Tissue microarrays: a practical guide

Clinical Significance of Tumour-Infiltrating B Lymphocytes (TIL-Bs) in Breast Cancer: A Systematic Literature Review

Although T lymphocytes have been considered the major players in the tumour microenvironment to induce tumour regression and contribute to anti-tumour immunity, much less is known about the role of tumour-infiltrating B lymphocytes (TIL-Bs) in solid malignancies, particularly in breast cancer, which has been regarded as heterogeneous and much less immunogenic compared to other common tumours like melanoma, colorectal cancer and non-small cell lung cancer. Such paucity of research could translate to limited opportunities for this most common type of cancer in the UK to join the immunotherapy efforts in this era of precision medicine. Here, we provide a systematic literature review assessing the clinical significance of TIL-Bs in breast cancer. Articles published between January 2000 and April 2022 were retrieved via an electronic search of two databases (PubMed and Embase) and screened against pre-specified eligibility criteria. The majority of studies reported favourable prognostic and predictive roles of TIL-Bs, indicating that they could have a profound impact on the clinical outcome of breast cancer. Further studies are, however, needed to better define the functional role of B cell subpopulations and to discover ways to harness this intrinsic mechanism in the fight against breast cancer.

Analysis of interleukins 6, 8, 10 and 17 in the lungs of premature neonates with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is an abnormality that occurs in premature neonate lung development. The pathophysiology is uncertain, but the inflammatory response to lung injury may be the responsible pathway. The objective of this study is to evaluate the role of interleukins 6, 8, 10, and 17 through the anatomopathological and immunohistochemical study of the lungs of premature neonates with BPD. Thirty-two cases of neonatal autopsies from the Pathology Department of the Clinics Hospital of the Universidade Federal do Paraná, who presented between 1991 and 2005 were selected. The sample included neonates less than 34 weeks of gestational age who underwent oxygen therapy and had pulmonary formalin-fixed paraffin-embedded (FFPE) samples. Pulmonary specimens were later classified into three groups according to histopathological and morphometric changes (classic BPD, new BPD, and without BPD) and subjected to immunohistochemical analysis. The antibodies selected for the study were anti-IL-6, anti-IL-8, anti-IL-10, and anti-IL-17A monoclonal antibodies. IL-6, IL-8, and IL-10 showed no significant differences in tissue expression among the groups. IL-17A had higher tissue immunoreactivity in the group without BPD compared with the classic BPD group (1686 vs. 866 μm², p = 0.029). This study showed that the involvement of interleukins 6, 8, and 10 might not be significantly different between the two types of BPD. We speculated that IL-17A could be a protective factor in this disease.

Using Digital Quantification of Stained Tissue Microarrays as a Medium-Throughput, Quantitative Method for Measuring the Kinetics of Signal Transduction

Determining how a molecular targeting agent affects signaling pathways is challenging. To facilitate this exploration, we use a combination of medium-throughput methodologies such as tissue microarrays (TMA) and digital image analysis for quantification of immunohistochemistry (IHC). Because TMAs enable the simultaneous analysis of up to 1000 tissues, this tool can be used to comprehensively assess changes in signal transduction pathways over time. TMAs can be digitized and analyzed using the Aperio ScanScope imaging system and Aperio ImageScope software to deliver semiquantitative data. This chapter describes the methodologies for tissue collection and for the construction, sectioning, staining, and digital analysis of TMAs.

Cell line and patient-derived xenograft models reveal elevated CDCP1 as a target in high-grade serous ovarian cancer

BACKGROUND

Development of targeted therapies for high-grade serous ovarian cancer (HGSC) remains challenging, as contributing molecular pathways are poorly defined or expressed heterogeneously. CUB-domain containing protein 1 (CDCP1) is a cell-surface protein elevated in lung, colorectal, pancreas, renal and clear cell ovarian cancer.

METHODS

CUB-domain containing protein 1 was examined by immunohistochemistry in HGSC and fallopian tube. The impact of targeting CDCP1 on cell growth and migration in vitro, and intraperitoneal xenograft growth in mice was examined. Three patient-derived xenograft (PDX) mouse models were developed and characterised for CDCP1 expression. The effect of a monoclonal anti-CDCP1 antibody on PDX growth was examined. Src activation was assessed by western blot analysis.

RESULTS

Elevated CDCP1 was observed in 77% of HGSC cases. Silencing of CDCP1 reduced migration and non-adherent cell growth in vitro and tumour burden in vivo. Expression of CDCP1 in patient samples was maintained in PDX models. Antibody blockade of CDCP1 significantly reduced growth of an HGSC PDX. The CDCP1-mediated activation of Src was observed in cultured cells and mouse xenografts.

CONCLUSIONS

CUB-domain containing protein 1 is over-expressed by the majority of HGSCs. In vitro and mouse model data indicate that CDCP1 has a role in HGSC and that it can be targeted to inhibit progression of this cancer.

Assessing fibrinogen extravasation into Alzheimer's disease brain using high-content screening of brain tissue microarrays

BACKGROUND

Tissue microarrays are commonly used to evaluate disease pathology however methods to automate and quantify pathological changes are limited.

NEW METHOD

This article demonstrates the utility of the VSlide scanner (MetaSystems) for automated image acquisition from immunolabelled tissue microarray slides, and subsequent automated image analysis with MetaXpress (Molecular Devices) software to obtain objective, efficient and reproducible data from immunolabelled tissue microarray sections.

RESULTS

Significant increases in fibrinogen immunolabelling were observed in 29 Alzheimer's disease cases compared to 28 control cases analysed from a single tissue microarray slide. Western blot analysis also demonstrated significant increases in fibrinogen immunolabelling in 6 Alzheimer's cases compared to 6 control cases. The observed changes were also validated with gold standard blinded manual H-scoring.

COMPARISON WITH EXISTING METHOD

VSlide Metafer software offers a 'tissue microarray acquisition' plugin for easy mapping of tissue cores with their original position on the tissue microarray map. High resolution VSlide images are compatible with MetaXpress image analysis software. This article details the coupling of these two technologies to accurately and reproducibly analyse immunolabelled tissue microarrays within minutes, compared to the gold standard method of manual counting using H-scores which is significantly slower and prone to inter-observer variation.

CONCLUSIONS

Here, we couple brain tissue microarray technology with high-content screening and automated image analysis as a powerful way to address bottle necks in data generation and improve throughput, as well as sensitivity to study biological/pathological changes in brain disease.

ROS1 expression in invasive ductal carcinoma of the breast related to proliferation activity

PURPOSE

ROS1 is an oncogene, expressed primarily in glioblastomas of the brain that has been hypothesized to mediate the effects of early stage tumor progression. In addition, it was reported that ROS1 expression was observed in diverse cancer tissue or cell lines and ROS1 is associated with the development of several tumors. However, ROS1 expression has not been studied in breast cancer to date. Therefore, we investigated ROS1 expression at the protein and gene level to compare expression patterns and to verify the association with prognostic factors in invasive ductal carcinoma (IDC) of the breast.

MATERIALS AND METHODS

Tissue samples from 203 patients were used. Forty-six cases were available for fresh tissue. We performed immunohistochemical staining and real-time polymerase chain reaction (PCR).

RESULTS

ROS1 expression was significantly lower in proportion to higher histologic grade, higher mitotic counts, lower estrogen receptor expression, and a higher Ki-67 proliferation index, although ROS1 expression was not significantly associated with the survival rate. The result of real-time PCR revealed similar trends, however not statistically significant.

CONCLUSION

Higher ROS1 expression may be associated with favorable prognostic factors of IDC and its expression in IDC is related to the proliferation of tumor cells.

Further evidence that E-cadherin is not a tumour suppressor gene in invasive ductal carcinoma of the breast: an immunohistochemical study

AIMS

E-cadherin is a cell adhesion molecule expressed in normal breast tissue; it is used generally as a phenotypical marker in breast cancer, with the absence of its expression observed frequently in lobular tumours. We have reported E-cadherin expression previously in 1516 ductal breast carcinoma using tissue microarray (TMA), where 7% of cases showed a complete absence of membrane staining. In this study, we investigated further the existence of E-cadherin-negative ductal carcinoma and evaluated the status of the E-cadherin-catenin complex in this subgroup.

MATERIAL AND METHODS

Full-face sections from excision specimens of 72 ductal breast carcinomas reported previously as E-cadherin-negative were assessed morphologically using haematoxylin and eosin staining, and immunohistochemically using two E-cadherin antibodies (HECD-1 and CDH1/4A2C7) and antibodies recognizing β-catenin and p120 proteins. Only membrane expression was considered.

RESULTS

Forty-seven ductal carcinomas were assessed after the exclusion of inappropriate cases; 34 of these showed positive E-cadherin (HECD-1) membrane expression which was focal and weak and seen mainly in invasion fronts. Ten cases showed E-cadherin (4A2C7) staining. Staining for p120 and β-catenin showed membrane staining in all cases for both antibodies, which was variable in both intensity and the proportion of positive cells.

CONCLUSION

These results demonstrate that E-cadherin-negative ductal carcinoma is rare, and in these cases p120 and β-catenin maintained their membranous localization, suggesting a functional E-cadherin-membrane complex.

Limited prognostic value of tissue protein expression levels of cyclin E in Danish ovarian cancer patients: from the Danish 'MALOVA' ovarian cancer study

The primary objective of this study was to assess the expression of cyclin E in tumour tissues from 661 patients with epithelial ovarian tumours. The second was to evaluate whether cyclin E tissue expression levels correlate with clinico-pathological parameters and prognosis of the disease. Using tissue arrays (TA), we analysed the cyclin E expression levels in tissues from 168 women with borderline ovarian tumours (BOT) (147 stage I, 4 stage II, 17 stage III) and 493 Ovarian cancer (OC) patients (127 stage I, 45 stage II, 276 stage III, 45 stage IV). Using a 10% cut-off level for cyclin E overexpression, 20% of the BOTs were positive with a higher proportion of serous than mucinous tumours. Sixty-two per cent of the OCs were positive for cyclin E expression with the highest percentage found in clear cell carcinomas. Results based on univariate and multivariate survival analyses with a 10% cut-off value showed that cyclin E had no independent prognostic value. In conclusion, we found cyclin E expression in tumour tissue to be of limited prognostic value to Danish OC patients.

Smarcc1 expression: a significant predictor of disease-specific survival in patients with clinically localized prostate cancer treated with no intention to cure

OBJECTIVE

The clinical outcome of prostate cancer (PC) is extremely variable and therefore difficult to predict at the early stage of the disease. Since curative-intended therapies are bound up with the risk of severe adverse events, identification of new prognostic markers in PC is essential in individualized clinical treatment. The Smarcc1 protein, a part of the intranuclear SWI/SNF complex, is up-regulated in PC, and has been suggested to be implicated in tumour dedifferentiation, progression and biochemical recurrence. This makes Smarcc1 a possible candidate marker for PC survival.

MATERIAL AND METHODS

Immunohistochemistry was used to measure protein expression levels of Smarcc1in on a tissue microarray containing specimens from 100 patients suffering from clinically localized PC treated with no intention to cure and followed to death.

RESULTS

The median age at diagnosis was 75.5 years (55-95 years) and the median survival time was 5 years (0.01-15 years). In total, 41 patients (41%) died of PC. Statistically, there was no significant association between Smarcc1 immunostaining (negative/positive) and Gleason score (p = 0.7/0.8) or the clinical T stage (p = 0.9). Positive staining for Smarcc1 in patients with clinically localized PC correlated with a prolonged disease-free survival as opposed to negative staining (p = 0.025).

CONCLUSION

In patients with clinically localized PC treated without intention of cure, Smarcc1 expression was a statistically significant and independent predictor of disease-specific survival.

Tissue Microarray: A rapidly evolving diagnostic and research tool

Tissue microarray is a recent innovation in the field of pathology. A microarray contains many small representative tissue samples from hundreds of different cases assembled on a single histologic slide, and therefore allows high throughput analysis of multiple specimens at the same time. Tissue microarrays are paraffin blocks produced by extracting cylindrical tissue cores from different paraffin donor blocks and re-embedding these into a single recipient (microarray) block at defined array coordinates. Using this technique, up to 1000 or more tissue samples can be arrayed into a single paraffin block. It can permit simultaneous analysis of molecular targets at the DNA, mRNA, and protein levels under identical, standardized conditions on a single glass slide, and also provide maximal preservation and use of limited and irreplaceable archival tissue samples. This versatile technique, in which data analysis is automated, facilitates retrospective and prospective human tissue studies. It is a practical and effective tool for high-throughput molecular analysis of tissues that is helping to identify new diagnostic and prognostic markers and targets in human cancers, and has a range of potential applications in basic research, prognostic oncology and drug discovery. This article summarizes the technical aspects of tissue microarray construction and sectioning, advantages, application, and limitations.

Tissue Microarray: A rapidly evolving diagnostic and research tool

Tissue microarray is a recent innovation in the field of pathology. A microarray contains many small representative tissue samples from hundreds of different cases assembled on a single histologic slide, and therefore allows high throughput analysis of multiple specimens at the same time. Tissue microarrays are paraffin blocks produced by extracting cylindrical tissue cores from different paraffin donor blocks and re-embedding these into a single recipient (microarray) block at defined array coordinates. Using this technique, up to 1000 or more tissue samples can be arrayed into a single paraffin block. It can permit simultaneous analysis of molecular targets at the DNA, mRNA, and protein levels under identical, standardized conditions on a single glass slide, and also provide maximal preservation and use of limited and irreplaceable archival tissue samples. This versatile technique, in which data analysis is automated, facilitates retrospective and prospective human tissue studies. It is a practical and effective tool for high-throughput molecular analysis of tissues that is helping to identify new diagnostic and prognostic markers and targets in human cancers, and has a range of potential applications in basic research, prognostic oncology and drug discovery. This article summarizes the technical aspects of tissue microarray construction and sectioning, advantages, application, and limitations.

Protein expression levels of carcinoembryonic antigen (CEA) in Danish ovarian cancer patients: from the Danish 'MALOVA'ovarian cancer study

AIMS

To determine the variation in expression of carcinoembryonic antigen (CEA) in 760 epithelial ovarian tumours from Denmark, and to correlate expression with clinicopathological parameters and prognosis for the disease.

METHODS

Using tissue arrays (TA), we analysed CEA expression in tissues from 189 women diagnosed with low malignant potential ovarian tumours (LMP, borderline ovarian tumours) and 571 women diagnosed with ovarian cancer (OC).

RESULTS

Using 30% as the cut-off level for CEA over-expression, 18% of LMPs and 4% of OCs were positive. A higher proportion of mucinous tumours were positive compared with other histological subtypes (p<0.00001). A univariate survival analysis suggested a shorter disease specific survival for patients with 30% or higher CEA expression in the tumour tissue (p = 0.004). In a Cox survival analysis, which included 569 OC cases subgrouped by stage (I to IV), the highest CEA expression compared with no expression was found to be a prognostic factor (level 3 versus negative: HR = 2.12, 95%CI 1.11-4.05). FIGO stage, residual tumour after primary surgery, age at diagnosis, other histological types versus serous adenocarcinoma and low versus high histological grade tumours were also prognostic factors.

CONCLUSION

These data suggest that CEA expression is an independent prognostic factor for mucinous OC in Danish patients.

Distribution of p53 expression in tissue from 774 Danish ovarian tumour patients and its prognostic significance in ovarian carcinomas

The clinical roles played by normal and altered p53 in cancer are under intensive investigation, but larger studies describing the pattern as well as the prognostic value are still needed. The aim of this study was, using tissue array (TA), to examine the overexpression of p53 protein in 774 epithelial ovarian tumour tissues from Danish women and to evaluate whether p53 tissue expression levels correlate with clinicopathological parameters and prognosis. The distribution of p53 expression levels at different stages of disease, in different histological subtypes, and the prognostic value of p53 tissue expression were examined. Overall, p53 was expressed in 24/189 (13%) low malignant potential ovarian tumours (LMP) and in 278/585 (48%) ovarian cancers (OC). No significant difference in frequency of p53 tissue expression in LMP tissue was noted with increasing tumour stage (p=0.98). By contrast, there was a significant increase in the frequency of p53 tissue expression in OC with increasing FIGO stage (p<0.00001). Multivariate Cox regression analysis found that less than 20% tissue expression of p53 was associated with longer OC disease-specific survival. Tissue p53 expression may be of prognostic value in women with OC.

Cancer antigen 125 and prognosis

PURPOSE OF REVIEW

This review addresses recently reported progress in cancer antigen 125 as a prognostic marker in patients with ovarian cancer.

RECENT FINDINGS

Serum cancer antigen 125 levels measured preoperatively in both early and late stage ovarian cancer may be of prognostic value. Before cancer antigen 125 determination may be implemented into clinical practice, cut-off levels must be evaluated and internationally defined. Studies examining serum cancer antigen 125 levels after surgery but before, during, or after treatment confirmed that changes in serum levels are of prognostic value. Furthermore, recent studies have shown that the level of expression of cancer antigen 125 in tissue may be an independent prognostic indicator in late stage ovarian cancer.

SUMMARY

Prognostic markers may potentially help to individualize treatment within subgroups of patients. In a recent study the level of cancer antigen 125 expression was consistently found to be of prognostic value. This finding supports implementation of cancer antigen 125 measurement in future clinical ovarian cancer trials to clarify whether this marker has value in selecting candidates for individually based treatments.

Expression level of Wilms tumor 1 (WT1) protein has limited prognostic value in epithelial ovarian cancer: from the Danish "MALOVA" ovarian cancer study

OBJECTIVES

To determine the WT1 expression level in tumor tissues from 774 women with an epithelial ovarian tumor. Secondly, to evaluate whether WT1 tissue expression levels correlate with clinico-pathological parameters and finally to investigate the prognostic value of WT1 expression levels in ovarian cancer (OC) patients.

METHODS

Using tissue array we analyzed the WT1 expression level in tissues from 186 women with Low Malignant Potential tumors (LMP) (160 stage I, 5 stage II and 21 stage III) and 560 OC patients (160 stage I, 60 stage II, 289 stage III and 51 stage IV).

RESULTS

Using 10% as cut-off level for WT1 overexpression an overall of 19% LMPs and 17% carcinomas, respectively, were found positive. For both, a higher proportion of positive tumors was found in the serous subtype compared to other histological subtypes (p<0.0001). Kaplan-Meier survival analysis stratified by FIGO stage performed on cases using a 10% cut-off showed a shorter disease specific survival in patients with a positive WT1 expression in the tumor tissue. In a Cox survival analysis including 559 stage I to IV OC prognostic factors included FIGO stage (II vs. I: HR=2.74, 95% CI: 1.42-5.29; III vs. II: HR=2.23, 95% CI: 1.49-3.36; IV vs. III: HR=1.75, 95% CI: 1.25-2.44), residual tumor after primary surgery (HR=2.82, 95% CI: 1.87-4.26), age at diagnosis (HR=1.02, 95% CI: 1.01-1.03), histological grade 3 of tumor versus grade 1 (grade 2 vs. grade 1: HR=1.31, 95% CI: 0.95-1.81; grade 3 vs. grade 1: HR=1.51, 95% CI: 1.08-2.09) and other histological tumor types vs. serous (mucinous vs. serous: HR=0.91, 95% CI: 0.53-1.56; endometrioid vs. serous: HR=1.02, 95% CI: 0.69-1.50; other histological types vs. serous: HR=1.40, 95% CI: 1.01-1.95). WT1 expression (HR=1.22, 95% CI: 0.94-1.59) had statistically no significant independent impact on survival.

CONCLUSION

In conclusion, based on our analyses we found that WT1 expression in clinical settings may be of limited prognostic value in Danish OC patients.

CA125 expression pattern, prognosis and correlation with serum CA125 in ovarian tumor patients. From The Danish "MALOVA" Ovarian Cancer Study

OBJECTIVES

To determine the CA125 tissue expression levels in borderline and invasive epithelial ovarian tumor tissues. Secondly, to evaluate whether CA125 tissue expression levels correlate with clinico-pathological parameters and serum CA125 levels and finally to investigate the prognostic value of tissue CA125 expression levels in ovarian cancer (OC) patients.

METHODS

We designed tissue arrays (TA) and analyzed the CA125 expression in tissues from 778 Danish women with an ovarian tumor. Furthermore, corresponding preoperative blood samples obtained before surgery were collected from 382 women with OC.

RESULTS

Significantly more CA125 expression positive tumors (no expression vs. expression) were found in the serous subtype compared to the percentage of positive tumors in mucinous, endometroid and other subtypes for patients both with borderline ovarian tumors and with OC (p<0.00001, p<0.00001). Similarly, a positive significant correlation was found between elevated serum CA125 levels and elevated levels of CA125 tissue expression (N=382 stage I-IV OC, Spearman rho=0.31, p<0.0001) (N=206 stage III OC, Spearman rho=0.30, p<0.0001). We found a significantly shorter survival for stage III/IV OC patients with no CA125 tissue expression compared to stage III/IV OC patients with positive CA125 tissue expression (p=0.0003).

CONCLUSION

Our finding that tissue CA125 expression was lacking in late stage primary OC tumor of Danish women with poor survival may be of value in selecting patients as eligible candidates for individually based treatments.

c-erbB-2 (HER-2/neu) immunohistochemistry in invasive breast cancer: is there concordance between standard sections and tissue microarrays?

AIMS

Immunohistochemical detection of the 185-kDa transmembrane glycoprotein product of the proto-oncogene c-erbB-2 (also known as HER-2/neu), located on chromosome 17q21, is a well established method of evaluation in invasive breast cancer. This investigation is currently performed on standard sections cut from the tumour containing paraffin block. It is uncertain if concordant results can be obtained on tissue microarray (TMA) sections, a high throughput technique that is particularly advantageous in research and validation protocols. Our aim in this study was to compare the results of c-erbB-2 immunoexpression in standard sections of invasive breast cancers with those of TMAs.

METHODS

Standard sections and TMAs constructed from archival paraffin-embedded breast cancers of 184 patients who had surgery in Singapore General Hospital during the period 1998-2002 were subjected to immunohistochemistry using the commercial antibody (A0485, Dako). c-erbB-2 over-expression was evaluated according to cytoplasmic membrane staining intensity, which was defined as 2+ and 3+ staining.

RESULTS

Over-expression of c-erbB-2 protein was found in 21.2% (39/184) and 18.6% (34/183) of cases on standard sections and TMAs, respectively. There was substantial agreement between these two types of sections (k = 0.724) when positive and negative staining was considered.

CONCLUSION

Immunohistochemistry on TMAs for c-erbB-2 expression in breast cancer is a reliable alternative to that performed on routine standard sections, as it is both cost effective and time efficient, especially in a research setting.

Phospho-proteomic immune analysis by flow cytometry: from mechanism to translational medicine at the single-cell level

Understanding a molecular basis for cellular function is a common goal of biomedicine. The complex and dynamic cellular processes underlying physiological processes become subtly or grossly perturbed in human disease. A primary objective is to demystify this complexity by creating and establishing relevant model systems to study important aspects of human disease. Although significant technological advancements over the last decade in both genomic and proteomic arenas have enabled progress, accessing the complexity of cellular interactions that occur in vivo has been a difficult arena in which to make progress. Moreover, there are extensive challenges in translating research tools to clinical applications. Flow cytometry, over the course of the last 40 years, has revolutionized the field of immunology, in both the basic science and clinical settings, as well as having been instrumental to new and exciting areas of discovery such as stem cell biology. Multiparameter machinery and systems exist now to access the heterogeneity of cellular subsets and enable phenotypic characterization and functional assays to be performed on material from both animal models and humans. This review focuses primarily on the development and application of using activation-state readouts of intracellular activity for phospho-epitopes. We present recent work on how a flow cytometric platform is used to obtain mechanistic insight into cellular processes as well as highlight the clinical applications that our laboratory has explored. Furthermore, this review discusses the challenges faced with processing high-content multidimensional and multivariate data sets. Flow cytometry, as a platform that is well situated in both the research and clinical settings, can contribute to drug discovery as well as having utility for both biomarker and patient-stratification.

Abnormalities of the RB1 pathway in ovarian serous papillary carcinoma as determined by overexpression of the p16(INK4A) protein

Dysfunction of proteins involved in the G1 to S transition of the cell cycle, such as p16(INK4A) and RB1, is common in many cancer types. A screen of p16 protein expression was performed in benign, borderline, and invasive ovarian tumors, together with endometrial cancers, aligned on a tissue microarray. We observed frequent p16 overexpression in serous papillary carcinomas of ovarian and endometrial origin. An extended cohort of ovarian serous papillary carcinomas was examined to further evaluate the frequency of p16 overexpression. Strong, uniform staining in the majority of cancer cells occurred commonly in invasive serous papillary ovarian cancers, particularly in grade 3 carcinomas. RB1 protein expression abnormalities were rare. Our data indicate that abnormalities in the retinoblastoma pathway, as determined by p16 overexpression, are common in serous papillary carcinomas and are probably an early event.

Gene expression profiling in breast cancer: towards individualising patient management

Breast cancer is a complex and clinically heterogeneous disease. The increase in knowledge of breast cancer biology has led to a number of clinical advances in the treatment of breast cancer, most notably the implementation of widespread mammography screening and advances in adjuvant treatment of early-stage disease. In the last 20 years, arrays of potential prognostic and/or predictive markers of breast cancer have been analysed. However, relatively few have proven to be clinically useful. To date, the only widely accepted markers for routine use in breast cancer are the oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor, HER-2 (c-erbB2/neu). Expression microarray technology and laser capture microdissection have now been employed to further our understanding of the molecular pathogenesis of breast cancer. Recently reported advances in array technology and RNA amplification methods are having a considerable impact in this field, allowing the analysis of pre-malignant and pre-invasive lesions. A number of studies have identified prognostic and predictive gene 'signatures', whose prediction of disease outcome and response to treatment is superior to conventional prognostic indicators. Despite major technological advances, a number of confounding issues remain concerning the potential clinical utility of gene expression profiling, including differences in study design, patient selection, array technology, chemistry, and methods of analysis. It seems likely, however, that following careful 'hypothesis driven' validation studies and clinical trials, expression profiling will be applied in the future to identify patient-specific disease profiles and provide rationale for individualised treatment. This review focuses on the current use and future potential of microarray profiling in breast cancer.