Early age at menarche, or first menstrual cycle, could play a role in the disproportionate incidence of estrogen receptor (ER)-negative breast cancers diagnosed among African-American women, according to a study published online June 17 in the Journal of the National Cancer Institute.
[Photo: Dr. Andrew Olshan]
The study is a result of a multicenter collaborative research effort that formed the African American Breast Cancer Epidemiology and Risk Consortium (AMBER). Dr. Andrew Olshan, professor and chair of the Department of Epidemiology at the University of North Carolina Gillings School of Global Public Health, is a consortium member. Dr. Olshan also is associate director for population science at the UNC Lineberger Comprehensive Cancer Center.
AMBER researchers investigated the epidemiologic and genetic causes for more aggressive breast cancer in African-American women. They combined four epidemiologic studies with large numbers of African-American participants: The Black Women’s Health Study (BWHS), the Multiethnic Cohort Study (MEC), the Carolina Breast Cancer Study (CBCS), and the Women’s Circle of Health Study (WCHS).
The goal was to examine whether relationships between age at menarche and breast cancer are the same for tumors that are ER-positive or ER-negative, particularly among African-American women. ER-negative breast cancer is generally more aggressive and known to be associated with a poorer prognosis than ER-positive disease.
Analysis of data from 4,426 African-American women diagnosed with breast cancer and more than 17,000 women without the disease showed that the pathways to ER-negative and ER-positive breast cancer appear to be different.
“It is known that exposures such as ionizing radiation have a great impact on the risk of women who are later diagnosed with breast cancer if the exposure occurs during puberty, a time when breast cells appear to be extremely sensitive,” said Dr. Christine Ambrosone, professor and chair of the Department of Cancer Prevention and Control at Roswell Park Cancer Institute and lead author of the study. “Indications are that the resulting cancers tend to be ER-negative. African-American girls tend to have earlier menarche than European-Americans, and that age is getting younger over time. It is possible that early age at menarche could play a role in the disproportionate number of ER-negative breast cancers diagnosed in African-American women.”