Risk Factors for Estrogen Receptor–Positive and –Negative Breast Cancer
In a study reported in the Journal of the National Cancer Institute, Kerlikowske et al identified risk factors for estrogen receptor–positive and –negative breast cancer using data from the Breast Cancer Surveillance Consortium. The analysis included 1,279,443 women, aged 35 to 74 years; of them, 14,969 developed estrogen receptor–positive and 3,617 developed estrogen receptor–negative invasive breast cancer, over a median follow-up of 8.3 years.
Associations With Benign Disease
For women aged 40 years, compared with no prior biopsy, the hazard ratio (HR) for estrogen receptor–positive vs –negative disease was 1.53 (95% confidence interval [CI] = 1.30–1.81) vs 1.26 (95% CI = 0.90–1.76) for nonproliferative disease, 1.63 (95% CI =1.23–2.17) vs 1.41 (95% CI = 0.78–2.57) for proliferative disease without atypia, and 4.47 (95% CI = 2.88–6.96) vs 0.20 (95% CI = 0.02–2.51) for proliferative disease with atypia. Risk of benign disease proliferation was higher for estrogen receptor–positive vs –negative cancer for women aged 35 years (P = .04), 40 years (P = .04), and 50 years (P = .06).
Other Associated Factors
Among pre/perimenopausal women, body mass index was more strongly associated with estrogen receptor–negative vs estrogen receptor–positive cancer (HR for obese II/III vs normal weight = 1.52, 95% CI = 1.19–1.94, vs 1.21, 95% CI = 1.08–1.36). Increasing body mass index was associated with a nonsignificantly increased risk for estrogen receptor–negative vs estrogen receptor–positive cancer among postmenopausal women currently using (P = .15) and not currently using hormone therapy (P = .08).
Associations with estrogen receptor subtype varied by race/ethnicity across all ages (P < .001) and by family history of breast cancer and breast density for specific ages. Black women had an increased risk of estrogen receptor–negative cancer risk vs white women for all ages, with the highest hazard ratio in women aged 35 years (3.05, 95% CI = 2.52–3.70) and lowest in women aged 70 years (1.56, 95% CI = 1.28–1.90).
Family history of breast cancer was more strongly associated with a risk for estrogen receptor–positive vs estrogen receptor–negative cancer for women older than age 50 years, with P values of .09 for age 50 years, .02 for age 60 years, and .03 for age 70 years. The strength of association of increasing breast density with risk declined with increasing age for estrogen receptor–positive cancer (P < .001 for interaction) but not for estrogen receptor–negative cancer (P = .34 for interaction).
The investigators concluded: “Strength of risk factor associations differed by [estrogen receptor] subtype. Separate risk models for [estrogen receptor] subtypes may improve identification of women for targeted prevention strategies.”
The study was supported by the National Institutes of Health, the National Cancer Institute, and the Breast Cancer Surveillance Consortium.
Karla Kerlikowske, MD, of San Francisco Veterans Affairs Medical Center, is the corresponding author of the Journal of the National Cancer Institute article.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
