Immunohistochemical evaluation of hormone receptors in breast cancer: which scoring system is suitable for highly sensitive procedures?

Application of Immunohistochemistry in Clinical Practices as a Standardized Assay for Breast Cancer

Immunohistochemistry (IHC) has become an indispensable tool in the clinical practices for breast cancer; however, to achieve its standardization, numerous issues need to be overcome. In this review, we describe the development of IHC as an important clinical tool, and the challenges in standardizing IHC results for patients. We also present ideas for resolving the remaining issues and unmet needs, along with future directions.

The Quantitative ER Immunohistochemical Analysis in Breast Cancer: Detecting the 3 + 0, 4 + 0, and 5 + 0 Allred Score Cases

Background and objectives: The currently used immunohistochemical approach in determining the estrogen receptor (ER) positivity of breast cancers (BCs) is inherently subjective and additionally limited by its semi-quantitative nature. The application of software in the analysis of digitized slide images may overcome some of these limitations. However, the utilization of such an approach requires that the entire staining procedure is standardized. Background and objectives: We aimed to establish a procedure for the photometric and morphometric analysis of BC immunohistochemical parameters that can possibly be used for a diagnostic purpose that is in line with the current semi-quantitative scoring system. Materials and Methods: Semi-quantitative analysis of ER-stained tissue sections was performed following the Allred scoring system guidelines. The quantitative analysis was performed in ImageJ software after color deconvolution. The quantitative analysis of 66 cases of invasive lobular BC included: Percent of ER-positive cells, average nuclear coloration intensity, and the quantitative ER score. The percent of ER-positive tumor cells was counted using a standard grid overlay, while optical density (0.0–1.0) was measured within each nucleus at the grid points. Results: A statistical analysis revealed a significant positive correlation (r = 0.886, p < 0.001) between the subjective semi-quantitative and quantitative ER scores, with a large effect size (d = 3.8215). We observed strong statistically significant correlations between individual parameters of the total ER score, percentage of ER-positive nuclei, and color intensity, obtained by the two independent methods. Conclusions: Additionally, besides excluding subjectivity, the up to now unreported cases of 3 + 0, 4 + 0, and 5 + 0 Allred scores were detected only by the application of the proposed quantitative approach.

Further evidence to support bimodality of oestrogen receptor expression in breast cancer

AIMS

Although oestrogen receptor (ER)-negative breast cancers (BCs) do not respond to hormone therapy, the response of ER-positive BCs is reported to be variable, which may suggest a dose-dependent effect. The aim of this study was to assess the pattern of ER expression in BCs at the protein (immunohistochemistry) and transcriptome (microarray-based gene expression) levels.

METHODS AND RESULTS

ER immunohistochemical (IHC) expression was assessed in a large series of BCs, including 3649 core biopsies and 1892 cases prepared as tissue microarrays (TMAs) stained with specific antibodies. ESR1 mRNA expression was assessed in the METABRIC study (1980 cases), by the use of the Linear Models for Microarray Data (limma) software, and the results were compared with protein levels. IHC data confirmed the bimodality of ER expression, with 92.2% and 89.2% of the cases showing completely negative (<1%) or highly positive (≥70%) expression on the cores and TMAs, respectively. Weakly positive cases (1-10%) and intermediately positive (11-69%) cases were infrequent (2.7% and 5.1%, and 1.6% and 9.2%, in cores and TMAs, respectively), and did not show survival difference from ER-negative tumours. When full-face sections of the corresponding excision specimens were immunostained, 47% of the ER-low/intermediate group were deemed to be ER-negative. Transcriptomic data not only showed a significant correlation between ESR1 mRNA and protein expression levels, but also confirmed the bimodality of ER expression at the mRNA level.

CONCLUSIONS

Our study provides further evidence that ER expression is bimodal, and that it is observed at both the mRNA and protein levels. The reported poor survival of BC patients with low ER expression in the early clinical trials may be related to the inclusion of ER-negative cases.

Ablation of osteopontin suppresses N-methyl-N-nitrosourea and Helicobacter pylori-induced gastric cancer development in mice

Several clinical studies have reported increased expression of osteopontin (OPN) in various types of human cancer, including gastric cancer. However, the precise mechanisms underlying tumor development remain unclear. In the present study, we investigated the pathogenic roles of OPN in Helicobacter pylori-induced gastric cancer development. Wild-type (WT) and OPN knockout (KO) mice were treated with N-methyl-N-nitrosourea (MNU) and infected with H.pylori. Mice were killed 50 weeks after treatment, and stomach tissues were assessed by histopathological examination, immunohistochemistry, quantitative real-time RT-PCR and western blotting. To clarify the carcinogenic effects of OPN, we also conducted an in vitro study using AGS human gastric cancer cell line and THP-1 human monocytic cell line. The overall incidence of gastric tumors was significantly decreased in OPN KO mice compared with WT mice. Apoptotic cell death was significantly enhanced in OPN KO mice and was accompanied by upregulation of signal transducer and activator of transcription 1 (STAT1) and inducible nitric oxide synthase (iNOS). In vitro study, OPN suppression also caused STAT1 upregulation and iNOS overexpression in AGS and THP-1 cells, which resulted in apoptosis of AGS cells. In addition, a negative correlation was clearly identified between expression of OPN and iNOS in human gastric cancer tissues. Our data demonstrate that loss of OPN decreases H.pylori-induced gastric carcinogenesis by suppressing proinflammatory immune response and augmenting STAT1 and iNOS-mediated apoptosis of gastric epithelial cells. An important implication of these findings is that OPN actually contributes to the development of gastric cancer.

Reliable quantification of protein expression and cellular localization in histological sections

In targeted therapy, patient tumors are analyzed for aberrant activations of core cancer pathways, monitored based on biomarker expression, to ensure efficient treatment. Thus, diagnosis and therapeutic decisions are often based on the status of biomarkers determined by immunohistochemistry in combination with other clinical parameters. Standard evaluation of cancer specimen by immunohistochemistry is frequently impeded by its dependence on subjective interpretation, showing considerable intra- and inter-observer variability. To make treatment decisions more reliable, automated image analysis is an attractive possibility to reproducibly quantify biomarker expression in patient tissue samples. We tested whether image analysis could detect subtle differences in protein expression levels. Gene dosage effects generate well-graded expression patterns for most gene-products, which vary by a factor of two between wildtype and haploinsufficient cells lacking one allele. We used conditional mouse models with deletion of the transcription factors Stat5ab in the liver as well Junb deletion in a T-cell lymphoma model. We quantified the expression of total or activated STAT5AB or JUNB protein in normal (Stat5ab^+/+ or JunB^+/+), hemizygous (Stat5ab^+/Δ or JunB^+/Δ) or knockout (Stat5ab^Δ/Δ or JunB^Δ/Δ) settings. Image analysis was able to accurately detect hemizygosity at the protein level. Moreover, nuclear signals were distinguished from cytoplasmic expression and translocation of the transcription factors from the cytoplasm to the nucleus was reliably detected and quantified using image analysis. We demonstrate that image analysis supported pathologists to score nuclear STAT5AB expression levels in immunohistologically stained human hepatocellular patient samples and decreased inter-observer variability.

Prognostic significance of ESR1 gene amplification, mRNA/protein expression and functional profiles in high-risk early breast cancer: a translational study of the Hellenic Cooperative Oncology Group (HeCOG)

BACKGROUND

Discrepant data have been published on the incidence and prognostic significance of ESR1 gene amplification in early breast cancer.

PATIENTS AND METHODS

Formalin-fixed paraffin-embedded tumor blocks were collected from women with early breast cancer participating in two HeCOG adjuvant trials. Messenger RNA was studied by quantitative PCR, ER protein expression was centrally assessed using immunohistochemistry (IHC) and ESR1 gene copy number by dual fluorescent in situ hybridization probes.

RESULTS

In a total of 1010 women with resected node-positive early breast adenocarcinoma, the tumoral ESR1/CEP6 gene ratio was suggestive of deletion in 159 (15.7%), gene gain in 551 (54.6%) and amplification in 42 cases (4.2%), with only 30 tumors (3%) harboring five or more ESR1 copies. Gene copy number ratio showed a significant, though weak correlation to mRNA and protein expression (Spearman's Rho <0.23, p = 0.01). ESR1 clusters were observed in 9.5% (57 gain, 38 amplification) of cases. In contrast to mRNA and protein expression, which were favorable prognosticators, gene copy number changes did not obtain prognostic significance. When ESR1/CEP6 gene ratio was combined with function (as defined by ER protein and mRNA expression) in a molecular classifier, the Gene Functional profile, it was functional status that impacted on prognosis. In univariate analysis, patients with functional tumors (positive ER protein expression and gene ratio normal or gain/amplification) fared better than those with non-functional tumors with ESR1 gain (HR for relapse or death 0.49-0.64, p = 0.003). Significant interactions were observed between gene gain/amplification and paclitaxel therapy (trend for DFS benefit from paclitaxel only in patients with ESR1 gain/amplification, p = 0.066) and Gene Functional profile with HER2 amplification (Gene Functional profile prognostic only in HER2-normal cases, p = 0.029).

CONCLUSIONS

ESR1 gene deletion and amplification do not constitute per se prognostic markers, instead they can be classified to distinct prognostic groups according to their protein-mediated functional status.

Performance comparison of machine learning methods for prognosis of hormone receptor status in breast cancer tissue samples

We examined the classification and prognostic scoring performances of several computer methods on different feature sets to obtain objective and reproducible analysis of estrogen receptor status in breast cancer tissue samples. Radial basis function network, k-nearest neighborhood search, support vector machines, naive bayes, functional trees, and k-means clustering algorithm were applied to the test datasets. Several features were employed and the classification accuracies of each method for these features were examined. The assessment results of the methods on test images were also experimentally compared with those of two experts. According to the results of our experimental work, a combination of functional trees and the naive bayes classifier gave the best prognostic scores indicating very good kappa agreement values (κ=0.899 and κ=0.949, p<0.001) with the experts. This combination also gave the best dichotomization rate (96.3%) for assessment of estrogen receptor status. Wavelet color features provided better classification accuracy than Laws texture energy and co-occurrence matrix features.

Expression of leptin receptor in endometrial biopsies of endometrial and ovarian cancer patients

The adipokine leptin plays a critical role in the regulation of reproductive function and there has been growing interest in its potential role in the development of cancers in which obesity is an established risk factor. Serum leptin levels were found to be higher in patients diagnosed with endometrial and ovarian cancer compared to those observed in healthy individuals. This study was conducted to determine the expression of the leptin receptor (Ob-R) in endometrial biopsies of patients diagnosed with endometrial and ovarian cancer. In this preliminary study, immunohistochemistry (IHC) and the color deconvolution method were used to assess the expression levels of the Ob-R protein in three groups of endometrial tissue: one from patients diagnosed with endometrioid endometrial carcinoma, one from patients diagnosed with ovarian cancer and one from individuals without any diagnosed gynecologic disease (control group). Our results demonstrated that the highest expression of Ob-R protein in endometrial biopsies was detected in the ovarian cancer group (P=0.000). This finding suggests that changes in Ob-R expression may be assessed through the measurement of the optical density of endometrial biopsies and may become a useful tool in preventive screening, particularly for ovarian cancer.

The miR-200 family regulates the epithelial-mesenchymal transition induced by EGF/EGFR in anaplastic thyroid cancer cells

The miR-200 family was recently identified as a suppressor of epithelial-mesenchymal transition (EMT). The loss or gain of miR-200 family members is associated with cancer invasion. The epidermal growth factor receptor (EGFR) is overexpressed in the majority of anaplastic thyroid cancers (ATCs). The activation of EGFR by its ligand, epidermal growth factor (EGF), activates a signaling cascade that results in the enhanced migration and invasiveness of thyroid cancer cells. However, little is known about the potential interrelationships between EGF/EGFR, miR-200s and the induction of EMT or mesenchymal-epithelial transition (MET) processes. This study aimed to investigate the regulatory role of miR-200s in EMT modulation by EGF/EGFR. Using transfection, real-time reverse transcription PCR and western blot analysis, we found that the EGF treatment of Nthy-ori 3-1 thyroid follicular cells resulted in the downregulation of E-cadherin and the upregulation of vimentin. By contrast, EGFR silencing in SW1736 human thyroid carcinoma cells led to the upregulation of E-cadherin and the downregulation of vimentin. In addition, EGF signaling correlated with the reduced expression of miR-200s and the re-expression of miR-200s abrogated the effects of EGF treatment and restored an epithelial phenotype to EGF-induced Nthy-ori 3-1 cells. Conversely, the silencing of miR-200s in SW1736 cells overcame siEGFR-induced changes in gene expression and phenotype. In addition, we demonstrate that miR-200s play a key role in in vitro EGF/EGFR-mediated thyroid cell invasion and in EMT in vivo. We, therefore, provide a mechanistic link between the miR-200 family and EGF/EGFR, which suggests that miR-200 upregulation may serve as a novel therapeutic strategy for highly invasive thyroid cancers.

Activation of phosphatidylinositol 3-kinase/Akt signaling by EGF downregulates membranous E-cadherin and β-catenin and enhances invasion in nasopharyngeal carcinoma cells

Dysregulation of E-cadherin and β-catenin function in cell-cell adhesion is common in nasopharyngeal carcinoma (NPC) and correlates with metastatic disease. In this study, we examined the role of EGF-activated phosphatidylinositol 3-kinase (PI3K)-Akt signaling in E-cadherin and β-catenin regulation. We found that reduced membranous E-cadherin and β-catenin expression was positively correlated with Akt phosphorylation in NPC tissues. EGF treatment disrupted cell-cell adhesion and resulted in mesenchymal morphological features in NPC cell lines (TW01, TW04, and TW06). Western blot analysis showed that the E-cadherin protein level was partially reduced in TW04 cells only and the β-catenin levels were not considerably affected upon EGF treatment. In contrast, quantitative real-time RT-PCR showed that the E-cadherin, but not β-catenin, mRNA levels were markedly reduced by EGF in all cell lines. Immunofluorescent staining revealed that E-cadherin and β-catenin appeared to be markedly reduced on the cell surface and more localized in the cytoplasm. Inhibition of PI3K by LY294002 did not abolish the EGF-induced downregulation of E-cadherin protein or mRNA in TW04 cells but moderately increased the β-catenin protein level in TW01 cells and mRNA level in TW06 cells. However, LY294002 substantially restored or increased cell surface E-cadherin and β-catenin in all EGF-treated cell lines, in concordance with the inhibition of cell morphological changes. Moreover, LY294002 significantly blocked EGF-driven cell invasion, correlating with the elevation of membranous E-cadherin and β-catenin levels. In conclusion, EGF-induced epithelial-to-mesenchymal transition may not be only dependent on downregulation of E-cadherin protein/mRNA but also on mislocalization of E-cadherin and β-catenin. The mechanisms involved may be related, at least in part, to the PI3K-Akt pathway.

Estrogen Receptor Negative Breast Cancer in India: Do We Really Have Higher Burden of this Subtype?

ER negative and Triple negative breast cancers carry a poorer prognosis and are not amenable to hormone therapy. It has been previously observed that Indian patients with breast cancer have a higher tendency to have these tumours. Whether this is due to inherent biological differences in the tumours of our patients is a matter of much debate. We have analysed 250 patients of breast cancer for hormone receptor status, compared them with western series, and attempted to support the hypothesis that the higher ER negativity and triple negativity is indeed due to different tumour biology.

Immunohistochemistry as an important tool in biomarkers detection and clinical practice

The immunohistochemistry technique is used in the search for cell or tissue antigens that range from amino acids and proteins to infectious agents and specific cellular populations. The technique comprises two phases: (1) slides preparation and stages involved for the reaction; (2) interpretation and quantification of the obtained expression. Immunohistochemistry is an important tool for scientific research and also a complementary technique for the elucidation of differential diagnoses which are not determinable by conventional analysis with hematoxylin and eosin. In the last couple of decades there has been an exponential increase in publications on immunohistochemistry and immunocytochemistry techniques. This review covers the immunohistochemistry technique; its history, applications, importance, limitations, difficulties, problems and some aspects related to results interpretation and quantification. Future developments on the immunohistochemistry technique and its expression quantification should not be disseminated in two languages—that of the pathologist and another of clinician or surgeon. The scientific, diagnostic and prognostic applications of this methodology must be explored in a bid to benefit of patient. In order to achieve this goal a collaboration and pooling of knowledge from both of these valuable medical areas is vital

Automated image analysis in histopathology: a valuable tool in medical diagnostics

Virtual pathology, the process of assessing digital images of histological slides, is gaining momentum in today's laboratory environment. Indeed, digital image acquisition systems are becoming commonplace, and associated image analysis solutions are viewed by most as the next critical step in automated histological analysis. Here, we document the advances in the technology, with reference to past and current techniques in histological assessment. In addition, the demand for these technologies is analyzed with major players profiled. As there are several image analysis software programs focusing on the quantification of immunohistochemical staining, particular attention is paid to this application in this review. Oncology has been a primary target area for these approaches, with example studies in this therapeutic area being covered here. Toxicology-based image analysis solutions are also profiled as these are steadily increasing in popularity, especially within the pharmaceutical industry. Reinforced by the phenomenal growth of the virtual pathology field, it is envisioned that the market for automated image analysis tools will greatly expand over the next 10 years.

Novel image analysis approach for quantifying expression of nuclear proteins assessed by immunohistochemistry: application to measurement of oestrogen and progesterone receptor levels in breast cancer

Introduction

Manual interpretation of immunohistochemistry (IHC) is a subjective, time-consuming and variable process, with an inherent intra-observer and inter-observer variability. Automated image analysis approaches offer the possibility of developing rapid, uniform indicators of IHC staining. In the present article we describe the development of a novel approach for automatically quantifying oestrogen receptor (ER) and progesterone receptor (PR) protein expression assessed by IHC in primary breast cancer.

Methods

Two cohorts of breast cancer patients (n = 743) were used in the study. Digital images of breast cancer tissue microarrays were captured using the Aperio ScanScope XT slide scanner (Aperio Technologies, Vista, CA, USA). Image analysis algorithms were developed using MatLab 7 (MathWorks, Apple Hill Drive, MA, USA). A fully automated nuclear algorithm was developed to discriminate tumour from normal tissue and to quantify ER and PR expression in both cohorts. Random forest clustering was employed to identify optimum thresholds for survival analysis.

Results

The accuracy of the nuclear algorithm was initially confirmed by a histopathologist, who validated the output in 18 representative images. In these 18 samples, an excellent correlation was evident between the results obtained by manual and automated analysis (Spearman's ρ = 0.9, P < 0.001). Optimum thresholds for survival analysis were identified using random forest clustering. This revealed 7% positive tumour cells as the optimum threshold for the ER and 5% positive tumour cells for the PR. Moreover, a 7% cutoff level for the ER predicted a better response to tamoxifen than the currently used 10% threshold. Finally, linear regression was employed to demonstrate a more homogeneous pattern of expression for the ER (R = 0.860) than for the PR (R = 0.681).

Conclusions

In summary, we present data on the automated quantification of the ER and the PR in 743 primary breast tumours using a novel unsupervised image analysis algorithm. This novel approach provides a useful tool for the quantification of biomarkers on tissue specimens, as well as for objective identification of appropriate cutoff thresholds for biomarker positivity. It also offers the potential to identify proteins with a homogeneous pattern of expression.

Effects of mutant human Ki-ras(G12C) gene dosage on murine lung tumorigenesis and signaling to its downstream effectors

Studies in cell culture have suggested that the level of RAS expression can influence the transformation of cells and the signaling pathways stimulated by mutant RAS expression. However, the levels of RAS expression in vivo appear to be subject to feedback regulation, limiting the total amount of RAS protein that can be expressed. We utilized a bitransgenic mouse lung tumor model that expressed the human Ki-ras(G12C) allele in a tetracycline-inducible, lung-specific manner. Treatment for 12 months with 500 microg/ml of doxycycline (DOX) allowed for maximal expression of the human Ki-ras(G12C) allele in the lung, and resulted in the development of focal hyperplasia and adenomas. We determined if different levels of mutant RAS expression would influence the phenotype of the lung lesions. Treatment with 25, 100 and 500 microg/ml of DOX resulted in dose-dependent increases in transgene expression and tumor multiplicity. Microscopic analysis of the lungs of mice treated with the 25 microg/ml dose of DOX revealed infrequent foci of hyperplasia, whereas mice treated with the 100 and 500 microg/ml doses exhibited numerous hyperplastic foci and also adenomas. Immunohistochemical and RNA analysis of the downstream effector pathways demonstrated that different levels of mutant RAS transgene expression resulted in differences in the expression and/or phosphorylation of specific signaling molecules. Our results suggest that the molecular alterations driving tumorigenesis may differ at different levels of mutant Ki-ras(G12C) expression, and this should be taken into consideration when inducible transgene systems are utilized to promote tumorigenesis in mouse models.

Value of staining intensity in the interpretation of immunohistochemistry for tumor markers in colorectal cancer

The purpose of this study was to determine whether staining intensity in conjunction with the percentage of positive tumor cells should be used as an indicator of protein expression detected by immunohistochemistry. A tissue microarray of 1,197 colorectal cancers was immunostained for p53, Her2/neu, epidermal growth factor receptor (EGFR), adenomatosis polyposis coli (APC), and beta-catenin. Immunoreactivity was described by the percentage of positive tumor cells (percent positivity) and by the staining intensity (weak, moderate, strong). The interobserver reproducibility of both was evaluated by two pathologists. The association of T stage, N stage, tumor grade, vascular invasion, and survival with percent positivity, staining intensity, and the combination of both was assessed. In univariate analysis, protein expression assessed by percent positivity resulted in 11 significant associations between the proteins and clinico-pathological features. Eight of these 11 were also demonstrated using only the degree of staining intensity. However, more than half of the associations identified by percent positivity alone were lost when staining intensity was also analyzed in combination with the percentage of positive tumor cells. A scoring method based on percent positivity, rather than on staining intensity, for p53, Her2/neu, EGFR, APC, and beta-catenin is reproducible and appears to be sufficient for establishing associations of the selected tumor markers with most clinico-pathological features.

Measurement of PTEN expression using tissue microarrays to determine a race-specific prognostic marker in breast cancer

CONTEXT

African American women with breast cancer have worse prognoses than non-African Americans and might benefit with a race-specific prognostic marker such as PTEN (phosphatase and tensin homologue), a tumor suppressor protein. Reduced PTEN expression is associated with worse outcomes and resistance to trastuzumab in human epidermal growth factor receptor 2-positive breast cancers. Standardized PTEN evaluation is therefore needed.

OBJECTIVE

To assess PTEN as a race-specific prognostic marker in breast cancer by using a novel semiquantitative score and a percent staining assessment.

DESIGN

Between 1991 and 1996, 146 patients with invasive ductal adenocarcinoma were grouped by race and recurrence; there was a median follow-up of 7.2 years with 63 recurrences. Immunostaining of PTEN in tissue microarrays was correlated with race, recurrence, node positivity, stage, size, age, estrogen/progesterone receptor status, grade, and DNA ploidy.

RESULTS

No significant racial difference was detected in mean PTEN values using either the semiquantitative score (P = .46) or the percent staining (P = .54). Unrelated to race, the percentage of tumor cells with positive PTEN expression correlated with longer time to recurrence (P = .047), positive estrogen receptor status (P = .009), and lower tumor grade (P = .005). The semiquantitative score correlated with positive estrogen receptor status (P = .01) and lower tumor grade (P = .001).

CONCLUSIONS

PTEN expression is not a race-specific biologic prognostic marker for invasive ductal adenocarcinoma. Increased PTEN expression correlates with longer time to recurrence, positive estrogen receptor status, and lower tumor grade. The novel semiquantitative score may be used to evaluate PTEN expression, but the approximate percentage of tumor cells with any PTEN staining may be the most useful measure of PTEN expression.

Expression of ER? and ER? in lobular carcinoma in situ

AIMS

Oestrogen is a modulator of cell growth and differentiation in the breast. It mediates most of its function through members of the oestrogen receptor (ER) family, ERalpha and ERbeta. Lobular carcinoma in situ (LCIS) is a known risk factor for the development of breast cancer; however, the use of tamoxifen for prevention is based upon data for ER+ (ERalpha) LCIS associated with invasion, but limited data exist on the use of tamoxifen in cases of ER+ (ERalpha) LCIS occurring in the absence of invasive carcinoma. The aim of this study was to examine ER expression in LCIS to determine the relationship of ERalpha to ERbeta and, thereby, to determine whether it is of clinical value to measure ERbeta along with ERalpha.

METHODS AND RESULTS

Core biopsy specimens from 50 patients were examined retrospectively. Histology was reviewed and histological parameters were assessed. Formalin-fixed paraffin-embedded tissue was available for E-cadherin, ERalpha and ERbeta immunohistochemistry. The degree of ERalpha and ERbeta nuclear reactivity was quantified. The patients' mean age was 55 years. The mean follow-up duration was 48 months. All 50 cases of LCIS were E-cadherin-negative. All cases were ERalpha+ and ERbeta+. The staining intensity of ERbeta was strong and included staining of periductal stromal cells. The median percentage of cells immunoreactive for ERalpha was 75% and for ERbeta 70% (range 10% weak positive to 100% strong positive). There was a statistically significant relationship between ERbeta staining intensity and incidence of ipsilateral breast cancer (P = 0.010).

CONCLUSIONS

The presence and intensity of both stromal and glandular ERbeta immunoreactivity suggest that the action of oestrogen on LCIS is on both stromal and glandular cells. Future studies are needed to determine whether the presence of ERbeta in LCIS could be targeted to influence the treatment of this disease and perhaps alter its natural history.

Practical aspects of planning, building, and interpreting tissue microarrays: The Cooperative Prostate Cancer Tissue Resource experience

This is a review of several new approaches developed at or adopted by the Cooperative Prostate Cancer Tissue Resource (CPCTR) to resolve issues involved in tissue microarray (TMA) construction and use. CPCTR developed the first needle biopsy TMA, allowing researchers to obtain 200 or more consecutive cancer sections from a single biopsy core. Using radiographs of original paraffin blocks to measure tissue thickness we developed a method to produce TMAs with a larger number of usable sections. The modular approach to plan TMA construction is also a novel concept wherein TMAs of different types, such as tumor grade TMAs, metastasis TMA and hormone refractory tumors TMA can be combined to form an ensemble of TMAs with expanded research utility, such as support for tumor progression studies. We also implemented an open access TMA Data Exchange Specification that allows TMA data to be organized in a self-describing XML document annotated with well-defined common data elements. It ensures inter-laboratory reproducibility because it offers information describing the preparation of TMA blocks and slides. There are many important aspects that may be missed by both beginners and experienced investigators in areas of TMA experimental design, human subjects protection, population sample size, selection of tumor areas to sample, strategies for saving tissues, choice of antibodies for immunohistochemistry, and TMA data management.

A simple and reproducible scoring system for EGFR in colorectal cancer: application to prognosis and prediction of response to preoperative brachytherapy

The aim of this study was to determine the predictive and prognostic value of epidermal growth factor receptor (EGFR) expression in rectal cancers treated with preoperative high-dose rate brachytherapy and in mismatch-repair (MMR)-proficient colorectal cancers (CRCs), respectively. We validate the use of receiver operating characteristic (ROC) curve analysis to select cutoff scores for EGFR overexpression for the end points studied. Immunohistochemistry (IHC) for EGFR was performed on 82 rectal tumour biopsies and 1197 MMR-proficient CRCs using a tissue microarray. Immunoreactivity was scored as the percentage of positive tumour cells by three pathologists and the inter-observer reliability was assessed. ROC curve-derived cutoffs were used to analyse the association of EGFR overexpression, tumour response and several clinicopathological features including survival. The scoring method was found to be reproducible in rectal cancer biopsies and CRCs. The selected cutoff scores from ROC curve analysis for each clinicopathological feature were highly consistent among pathologists. EGFR overexpression was associated with response to radiotherapy (P-value <0.001) and with worse survival time (P-value <0.001). In multivariate analysis, EGFR overexpression was independently associated with adverse prognosis (P-value <0.001). Epidermal growth factor receptor is a predictive marker of response to preoperative radiotherapy and an independent adverse prognostic factor CRC.

Elevated levels of the mismatch repair protein PMS2 are associated with prostate cancer

BACKGROUND

Defects in mismatch repair (MMR) proteins have been identified in various types of cancer. However, an association with prostate cancer has been controversial. Defective MMR results in genome instability with detrimental consequences that significantly contribute to tumorigenesis. This study determined alterations in key MMR protein levels in prostate cancer with the goal to identify prognostic markers.

METHODS

Prostatectomy samples were immunohistochemically stained and the relative presence or absence of key proteins MSH2, MLH1, and PMS2 determined. Cancer tissue of distinct grades was compared with the normal surrounding tissue. Microsatellite instability (MSI) in altered tissues was determined according to NCI guidelines.

RESULTS

In contrast to reports that associate a lack of individual MMR proteins with tumorigenesis, a significant increase in PMS2 levels was identified in PIN lesions and prostate cancer tissue. This elevation in PMS2 was independent of changes in levels in its heterodimeric partner, MLH1. Prostate tumors with elevated levels of PMS2 were genetically unstable, which was corrected by MLH1 co-elevation.

CONCLUSIONS

This is the first documentation of detrimental consequences associated with the increase in a MMR protein in human cancer. This study recognizes PMS2 elevation as a prognostic marker in pre-neoplastic and prostate cancer lesions. This result has significant implications for future diagnostic and treatment measures.

Quantification of immunohistochemistry--issues concerning methods, utility and semiquantitative assessment II

Immunohistochemistry is entering its fourth decade of use on formalin-fixed paraffin-embedded tissues. Over this period the method has evolved to become a major part of the practice of diagnostic surgical pathology worldwide. From the beginning immunohistochemistry has been adapted to provide a range of markers of cell lineage and tissue type, with particular application to the diagnosis and classification of tumours. In this modality immunohistochemical methods were employed simply as 'special stains', the results of which were evaluated qualitatively by the pathologist, as for any other stain. More recently, attention has shifted to the demonstration of prognostic markers in tumour cells, driven by the advent of molecular biology and the discovery of numerous regulatory molecules, coupled with manufacture of the corresponding specific antibodies. Immunohistochemistry has rapidly adapted to this new use, but in so doing the demand for quantification has become paramount; it is no longer enough that the 'stain' is there; rather it is a question of 'How much is there?'. This review explores the limitations of immunohistochemistry when employed in a semiquantitative mode, and explores the possibility of fulfilling the full potential of immunohistochemistry, as a true quantitative immunoassay applied in a tissue section environment.

TMA-Combiner, a simple software tool to permit analysis of replicate cores on tissue microarrays

We have previously published a suite of software tools that facilitates the reformulation of tissue microarray (TMA) data so that it may be analyzed using techniques originally devised for analysis of cDNA microarray data. However, current microarray data often feature multiple scores for a given tissue sample and antibody combination. Furthermore, an efficient and systematic method for combining scores that takes into account the differing staining properties of tissue epitopes has not been described. We thus present the TMA-Combiner, a new Microsoft Excel-based macro that permits analysis of data for which tissues may have two or more scores per antibody, and permits combination of data from multiple different tissue microarrays. It accomplishes this by rendering one score per tissue per antibody from two or more scores, using one of multiple user-selectable combination rules developed to account for the differing staining properties of tissue epitopes. This greatly facilitates analysis of tissue microarrays, particularly for users with large repositories of data, and may facilitate discovery of biological trends and help refine diagnostic accuracy of tissue markers in clinical samples.

Bimodal frequency distribution of estrogen receptor immunohistochemical staining results in breast cancer: an analysis of 825 cases

Immunohistochemical analysis is used routinely to determine the estrogen receptor (ER) status of breast cancers in paraffin sections. However, lack of standardization has raised concerns that weakly ER+ tumors often are classified erroneously as ER-. To determine the frequency of weakly ER+ tumors, we reviewed ER immunostains of 825 breast cancers. For each case, we estimated the proportion of ER+ tumor cells and also determined an Allred score (which results in scores of 0 or 2 through 8, based on staining intensity and proportion of positive cells). In 817 cases (99.0%), tumor cells showed complete absence of staining or staining in 70% or more of the cells. Similarly, 818 cases (99.2%) exhibited Allred scores of 0 or of 7 or 8. Thus, with the immunohistochemical method used in our laboratory, ER staining is essentially bimodal. The overwhelming majority of breast cancers are either completely ER- or unambiguously ER+, and cases with weak ER immunostaining are rare.