HER2 molecular subtype is a dominant subtype of mammary Paget's cells. An immunohistochemical study

Sek P, Zawrocki A, Biernat W & Piekarski J H
(2010) Histopathology 57 , 564–571
HER2 molecular subtype is a dominant subtype of mammary Paget’s cells. An immunohistochemical study Aims: To test the hypothesis that the similarity of the molecular subtypes of Paget’s cells to the molecular subtypes of the underlying breast carcinomas favours the epidermotrophic theory of the origin of Paget’s cells. Methods and results: The immunohistochemical expression of markers that define particular molecular subtypes of breast carcinomas were analysed. The whole analysis was performed by means of tissue microarrays in mammary Paget’s disease and in the underlying breast carcinoma(s). Human epidermal growth factor receptor type 2 (HER2)‐overexpression subtype [oestrogen receptor (ER^?); HER2⁺] was a dominant molecular subtype of Paget’s cells (37 of 43 analysed cases; 86%). Luminal B (ER⁺; HER2⁺) and luminal A (ER⁺; HER^?) subtypes were identified in 12% and 2% of cases, respectively. None of the analysed tumours presented a basal‐like phenotype. A similar distribution of molecular subtypes was identified in the underlying in situ breast carcinomas (HER2 subtype, 82%; luminal A, 6%; luminal B, 6%; basal‐like, 6% of cases) and in the invasive component (HER2 subtype, 84%; luminal A, 8%; luminal B, 8%; basal‐like, 0% of cases). Conclusions: HER2 molecular subtype is the dominant, but not the sole subtype seen in Paget’s cells of the nipple. A similar distribution of molecular subtypes in both Paget’s cells and in the underlying carcinomas strongly suggests their common origin.     

Salivary duct carcinomas can be classified into luminal androgen receptor‐positive,HER2 and basal‐like phenotypes*

Di Palma S, Simpson R H W, Marchiò C, Skálová A, Ungari M, Sandison A, Whitaker S, Parry S & Reis‐Filho J S
(2012) Histopathology  61, 629–643 Salivary duct carcinomas can be classified into luminal androgen receptor‐positive, HER2 and basal‐like phenotypes Aims: The aim of this study was to devise a molecular classification for salivary duct carcinomas (SDCs) based on the similarities between SDCs and breast carcinomas and on characteristics of the microarray‐based gene expression profiling‐defined molecular subtypes of breast cancer. Methods and results: Forty‐two pure salivary duct carcinomas, 35 of which contained an in‐situ component as defined by histological review and/or immunohistochemical analysis, were stained with antibodies for oestrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR), human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor (EGFR) and cytokeratin (CK) 5/6. Based on these markers, tumours were classified into HER2, luminal androgen receptor‐positive, basal‐like, luminal and indeterminate phenotype. Analysis revealed that 16.7%, 69%, 4.8%, 9.5% and 0% were of HER2, luminal androgen receptor‐positive, basal‐like, indeterminate and luminal phenotype, respectively. The in‐situ and invasive components displayed the same molecular subtype in all but one case. Conclusions: Salivary duct carcinomas can be classified into molecular subgroups approximately equivalent to those in the breast. We also report on the existence of a subgroup of bona fide pure salivary duct carcinomas that have a ‘basal‐like’ phenotype. Understanding the phenotypic complexity of SDCs may help to expedite the identification of novel therapeutic targets for these aggressive tumours.     

PIK3CA mutations and loss of ARID1A protein expression are early events in the development of cystic ovarian clear cell adenocarcinoma

Somatic mutations of PIK3CA and ARID1A are the most common genetic alterations observed in ovarian clear cell adenocarcinomas (CCA). In a previous report, we showed that PIK3CA gene mutations and loss of ARID1A expression occur early during the development of CCA. In the present study, using direct genomic DNA sequencing for exons 9 and 20 of PIK3CA and immunohistochemistry for ARID1A protein expression, we analyzed the association of these molecular alterations with various clinicopathological parameters in a total of 90 cases of primary ovarian CCA, including 42 previously examined cases. The presence of PIK3CA mutations, identified in 34 (39%) of the 88 informative cases, was significantly associated with a grossly cystic tumor, the presence of adjacent endometriosis, prominent papillary architecture of tumor growth, the presence of hyalinized and mucoid stroma, and the absence of clear cell adenofibroma components (P < 0.05, each). There was no significant association of PIK3CA mutations with other clinical variables, such as age, clinical stage, or clinical outcome of the patients. The intensity of immunoreactivity for ARID1A was assigned as negative, weakly positive, and strongly positive in 44%, 22%, and 33% of tumors, respectively. Compared to tumors immunoreactive for ARID1A, ARID1A-negative tumors were significantly associated with the presence of adjacent endometriosis (P = 0.025), but there was no statistically supported association with other examined clinicopathological parameters. Compared with CCAs strongly positive for ARID1A, CCAs negative for ARID1A more frequently harbor PIK3CA mutations (P = 0.013). PIK3CA gene mutations and ARID1A immunohistochemistry lacked prognostic significance. These data further support the idea that these molecular alterations occur as very early events during tumor development of ovarian CCA.     

Coordinated expression of ER, PR and HER2 define different prognostic subtypes among poorly differentiated breast carcinomas

Aims:  Histological grade is one of the most important prognostic factors in breast carcinomas, but poorly differentiated neoplasms still have quite heterogeneous biological behaviour, since they can be genetically classified as basal-like, HER2+ or even luminal. The aim was to analyse the frequency of oestrogen receptor (ER), progesterone receptor (PR) and HER2 expression profiles among breast carcinomas with <10% tubular formation, and their correlation with classic prognostic factors.
Methods and results:  One hundred and thirty-four samples of paraffin-embedded tumours were studied retrospectively. The tumours were classified in to four groups by their ER/PR/HER2 profile: (i) ER+ and/or PR+ but HER2−; (ii) ER+ and/or PR+ and HER2+; (iii) ER− and/or PR− but HER2+; and (iv) ER−, PR− and HER2− (triple-negative). The histological features of triple-negative and HER2+ carcinomas overlap. The only difference was the expression of basal cytokeratins (basal CK), which was more frequent among triple-negative carcinomas. Basal-CK expression defined a more aggressive group of tumours, according to the pathological features, regardless of the immunohistochemical profile.
Conclusions:  Group 1 and 2 tumours (ER+ and/or PR+ tumours with or without HER2 expression) were not statistically different, suggesting that poorly differentiated carcinomas with hormone receptors correspond to the luminal B type of tumour. Among poorly differentiated breast carcinomas, the classic profile associated with basal-CK identifies distinct subtypes equivalent to those seen by genetic classification.     

Identification of a basal-like subtype of breast ductal carcinoma in situ

Microarray profiling of invasive breast carcinomas has identified subtypes including luminal A, luminal B, HER2-overexpressing, and basal-like. The poor-prognosis, basal-like tumors have been immunohistochemically characterized as estrogen receptor (ER)-negative, HER2/neu-negative, and cytokeratin 5/6-positive and/or epidermal growth factor receptor (EGFR)-positive. The aim of this study was to determine the prevalence of basal-like ductal carcinoma in situ in a population-based series of cases using immunohistochemical surrogates. A total of 245 pure ductal carcinoma in situ cases from a population-based, case-control study were evaluated for histologic characteristics and immunostained for ER, HER2/neu, EGFR, cytokeratin 5/6, p53, and Ki-67. The subtypes were defined as: luminal A (ER+, HER2-), luminal B (ER+, HER2+), HER2 positive (ER-, HER2+), and basal-like (ER-, HER2-, EGFR+, and/or cytokeratin 5/6+). The prevalence of breast cancer subtypes was basal-like (n = 19 [8%]); luminal A, n = 149 (61%); luminal B, n = 23 (9%); and HER2+/ER-, n = 38 (16%). Sixteen tumors (6%) were unclassified (negative for all 4 defining markers). The basal-like subtype was associated with unfavorable prognostic variables including high-grade nuclei (P < .0001), p53 overexpression (P < .0001), and elevated Ki-67 index (P < .0001). These studies demonstrate the presence of a basal-like in situ carcinoma, a potential precursor lesion to invasive basal-like carcinoma.     

Estrogen receptor (ER), progesterone receptor (PR), and HER2 expression pre- and post- neoadjuvant chemotherapy in primary breast carcinoma: a single institutional experience

Background

The estrogen receptor (ER), progesterone receptor (PR), and HER2 profile of a primary breast carcinoma plays a significant role in patient management and treatment. Because of the increasing utilization of neoadjuvant chemotherapy or hormone therapy, surgically-resected carcinomas often show marked treatment effect. The aim of this study was to compare immunohistochemical (IHC) profiles (ER, PR, HER2, HER2 FISH) of primary breast carcinomas before and after neoadjuvant chemotherapy to assess the subsequent effects on hormone receptor status.

Design

Primary breast carcinomas from 38 female patients treated with neoadjuvant therapy after needle core biopsy or fine needle aspiration diagnosis were included. Histologic data was collected for each case, including site, type, grade, tumor size (cm), pre- and post- neoadjuvant treatment IHC panel (ER, PR, HER2), and fluorescence in-situ hybridization (FISH) for HER2.

Results

Of the 38 carcinomas studied, 45 % were positive for ER by IHC both pre- and post- neoadjuvant treatment (P=1.00). IHC studies for PR in these 38 patients showed 37% positivity for PR pre-neoadjuvant therapy and 21% positivity post-treatment (p=0.03). For 37 patients with HER2 IHC, 32% were positive pre-treatment, and 22% were positive post-treatment (P = 0.20). For 7 patients, HER2 FISH was positive in 71% pre-therapy and in 57% post-treatment (P=0.32).

Conclusions

Profiles for ER, HER2 IHC, and HER2 FISH were not significantly different in primary breast carcinomas before and after neoadjuvant chemotherapy. Further investigation is warranted to assess reproducibility of technique and investigate clinical implications of significant loss of PR status in treated patients.     

Mutation screening of 10 cancer susceptibility genes in unselected breast cancer patients

Variants of cancer susceptibility genes other than BRCA1/2 have been proved to be associated with increased risks of breast cancer. This study was performed to investigate the spectrum and prevalence of mutations in 10 cancer susceptibility genes in paired tumor/normal tissues of 292 unselected Chinese breast cancer patients. We performed an analysis of germline and somatic variants in ATM, CDH1, CHEK2, ESR1, GATA3, MAP3K1, MSH2, PALB2, RB1 and STK11 genes by integrating microfluidic PCR‐based target enrichment and next‐generation sequencing technologies. In total, 3 germline and 25 somatic deleterious mutations were found among 27 patients (9.25%), and 17 of them were novel mutations. Most deleterious mutations were prevalent in luminal A invasive breast cancer (P = .014). We also observed 83 variants of uncertain significance (VUS) in 100 patients (34.25%), 23 of which were predicted to be deleterious by in silico prediction programs (MetaSVM and MetaLR). VUS carriers had higher positive rate of lymph node metastasis than non‐carriers (P = .008) and were predominantly present in ER+ tumors (P = .018). Our findings would enhance the understanding of the molecular mechanisms of breast cancer in Chinese population.     

Oestrogen receptor/progesterone receptor and human epidermal growth factor receptor 2 status in breast cancer: a 9-year study at Princess Noorah Oncology Center, Saudi Arabia

Satti M B
(2011) Histopathology 59 , 537–542 Oestrogen receptor/progesterone receptor and human epidermal growth factor receptor 2 status in breast cancer: a 9‐year study at Princess Noorah Oncology Center, Saudi Arabia Objective: To determine the oestrogen receptor/progesterone receptor (ER/PR) and human epidermal growth factor receptor 2 (HER2) status in Saudi Arabian patients presenting with breast cancer to Princess Noorah Oncology Center (PNOC) and to explore the correlation of these markers to each other, to tumour type and to grade. Methods and results: Pathology material and records of symptomatic patients presenting to the centre during 2001–2009 were reviewed for patients’ age, tumour size, type and grade and ER/PR and HER2 immunohistochemistry (IHC) status using the Dako HercepTest Kit as well as fluorescence in situ hybridization (FISH) for HER2 IHC 2+ score cases, as per the 2007 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines. There were 852 cases, with a mean age of 49 years and a mean tumour size of 3.0 cm with 75% node positivity. Of all cases, 772 (90.6%) were ductal carcinoma; 64% were ER/PR⁺ and 23% were HER2⁺; triple‐negative cases accounted for 24%. Conclusions: ER/PR and HER2 status did not differ from that reported previously, showing a direct correlation to tumour type and grade of ductal carcinoma. However, a difference exists in the relatively lower ER positivity in patients aged >50 years and the higher percentage of triple‐negative cases. This study would serve as a baseline for other future national studies and for planning strategies to targeted therapy.     

Androgen receptor is frequently expressed in HER2-positive, ER/PR-negative breast cancers

The estrogen receptor (ER)/progesterone receptor (PR)-negative breast carcinomas (BCs) encompass three molecular subtypes: one with human epidermal growth factor receptor 2 (HER) overexpression, one normal like, and the triple negative. The androgen receptor (AR) is expressed in 70–90% of invasive BCs. The aim of our study is to detect the expression of AR in a series of ER/PR-negative BCs to ascertain if there is clinical significance in relation to BC molecular subtypes. A immunohistochemical study for all receptors and cytokeratin expression was performed in 232 cases of ER/PR-negative BCs. According to cytokeratin expression, BCs were classified into two groups: luminal-type BCs (44.2%) and basal-like-type BCs (55.8%). According to the expression of HER2, 59.3% were triple-negative BCs (when ER, PR, and HER2 were negative) and 40.7% were HER2-positive BCs. AR expression was observed in 128 tumors (56.6%). One hundred and ten cases (48.8%) had >10% and 18 (7.8%) had <10% of positively stained cells. AR immunoreactivity was found in 31.2% basal-like BCs, while in the luminal group 71.1% of cases were positive, showing highly significant correlation (p < 10⁻⁸). Regarding HER2 status, 76.7% of HER2-positive BC cases were AR positive compared with only 30.4% of triple-negative BC types, showing a strong statistically significant correlation. In conclusion, we show that AR is frequently expressed in ER/PR-negative BCs and that expression of HER2 and AR is highly correlated (p < 0.005). Our results point out the role of AR and HER2 in the pathogenesis of BCs and suggest the potential role of AR in clinical management of ER/PR-negative BCs.     

Assessment of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status in the fine needle aspirates of metastatic breast carcinomas

The assessment of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor (HER2) status in the fine needle aspirates of metastatic breast carcinomas has prognostic and therapeutic implications. In this study, expression of ER, PR, and HER2 was assessed by immunohistochemical study in 70 cases of metastatic breast carcinomas and HER2 gene amplification was further evaluated by fluorescence in situ hybridization (FISH) in 38 (54%) cases. Positive expression of ER and PR was seen in 42 (60%) and 16 (23%) cases of metastatic breast carcinomas, respectively. HER2 immunoreactivity was scored as 0/1+ in 39 (56%), 2+ in 10 (14%), and 3+ in 21 (30%) cases. HER2 gene amplification was seen in 20% of HER2 2+ and 64% of HER2 3+ cases. ER, PR, and HER2 status in primary breast cancers were available to comparison in 31 cases (44%). The concordance rates between metastatic and primary breast carcinomas were 81% for ER, 65% for PR and 71% for HER2. Our study demonstrates that ER, PR, and HER2 status can be assessed in the fine needle aspirates of metastatic breast carcinomas and ER has a higher concordance rate between metastatic and primary breast carcinomas than PR and HER2. The addition of HER2 gene amplification FISH test helps in accurate assessment of HER2 status in metastatic breast carcinomas.     

Oestrogen receptor‐β1 but not oestrogen receptor‐βcx is of prognostic value in apocrine carcinoma of the breast

Apocrine carcinoma of the breast, which frequently expresses oestrogen receptor‐β (ER‐β) in the absence of ER‐α and only infrequently is treated endocrinologically, gives an opportunity to investigate the clinicopathological role of ER‐β in breast cancer independent of ER‐α expression or tamoxifen treatment. Several isotypes of ER‐β, ER‐β1–5 etc., have been identified thus far; however, the clinicopathological importance of each ER‐β isotype in breast cancer is still uncertain. Here we aimed to clarify the clinicopathological importance of ER‐β1 and ER‐βcx (ER‐β2) in apocrine carcinomas, immunohistochemically examining expressions of ER‐β1 and ER‐βcx in 47 apocrine carcinomas. Positivity for ER‐β1 and ER‐βcx was observed in 41 (87%) and 18 (38%) of 47 cases, respectively. ER‐β1 positivity was related to smaller tumor size (P=0.0359), lower histological grade (P=0.0322), and higher disease‐free survival (P<0.0001), whereas ER‐βcx status was related to none of these parameters. ER‐β1 positivity was also associated with favorable clinical outcome in 24 so‐called triple‐negative (ER‐α‐negative/PR‐negative/HER2‐negative) apocrine carcinomas. ER‐β1 itself, independent of ER‐α expression and tamoxifen treatment, seems to have a tumor‐suppressive effect, at least in apocrine carcinomas. Further study of ER‐β1 is desired to optimize breast cancer treatment.     

Gene expression analysis of invasive breast carcinoma yields differential patterns in luminal subtypes of breast cancer

Breast cancer is a heterogeneous disease, and new biomarkers are needed for more accurate classification and prediction of prognosis. The goal of this study is to assess the expression of breast cancer classification genes, to identify new molecular signatures in different intrinsic subtypes of breast cancer and to correlate their expression with different clinical variables. The study included 84 female patients newly diagnosed with non-metastatic breast cancer at the outpatient clinic at the National Cancer Institute, Cairo University, Egypt. Detection of 17 breast cancer classification genes was done using RT-PCR in tumor and normal tissues. Estrogen receptor (ER), progesterone receptor (PR), HER2, and Ki67 expression were assessed using IHC assay for intrinsic subtyping. Combined expression of FOXA1 and GATA3 was statistically higher in luminal subtypes in comparison to non-luminal subtypes. In Luminal A subtype; GRB7, EGFR, PTGS2, ID1, and KRT5 were significantly downregulated. FOXA1 and GATA3 were significantly upregulated in luminal B subtype, where EGFR and PTGS2 were significantly downregulated. While ESR1, EGFR, KRT5 and PTGS2 showed significantly low expression in tumor tissue in Her2 enriched subtype, TFF3 was significantly downregulated in triple negative subtype. GATA3 and FOXA1 expression exhibited significant correlation with tumor grade. Furthermore, GATA3, FOXA1, ESR1, and ID1 were also correlated significantly with staging of the tumor. Combined expression of ESR1, FOXA1 and GATA3 represents a molecular signature of luminal subtypes. Long term follow-up is needed to investigate the prognostic effect of breast cancer classification genes found in this study.     

Identification of somatic gene mutations in penile squamous cell carcinoma

There is a lack of studies on somatic gene mutations and cell signaling driving penile carcinogenesis. Our objective was to analyze somatic mutations in genes downstream of EGFR in penile squamous cell carcinomas, especially the mTOR and RAS/MAPK pathways. We retrospectively analyzed somatic mutations in 10 in situ and 65 invasive penile squamous cell carcinomas by using Sequenom's Mass Spectrometry iPlex Technology and Oncocarta v1.0 Panel. The DNA was extracted from FFPE blocks and we identified somatic missense mutations in three in situ tumors and in 19 invasive tumors, mostly in PIK3CA, KRAS, HRAS, NRAS, and PDGFA genes. Somatic mutations in the PIK3CA gene or RAS family genes were neither associated with tumor grade, stage or outcome, and were equally often identified in hrHPV positive and in hrHPV negative tumors that showed no p53 expression. Mutations in PIK3CA, KRAS, and HRAS are frequent in penile squamous cell carcinoma and likely play a role in the development of p53‐negative tumors. Although the presence of these mutations does not seem to correlate with tumoral behavior or outcome, they could be biomarkers of treatment failure with anti‐EGFR mAb in patients with penile squamous cell carcinoma. © 2015 Wiley Periodicals, Inc.     

Identification of molecular phenotypes in canine mammary carcinomas with clinical implications: application of the human classification

Similarly to humans, canine mammary cancer represents a heterogeneous group in terms of morphology and biological behaviour. In the present study, we evaluated a series of canine mammary carcinomas based on a new human classification, initially based on gene expression profiling analysis. Similarly to human breast cancer, by using an immunohistochemistry surrogate panel based on five molecular markers [estrogen receptor, human epidermal growth factor receptor 2 (HER2), cytokeratin 5, p63 and P-cadherin], we were able to classify canine mammary carcinomas into four different subtypes: luminal A [estrogen receptor (ER)+/HER2-; 44.8%], luminal B (ER+/HER2+; 13.5%), basal (ER-/HER2- and a basal marker positive; 29.2%) and HER2 overexpressing tumours (ER-/HER2+; 8.3%). Luminal A-type tumours were characterised by lower grade and proliferation rate, whereas basal-type tumours were mostly high grade, high proliferative and positive for cytokeratin 5, p63 and P-cadherin. In addition, as in humans, basal subtype was significantly associated with shorter disease-free and overall survival rates, and we propose canine mammary carcinomas as a suitable natural model for the study of this particular subset of human carcinomas.     

雄激素受体在乳腺癌中的表达及其与雌、孕激素受体和HER2的关系

目的 研究雄激素受体(AR)在乳腺浸润性导管癌中的表达及其与雌激素受体(ER)、孕激素受体(PR)和HER2状态的关系,探讨其作为乳腺癌治疗靶点的可行性.方法 采用免疫组织化学EnVision法检测AR、ER、PR、HER2在175例乳腺浸润性导管癌中的表达,依据结果分为腺腔A型、腺腔B型、HER2过表达型和三阴性型(ER-/PR-/HER2-)组.结果 175例中AR阳性88例(50.3%),AR表达与ER、PR、HER2均呈正相关(P＜0.01).腺腔A型53例(30.3%),腺腔B型33例(18.9%),HER2过表达型23例(13.1%),三阴性型66例(37.7%),AR阳性率分别为56.6%(30/53),75.8%(25/33)、47.8%(11/23)和33.3%(22/66),组间AR阳性率差异显著(x2=17.054,P=0.001).三阴性型组AR阳性者核分裂象较少(x2=5.140,P=0.023),腺腔A型组AR阳性者多为年轻患者(x2=4.567,P=0.033),差异有统计学意义.其他组内AR表达与否和临床病理学特征比较无统计学意义.结论 AR在乳腺癌中有较高的阳性率,可作为乳腺癌,特别是三阴性型乳腺癌的治疗靶点.     

雄激素受体在乳腺癌中的表达及其与雌、孕激素受体和HER2的关系

目的 研究雄激素受体(AR)在乳腺浸润性导管癌中的表达及其与雌激素受体(ER)、孕激素受体(PR)和HER2状态的关系,探讨其作为乳腺癌治疗靶点的可行性.方法 采用免疫组织化学EnVision法检测AR、ER、PR、HER2在175例乳腺浸润性导管癌中的表达,依据结果分为腺腔A型、腺腔B型、HER2过表达型和三阴性型(ER-/PR-/HER2-)组.结果 175例中AR阳性88例(50.3%),AR表达与ER、PR、HER2均呈正相关(P＜0.01).腺腔A型53例(30.3%),腺腔B型33例(18.9%),HER2过表达型23例(13.1%),三阴性型66例(37.7%),AR阳性率分别为56.6%(30/53),75.8%(25/33)、47.8%(11/23)和33.3%(22/66),组间AR阳性率差异显著(x2=17.054,P=0.001).三阴性型组AR阳性者核分裂象较少(x2=5.140,P=0.023),腺腔A型组AR阳性者多为年轻患者(x2=4.567,P=0.033),差异有统计学意义.其他组内AR表达与否和临床病理学特征比较无统计学意义.结论 AR在乳腺癌中有较高的阳性率,可作为乳腺癌,特别是三阴性型乳腺癌的治疗靶点.     

p63, cytokeratin 5, and P-cadherin: three molecular markers to distinguish basal phenotype in breast carcinomas

Human breast carcinomas represent a heterogeneous group of tumors diverse in behavior, outcome, and response to therapy. However, the current system of pathological classification does not take into account biologic determinants of prognosis. The purpose of this study was to classify and characterize breast carcinomas based on variations in protein expression patterns derived from immunohistochemical analyses on tissue microarrays (TMAs). Therefore, 11 TMAs representing 168 invasive breast carcinomas were constructed. Breast tumors were classified into four different subtypes depending on estrogen receptor (ER) and HER2 expression. Basal-type tumors expressed neither of these proteins and represented 7.6% of our series; basal-like HER2-overexpressing tumors did not express ER and represented 17.7%; luminal-type tumors expressed ER and represented 72.8% of this series (luminal A 56.3%, luminal B 16.5%). Moreover, we characterized each subtype based on P-cadherin (P-CD), p63, cytokeratin (CK)5, BCL2, and Ki67 expression. Basal-type tumors were mostly grade III, more frequently P-CD-, p63-, and CK5-positive, and had a high proliferation rate. Conversely, luminal-type tumors rarely expressed basal markers and had a low grade and proliferation rate. Basal-like HER2-overexpressing tumors showed a basal-type profile similar with a high grade and up-regulation of P-CD and CK5. With this study, we show that P-CD, p63, and CK5 are important molecular markers that can be used to distinguish a basal phenotype. In addition, we also demonstrate the usefulness of TMAs in breast carcinoma immunoprofiling.     

Expression of the HER1-4 family of receptor tyrosine kinases in breast cancer

EGFr/HER1 and c-erbB-2/HER2 expression are associated with poor prognosis in breast cancer. The type I receptor tyrosine kinase (RTK) family to which they belong has four members (HER1-4). In this study, expression of HER1-4 and oestrogen receptor (ER) expression were determined by immunohistochemistry in 220 breast carcinomas. Elevated expression of HER1 was observed in 16.4%, HER2 in 22.8%, HER3 in 17.5%, and HER4 in 11.9% of these tumours. Patients whose tumours overexpressed HER1, 2 or 3 had reduced survival (p= <0.001), whereas those whose tumours overexpressed HER4 had increased survival (p=0.013); 38.6% of cases overexpressed one or more of HER1, 2 or 3. HER4 was rarely overexpressed with other HERs (1.4% of cases). Cox's multiple regression analysis demonstrated that overexpression of HER1/2/3, HER4, and standard prognostic indicators independently affected survival. HER1-3 expression was related to ER negativity (p<0.0001, chi2). Patients with ER-positive, HER1-3-positive tumours had a significantly poorer survival (p<0.001) than those with ER-positive/HER-negative or HER4-positive tumours. Expression of HER RTKs displays complex interactions between different family members. There is a strong interaction, in terms of survival, between HER expression and ER expression. The development of HER-targeted agents (eg Herceptin, Iressa), and agents targeted at the downstream signalling pathways, therefore provides new possibilities in the treatment of breast cancer.     

Phenotypic evaluation of the basal-like subtype of invasive breast carcinoma.

Microarray profiling of invasive breast carcinomas has identified five distinct subtypes of tumors (luminal A, luminal B, normal breast-like, HER2 overexpressing, and basal-like) that are associated with different clinical outcomes. The basal-like subtype is associated with poor clinical outcomes and is the subtype observed in BRCA1-related breast cancers. The aim of this study was to characterize the histologic and immunophenotypic properties of breast basal-like carcinomas that were first positively identified using DNA microarray analysis. Detailed histologic review was performed on 56 tumors with known microarray profiles (23 basal-like, 23 luminal, and 12 HER2+). Immunohistochemistry for estrogen receptor (ER), HER2, EGFR, smooth muscle actin (SMA), p63, CD10, cytokeratin 5/6, cytokeratin 8/18, and vimentin was performed on 18 basal-like, 16 luminal, and 12 HER2+ tumors. The basal-like tumors were grade 3 ductal/NOS (21/23) or metaplastic (2/23) carcinomas that frequently showed geographic necrosis (17/23), a pushing border of invasion (14/23), and a stromal lymphocytic response (13/23). Most basal-like tumors showed immunoreactivity for vimentin (17/18), luminal cytokeratin 8/18 (15/18), EGFR (13/18), and cytokeratin 5/6 (11/18), while positivity for the myoepithelial markers SMA (4/18), p63 (4/18) and CD10 (2/18) was infrequent. All basal-like tumors tested were ER- and HER2-. Morphologic features significantly associated with the basal-like subtype included markedly elevated mitotic count (P<0.0001), geographic tumor necrosis (P=0.0003), pushing margin of invasion (P=0.0001), and stromal lymphocytic response (P=0.01). The most consistent immunophenotype seen in the basal-like tumors was negativity for ER and HER2, and positivity for vimentin, EGFR, cytokeratin 8/18, and cytokeratin 5/6. The infrequent expression of myoepithelial markers in basal-like carcinomas does not support a direct myoepithelial cell derivation of these tumors. These findings should further assist in the identification of basal-like carcinomas in clinical specimens, facilitating treatment and epidemiologic studies of this tumor subtype.