Racial Disparities in Breast Cancer Outcomes in the Metropolitan Atlanta Area: New Insights and Approaches for Health Equity

Abstract Background Racial disparities in breast cancer (BC) outcomes persist where non-Hispanic black (NHB) women are more likely to die from BC than non-Hispanic white (NHW) women, and the extent of this disparity varies geographically. We evaluated tumor, treatment, and patient characteristics that contribute to racial differences in BC mortality in Atlanta, Georgia, where the disparity was previously characterized as especially large. Methods We identified 4943 NHW and 3580 NHB women in the Georgia Cancer Registry with stage I–IV BC diagnoses in Atlanta (2010–2014). We used Cox proportional hazard regression to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) comparing NHB vs NHW BC mortality by tumor, treatment, and patient characteristics on the additive and multiplicative scales. We additionally estimated the mediating effects of these characteristics on the association between race and BC mortality. Results At diagnosis, NHB women were younger—with higher stage, node-positive, and triple-negative tumors relative to NHW women. In age-adjusted models, NHB women with luminal A disease had a 2.43 times higher rate of BC mortality compared to their NHW counterparts (95% CI = 1.99 to 2.97). High socioeconomic status (SES) NHB women had more than twice the mortality rates than their white counterparts (HR = 2.67, 95% CI = 1.65 to 4.33). Racial disparities among women without insurance, in the lowest SES index, or diagnosed with triple-negative BC were less pronounced. Conclusions In Atlanta, the largest racial disparities are observed in luminal tumors and most pronounced among women of high SES. More research is needed to understand drivers of disparities within these treatable features.

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Oncotype DX recurrence score implications for disparities in chemotherapy and breast cancer mortality in Georgia

npj Breast Cancer ◽

10.1038/s41523-019-0129-3 ◽

2019 ◽

Vol 5 (1) ◽

Cited By ~ 2

Author(s):

Lindsay J. Collin ◽

Ming Yan ◽

Renjian Jiang ◽

Kevin C. Ward ◽

Brittany Crawford ◽

...

Keyword(s):

Breast Cancer ◽

Racial Disparities ◽

Breast Cancer Mortality ◽

Recurrence Score ◽

Oncotype Dx ◽

Proportional Hazard ◽

Cox Proportional Hazard ◽

Hazard Ratios ◽

Cox Proportional Hazard Regression ◽

To Receive

Abstract Among women diagnosed with stage I–IIIa, node-negative, hormone receptor (HR)-positive breast cancer (BC), Oncotype DX recurrence scores (ODX RS) inform chemotherapy treatment decisions. Differences in recurrence scores or testing may contribute to racial disparities in BC mortality among women with HR+ tumors. We identified 12,081 non-Hispanic White (NHW) and non-Hispanic Black (NHB) BC patients in Georgia (2010–2014), eligible to receive an ODX RS. Logistic regression was used to estimate the odds of chemotherapy receipt by race and ODX RS. Cox proportional hazard regression was used to calculate the hazard ratios (HRs) comparing BC mortality rates by race and recurrence score. Receipt of Oncotype testing was consistent between NHB and NHW women. Receipt of chemotherapy was generally comparable within strata of ODX RS—although NHB women with low scores were slightly more likely to receive chemotherapy (OR = 1.16, 95% CI 0.77, 1.75), and NHB women with high scores less likely to receive chemotherapy (OR = 0.77, 95% CI 0.48, 1.24), than NHW counterparts. NHB women with a low recurrence score had the largest hazard of BC mortality (HR = 2.47 95% CI 1.22, 4.99) compared to NHW women. Our data suggest that additional tumor heterogeneity, or other downstream treatment factors, not captured by ODX, may be drivers of racial disparities in HR+ BC.

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Breast Cancer Outcomes in a Racially and Ethnically Diverse Cohort of Insured Women

Ethnicity & Disease ◽

10.18865/ed.28.4.565 ◽

2018 ◽

Vol 28 (4) ◽

pp. 565-574 ◽

Cited By ~ 2

Author(s):

Reina Haque ◽

Xiaoqing Xu ◽

Jiaxiao Shi ◽

Marilyn L. Kwan ◽

Rowan T. Chlebowski

Keyword(s):

Breast Cancer ◽

Triple Negative ◽

Cancer Outcomes ◽

Luminal A ◽

Luminal B ◽

Breast Cancer Outcomes ◽

Increased Risk ◽

Biologic Subtype ◽

Race Ethnicity ◽

Cancer Rates

Background: It is unknown how subsequent breast cancer outcomes vary by biologic subtype and race/ethnicity in a diverse cohort of breast cancer survivors.Methods: We conducted a prospective cohort study of 6,154 insured breast cancer survivors (AJCC TNM stages 0–IV) diagnosed between 1996-2007 and followed them through 1/1/2010 for subsequent breast cancer events (recurrence, contralateral breast cancer, metastasis, mortality). We compared subsequent breast cancer rates by race/ethnicity groups and biologic subtype (luminal A, luminal B, HER2-enriched, and triple negative). We calculated hazard ratios (HRs) with 95% CIs using multivariable Cox proportional hazards models, adjusted for sociodemographics, cancer treatments, and tumor characteristics.Results: The cohort was diverse: 62.4% non-Hispanic White, 13.2% Hispanic, 14.9% African American, and 9.5% Asian. We identified 1,456 subsequent breast cancer events over 22,830 person-years. Although certain Asian women had higher crude subsequent breast cancer rates compared with Whites, within each biologic subtype category, these disparities disappeared in the multivariable analyses. After accounting for race/ethnicity, compared with women with luminal A tumors (reference), women with luminal B (adjusted HR=3.65, 95% CI: 3.08-4.32), HER2- enriched (adjusted HR=2.81, 95% CI: 2.25-3.51) and triple negative (adjusted HR=1.25, 95% CI: 1.01-1.54) tumors had statistically increased risks of subsequent breast cancer. Factors that were statistically significantly associated with increased risk included higher stage, larger tumor size, positive lymph nodes, and no adjuvant endocrine or chemotherapy (all P<.025).Discussion: Our data suggest that disparities in subsequent breast cancer outcomes were more strongly associated with tumor characteristics and non-use of adjuvant treatments than race/ethnicity. Ethn Dis. 2018;28(4):565-574; doi:10.18865/ed.28.4.565.

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Genetic co-expression networks contribute to creating predictive model and exploring novel biomarkers for the prognosis of breast cancer

Scientific Reports ◽

10.1038/s41598-021-84995-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Chi-Ming Chu ◽

Huan-Ming Hsu ◽

Chi-Wen Chang ◽

Yuan-Kuei Li ◽

Yu-Jia Chang ◽

...

Keyword(s):

Breast Cancer ◽

Prediction Models ◽

Reference Model ◽

External Validation ◽

Risk Scores ◽

Consistent Finding ◽

Hazard Ratios ◽

Genetic Predictors ◽

Novel Biomarkers ◽

Cox Proportional Hazard Regression

AbstractGenetic co-expression network (GCN) analysis augments the understanding of breast cancer (BC). We aimed to propose GCN-based modeling for BC relapse-free survival (RFS) prediction and to discover novel biomarkers. We used GCN and Cox proportional hazard regression to create various prediction models using mRNA microarray of 920 tumors and conduct external validation using independent data of 1056 tumors. GCNs of 34 identified candidate genes were plotted in various sizes. Compared to the reference model, the genetic predictors selected from bigger GCNs composed better prediction models. The prediction accuracy and AUC of 3 ~ 15-year RFS are 71.0–81.4% and 74.6–78% respectively (rfm, ACC 63.2–65.5%, AUC 61.9–74.9%). The hazard ratios of risk scores of developing relapse ranged from 1.89 ~ 3.32 (p < 10–8) over all models under the control of the node status. External validation showed the consistent finding. We found top 12 co-expressed genes are relative new or novel biomarkers that have not been explored in BC prognosis or other cancers until this decade. GCN-based modeling creates better prediction models and facilitates novel genes exploration on BC prognosis.

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Inflammatory Breast Cancer: Clinical Characteristics and Influence of Molecular Subtypes on Treatment Response

Tumori Journal ◽

10.1177/03008916211012341 ◽

2021 ◽

Vol 107 (1_suppl) ◽

pp. 12-12

Author(s):

D Aissaoui ◽

M Bohli ◽

R Ben Amor ◽

J Yahyaoui ◽

A Hamdoun ◽

...

Keyword(s):

Breast Cancer ◽

Treatment Response ◽

Inflammatory Breast Cancer ◽

Hormone Receptor ◽

Triple Negative ◽

Molecular Subtypes ◽

Luminal A ◽

Her2 Positive ◽

Luminal B ◽

Significant Difference

Introduction: Inflammatory Breast Cancer (IBC) is a rare and very aggressive breast cancer with poor prognosis. The prevalence is different from a country to another. In Tunisia, it is about 5 to 7% of breast cancer. The aim of this study is to describe the epidemiological and histopathological features of patients with inflammatory breast cancer and to evaluate the treatment response according to the molecular subtypes. Methods: This retrospective review identified 31 patients with no metastatic IBC treated in our radiotherapy department between December 2019 and November 2020. IBC was confirmed using the clinical criteria. Baseline clinic-pathological and treatment information was retrieved from medical records. Statistical analysis was performed with IBM SPSS V.20. Results: Median age was 51.3 years [27-68]. 48% of tumors were grade 3. The average tumor size was 36mm [10-90]. The histological type was ductal carcinoma in 97%. Vascular invasion was noted in 24 patients (77%). Thirty patients were classified as stage IIIB and one patient was IIIC. 74% were hormone receptor positive and 45% were HER2 positive. Luminal B was the predominant subtype (52%) followed by Her2 positive (32%), Luminal A (23%), and triple negative (3%) All patients had chemotherapy: neoadjuvant for 26 patients (84%) and adjuvant for 5 patients (16%). Nine patients (29%) had tumor pathological complete response (pCR). Partial response was observed in 18 patients (58%). Lymph node pCR was noted in 16% of cases (n=5). Endocrine therapy and trastuzumab were given to 76% and 45% of patients, respectively. The influence of the molecular subtype was not statistically significant on the response to neoadjuvant treatment. The highest rate of pCR were 43% for Her2positive, then 27%, 21% and 9% for Luminal B, Luminal A and Triple negative, respectively (p=0.2). Conclusion: Our study showed a high percentage of hormone receptor and Her2+ (74% and 45% respectively) in IBC. Luminal B was the most frequent subtype. Anthracycline-based chemotherapy and trastuzumab improved the pCR rate: 44% for Her2positive. Triple negative showed poorer pCR than other breast cancer subtype without a significant difference. A larger study is warranted to confirm our findings.

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Diffusion-Weighted Imaging of Different Breast Cancer Molecular Subtypes: A Systematic Review and Meta-Analysis

Breast Care ◽

10.1159/000514407 ◽

2021 ◽

pp. 1-8

Author(s):

Hans-Jonas Meyer ◽

Andreas Wienke ◽

Alexey Surov

Keyword(s):

Breast Cancer ◽

Systematic Review ◽

Diffusion Weighted Imaging ◽

Triple Negative ◽

Molecular Subtypes ◽

Luminal A ◽

Diagnose Breast Cancer ◽

Luminal B ◽

Diffusion Weighted ◽

Adc Values

Background: Magnetic resonance imaging can be used to diagnose breast cancer (BC).Diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) can be used to reflect tumor microstructure. Objectives: This analysis aimed to compare ADC values between molecular subtypes of BC based on a large sample of patients. Method: The MEDLINE library and Scopus database were screened for the associations between ADC and molecular subtypes of BC up to April 2020. The primary end point of the systematic review was the ADC value in different BC subtypes. Overall, 28 studies were included. Results: The included studies comprised a total of 2,990 tumors. Luminal A type was diagnosed in 865 cases (28.9%), luminal B in 899 (30.1%), human epidermal growth factor receptor (Her2)-enriched in 597 (20.0%), and triple-negative in 629 (21.0%). The mean ADC values of the subtypes were as follows: luminal A: 0.99 × 10–3 mm2/s (95% CI 0.94–1.04), luminal B: 0.97 × 10–3 mm2/s (95% CI 0.89–1.05), Her2-enriched: 1.02 × 10–3 mm2/s (95% CI 0.95–1.08), and triple-negative: 0.99 × 10–3 mm2/s (95% CI 0.91–1.07). Conclusions: ADC values cannot be used to discriminate between molecular subtypes of BC.

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CD44 Targeted Nanomaterials for Treatment of Triple-Negative Breast Cancer

Cancers ◽

10.3390/cancers13040898 ◽

2021 ◽

Vol 13 (4) ◽

pp. 898

Author(s):

Ghazal Nabil ◽

Rami Alzhrani ◽

Hashem Alsaab ◽

Mohammed Atef ◽

Samaresh Sau ◽

...

Keyword(s):

Breast Cancer ◽

Triple Negative Breast Cancer ◽

Triple Negative ◽

In Vivo Studies ◽

High Dose ◽

Luminal A ◽

Combination Strategy ◽

Ongoing Research

Identified as the second leading cause of cancer-related deaths among American women after lung cancer, breast cancer of all types has been the focus of numerous research studies. Even though triple-negative breast cancer (TNBC) represents 15–20% of the number of breast cancer cases worldwide, its existing therapeutic options are fairly limited. Due to the pivotal role of the presence/absence of specific receptors to luminal A, luminal B, HER-2+, and TNBC in the molecular classification of breast cancer, the lack of these receptors has accounted for the aforementioned limitation. Thereupon, in an attempt to participate in the ongoing research endeavors to overcome such a limitation, the conducted study adopts a combination strategy as a therapeutic paradigm for TNBC, which has proven notable results with respect to both: improving patient outcomes and survivability rates. The study hinges upon an investigation of a promising NPs platform for CD44 mediated theranostic that can be combined with JAK/STAT inhibitors for the treatment of TNBC. The ability of momelotinib (MMB), which is a JAK/STAT inhibitor, to sensitize the TNBC to apoptosis inducer (CFM-4.16) has been evaluated in MDA-MB-231 and MDA-MB-468. MMB + CFM-4.16 combination with a combination index (CI) ≤0.5, has been selected for in vitro and in vivo studies. MMB has been combined with CD44 directed polymeric nanoparticles (PNPs) loaded with CFM-4.16, namely CD44-T-PNPs, which selectively delivered the payload to CD44 overexpressing TNBC with a significant decrease in cell viability associated with a high dose reduction index (DRI). The mechanism underlying their synergism is based on the simultaneous downregulation of P-STAT3 and the up-regulation of CARP-1, which has induced ROS-dependent apoptosis leading to caspase 3/7 elevation, cell shrinkage, DNA damage, and suppressed migration. CD44-T-PNPs showed a remarkable cellular internalization, demonstrated by uptake of a Rhodamine B dye in vitro and S0456 (NIR dye) in vivo. S0456 was conjugated to PNPs to form CD44-T-PNPs/S0456 that simultaneously delivered CFM-4.16 and S0456 parenterally with selective tumor targeting, prolonged circulation, minimized off-target distribution.

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Trends in breast cancer mortality according to molecular subtypes: A population-based study.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.15_suppl.572 ◽

2021 ◽

Vol 39 (15_suppl) ◽

pp. 572-572

Author(s):

Yunan Han ◽

Shuai Xu ◽

Graham A. Colditz ◽

Adetunji T. Toriola

Keyword(s):

Breast Cancer ◽

Cancer Mortality ◽

Triple Negative ◽

Molecular Subtypes ◽

Breast Cancer Mortality ◽

Treatment Strategies ◽

Luminal A ◽

Her2 Positive ◽

Mortality Trends ◽

Luminal B

572 Background: Breast cancer is the second leading cause of cancer death in U.S. women. On the molecular level, breast cancer is a heterogeneous disease. Heterogeneous expressions of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) are etiologically and clinically meaningful, as they map to distinct risk factors and different treatment strategies. Although breast cancer mortality has been declining since 1990, little is known about mortality trends according to molecular subtypes at the population level. Methods: We examined the incidence-based mortality rates and trends among women who were diagnosed with invasive breast cancer from 2010 through 2017 using the Surveillance, Epidemiology, and End Results (SEER) database. We defined incidence-based mortality using a moving 5-year calendar period starting in 2014. We further assessed mortality according to breast cancer molecular subtypes: luminal A (ER and/or PR positive, HER2 negative), luminal B (ER and/or PR positive, HER2 positive), HER2-enriched (HER2 over-expressed or amplified, ER and PR negative) and triple-negative (ER and PR negative, HER2 negative) tumors. We calculated annual percent changes (APC) in incidence-based mortality using joinpoint regression models. Results: Overall, incidence-based mortality for breast cancer significantly decreased by 1.5% annually from 2014 through 2017 (APC, -1.5%; 95% coefficient interval [CI], -2.3% to -0.7%; p<0.001). Incidence-based mortality decreased annually by 2.0% for luminal A breast cancer (APC, -2.0%; 95% CI, -3.7% to -0.3%; p<0.001), 2.1% for luminal B breast cancer (APC, -2.1%; 95% CI, -5.4% to 1.4%; p=0.1), 1.1% for triple-negative breast cancer (TNBC) (APC, -1.1%; 95% CI, -2.1% to -0.0%; p<0.001). However, incidence-based mortality for HER2-enriched breast cancer increased 2.3% annually during the study period (APC, 2.3%; 95% CI, -2.4% to 7.2%; p=0.2). Conclusions: Between 2014 and 2017, incidence-based mortality for luminal A, luminal B, and TNBC decreased among U.S. women, with a larger decrease observed for luminal tumors. However, incidence-based mortality for HER2-enriched breast cancer increased. The favorable incidence-based mortality trends for luminal tumors and TNBC are likely due to the continuing improvement in treatments and early detection. The increasing trend of incidence-based mortality for HER2-enriched breast cancer constitutes a priority for cancer control activities and further research.

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Geographical disparities of incidence and prevalence of triple-negative breast cancers: Multistate study data analysis.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.15_suppl.e12599 ◽

2021 ◽

Vol 39 (15_suppl) ◽

pp. e12599-e12599

Author(s):

Hyein Jeon ◽

Myeong Lee ◽

Mohammed Jaloudi

Keyword(s):

Breast Cancer ◽

Black Women ◽

Significant Relationship ◽

White Women ◽

Triple Negative ◽

The State ◽

Luminal A ◽

Black Females ◽

Black And White ◽

State Effect

e12599 Background: Higher prevalence of triple negative breast cancer (TNBC) in black women with associated poor outcomes due to various disparities is well documented within a single state. We examine multiple states to better understand the state effect on such differences in incidence and prevalence of TNBC in black women. Methods: Female patients of ages 19 years old and above with breast cancer from the Surveillance, Epidemiology and End Results (SEER) Program across 13 states (608 counties) from 2015 (n = 66,444) and 2016 (n = 66,122) were examined. The relationships between the proportion of black and white women and the rate of patients with different tumor subtypes (luminal A, luminal B, HR-HER2+, and triple negative) were examined at the county level using ordinary least-square regression models. In parallel, due to consideration of various state-specific healthcare policies, socio-cultural norms, and socio-economic disparities, multi-level regression models were applied to examine the nested, random effect of each state on TNBC prevalence in each county. Bonferroni correction was applied to reduce the Type I error caused by repeated use of the same variables in multiple tests. Results: The baseline breast cancer rates between black and white women were similar in the population (0.171% for black and 0.168% for white). Consistent to previous studies, we demonstrate a significant positive correlation (p < 0.001) in TNBC in black females in both years. Surprisingly, when accounted for the random effects on states, 38.2% (2015) and 34.3% (2016) increase in incidence of TNBC in black females were seen, suggestive of state-specific disparity affecting race-specific health. In 2015, other subtypes of breast cancer in both black and white females did not result in significant relationship. Interestingly, in 2016, there was a significant relationship seen between the TNBC rate in white females and the white female population rate only after adjusting for the state effect (p = 0.026). This indicates the impact of non-biological factors such as state-wide health policies. Additionally, HR-HER2+ black females had a significant relationship against respective population rate only after adjusting for the state effect as well (p = 0.0394). For luminal A white females, a 15% decrease in incidence was seen after adjusting for state effect (p = 0.0424). Conclusions: This is the first known across-state examination of breast cancer subtypes by race with random effects on state. This study shows the role of state-specific factors affecting incidence in black and white females and potentially indicates the importance of state-level management for breast cancer on health disparities in addition to race-driven effects. Further studies are needed to elucidate comparable differences between states affecting the rates of various subtypes of breast cancer and thus health outcomes.

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Low KIBRA Expression Is Associated with Poor Prognosis in Patients with Triple-Negative Breast Cancer

Medicina ◽

10.3390/medicina57080837 ◽

2021 ◽

Vol 57 (8) ◽

pp. 837

Author(s):

So-Woon Kim ◽

Jinah Chu ◽

Sung-Im Do ◽

Kiyong Na

Keyword(s):

Breast Cancer ◽

Triple Negative Breast Cancer ◽

Poor Prognosis ◽

Triple Negative ◽

Histological Grade ◽

Growth Factor Receptor ◽

Hippo Signaling ◽

Luminal A ◽

Luminal B ◽

Epidermal Growth

Background and Objectives: Kidney and brain protein (KIBRA) is a protein encoded by the WW and C2 domain containing 1 (WWC1) gene and is involved in the Hippo signaling pathway. Recent studies have revealed the prognostic value of KIBRA expression; however, its role in breast cancer remains unclear. The aim of this study was to examine KIBRA expression in relation to the clinical and pathological characteristics of patients with breast cancer and to disease outcomes. Materials and Methods: We analyzed the expression of KIBRA and its correlation with event-free survival (EFS) outcomes in resected samples from 486 patients with breast cancer. Results: KIBRA expression was significantly different among the molecular subgroups (low KIBRA expression: luminal A, 46.7% versus 50.0%, p = 0.641; luminal B, 32.7% versus 71.7%, p < 0.001; human epidermal growth factor receptor 2 (HER2)-enriched, 64.9% versus 45.5%. p = 0.001; triple-negative, 73.6% versus 43.8%, p < 0.001). Low KIBRA expression was also associated with high nuclear grade (60.4% versus 37.8%, p < 0.001), high histologic grade (58.7% versus 37.0%, p < 0.001), and estrogen receptor (ER) negativity (54.2% versus 23.6%, p < 0.001). Low KIBRA expression was significantly associated with poor EFS (p = 0.041; hazard ratio (HR) 1.658; 95% confidence interval (CI), 1.015–2.709). Low KIBRA expression was an independent indicator of poor prognosis (p = 0.001; HR = 3.952; 95% CI = 1.542–10.133) in triple-negative breast cancer (TNBC). Conclusion: Low KIBRA expression was associated with higher histological grade, ER negativity and poor EFS of breast cancer. In particular, our data highlight KIBRA expression status as a potential prognostic marker for TNBC.

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Analysis of prolactin receptor expression in breast cancer subtypes

Biomeditsinskaya Khimiya ◽

10.18097/pbmc20206601089 ◽

2020 ◽

Vol 66 (1) ◽

pp. 89-94

Author(s):

T.S. Kalinina ◽

V.V. Kononchuk ◽

S.V. Sidorov ◽

L.F. Gulyaeva

Keyword(s):

Breast Cancer ◽

Triple Negative ◽

Prolactin Receptor ◽

Mrna Level ◽

Receptor Expression ◽

Mrna Levels ◽

Luminal A ◽

Her2 Positive ◽

Tissue Samples ◽

Luminal B

Breast cancer (BC) is the most common cancer among women. It is known that the prolactin receptor (PRLR) may play a role in breast carcinogenesis, but the available data are often contradictory. To get a more complete picture of the relationship between the receptor and mammary gland carcinogenesis, we examined the association between changes in PRLR expression level and tumor subtype (and its main characteristics). To do this, using real-time PCR, we evaluated the level of PRLR mRNA in BC tissue samples and untransformed adjoining tissue samples (89 pairs). Since the androgen receptor (AR) has begun to be seen as a prognostic marker in breast cancer, we also evaluated the association between mRNA levels of AR and PRLR. We found a significant increase in PRLR expression in luminal subtypes; the highest level of PRLR mRNA was detected in luminal A subtype. In HER2-positive ER-, PR-negative BC, the PRLR mRNA level decreases in tumor tissues compared with untransformed tissues. High PRLR expression is also associated with smaller tumor size in luminal B HER2-negative subtype. In ER-, PR-negative tumors, PRLR expression is associated with AR expression: PRLR mRNA level is increased when AR mRNA level is reduced by more than 8 times in triple-negative tumors; in contrast, in HER2-positive subtype it decreases more significantly when AR expression is reduced by more than 3 times. A tendency towards an increase in PRLR expression with an increase in the AR mRNA level was also discovered in luminal subtypes. The level of PRLR expression depends on the age of patients. In luminal A, PRLR expression is higher in patients under 65 years. In contrast, in luminal B HER2-negative and triple-negative BC, reduced PRLR expression was observed in patients under the age of 40 years and under the age of 50 years, respectively. In this group of patients under the age of 40 years with luminal B HER2-negative BC, ER expression was also reduced (0-4 score according to the IHC assay). Thus, PRLR probably plays a different role in the development and progression of BC: in luminal A and luminal B HER2-positive subtypes PRLR may act as an oncogen, and in luminal B HER2-negative and ER-, PR-negative subtypes can play a tumor suppressor role.

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