AMHERST, Mass. – Breastfeeding women with a pathogenic BRCA1 or BRCA2 genetic mutation face a significant risk, even at a young age, of breast and ovarian cancer. Yet no fully effective breast cancer screening method exists for nursing mothers in this high-risk group, some of whom are diagnosed after the disease has spread, possibly becoming fatally metastatic.
University of Massachusetts Amherst cancer researchers hope to change that by developing a new, noninvasive test that uses women’s breast milk to detect breast cancer in its earliest stages. New mothers, and to a greater extent those with a BRCA mutation, face an increased risk of pregnancy-associated breast cancer (PABC), which is often aggressive, for about a decade postpartum.
“This could eliminate the risk of metastasis-associated mortality related to postpartum, pregnancy-associated breast cancer in women with the BRCA mutation,” says lead investigator Kathleen Arcaro, professor of veterinary and animal sciences in the College of Natural Sciences, whose UMass Breastmilk Lab develops tools to assess breast cancer risk. “We also hope to better understand breast tumor development and progression in these at-risk women.”
Supported by an $718,000 grant from the Department of Defense’s Breast Cancer Research Program, Arcaro and lab colleague Brian Pentecost, UMass Amherst research associate, will conduct a national study of breastfeeding women who have tested positive for the inherited BRCA1 or BRCA2 mutation. A control group of breastfeeding women with neither a BRCA mutation nor multiple close relatives with breast cancer is also being recruited.
“Breast milk essentially provides a liquid biopsy of the entire breast,” Arcaro says. “This will be the first noninvasive, genetic and epigenetic study of breast epithelial cells of BRCA carriers. The study design provides a unique opportunity to examine breast cells from non-symptomatic BRCA carriers of reproductive-age in a critical period of breast cancer development.”
Arcaro is recruiting participants from across the U.S. through social media and with the help of breast surgeons and lactation specialists, including Dr. Katrina Mitchell of Ridley-Tree Cancer Center at Sansum Clinic in Santa Barbara, California, and Dr. Shannon Tierney of Funkhauser Women’s Center in Harrisburg, Virginia.
“It is an honor to participate in such groundbreaking research with this team,” Dr. Mitchell says. “Breast milk is a fascinating biospecimen with potential to change our approach to the early detection of breast cancer.”
Women in the study will provide breast milk samples, a saliva sample and a copy of their BRCA test results. They will also complete a health questionnaire and agree to annual, long-term follow-up. The researchers are also seeking samples from a small number of breastfeeding mothers who already have breast cancer in an effort to understand what a positive disease signal looks like.
BRCA1 and BRCA2 mutations prevent the tumor-suppressor genes from repairing DNA damage, which leads to the high lifetime risk of breast and ovarian cancer. At least 50 percent of women with a BRCA mutation will develop breast cancer by age 70, and 30 percent will develop ovarian cancer, according to the Centers for Disease Control and Prevention.
Arcaro and colleagues will examine breast milk for somatic mutations, or genetic changes that occur any time after conception. Somatic mutations cannot be passed on to offspring – unlike hereditary, or germ-line, mutations like BRCA. The researchers also will look for epigenetic changes, such as DNA methylation. These are chemical changes to DNA that affect gene expression and can be passed on to offspring but don’t change the DNA sequence.
“Breast milk from all women contains millions of epithelial cells from the target tissue, providing assessment at the earliest stages of disease development,” Arcaro says. “This is in contrast to assessment of cell-free DNA in blood, where the amount of DNA is extremely limited and likely indicative of advanced disease and metastasis.”
Through the examination of the breast milk cells, Arcaro hopes “to uncover profiles that may identify breasts at increased risk of breast disease, as well as to shed light on breast cancer development in women with defects of DNA repair.”