Multiethnic PDX models predict a possible immune signature associated with TNBC of African ancestry.

PURPOSE: Triple-negative breast cancer (TNBC) is an aggressive subtype most prevalent among women of Western Sub-Saharan African ancestry. It accounts for 15-25% of African American (AA) breast cancers (BC) and up to 80% of Ghanaian breast cancers, thus contributing to outcome disparities in BC for black women. The aggressive biology of TNBC has been shown to be regulated partially by breast cancer stem cells (BCSC) which mediate tumor recurrence and metastasis and are more abundant in African breast tumors. METHODS: We studied the biological differences between TNBC in women with African ancestry and those of Caucasian women by comparing the gene expression of the BCSC. From low-passage patient derived xenografts (PDX) from Ghanaian (GH), AA, and Caucasian American (CA) TNBCs, we sorted for and sequenced the stem cell populations and analyzed for differential gene enrichment. RESULTS: In our cohort of TNBC tumors, we observed that the ALDH expressing stem cells display distinct ethnic specific gene expression patterns, with the largest difference existing between the GH and AA ALDH+ cells. Furthermore, the tumors from the women of African ancestry [GH/AA] had ALDH stem cell (SC) enrichment for expression of immune related genes and processes. Among the significantly upregulated genes were CD274 (PD-L1), CXCR9, CXCR10 and IFI27, which could serve as potential drug targets. CONCLUSIONS: Further exploration of the role of immune regulated genes and biological processes in BCSC may offer insight into developing novel approaches to treating TNBC to help ameliorate survival disparities in women with African ancestry.

Hereditary Susceptibility for Triple Negative Breast Cancer Associated With Western Sub-Saharan African Ancestry: Results From an International Surgical Breast Cancer Collaborative.

OBJECTIVE: To investigate subtype-specific risk of germline alleles associated with triple negative breast cancer (TNBC) in African ancestry populations. BACKGROUND: Breast cancer (BC) mortality is higher in African American (AA) compared to White American (WA) women; this disparity is partly explained by 2-fold higher TNBC incidence. METHODS: We used a surgically maintained biospecimen cohort of 2884 BC cases. Subsets of the total (760 AA; 962 WA; 910 West African/Ghanaian; 252 East African/Ethiopian) were analyzed for genotypes of candidate alleles. A subset of 417 healthy controls were also genotyped, to measure associations with overall BC risk and TNBC. RESULTS: TNBC frequency was highest in Ghanaian and AA cases (49% and 44% respectively; P < 0.0001) and lowest in Ethiopian and WA cases (17% and 24% respectively; P < 0.0001). TNBC cases had higher West African ancestry than non-TNBC (P < 0.0001). Frequency of the Duffy-null allele (rs2814778; an African ancestral variant adopted under selective pressure as protection against malaria) was associated with TNBC-specific risk (P < 0.0001), quantified West African Ancestry (P < 0.0001) and was more common in AA, Ghanaians, and TNBC cases. Additionally, rs4849887 was significantly associated with overall BC risk, and both rs2363956 and rs13000023 were associated with TNBC-specific risk, although none as strongly as the Duffy-null variant. CONCLUSIONS: West African ancestry is strongly correlated with TNBC status, as well as germline variants related to BC risk. The Duffy-null allele was associated with TNBC risk in our cohort.

Comparative Analysis of Breast Cancer Phenotypes in African American, White American, and West Versus East African patients: Correlation Between African Ancestry and Triple-Negative Breast Cancer.

INTRODUCTION: Triple-negative breast cancer (TNBC) is more common among African American (AA) and western sub-Saharan African breast cancer (BC) patients compared with White/Caucasian Americans (WA) and Europeans. Little is known about TNBC in east Africa. METHODS: Invasive BC diagnosed 1998-2014 were evaluated: WA and AA patients from the Henry Ford Health System in Detroit, Michigan; Ghanaian/west Africans from the Komfo Anokye Teaching Hospital in Kumasi, Ghana; and Ethiopian/east Africans from the St. Paul's Hospital Millennium Medical College in Addis Ababa, Ethiopia. Histopathology and immunohistochemistry for estrogen receptor (ER), progesterone receptor (PR), and HER2/neu expression was performed in Michigan on formalin-fixed, paraffin-embedded samples from all cases. RESULTS: A total of 234 Ghanaian (mean age 49 years), 94 Ethiopian (mean age 43 years), 272 AA (mean age 60 years), and 321 WA (mean age 62 years; p = 0.001) patients were compared. ER-negative and TNBC were more common among Ghanaian and AA compared with WA and Ethiopian cases (frequency ER-negativity 71.1 and 37.1 % vs. 19.8 and 28.6 % respectively, p < 0.0001; frequency TNBC 53.2 and 29.8 % vs. 15.5 and 15.0 %, respectively, p < 0.0001). Among patients younger than 50 years, prevalence of TNBC remained highest among Ghanaians (50.8 %) and AA (34.3 %) compared with WA and Ethiopians (approximately 16 % in each; p = 0.0002). CONCLUSIONS: This study confirms an association between TNBC and West African ancestry; TNBC frequency among AA patients is intermediate between WA and Ghanaian/West Africans consistent with genetic admixture following the west Africa-based trans-Atlantic slave trade. TNBC frequency was low among Ethiopians/East Africans; this may reflect less shared ancestry between AA and Ethiopians.

Differences between Breast Conservation-Eligible Patients and Unilateral Mastectomy Patients in Choosing Contralateral Prophylactic Mastectomies.

There has been an increasing use of bilateral mastectomy (BM) for breast cancer. We sought to examine our trends among breast conservation (BCT) candidates and women recommended for unilateral mastectomy (UM). Our prospective breast cancer database was queried for women with a first-time, unilateral breast cancer. Patient and histologic factors and surgical treatment, including reconstruction, were evaluated. A detailed chart review was performed among patients from two representative time periods as to the reasons the patient underwent mastectomy. We identified 3,892 women between 2000 and 2012 of whom 60% underwent BCT, 1092 (28%) had UM and 12% underwent BM. BM rose from 4% in 2000 to a high of 19% in 2011, increasing around 2002 for women <40. BCT was less likely with decreasing age (p < 0.0001), lobular histology (p < 0.0001), higher stage (p < 0.0001) and decreasing BMI (p < 0.0001). Among mastectomy patients, contralateral mastectomy was associated with decreasing age (p < 0.0001), Caucasian race (p < 0.0001), and lower stage (p = 0.005). Over time, indications for mastectomy decreased while patients deemed BCT-eligible opting for UM or BM increased dramatically. Increases in the use of BM are in large part among women who were otherwise BCT-eligible. Factors associated with BM use are different for BCT-eligible patients and those recommended for UM. A better understanding of the factors driving individual patient choices is needed.

Global surgical oncology disease burden: addressing disparities via global surgery initiatives: the University of Michigan International Breast Cancer Registry.

BACKGROUND: Disparities in breast cancer incidence and outcome between African American and white American women are multifactorial in etiology. The increased frequency of triple-negative breast cancers (TNBC) in African American patients suggests the possible contribution of hereditary factors related to African ancestry. METHODS: The University of Michigan (UM)-Komfo Anoyke Teaching Hospital (KATH) Breast Cancer Research Collaborative and International Breast Registry was established in 2004. It features epidemiologic information, tumor tissue, and germline DNA specimens from African American, white American, and Ghanaian women. RESULTS: This research collaborative has generated valuable findings regarding the pathogenesis and patterns of TNBC while concomitantly improving the standard of breast oncology care in Ghana. This partnership has also yielded important opportunities for academic and educational exchange. It has expanded to involve other sites in Africa and Haiti. CONCLUSIONS: The UM-KATH collaborative is a model for demonstrating the research and academic exchange value of international partnerships.

African Ancestry-Associated Gene Expression Profiles in Triple-Negative Breast Cancer Underlie Altered Tumor Biology and Clinical Outcome in Women of African Descent.

Women of sub-Saharan African descent have disproportionately higher incidence of triple-negative breast cancer (TNBC) and TNBC-specific mortality across all populations. Population studies show racial differences in TNBC biology, including higher prevalence of basal-like and quadruple-negative subtypes in African Americans (AA). However, previous investigations relied on self-reported race (SRR) of primarily U.S. populations. Due to heterogeneous genetic admixture and biological consequences of social determinants, the true association of African ancestry with TNBC biology is unclear. To address this, we conducted RNA sequencing on an international cohort of AAs, as well as West and East Africans with TNBC. Using comprehensive genetic ancestry estimation in this African-enriched cohort, we found expression of 613 genes associated with African ancestry and 2,000+ associated with regional African ancestry. A subset of African-associated genes also showed differences in normal breast tissue. Pathway enrichment and deconvolution of tumor cellular composition revealed that tumor-associated immunologic profiles are distinct in patients of African descent. SIGNIFICANCE: Our comprehensive ancestry quantification process revealed that ancestry-associated gene expression profiles in TNBC include population-level distinctions in immunologic landscapes. These differences may explain some differences in race-group clinical outcomes. This study shows the first definitive link between African ancestry and the TNBC immunologic landscape, from an African-enriched international multiethnic cohort. See related commentary by Hamilton et al., p. 2496. This article is highlighted in the In This Issue feature, p. 2483.

Investigation of triple-negative breast cancer risk alleles in an International African-enriched cohort.

Large-scale efforts to identify breast cancer (BC) risk alleles have historically taken place among women of European ancestry. Recently, there are new efforts to verify if these alleles increase risk in African American (AA) women as well. We investigated the effect of previously reported AA breast cancer and triple-negative breast cancer (TNBC) risk alleles in our African-enriched International Center for the Study of Breast Cancer Subtypes (ICSBCS) cohort. Using case-control, case-series and race-nested approaches, we report that the Duffy-null allele (rs2814778) is associated with TNBC risk (OR = 3.814, p = 0.001), specifically among AA individuals, after adjusting for self-indicated race and west African ancestry (OR = 3.368, p = 0.007). We have also validated the protective effect of the minor allele of the ANKLE1 missense variant rs2363956 among AA for TNBC (OR = 0.420, p = 0.005). Our results suggest that an ancestry-specific Duffy-null allele and differential prevalence of a polymorphic gene variant of ANKLE1 may play a role in TNBC breast cancer outcomes. These findings present opportunities for therapeutic potential and future studies to address race-specific differences in TNBC risk and disease outcome.

Breast Cancer Knowledge and Decisions Made for Contralateral Prophylactic Mastectomy: A Survey of Surgeons and Women in the General Population.

BACKGROUND: Decisions made to undergo contralateral prophylactic mastectomy, in women at low risk for bilateral disease, are often attributed to a lack of knowledge. This study examines the role knowledge plays in determining surgical treatment for unilateral breast cancer made by laywomen and surgeons for themselves or loved ones. METHODS: The study cohort had three groups: (1) laywomen in the general population, (2) breast surgeons, and (3) plastic surgeons. Laywomen were recruited using Amazon Mechanical Turk Crowd Sourcing. Breast and plastic surgeons from nine states were sent electronic surveys. Demographic and contralateral prophylactic mastectomy-specific data on decisions and knowledge were collected and analyzed. RESULTS: Surveys from 1333 laywomen, 198 plastic surgeons, and 142 breast surgeons were analyzed. A significantly greater proportion of laywomen in the general population favored contralateral prophylactic mastectomy (67 percent) relative to plastic (50 percent) and breast surgeons (26 percent) (p < 0.0001). Breast surgeons who chose contralateral prophylactic mastectomy were younger (p = 0.044) and female (0.012). On assessment of knowledge, 78 percent of laywomen had a low level of breast cancer knowledge. Laywomen with higher levels of breast cancer knowledge had lower odds of choosing contralateral prophylactic mastectomy (OR, 0.37; 95 percent CI, 0.28 to 0.49). CONCLUSIONS: Fewer women are likely to make decisions in favor of contralateral prophylactic mastectomy with better breast cancer-specific education. A knowledge gap likely explains the lower rates with which surgeons choose contralateral prophylactic mastectomy for themselves or loved ones; however, some surgeons who were predominantly young and female favor contralateral prophylactic mastectomy. Improving patient education on surgical options for breast cancer treatment is critical, with well-informed decisions as the goal.

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.

Postmastectomy Radiation Therapy and Two-Stage Implant-Based Breast Reconstruction: Is There a Better Time to Irradiate?

BACKGROUND: The ideal timing of postmastectomy radiation therapy (PMRT) in the setting of two-stage implant-based breast reconstruction remains unclear. In this cohort study, the authors sought to determine whether complication rates differed between patients who received PMRT following tissue expander placement (TE-XRT) and those who received PMRT after exchange for permanent implants (Implant-XRT) utilizing using prospective, multicenter data. METHODS: Eligible patients in the Mastectomy Reconstruction Outcomes Consortium study from 11 institutions across North America were included in the analysis. All patients had at least 6-month follow-up after their last intervention (i.e., implant exchange for TE-XRT patients, and radiation for Implant-XRT patients). Complications including seroma, hematoma, infection, wound dehiscence, capsular contracture, and implant loss were recorded. RESULTS: The authors identified a total of 150 patients who underwent immediate, two-stage implant-based breast reconstruction and received PMRT. Of these, there were TE-XRT 104 patients (69.3 percent) and 46 (30.7 percent) Implant-XRT patients. There were no differences in the incidence of any complications or complications leading to reconstructive failure between the two cohorts. After adjusting for patient characteristics and site effect, the timing of PMRT (i.e., TE-XRT versus Implant-XRT) was not a significant predictor in the development of any complication, a major complication, or reconstructive failure. CONCLUSION: In the setting of PMRT and two-stage implant-based reconstruction, patients who received PMRT after expander placement (TE-XRT) did not have a higher incidence or increased odds of developing complications than those who received PMRT after exchange for a permanent implant (Implant-XRT). CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.