Breast-feeding Reduced Risk for ER/PR-negative Breast Cancer

• Childbirth without breast-feeding increased ER/PR-negative breast cancer risk.
• Oral contraceptives were not associated with ER/PR-negative breast cancer.
• Findings consistent with studies of breast-feeding and triple-negative breast cancer.

ANAHEIM, Calif. — Breast-feeding reduced the risk for estrogen receptor-negative and progesterone receptor-negative breast cancer, according to results presented at the 11th Annual AACR International Conference on Frontiers in Cancer Prevention Research, held here Oct. 16-19, 2012.

“We found an increased risk for estrogen receptor- and progesterone receptor- (ER/PR) negative breast cancer in women who do not breast-feed, but in women who have children and breast-feed, there is no increased risk,” said Meghan Work, M.P.H., doctoral student in the department of epidemiology at Columbia University’s Mailman School of Public Health in New York, N.Y.   

Work and colleagues examined the relationship between reproductive risk factors — such as the number of children a woman delivers, breast-feeding and oral contraceptive use — and ER/PR-negative breast cancer. ER/PR-negative breast cancer often affects younger women and has a poor prognosis, according to Work.

The researchers used data from three sites of the Breast Cancer Family Registry, which includes women with and without breast cancer from the United States, Canada and Australia. This study included 4,011 women with breast cancer and 2,997 population-based controls.

The results indicated that having three or more children without breast-feeding was associated with an increased risk for ER/PR-negative breast cancer.

“Women who had children but did not breast-feed had about 1.5 times the risk for ER/PR-negative breast cancer when compared with a control population,” Work said. “If women breast-fed their children, there was no increased risk for ER/PR-negative cancer.”

Further, the researchers found that oral contraceptive use was not associated with ER/PR-negative cancer risk, with the exception of those formulations available before 1975. “These earlier formulations contained higher doses of estrogen and progestin than more recent versions,” Work said.

These findings are in line with previous findings that have demonstrated breast-feeding benefit in triple-negative breast cancer. “This is particularly important as breast-feeding is a modifiable factor that can be promoted and supported through health policy,” Work said.

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About the American Association for Cancer Research
Founded in 1907, the American Association for Cancer Research (AACR) is the world’s first and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR membership includes more than 34,000 laboratory, translational and clinical researchers; population scientists; other health care professionals; and cancer advocates residing in more than 90 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis and treatment of cancer by annually convening more than 20 conferences and educational workshops, the largest of which is the AACR Annual Meeting with more than 17,000 attendees. In addition, the AACR publishes seven peer-reviewed scientific journals and a magazine for cancer survivors, patients and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the scientific partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration and scientific oversight of team science and individual grants in cancer research that have the potential for near-term patient benefit. The AACR actively communicates with legislators and policymakers about the value of cancer research and related biomedical science in saving lives from cancer.

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