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Age at menarche influences breast cancer risk in black women
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Early age at menarche may correspond with an increased risk for ER-negative breast cancer among black women, according to study results.
The association persisted even among women who never gave birth, the study also found.
“African American girls tend to have earlier menarche than European Americans, and that age is getting younger over time,” Christine B. Ambrosone, PhD, distinguished professor of oncology and chair of the department of cancer prevention and control at Roswell Park Cancer Institute, said in a press release. “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."
Ambrosone and colleagues formed the African American Breast Cancer Epidemiology and Risk (AMBER) Consortium to investigate the association between age at menarche and rates of ER-negative breast cancer in black women.
The analysis included data from 4,426 black women diagnosed with breast cancer (ER-negative, n = 1,464; ER-positive, n = 2,962) and 17,474 controls.
Women who experienced menarche at or after age 15 years had a lower rate for breast cancer, compared with women whose menarche occurred before age 11 years. This association occurred in women who gave birth (OR = 0.62; 95% CI, 0.48-0.81) and women who never had children (OR = 0.56; 95% CI, 0.29-1.1). Age at first live birth did not impact this association.
Menarche at or after 15 years also conferred a reduced risk for ER-positive (OR = 0.74; 95% CI, 0.61-0.89), ER-negative (OR = 0.62; 95% CI, 0.49-0.8) and triple-negative breast cancer (OR = 0.7; 95% CI, 0.49-1.01).
Among women who gave birth, older age at menarche corresponded with a decreased risk for ER-positive breast cancer, particularly in women whose menarche occurred at or after 15 years (OR = 0.7; 95% CI, 0.56-0.86). However, later age at menarche did not significantly reduce the risk for ER-positive breast cancer among women who never gave birth.
Women whose first live birth occurred between the ages of 25 and 29 years had an increased risk for ER-positive (OR = 1.21; 95% CI, 1.02-1.44) and ER-negative (OR = 1.17; 95% CI, 0.93-1.47) breast cancer. However, a first live birth occurring at or after age 30 years did not increase breast cancer risk.
Compared with women whose first live birth occurred within 5 years of menarche, a longer interval (≥ 20 years) between menarche and first live birth was associated with a greater risk for ER-positive breast cancer (OR = 1.39; 95% CI, 1.08-1.79). However, an increased interval between menarche and first live birth did not significantly increase the risk for ER-negative breast cancer, except for intervals in the range of 10 to 14 years (OR = 1.4; 95% CI, 1.1-1.8).
The researchers acknowledged incomplete data regarding receptor status and the small number of women with triple-negative breast cancer as limitations of their study.
“Our findings add further evidence to the growing knowledge that there are distinct etiologic pathways for ER-negative and ER-positive breast cancer," Ambrosone said. “This study underscores that these differences likely begin at a very early age.” – by Cameron Kelsall
Disclosure: The researchers report no relevant financial disclosures.
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