Association Between Benign Breast Disease in African American and White American Women and Subsequent Triple-Negative Breast Cancer.

IMPORTANCE: Compared with white American (WA) women, African American (AA) women have a 2-fold higher incidence of breast cancers that are negative for estrogen receptor, progesterone receptor, and ERBB2 (triple-negative breast cancer [TNBC]). Triple-negative breast cancer, compared with non-TNBC, likely arises from different pathogenetic pathways, and benign breast disease (BBD) predicts future non-TNBC. OBJECTIVE: To determine whether AA identity remains associated with TNBC for women with a prior diagnosis of BBD. DESIGN, SETTING, AND PARTICIPANTS: This study is a retrospective analysis of data of a cohort of 2588 AA and 3566 WA women aged between 40 and 70 years with a biopsy-proven BBD diagnosis. The data-obtained from the Pathology Information System of Henry Ford Health System (HFHS), an integrated multihospital and multispecialty health care system headquartered in Detroit, Michigan-include specimens of biopsies performed between January 1, 1994, and December 31, 2005. Data analysis was performed from November 1, 2015, to June 15, 2016. MAIN OUTCOMES AND MEASURES: Subsequent breast cancer was stratified on the basis of combinations of hormone receptor and ERBB2 expression. RESULTS: Case management, follow-up, and outcomes received or obtained by our cohort of 2588 AA and 3566 WA patients were similar, demonstrating that HFHS delivered care equitably. Subsequent breast cancers developed in 103 (4.1%) of AA patients (mean follow-up interval of 6.8 years) and 143 (4.0%) of WA patients (mean follow-up interval of 6.1 years). More than three-quarters of subsequent breast cancers in each subset were ductal carcinoma in situ or stage I. The 10-year probability estimate for developing TNBC was 0.56% (95% CI, 0.32%-1.0%) for AA patients and 0.25% (95% CI, 0.12%-0.53%) for WA patients. Among the 66 AA patients who developed subsequent invasive breast cancer, 16 (24.2%) developed TNBC compared with 7 (7.4%) of the 94 WA patients who developed subsequent invasive breast cancers and had complete biomarker data (P = .01). CONCLUSIONS AND RELEVANCE: This study is the largest analysis to date of TNBC in the context of racial/ethnic identity and BBD as risk factors. The study found that AA identity persisted as a significant risk factor for TNBC. This finding suggests that AA identity is associated with inherent susceptibility for TNBC pathogenetic pathways.

Cell signaling events differentiate ER-negative subtypes from ER-positive breast cancer.

Currently available markers routinely used in clinical practice are of limited value to patients with estrogen receptor-negative (ER(-)) breast cancer [basal-like and HER2neu-positive (HER(+))], an aggressive subtype. Our aim was to uncover molecular pathways and signaling networks exposed by differentially methylated genes informative of the biology of ER(-) breast cancer (BC) subtypes versus ER-positive (ER(+)). Whole-genome methylation array analysis was carried out using the Illumina Infinium HumanMethylation27 BeadChip on 14 primary BC: five ER(+), four triple-negative (TNBC), and five ER(-)HER2(+). Degree of methylation was calculated as a ß-value (ranging from 0 to 1), and M-values [log (ß/(1 - ß)] were used for significance tests. To identify methylated genes associated with ER(-) subtypes (TNBC and ER(-)HER2(+)) and distinct from ER(+), a weighted algorithm, developed to increase statistical rigor, called out genes in which methylation changed dramatically between ER(+) and ER(-) subtypes. Differentially methylated gene lists examined using Ingenuity Pathway Analysis called out canonical pathways and networks with clues to biological distinctiveness as well as relatedness between ER(-) subtypes as compared to ER(+) BC. The study highlights the interplay of ER(-) subtype-specific genes and their signaling pathways as potential putative fingerprints in refining classification of BC subtypes and as potential biological markers designed to hit multiple targets.