. Whether they choose to breastfeed or not, all produce colostrum, the first form of breast milk released by the mammary glands immediately after giving birth.  

“Imagine if I told you we could obtain a small sample of lung tissue from 80 percent of the population to improve understanding of lung disease,” she said. “That would be amazing.”  

To this end, Arcaro, in collaboration with Professor of Polymer Science and Engineering Maria Santore and with funding from NCI, is working to create a paper-based breast milk collection system that will facilitate nationwide breast cancer screening for new mothers. The idea is based on Guthrie cards, used in countries around the world to collect drops of blood from newborn heel pricks to screen for rare diseases and facilitate health research on a national scale.

Dating back to her earliest work documenting the health effects of exposure to environmental contaminants, Arcaro’s research is responsive to the needs of specific populations and situations. For example, in early 2020, she quickly pivoted to studying the immune response in milk to COVID-19 infections and immunization with an mRNA vaccine. She led three studies of the immune profile in human milk and infant stool, finding strong evidence that breastfeeding helps protect infants against COVID-19 infection.  

This research has garnered significant attention, especially in the Black community. In 2022, Arcaro partnered with Reaching Our Sisters Everywhere (ROSE), an organization working to reduce breastfeeding disparities among African American women, to expand the diversity of participants in her breast milk research. With funding from the Avon Foundation, she enrolled 300 lactating Black/African American women in a study to assess associations with breast cancer risk and the inflammatory profile in milk.  

Arcaro also studies the potential of dietary interventions to decrease cancer risk. For the past five years, the multi-PI team including Arcaro, Lindiwe Sibeko, associate professor and chair of nutrition, and Susan Sturgeon, professor of epidemiology, have run the New Moms Wellness Study, a randomized clinical trial to assess how increased fruit and vegetable intake affects breast cancer risk. Half of the participants receive regular deliveries of fresh fruits and vegetables, with instructions to eat 8–10 servings of produce daily, and get nutrition counseling from undergraduate nutrition majors at UMass. To date, nearly 400 women have participated in the study. The research team will be comparing the breast inflammatory and DNA methylation profiles of the participants in the intervention group and the control group, as well as studying the effects of maternal nutrition on the nursing infants’ gut microbiome.

According to Arcaro, several participants in the wellness study have shared that the support they received allowed them to breastfeed much longer, dramatically improved their diets, lowered their blood pressure, and helped them make other positive changes.  

Most recently Arcaro and collaborator, Sallie Schneider, Director of HistoSpring, a core facility at the Pioneer Valley Life Sciences Institute, received a five-year, $3.3 million grant from the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) to study mammary gland permeability and how it affects milk supply, lactation outcomes, and infant health.  

“We’re really trying to understand if there might be ways we can help women who want to breastfeed longer but struggle with milk supply,” she said.

Throughout her career, despite being warned about the difficulty of recruiting participants for research studies, Arcaro has been delighted to find a vast number of women who “go out of their way to help.”

“I never imagined I would be interacting with women like this in my work,” she said. “It’s unbelievably rewarding when women thank us for doing this research.”

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