Triple-negative breast cancer: clinicopathological characteristics and relationship with basal-like breast cancer

Sonographic features of triple-negative and non-triple-negative breast cancer

OBJECTIVES

Triple-negative breast cancer (TNBC) is known to have unique molecular, clinical, and pathologic characteristics. The growth pattern of this cancer may also affect its appearance on sonography. Our study evaluated the sonographic features of TNBC according to the American College of Radiology Breast Imaging Reporting and Data System sonographic classification system and compared these features with those of non-TNBC.

METHODS

Data from 315 consecutive breast cancer cases were collected. The images were reevaluated by an examiner blinded to the patients' characteristics and histologic results according to the Breast Imaging Reporting and Data System. The sonographic features of TNBC (n = 33) and non-TNBC (n = 282) were compared.

RESULTS

Triple-negative breast cancer was significantly correlated with a younger patient age (P = .002) and was associated with higher tumor grades (P < .001), more lymph node involvement (P = .014), and a trend toward a larger tumor size. With regard to sonographic features, the margin of TNBC was more frequently described as lobulated or microlobulated (75.8% versus 49.5% in non-TNBC; P = .005). The echoic halo was observed significantly less often in TNBC than in non-TNBC(39.4% versus 62.8%; P = .014). Cooper ligaments were displaced rather than disrupted in TNBC compared to non-TNBC (P = .003). Regarding the posterior acoustic features, enhancement was observed significantly more often in TNBC (36.4% versus 13.0% in non-TNBC; P = .031).

CONCLUSIONS

Triple-negative breast cancer and non-TNBC have different sonographic features. This finding can be explained by the pathologic profile of this breast cancer subtype. Some of the distinct sonographic criteria for TNBC are more likely to be associated with benign masses. Knowledge of the distinct sonographic features of TNBC would help the examiner avoid false-negative classification of this tumor type.

Triple-negative breast cancer is associated with EGFR, CK5/6 and c-KIT expression in Malaysian women

BACKGROUND

Triple-negative breast cancer (TNBC) is a heterogeneous subgroup of breast cancer characterized by the lack of estrogen receptor (ER), progesterone receptor (PR) and the human epidermal growth factor receptor 2 (HER2) expressions. This subgroup of refractory disease tends to have aggressive clinical behavior, high frequency of metastasis and lack of response to current hormonal or targeted therapies. Despite numerous studies reporting the clinicopathological features of TNBC and its association with the basal-like phenotype in the Western population, only limited data are available in the Asian population. Therefore, the aim of this study was to investigate the clinicopathological characteristics of TNBC and its association with epidermal growth factor receptor (EGFR), cytokeratin 5/6 (CK5/6) and mast/stem cell growth factor receptor (c-KIT or CD117) expression in Malaysian women.

METHODS

A total of 340 patients diagnosed with primary breast cancer between 2002 and 2006 in Malaysia were reviewed and analyzed.

RESULTS

The incidence of TNBC was 12.4% (42/340). Bivariate analysis revealed that TNBC was strongly associated with a younger age, higher grade tumor and p53 expression. Further immunohistochemical analysis suggested that TNBC in Malaysian women was strongly associated with EGFR, CK5/6 and c-KIT expression with high a Ki-67 proliferation index.

CONCLUSION

In conclusion, our study confirms the association of TNBC with basal-like marker expression (EGFR, CK5/6 and c-KIT) in Malaysian women, consistent with studies in other populations.

Curcumin induces apoptosis of triple-negative breast cancer cells by inhibition of EGFR expression

Curcumin is the major component of the spice turmeric, extracted from the rhizomes of the plant Curcuma longa. It exerts a number of therapeutic effects, including the inhibition of cancer cell proliferation. However, the anti-carcinogenic mechanism of curcumin has not been fully elucidated. Triple-negative breast cancer (TNBC), which lacks expression of the estrogen receptor (ER), progesterone receptor (PR) and epidermal growth factor receptor 2 (HER2/EGFR2), is an aggressive breast cancer phenotype with a poor prognosis. In this study, we investigated the effects of curcumin on triple-negative breast cancer cells and the possible molecular mechanisms. The MDA-MB-231 TNBC cells were treated with curcumin, the growth inhibition ratio of the cells was measured by MTT assay, apoptosis was detected by flow cytometry and the expression levels of extracellular regulated protein kinase (ERK1/2), pERK1/2, EGFR and pEGFR were detected by western blotting. After treatment with different concentrations of curcumin, the growth inhibition rates of the MDA-MB-231 breast cancer cells of the 30 µmol/ml curcumin-treated group were significantly different from those of the other groups. The level of apoptosis of the curcumin-treated group (26.34%) was significantly different from that of the control group (2.76%). The expression levels of pERK1/2 and pEGFR in the curcumin-treated group were significantly decreased compared with those of the control group. These results indicate that curcumin is able to inhibit the proliferation of TNBC cells. Inhibition of the EGFR signaling pathway is the likely underlying molecular mechanism.

Update on triple-negative breast cancer: prognosis and management strategies

Triple negative breast cancer (TNBC) is a heterogeneous disease comprehending different orphan breast cancers simply defined by the absence of ER/PR/HER-2. Approximately 15%-20% of all breast cancers belong to this phenotype that has distinct risk factors, distinct molecular features, and a particular clinical presentation and outcome. All these features will be discussed in this review. The risk of developing TNBC varies with age, race, genetics, breastfeeding patterns, and parity. Some TNBC are very chemo-sensitive and the majority of patients confronted with and treated for TNBC will never relapse. Some (histological) subgroups of TNBC may have good prognosis even in the absence of chemotherapy. Distinct molecular subgroups within TNBC have been defined now as well. In case metastatic relapse occurs, this is usually within 5 years following surgery, and survival following metastatic relapse is shorter compared to other breast cancer subtypes; treatment options are few and responses lack durability. Novel drug targets and new biomarkers are needed to improve breast cancer care for patients presenting with TNBC. Further molecular/biological unraveling of TNBC is needed.

Efficacy of everolimus, a novel mTOR inhibitor, against basal-like triple-negative breast cancer cells

Patients with triple-negative breast cancers (TNBCs) typically have a poor prognosis because such cancers have no effective therapeutic targets, such as estrogen receptors for endocrine therapy or human epidermal growth factor receptor 2 (HER2) receptors for anti-HER2 therapy. As the phosphatidylinositol 3' kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) cascade is activated in TNBCs, mTOR is a potential molecular target for anticancer therapy. In this study, we investigated the antitumor activities of everolimus, an oral mTOR inhibitor, in nine TNBC cell lines. Everolimus effectively inhibited cell growth at concentrations under 100 nM (IC(50)) in five cell lines and even in the 1-nM range in three of the five cell lines. To identify specific characteristics that could be used as predictive markers of efficacy, we evaluated the expressions of proteins in the mTOR cascade, basal markers, and cancer stem cell markers using western blotting, fluorescent in situ hybridization (FISH), or immunohistochemistry. All five of the sensitive cell lines were categorized as a basal-like subtype positive for either epidermal growth factor receptor (EGFR) or CK5/6, although resistant cell lines were not of this subtype and tended to exhibit the characteristics of cancer stem cells, with decreased E-cadherin and the increased expression of Snail or Twist. In vivo assays demonstrated antitumor activity in a mouse xenograft model of basal-like breast cancer, rather than non-basal breast cancer. These results suggest that everolimus has favorable activity against basal-like subtypes of TNBCs. Epidermal growth factor receptor and CK5/6 are positive predictive markers of the TNBC response to everolimus, while cancer stem cell markers are negative predictive markers.

Treating metastatic breast cancer with systemic chemotherapies: current trends and future perspectives

Treatment selection for metastatic breast cancer (MBC) is guided by multiple factors, most importantly hormone receptor (HR) or HER2 expression, treatment history, and prognostic factors such as short disease-free interval, presence of visceral metastases, performance status, and degree of symptoms. Chemotherapy is indicated as initial therapy for patients with HR-negative disease and following failure of hormonal therapies in HR-positive disease. Patients treated with an anthracycline or a taxane in early-stage settings may no longer be candidates for those drugs in MBC, thus underscoring the need for alternative options. Sequential single-agent therapy or combination therapy are viable strategies. Trials have shown that ixabepilone plus capecitabine significantly improves progression-free survival compared with capecitabine alone in anthracycline- or taxane-pretreated or -resistant patients, and single-agent eribulin improves survival compared with the physician's choice of treatment in patients treated previously with at least two regimens for MBC. Regardless of the regimen, proactive management to detect treatment-related adverse events in a timely manner remains important for ensuring effective delivery of treatment. Many promising investigational agents are in development, including T-DM1 (trastuzumab emtansine) and pertuzumab for HER2-positive disease, as well as PARP-1 (poly[adenosine diphosphate ribose] polymerase-1) inhibitors and cetuximab for triple-negative disease. In addition, new options for the treatment of MBC following failure of an anthracycline and a taxane promise to improve patient outcomes. Nurses should remain vigilant for adverse events and remember that the goal of treatment remains control of the disease and palliation.

Molecular subtypes of breast carcinoma in Egyptian women: clinicopathological features

Breast carcinoma may be classified into distinct molecular subtypes based on immunohistochemical markers for estrogen, progesterone and Her-2/neu receptors. The aim of the study was to identify the clinicopathological features of the molecular subtypes of breast carcinoma in our locality. A total of 274 surgically resected breast carcinomas were selected from the files of the Dr. KRZ referral pathology laboratory, Mansoura, Egypt, and the Pathology Department of Mansoura University. Molecular subtypes were classified into luminal A, luminal B, Her-2/neu-expressing and triple-negative. Clinicopathological and histological features of molecular subtypes were analyzed. Luminal A subtype was the most prevalent (41.2%), followed by triple-negative subtype (28.5%), then Her2-expressing subtype (19.4%) and luminal B subtype (13.9%). The commonest histological type was infiltrating duct carcinoma (83.2%), followed by infiltrating lobular carcinoma (9.1%) and medullary carcinoma (3.2%). The luminal A subtype was significantly correlated to low tumor grade, lower number of positive lymph nodes metastasis, absence of both necrosis and syncytial growth pattern. We concluded that the commonest molecular subtype of invasive breast carcinoma among Egyptian women is luminal subtype A, which displayed favorable features. Triple-negative subtype and medullary carcinomas are present in a ratio higher than in western countries.

Overexpression of Cell Cycle Progression Inhibitor Geminin is Associated with Tumor Stem-Like Phenotype of Triple-Negative Breast Cancer

PURPOSE

Triple-negative breast cancer, has a significant clinical relevance being associated with a shorter median time to relapse and death and does not respond to endocrine therapy or other available targeted agents. For this reason, identifying the molecular pathways associated with increased aggressiveness, for example the presence of stem cell populations within the tumor and alteration of genes associated with cell cycle regulation represents an important objective in the clinical research into this neoplasm.

METHODS

To investigate the role of cell cycle progression inhibitor Geminin in triple-negative breast cancers and its potential correlation with stem-like phenotype of this neoplasm, we used tissue microarray technology to build a specific triple-negative breast cancer tissue micro-array. Geminin and cancer stem cell marker CD133 expression was further investigated at the mRNA level for selected breast tumor samples through realtime polymerase chain reaction quantification.

RESULTS

Our results showed that CD133 expression was significantly associated to high Geminin expression (p=0.017), a strong association between Ki-67 and tumor grade (p=0.020) and an inverse association between Geminin expression and lymphonode metastases (p=0.058), and a trend of statistically significance between Geminin marker expression and survival of triple-negative breast cancer patients (p=0.076).

CONCLUSION

The strong association between the expression of CD133 and Geminin could be useful in molecular stratification of breast tumors and in particular of triple-negative breast cancers.

Metastatic triple-negative breast cancer

The triple-negative class (oestrogen receptor-negative, progesterone receptor-negative and human epidermal growth factor receptor 2 [HER2]-negative) comprises about 15% of breast cancer. It is associated with a poor prognosis compared with tumours that are positive for hormone receptors or HER2. Despite being sensitive to chemotherapy, many women with metastatic triple-negative breast cancer (TNBC) relapse quickly, and commonly develop visceral metastasis, including lung, liver and brain metastasis. TNBC has molecular features that overlap with breast cancer in BRCA1 germline mutation carriers and with those of the basal-like molecular class of tumours. Furthermore, tumours with the triple-negative phenotype have specific features and express markers that are potential therapeutic targets, for example an impaired DNA repair mechanism and increased expression of proliferation and basal-associated markers. The presence of these features has important implications for clinical practice and for the design of clinical trials looking at novel therapies. Targeted agents that are currently being investigated include poly (ADP-ribose) polymerase inhibitors, epidermal growth factor receptor inhibitors and anti-angiogenic compounds. Here we discuss the epidemiology, morphological and molecular spectrum of TNBC, the clinical significance of this important class of breast cancer and the current treatment options.

Role of p63 in cancer development

Since their initial identification p53 homologues p63 and p73 have been expected to play a role in cancer development due to their close homology to p53, notoriously one of the most mutated genes in cancer. However soon after their discovery the awareness that these genes were rarely mutated in cancer seemed to indicate that they did not play a role in its development. However a large number of data collected in the following years indicated that altered expression rather than mutation could be found in different neoplasia and play a role in its biology. In particular p63 due to its fundamental role in epithelial development seems to play a role in a number of tumors of epithelial origin. In this review we summarize some of the evidence linking p63 to carcinogenesis.

Pathologic progression of mammary carcinomas in a C3(1)/SV40 T/t-antigen transgenic rat model of human triple-negative and Her2-positive breast cancer

The C3(1) component of the rat prostate steroid binding protein has been used to target expression of the SV40 T/t-antigen to the mammary epithelium of mice resulting in pre-neoplastic lesions that progress to invasive and metastatic cancer with molecular features of human basal-type breast cancer. However, there are major differences in the histologic architecture of the stromal and epithelial elements between the mouse and human mammary glands. The rat mammary gland is more enriched with epithelial and stromal components than the mouse and more closely resembles the cellular composition of the human gland. Additionally, existing rat models of mammary cancer are typically estrogen receptor positive and hormone responsive, unlike most genetically engineered mouse mammary cancer models. In an attempt to develop a mammary cancer model that might more closely resemble the pathology of human breast cancer, we generated a novel C3(1)/SV40 T/t-antigen transgenic rat model that developed progressive mammary lesions leading to highly invasive adenocarcinomas. However, aggressive tumor development prevented the establishment of transgenic lines. Characterization of the tumors revealed that they were primarily estrogen receptor and progesterone receptor negative, and either her2/neu positive or negative, resembling human triple-negative or Her2 positive breast cancer. Tumors expressed the basal marker K14, as well as the luminal marker K18, and were negative for smooth muscle actin. The triple negative phenotype has not been previously reported in a rat mammary cancer model. Further development of a C3(1)SV40 T/t-antigen based model could establish valuable transgenic rat lines that develop basal-type mammary tumors.

Mutations in the epidermal growth factor receptor (EGFR) gene in triple negative breast cancer: possible implications for targeted therapy

Introduction

Triple negative breast cancer is associated with poorer prognosis and unresponsiveness to endocrine and anti-HER2 directed agents. Despite emerging data supporting the use of polyADP-ribose polymerase (PARP) inhibitors, complete and durable responses are rare and exploration of additional targeted therapies is needed. Epidermal growth factor receptor (EGFR) is expressed in triple negative breast cancer and several clinical trials are testing the role of anti-EGFR directed therapy. However, the rate of EGFR mutations is poorly defined. We, therefore, sought to characterize EGFR mutations in triple negative breast cancers.

Methods

Seventy samples were randomly chosen from a cohort of 653 triple negative breast tumours for EGFR mutation analysis. These samples were immunostained for EGFR protein expression and consisted of negatively stained and positively stained cases. DNA was extracted from paraffin blocks and polymerase chain reaction was performed to amplify exon regions 18 to 21 of the EGFR gene. Direct sequencing of the purified PCR products was performed.

Results

EGFR mutations were found in 8 of 70 samples (11.4%). Mutations were predominantly exon 19 deletions (4 of 70 samples, 5.7%), which clustered in the region spanning codons 746 to 759 within the kinase domain of EGFR. Two types of exon 19 deletions were seen: a 15 nucleotide deletion (del E746-A750) (2 of 70 samples) and a 24 nucleotide deletion (del S752 - I759) (2 of 70 samples). Other exon 19 mutations observed were the inversion of the complementary strand (1 of 70 samples). Exon 21 mutations included missense substitution, L858R (1 of 70 samples) and T847I (2 of 70 samples). Mutations observed were independent of EGFR protein expression determined by immunohistochemical staining.

Conclusions

This study is among the first to document the presence and estimate the prevalence of EGFR mutations in triple negative breast cancer. These findings have potential implications for the design of clinical trials involving anti-EGFR directed therapy which currently do not select for patients based on presence of activating EGFR mutations, which may hence be underpowered to detect significant benefit in unselected populations. More complete sampling of EGFR mutation status in triple negative breast cancer is needed to determine the true mutation rate.

MicroRNA profiles of healthy basal and luminal mammary epithelial cells are distinct and reflected in different breast cancer subtypes

In order to determine the microRNA expression pattern in normal basal and luminal breast epithelium and to analyze the relationship of this expression pattern to different breast cancer subtypes, laser-microdissected luminal and basal cells isolated from plastic surgery tissue samples were used for comprehensive expression profiling, measuring 664 microRNAs by low-density TaqMan arrays. In a test (n = 5) and validation set (n = 9) 10 differentially expressed microRNAs were identified by TaqMan RT-qPCR. These microRNAs were studied in laser-microdissected cells of luminal A (n = 5), luminal B (n = 5), basal-like subtypes of breast cancer (n = 10), and malignant myoepithelioma of the breast (n = 10). From 116 microRNAs unequivocally expressed in normal breast epithelial cells, we identified 8 basal microRNAs (let7c, miR-125b, miR-126, miR-127-3p, miR-143, miR-145, miR-146b-5p, and miR-199a-3p), preferentially expressed in normal basal cells, exceeding luminal cells by a factor from 4 to 1000. All of these microRNAs were also found to be significantly elevated in malignant myoepithelioma but not in basal-type of breast cancer. Two members of the miR-200 family (miR-200c and miR-429) were predominantly luminal. Both microRNAs were expressed in the luminal and basal type of breast cancer in contrast to malignant myoepithelioma, which revealed significantly lower levels potentially contributing to its mesenchymal phenotype. In conclusion, normal luminal and basal mammary epithelial cells exhibit a different microRNA expression profile. Malignant myoepithelioma seems to exhibit a basal pattern of microRNA expression, whereas the so-called basal-like breast cancer is clearly different and reveals a luminal type pattern.

Expression of high-molecular-weight cytokeratin (34betaE12) is an independent predictor of disease-free survival in patients with triple-negative tumours of the breast

One-fifth of breast cancers have the triple-negative phenotype; a good prognostic marker has yet not been described for these tumours. Tumour microarrays from 58 triple-negative patients treated with surgery followed by chemotherapy were analysed for expression of cytokeratin 5/6 (CK5/6), epidermal growth factor receptor (EGFR), vimentin, p63 and cytokeratin 34betaE12. The mean patient age was 59.2 years with a follow-up from 39 to 168 months. Clinicopathological variables and survival data were correlated with biomarker expression. The frequency of expression of cytokeratin 5/6, EGFR, vimentin, p63 and 34betaE12 was 33%, 65%, 50%, 19% and 85%, respectively. Each of 34betaE12, p63, EGFR and T stage significantly correlated with both disease-free survival and overall survival. T stage and 34betaE12 were independent predictors of overall survival in a multivariate analysis. Expression of 34betaE12 predicts disease-free and overall survival in patients with triple-negative tumours. Additional studies are planned to confirm these initial findings.

Hormone Receptors and HER-2 Status as Surrogates for Breast Cancer Molecular Subtypes Prognosticate for Disease Control in Node Negative Asian Patients Treated with Breast Conservation Therapy

Introduction: Our study investigates whether an approximation of breast cancer molecular subtypes using the hormone receptors and HER-2 status prognosticates for disease control after breast conservation therapy (BCT) in node-negative Asian breast cancer patients. Methods and Materials: We retrospectively reviewed 541 women with node-negative breast cancers treated with BCT between 1989 and 2007. Hormone receptors and HER-2 status were obtained from patients’ histological report. All patients received radiotherapy. Thirty-six percent and 68% of women received chemotherapy and hormonal treatment respectively. Results: Median follow-up of patients is 72 months. Five-year local recurrence free survival (LRFS) is 97.2% for the cohort but differs between subtypes: luminal A, 0.8%; luminal B, 1.4%; HER-2, 3.6% and basal-like, 12.7% (P = 0.047). The 5-year distant disease free survival (DDFS) is 96.4% for the cohort but differs between subtypes: luminal A, 98.2%; luminal B, 92.6%; HER-2, 89.5% and basal-like, 91.5% (P = 0.019). The 5-year disease free survival (DFS) is 94.4% for the cohort but differs between subtypes: luminal A, 97.4%; luminal B, 92.7%; HER-2, 86.3% and basal-like, 85.0% (P = 0.007). Univariate analysis with luminal A as baseline revealed an association of the other 3 subtypes with decreased DFS (P = 0.007), Hazard Ratio (HR) of 2.2, 4.4 and 3.3 to Luminal B, HER-2 and basal subtypes, respectively. On multivariate analysis, HER-2 subtype (AHR = 3.3, 95% CI, 1.1 to 9.8, P = 0.036) and basal-like subtype (HR = 3.5, 95% CI, 1.2 to 9.9, P = 0.019) prognosticate adversely for DFS. Conclusion: The combination of hormone receptors and HER-2 status can be used as surrogates for molecular subtypes in Asian breast cancer patients with node-negative disease to prognosticate LRFS, DFS and DDFS. Keywords: Histological subtypes, Lumpectomy, Outcomes, Prognostic factors

Basal-like and triple-negative breast cancers: a critical review with an emphasis on the implications for pathologists and oncologists

Breast cancer is a heterogeneous disease encompassing a variety of entities with distinct morphological features and clinical behaviors. Although morphology is often associated with the pattern of molecular aberrations in breast cancers, it is also clear that tumors of the same histological type show remarkably different clinical behavior. This is particularly true for 'basal-like cancer', which is an entity defined using gene expression analysis. The purpose of this article was to review the current state of knowledge of basal-like breast cancers, to discuss the relationship between basal-like and triple-negative breast cancers, and to clarify practical implications of these diagnoses for pathologists and oncologists.

Clinicopathological features and treatment strategy for triple-negative breast cancer

Breast cancers are divided into at least 4 subtypes on the basis of gene expression profiles and expression of receptors (hormone receptors (HR) and HER2) as measured by immunohistochemistry. These subtypes have different prognoses and responses to treatments such as endocrine manipulation, anti-HER2 therapy, and chemotherapy. Triple-negative breast cancer (TNBC) is immunohistochemically defined as lacking estrogen and progesterone receptors and not overexpressing HER2. TNBC accounts for approximately 15% of breast cancer patients, and is more chemosensitive but has a worse prognosis than the HR-positive/HER2-negative phenotype. TNBC is a heterogeneous disease that does not offer specific targets in the same way as HR-positive and HER2-positive breast cancers, and is similar to basal-like breast cancer and BRCA1-related breast cancer. At present, the lack of highly effective therapeutic targets for TNBC leaves standard chemotherapy, for example the combination of anthracycline and taxane, as the only medical treatment, but this is insufficiently efficacious. Novel approaches for TNBC, for example DNA damaging agents, PARP-1 inhibitors, receptor tyrosin kinase inhibitors (TKIs), and antiangiogenesis agents, have been examined in clinical settings. Concerning therapeutic strategies for TNBC, it is most important to develop novel effective approaches for TNBC treatment and high-throughput predictive tools for standard chemotherapy and novel agents.

Triple negative breast cancer: outcome correlation with immunohistochemical detection of basal markers

We earlier evaluated the relationship of 653 triple negative breast cancers (TNBC) with basal immunophenotypic expression by using antibodies to basal cytokeratins (CK5/6, CK14, CK17, 34betaE12), p63, smooth muscle actin (SMA), epidermal growth factor receptor, and CD117, and found that a triple panel of CK14, 34betaE12 and epidermal growth factor receptor determined 84% of our cases to be basal-like. Women with basal-like TNBC tended to be younger (P=0.04), have histologically higher-grade tumors (P=0.047), with positive nodal status (P=0.047), than those whose tumors were nonbasal-like. Using univariate Cox regression analysis, tumor size (P=0.003), histologic grade (P=0.006), and nodal status (P=0.017) were significant factors for disease-free survival (DFS) among TNBC, whereas age (P=0.004), tumor size (P=0.001), histologic grade (P<0.001), nodal status (P=0.011), lymphovascular invasion (P=0.032), and pushing borders (P=0.042) were important for overall survival (OS). On multivariate analysis, age was statistically significant for both DFS and OS (P=0.033, 0.001 respectively), whereas histologic grade was important for OS (P<0.001). Kaplan Meier curves showed CK17 positivity to impact adversely on DFS (P=0.003) and OS (P=0.014), whereas CD117 positive staining was accompanied by diminished OS (P=0.036). SMA expression in TNBC however, revealed a trend for improved DFS (P=0.05). Our findings indicate that basal-like TNBC are associated with adverse clinicopathologic parameters, and that individual biologic markers of CK17, CD117, and SMA have prognostic implications on survival. Possibilities exist for future targeted therapy for this challenging group of breast cancers.

Mammary gland growth factors: roles in normal development and in cancer

Normal development of the mammary gland proceeds via interactions between the epithelium and the mesenchyme that start during embryogenesis and continue during pubertal outgrowth and differentiation. The function of specific peptide growth factors that bind members of the receptor tyrosine kinase family and the cytokine receptor family are required at each stage. In many cases the peptides are produced in one compartment and act on receptors in the other compartment. One of the striking differences between normal development and cancer is the loss of this cross-talk. Mammary tumor cells often produce a peptide and express the receptor on the same cell leading to autocrine activation of signaling pathways, a mechanism that is characteristic for cancer cells. We will discuss different peptides in the context of normal development and cancer in this review.

Biomarkers for Basal-like Breast Cancer

Initially recognized through microarray-based gene expression profiling, basal-like breast cancer, for which we lack effective targeted therapies, is an aggressive form of carcinoma with a predilection for younger women. With some success, immunohistochemical studies have attempted to reproduce the expression profile classification of breast cancer through identification of subtype-specific biomarkers. This review aims to present an in depth summary and analysis of the current status of basal-like breast cancer biomarker research. While a number of biomarkers show promise for future clinical application, the next logical step is a comprehensive investigation of all biomarkers against a gene expression profile gold standard for breast cancer subtype assignment.

Breast cancer genomes--form and function

This review summarizes advances in our understanding of the genomic and epigenomic abnormalities in breast cancers that are being revealed by the increasingly powerful suite of genomic analysis technologies. It summarizes the remarkable genomic heterogeneity that characterizes the disease, describes mechanisms that shape cancer genomes as they evolve toward metastasis, summarizes important recurrent aberrations that exist in spite of the genomic chaos and that contribute to breast cancer pathophysiology, and describes the use of preclinical models to identify drugs that will be effective against subsets of breast cancers carrying specific genomic and epigenomic abnormalities.