Overexpression of the c-erbB-2 oncoprotein: why does this occur more frequently in ductal carcinoma in situ than in invasive mammary carcinoma and is this of prognostic significance?

Prognostic and Predictive Value of HER2 Expression in Ductal Carcinoma In Situ: Results from the UK/ANZ DCIS Randomized Trial

PURPOSE

HER2 is overexpressed more frequently in ductal carcinoma in situ (DCIS) than in invasive breast cancer but its prognostic significance and predictive role for radiotherapy has not been clearly established. We investigated the prognostic and predictive value of HER2 overexpression in DCIS.

EXPERIMENTAL DESIGN

HER2 expression was evaluated by IHC using the HercepTest™ in samples from UK/ANZ DCIS trial participants (n = 755) with IHC 3+ expression categorized as HER2 positive for primary analyses. Sensitivity analyses included HER2 categorization as negative (IHC 0,1+), equivocal (IHC 2+), and positive (IHC 3+) and analyses restricted to a nested case-control component where 181 cases (with recurrence) were matched to 362 controls by treatment arm and age.

RESULTS

Two-hundred and forty-five (34.4%) of evaluable 713 samples [181 ipsilateral breast events (IBE)] were HER2 positive. HER2 overexpression was associated with significantly increased risk of IBE [HR = 2.29; 95% confidence interval (95% CI), 1.64-3.14; P < 0.0001] and in situ IBE (DCIS-IBE; HR = 2.90; 95% CI, 1.91-4.40; P < 0.0001), but not of invasive IBE (I-IBE; HR = 1.40; 95% CI, 0.81-2.42; P = 0.23; Pheterogeneity = 0.04). Inclusion of HER2 significantly improved [Δχ2 (1d.f.) 12.25; P = 0.0005] a prognostic model of clinicopathological and treatment variables, HER2 being an independent predictor of IBE (multivariate HR = 1.91; 95% CI, 1.33-2.76; P = 0.0004). Radiotherapy benefit in preventing DCIS-IBE was significantly greater (Pheterogeneity = 0.04) in HER2-positive DCIS (HR = 0.16; 95% CI, 0.07-0.41) compared with HER2-negative DCIS (HR = 0.58; 95% CI, 0.28-1.19).

CONCLUSIONS

HER2 overexpression is associated with significantly increased risk of in situ recurrence and is also predictive of radiotherapy benefit, with greater reductions in in situ but not invasive recurrences in HER2-positive DCIS.

Comparison of HER2 amplification status among breast cancer subgroups offers new insights in pathways of breast cancer progression

Although the prognostic and predictive significance of human epidermal growth factor receptor 2 (HER2) in invasive breast cancer is well established, its role in ductal carcinoma in situ (DCIS) remains unclear. Reports on combined evaluation of both HER2 protein expression and HER2 amplification status in pure DCIS and DCIS adjacent to invasive ductal carcinoma (i.e., admixed DCIS) are scarce. In this study, immunohistochemistry and fluorescence in situ hybridization (FISH) were used to assess HER2 status in 72 cases of pure DCIS, 73 cases of DCIS admixed with invasive ductal carcinoma (IDC), and 60 cases of pure IDC. HER2 copy number-based amplification was present in 49% of pure DCIS, 16% of admixed DCIS, 18% of admixed IDC, and 8% of pure IDC. Amplified pure DCIS with clusters of HER2 signals showed a significantly lower HER2 copy number than amplified admixed DCIS with clusters. Whereas pure DCIS and admixed DCIS presented significant differences, the in situ and invasive component of admixed tumors showed striking similarities regarding mean HER2 and chromosome 17 centromere (CEP17) copy number, grade, and estrogen and progesterone receptor expression. The discrepant prevalence of HER2 amplification among breast cancer subgroups indirectly suggests that HER2 may not play a crucial role in the transition of in situ to invasive breast cancer. The similarities in HER2 amplification status between the in situ and invasive component of admixed tumors hint at a common biological pathway for both components. Our data support the theory that pure DCIS, pure IDC, and admixed lesions have a common progenitor, but can progress as separate lineages.

Prediction of heterogeneity in breast cancer immunophenotype at ductal carcinoma in situ stage?

INTRODUCTION

Ductal carcinoma in situ (DCIS) is considered a heterogeneous lesion at the molecular level. However, there is a paucity of literature about the existence of molecular subtypes in DCIS which can predict their biological behavior at the preinvasive stage.

MATERIALS AND METHODS

Precise prevalence of molecular subtypes of pure DCIS and DCIS component of infiltrating duct carcinoma (IDC) was evaluated using immunohistochemistry and correlated with known prognostic factors.

RESULTS

DCIS cases were classified as luminal A (46.6% in each group), luminal B (pure DCIS 20% and DCIS component of IDC 13.3%), HER2 overexpressing, basal and nonbasal (pure DCIS 3.3% and 26.6% and DCIS component of IDC 3.3% and 33.3%, respectively), and triple negative, nonbasal (pure DCIS and DCIS component of IDC 3.3% each). The molecular phenotype of DCIS correlated well with that of the coexisting IDC.

CONCLUSIONS

This study demonstrated molecular heterogeneity in DCIS; however, similar molecular phenotypes were seen in the coexisting IDC suggesting that DCIS is a precursor lesion and can predict phenotype of the invasive component. This also suggests that the invasiveness of DCIS is not dependent solely on the molecular character of the tumor epithelial cells, but factors such as tumor microenvironment may play a role.

Next-Generation Assessment of Human Epidermal Growth Factor Receptor 2 (ERBB2) Amplification Status: Clinical Validation in the Context of a Hybrid Capture-Based, Comprehensive Solid Tumor Genomic Profiling Assay

Establishing ERBB2 [human epidermal growth factor receptor 2 (HER2)] amplification status in breast and gastric carcinomas is essential to treatment selection. Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) constitute the current standard for assessment. With further advancements in genomic medicine, new clinically relevant biomarkers are rapidly emerging and options for targeted therapy are increasing in patients with advanced disease, driving the need for comprehensive molecular profiling. Next-generation sequencing (NGS) is an attractive approach for up-front comprehensive assessment, including ERBB2 status, but the concordance with traditional methods of HER2 assessment is not well established. The Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) assay, a hybrid capture-based NGS assay interrogating the coding regions of 410 cancer-related genes, was performed on manually macrodissected unstained sections from formalin-fixed, paraffin-embedded breast (n = 213) and gastroesophageal (n = 39) tumors submitted for clinical mutation profiling. ERBB2 status was assessed using a custom bioinformatics pipeline, and NGS results were compared to IHC and FISH. NGS ERBB2 amplification calls had an overall concordance of 98.4% (248/252) with the combined IHC/FISH results in this validation set. Discrepancies occurred in the context of low tumor content and HER2 heterogeneity. ERBB2 amplification status can be reliably determined by hybridization capture-based NGS methods, allowing efficient concurrent testing for other potentially actionable genomic alterations, particularly in limited material.

Hormonal receptor status, Ki-67 and HER2 expression: Prognostic value in the recurrence of ductal carcinoma in situ of the breast?

PURPOSE

Local recurrence is considered a major concern in patients diagnosed with ductal carcinoma in situ (DCIS), as its invasive occurrence is associated with high rates of distant disease and mortality. This study aims to assess the possible correlation of hormonal receptor status, Ki-67 and HER2 expression with recurrence rates in women with DCIS, taking also into account the potential prognostic effects of grade and age at diagnosis.

METHODS

230 consecutive patients with DCIS were included in this study. Invasive and non-invasive recurrence events were recorded, as a total. Clinicopathological information, as well as PR positivity, ER positivity, HER2 positivity and ki-67 expression were analyzed. Multivariable Cox regression analysis was performed, examining the risk factors for recurrence.

RESULTS

Recurrence was noted in 17.8% of cases; the median follow-up was 44 months. Higher grade (adjusted HR = 1.72, 95%CI: 1.06-2.78), age at diagnosis (adjusted HR = 0.60, 95%CI: 0.43-0.83), Ki-67 expression (adjusted HR = 1.78, 95%CI: 1.11-2.88), and type of administered treatment were independently associated with increased recurrence rates. Recurrence rates were not significantly associated with ER, PR status or HER2 expression.

CONCLUSION

In addition to high grade, administered treatment and younger age at diagnosis, high Ki-67 expression seems to be independently associated with increased likelihood of recurrence in patients with DCIS. Future studies with additional molecular markers seem necessary to further improve the identification of high-risk patients for DCIS recurrence.

Loss of the E3 ubiquitin ligase HACE1 results in enhanced Rac1 signaling contributing to breast cancer progression

The transition from ductal carcinoma in situ (DCIS) to invasive breast cancer (IBC) is a crucial step in breast cancer progression. The specific alterations that govern this transition have not been elucidated. HER2/neu is frequently overexpressed in DCIS but is less common in IBC, thereby suggesting additional requirements for transformation. To identify genes capable of cooperating with HER2/neu to fully transform mammary epithelial cells, we used an insertional mutagenesis screen on cells isolated from wild-type neu expressing mice and identified the E3 ligase HACE1 as HER2 cooperative tumor suppressor gene. Loss of HACE1 expression is commonly seen in clinical breast cancer data sets. HACE1 downregulation in normal human mammary epithelial cells (HMECs) results in the accumulation of the activated GTP-bound Rac1 partially transforming these cells. Overexpression of HER2 activates Rac1, which further accumulates upon HACE1 loss resulting in Rac1 hyperactivation. Although the knockdown of HACE1 or overexpression of HER2 alone in HMECs is not sufficient for tumorigenesis, HER2 overexpression combined with HACE1 downregulation fully transforms HMECs resulting in robust tumor formation. The pharmaceutical interference of Rac function abrogates the effects of HACE1 loss both in vitro and in vivo, resulting in marked reduction in tumor burden. Our work supports a critical role for HACE1 in breast cancer progression and identifies patients that may benefit from Rac-targeted therapies.

MTA1--a stress response protein: a master regulator of gene expression and cancer cell behavior

Gene mutation's role in initiating carcinogenesis has been controversial, but it is consensually accepted that both carcinogenesis and cancer metastasis are gene-regulated processes. MTA1, a metastasis-associated protein, has been extensively researched, especially regarding its role in cancer metastasis. In this review, I try to elucidate MTA1's role in both carcinogenesis and metastasis from a different angle. I propose that MTA1 is a stress response protein that is upregulated in various stress-related situations such as heat shock, hypoxia, and ironic radiation. Cancer cells are mostly living in a stressful environment of hypoxia, lack of nutrition, and immune reaction attacks. To cope with all these stresses, MTA1 expression is upregulated, plays a role of master regulator of gene expression, and helps cancer cells to survive and migrate out of their original dwelling.

Does background parenchymal enhancement on MRI affect the rate of positive resection margin in breast cancer patients?

OBJECTIVE

The purpose of our study was to evaluate whether strong background parenchymal enhancement (BPE) would be a significant independent factor associated with positive resection margin in patients treated initially with breast-conserving surgery (BCS).

METHODS

Retrospective evaluation of breast MRI examinations of 314 patients with breast cancer was carried out. Breast cancer was histologically confirmed in all patients who underwent BCS from January 2008 to December 2010. BPE was dichotomized into weak (minimal or mild) and strong (moderate or marked) enhancement for statistical analysis. Histopathological features of attained specimens were evaluated by an experienced pathologist and were also dichotomized for statistical analysis.

RESULTS

On univariate analysis, positive extensive intraductal component (p < 0.001), strong BPE (p = 0.001) and human epidermal growth factor receptor 2 (HER2) positivity (p = 0.08) had significant association with positive surgical margin. Tumour size, axillary lymph node metastasis, nuclear grade, histological grade, lymphovascular invasion, oestrogen receptor and progesterone receptor did not show significant correlation with positive surgical margin. On multivariate analysis, the significant independent predictors were extensive intraductal component [odds ratio, 5.68; 95% confidence interval (CI), 2.72-11.82] and strong BPE (odds ratio, 2.39; 95% CI, 1.20-4.78).

CONCLUSION

Strong BPE is a significant independent factor for positive resection margin along with positive extensive intraductal component, and performing MRI during the period of lower parenchymal enhancement is needed in patients with strong BPE.

ADVANCES IN KNOWLEDGE

As far as we know, this is the first study to reveal that BPE is a significant independent factor associated with positive resection margin.

Histopathological characterization of ductal carcinoma in situ (DCIS) of the breast according to HER2 amplification status and molecular subtype

This study aimed to characterize ductal carcinoma in situ (DCIS) according to human epidermal growth factor receptor 2 (HER2) amplification status and molecular subtype. In addition, we performed a detailed HER2 and CEP17 copy number analysis and we assessed the impact of recent changes in the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines on HER2 immunohistochemical (IHC) scores in DCIS. Nuclear grade, extensive comedonecrosis, stromal architecture, stromal inflammation, and progesterone receptor (PR) expression were significantly associated with HER2 amplification status. In multivariate analysis, stromal inflammation and extensive comedonecrosis were the only two features that remained significantly related to HER2 amplification status. The recent changes in ASCO/CAP guidelines resulted in significant upgrading of HER2 IHC score. Remarkably, about one in five non-amplified DCIS presented a 3+ IHC score, regardless of the scoring method. The biological significance of this phenomenon is presently unknown. After categorization according to molecular subtype, luminal A DCIS mainly presented histopathological features associated with good prognosis, whereas luminal B/HER2+ and HER2+ categories displayed a more aggressive phenotype. Overall, our results demonstrate that HER2-amplified DCIS constitute a clearly distinct subgroup which is characterized by histopathological features associated with poor prognosis. Further studies are required to elucidate the biological significance of a 3+ IHC score in non-amplified DCIS, as well as its mechanism.

Invasive cancers are not necessarily from preformed in situ tumours - an alternative way of carcinogenesis from misplaced stem cells

Cancers are thought to be the result of accumulated gene mutations in cells. Carcinomas, which are cancers arising from epithelial tissues usually go through several stages of development: atypical hyperplasia, carcinoma in situ and then invasive carcinoma, which might further metastasize. However, we think that the present pathological data are enough to prove that there might be an alternative way of carcinogenesis. We propose that majority of invasive cancers arise in the connective tissue stroma de novo, from the misplaced epithelial stem cells which come to the wrong land of connective tissue stroma by accident. The in situ carcinomas, which are mostly curable, should not be considered genuine cancer, but rather as quasi-cancer. We design this new theory of carcinogenesis as the stem cell misplacement theory (SCMT). Our SCMT theory chains together other carcinogenesis theories such as the inflammation-cancer chain, the stem cell theory and the tissue organization field theory. However, we deny the pathway of somatic mutation theory as the major pathway of carcinogenesis.

Ductal carcinoma in situ associated with triple negative invasive breast cancer: evidence for a precursor-product relationship

AIMS

We evaluated pathological features of the ductal carcinoma in situ component of 241 triple negative invasive breast cancers.

RESULTS

We found that 151 (62.6%) in situ lesions were of high nuclear grade, and 236 (97.9%) were triple negative (oestrogen receptor, progesterone receptor, cerbB2 negative). Immunohistochemistry for cytokeratin (CK)5/6, CK14, CK17, epidermal growth factor receptor (EGFR), CD117, 34βE12, p63 and smooth muscle actin (SMA) revealed positive staining in 5 (2.1%), 60 (24.9%), 69 (28.6%), 37 (15.4%), 69 (28.6%), 137 (56.8%), 3 (1.2%) and 22 (9.1%) in situ ductal components respectively, with fair to substantial agreement of staining results (positive versus negative) between in situ and corresponding invasive elements for CK5/6, CK14, CK17, EGFR, CD117 and 34βE12; but none to fair agreement for p63 and SMA respectively. When the tri-panel of CK14, EGFR and 34βE12 was used to define the basal phenotype, 68% revealed basal-like expression of both in situ and invasive components of the same case.

CONCLUSIONS

Our data support the notion that triple negative ductal carcinoma in situ is the precursor of the corresponding invasive counterpart, and that basal-like expression is maintained in the majority of invasive cancers associated with basal-like in situ disease. Future studies that prospectively evaluate morphological and biological characteristics of invasive cancers that develop from triple negative and basal-like ductal carcinoma in situ lesions will assist in validating these findings.

Measurement of HER2 in saliva of women in risk of breast cancer

HER2 amplification can be present in ductal carcinoma in situ (DCIS). The aim of the present study was to test the feasibility of measuring soluble HER2 in the saliva of patients at risk of breast cancer towards early diagnosis and prognosis. Women with lesions classified as 4 according to BIRADS and women with spontaneous nipple discharge (NAF) were recruited for this study. Quantification of soluble HER2 in saliva was performed using the enzyme immunoassay ELISA. Median values of HER2 were quantified in saliva of the control groups and in the patient groups. The statistical test nonparametric Mann-Whitney was applied for the evaluation of median differences. Although the medians increased with the severity of the clinical status, no significant difference was found in all possibilities (p > 0.05) when comparing the medians among the patients groups. Interestingly, inter-individual HER2 quantity variations in the saliva were detected in this study in some subjects from each group. Considering possible inter-individual variations, research on saliva-based circulating HER2 has to be reinforced to ensure its correct application in diagnosis, treatment and in follow-up of breast cancer patients. Older and current issues surrounding the controversy about the appropriate methods for HER2 evaluation are discussed.

Significance of HER2 protein examination in ductal carcinoma in situ

BACKGROUND

HER2 expression is routinely checked in ductal carcinoma in situ, as in invasive ductal carcinoma. However, the effect of HER2 status in ductal carcinoma in situ on the development of malignancy and the significance of overexpression of HER2 are still not clear.

MATERIALS AND METHODS

We experienced 103 cases that were diagnosed as pure ductal carcinoma in situ from operative specimens in the 2-y period from 2006 to 2007. We examined their HER2 status and other markers. We added 38 cases of ductal carcinoma in situ with small invasive disease 5mm or less in diameter as subjects. We also examined how accurately HER2 status in biopsy specimens predicted the existence of an invasive component.

RESULTS

In pure ductal carcinoma in situ, tumors that were comedo type, high grade, or ER negative showed a high frequency of HER2 overexpression. In cases with small invasion, HER2 expression was higher than that in pure ductal carcinoma in situ. Among cases that were diagnosed as ductal carcinoma in situ by biopsy, 28% had invasive disease in operative specimens. In tumors that were palpable, large, or expressed HER2 3+ in biopsy samples, invasive disease was frequently observed in operative specimens.

CONCLUSIONS

Overexpression of HER2 in ductal carcinoma in situ might not always be necessary for progression to invasive ductal carcinoma. To clarify the significance of HER2 examination in DCIS, further investigations of the potential for invasive ductal carcinoma and the prognosis are still needed.

Identification of biomarkers in ductal carcinoma in situ of the breast with microinvasion

Background

Widespread use of mammography in breast cancer screening has led to the identification of increasing numbers of patients with ductal carcinoma in situ (DCIS). DCIS of the breast with an area of focal invasion 1 mm or less in diameter is defined as DCIS with microinvasion, DCIS-Mi. Identification of biological differences between DCIS and DCIS-Mi may aid in understanding of the nature and causes of the progression of DCIS to invasiveness.

Methods

In this study, using resected breast cancer tissues, we compared pure DCIS (52 cases) and DCIS-Mi (28 cases) with regard to pathological findings of intraductal lesions, biological factors, apoptosis-related protein expression, and proliferative capacity through the use of immunohistochemistry and the TdT-mediated dUTP-biotin nick end labeling (TUNEL) method.

Results

There were no differences in biological factors between DCIS and DCIS-Mi, with respect to levels of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor type 2. The frequency of necrosis and positive expression ratio of survivin and Bax were significantly higher in DCIS-Mi than in DCIS. In addition, apoptotic index, Ki-67 index, and positive Bcl-2 immunolabeling tended to be higher in DCIS-Mi than in DCIS. Multivariate analysis revealed that the presence of necrosis and positive survivin expression were independent factors associated with invasion.

Conclusion

Compared with DCIS, DCIS-Mi is characterized by a slightly elevated cell proliferation capacity and enhanced apoptosis within the intraductal lesion, both of which are thought to promote the formation of cell necrotic foci. Furthermore, the differential expression of survivin may serve in deciding the response to therapy and may have some prognostic significance.

Gene expression analyses in breast cancer epidemiology: the Norwegian Women and Cancer postgenome cohort study

Introduction

The introduction of high-throughput technologies, also called -omics technologies, into epidemiology has raised the need for high-quality observational studies to reduce several sources of error and bias.

Methods

The Norwegian Women and Cancer (NOWAC) postgenome cohort study consists of approximately 50,000 women born between 1943 and 1957 who gave blood samples between 2003 and 2006 and filled out a two-page questionnaire. Blood was collected in such a way that RNA is preserved and can be used for gene expression analyses. The women are part of the NOWAC study consisting of 172,471 women 30 to 70 years of age at recruitment from 1991 to 2006 who answered one to three questionnaires on diet, medication use, and lifestyle. In collaboration with the Norwegian Breast Cancer Group, every NOWAC participant born between 1943 and 1957 who is admitted to a collaborating hospital for a diagnostic biopsy or for surgery of breast cancer will be asked to donate a tumor biopsy and two blood samples. In parallel, at least three controls are approached for each breast cancer case in order to obtain blood samples from at least two controls per case. The controls are drawn at random from NOWAC matched by time of follow-up and age. In addition, 400 normal breast tissues as well as blood samples will be collected among healthy women participating at the Norwegian Mammography Screening program at the Breast Imaging Center at the University Hospital of North-Norway, Tromsø.

Results

The NOWAC postgenome cohort offers a unique opportunity (a) to study blood-derived gene expression profiles as a diagnostic test for breast cancer in a nested case-control design with adjustment for confounding factors related to different exposures, (b) to improve the reliability and accuracy of this approach by adjusting for an individual's genotype (for example, variants in genes coding for hormone and drug-metabolizing and detoxifying enzymes), (c) to study gene expression profiles from peripheral blood as surrogate tissue to biomonitor defined exposure (for example, hormone) and its association with disease risk (that is, breast cancer), and (d) to study gene variants (single nucleotide polymorphisms and copy number variations) and environmental exposure (endogenous and exogenous hormones) and their influence on the incidence of different molecular subtypes of breast cancer.

Conclusion

The NOWAC postgenome cohort combining a valid epidemiological approach with richness of biological samples should make an important contribution to the study of the etiology and system biology of breast cancer.

Chromogenic in situ hybridisation testing for HER2 gene amplification in breast cancer produces highly reproducible results concordant with fluorescence in situ hybridisation and immunohistochemistry

AIMS

The objective of this study was to evaluate the accuracy, ease of use and reproducibility of chromogenic in situ hybridisation (CISH) for HER2 testing by studying its inter-laboratory concordance in five Australian pathology laboratories.

METHODS

The HER2 status of 49 breast cancers was determined by CISH twice in two different laboratories. Each sample had previously been tested by immunohistochemistry (IHC; 2+ and 3+ cases selected) and fluorescence in situ hybridisation (FISH). Participating laboratories were blinded to these test results. Oestrogen receptor (ER) status was also evaluated for each cancer.

RESULTS

High correlation was observed between FISH and CISH results. No cases showing high gene amplification by FISH were scored as non-amplified by CISH (kappa coefficient = 1). High correlation was observed between IHC and CISH, all IHC 3+ samples showing amplification by CISH. Inter-laboratory CISH concordance was also good (kappa coefficient = 0.67). Fifty-six per cent of HER2-amplified samples tested ER positive, while 42% of ER-positive cases showed HER2 gene amplification, confirming that HER2 testing should not be confined to ER-negative breast cancers.

CONCLUSIONS

These findings demonstrate that CISH is a robust test to assess HER2 status in breast cancer and therefore is an important addition to the HER2 testing algorithm.

The natural history of ductal carcinoma in situ of the breast: a review

BACKGROUND

Ductal carcinoma in situ represents about 20% of all tumours diagnosed within mammographic screening programs. The natural history of DCIS is poorly understood, as it cannot be observed directly. Estimates of the proportion of DCIS that progress to invasive cancer, as well as factors that may influence progression, are important for clinical management. Here we review various sources of evidence regarding the natural history of DCIS.

METHODS

We identified relevant publications of studies on: follow-up studies of DCIS initially misdiagnosed as benign, studies of recurrence of DCIS as invasive cancer, autopsy studies, studies of risk factors for DCIS, animal studies and studies that used mathematical models to study growth of DCIS and invasive cancer. Data sources included the MEDLINE data base, searches of articles cited in key reviews and editorials.

RESULTS

The most direct evidence regarding the progression of DCIS to invasive cancer comes from studies where DCIS was initially misdiagnosed as benign and treated by biopsy alone. These studies suggest that between 14-53% of DCIS may progress to invasive cancer over a period of 10 or more years. The reported prevalence of undiagnosed DCIS in autopsy studies, of approximately 9%, has been used to suggest a larger reservoir of DCIS may exist in the population. All types of study designs reviewed had limitations that may bias the estimate of progression in either direction.

CONCLUSION

The available evidence suggests not all DCIS will progress to invasive cancer in the medium term but precise estimates of progression are not possible given the limitations of the data. Mathematical modelling of various scenarios of progression and studies of genetic factors involved in progression may shed further light on the natural history of DCIS.

Biological variables and prognosis of DCIS

Based on current knowledge, biological factors that have been investigated in ductal carcinoma in situ (DCIS) include histology of these lesions, the impact of margin status on local recurrence, and several genetic alterations. Optimal integration of these factors in guiding optimal therapy is of great importance, since the incidence of DCIS is rising as a result of population-based mammographic screening. Mastectomy will almost always cure patients with DCIS but represents overtreatment for many. Less extensive treatment options should combine an optimal cosmetic result with the same safety for outcome of disease as mastectomy. To guide such optimal treatment, histological classification is not sufficient and additional biological factors are being investigated for their ability to predict outcome for individual patients with DCIS. In this review, the histological classification of DCIS is described and in addition the emerging knowledge on genetic alterations is summarised. For clinical management of DCIS patients, genetic or other biological factors should be identified that can predict the risk of progression of DCIS to invasive breast cancer and distant metastases. At present, insufficient knowledge on prognostic and predictive factors in DCIS is available. Research in this area is hampered by the difficulties in obtaining DCIS tumour tissue, as the tumour cells grow in the lumen of pre-existing ducts and lobules. As the recurrence rates are relatively low and the most relevant clinical endpoint, distant metastases, is indeed very rare, large numbers of patients (hundreds to a few thousand) need to be studied. Integration of translational studies into clinical trials aimed at optimising the treatment of DCIS are required to achieve this goal.

Central nervous system metastases in breast cancer patients administered trastuzumab

Amplification or over-expression of the HER2/neu receptor is present in 20-30% of invasive breast cancers and in 60% of intraductal breast carcinomas. Patients with HER2/neu gene aberrations have more aggressive disease, frequent disease recurrence and a shorter survival. Trastuzumab (herceptin) is a monoclonal antibody selectively directed against the HER2/neu receptor. The addition of trastuzumab to chemotherapy in HER2/neu-positive advanced breast cancer patients has increased complete and partial response rates, and prolonged time to progression and overall survival. However, a relatively common failure site in patients administered trastuzumab is the central nervous system (CNS). CNS metastases in these patients seem to develop despite responses achieved in extracerebral sites. This pattern of failure has mainly been attributed to the lack of trastuzumab penetration to the CNS owing to the high molecular weight (145 kDa) of this molecule. Additionally, increased risk of CNS relapse may be associated with improved systemic control of extracerebral metastases and prolonged survival without brain protection (a sanctuary site). Finally, it was postulated that HER2/neu over-expression and/or amplification might predispose to brain metastases. The aim of this article is to discuss the pathophysiology of this phenomenon and its clinical implications.

Histopathological and cell biological characteristics of ductal carcinoma in situ (DCIS) of the breast—a comparison between the primary DCIS and subsequent ipsilateral and contralateral tumours

The rate of ipsilateral local recurrence after ductal carcinoma in situ (DCIS) varies (between 5% and 30%) and depends on the type of operation (mastectomy vs. breast-conserving operation), and whether postoperative radiotherapy has been used. Ipsilateral local recurrence can either emanate from the primary lesion or be a new primary tumour. Contralateral lesions may also develop after DCIS. We compared histopathological and cell biological characteristics in 37 subsequent ipsilateral tumours (25 DCIS and 12 invasive cancers) and 13 subsequent contralateral invasive breast cancers with their corresponding primary DCIS. The histopathological parameters were re-evaluated and the cell biological factors were analysed using conventional immunohistochemical techniques in paraffin-embedded material. The concordance rate for high grade (nuclear grade 3) vs. non-high grade (nuclear grades 1+2) between the primary DCIS and the subsequent ipsilateral tumour was higher than between the primary DCIS and the subsequent contralateral invasive cancer (68% vs. 31%). Similar patterns in the concordance rates between the primary DCIS and ipsilateral vs. contralateral tumours were also found in the oestrogen receptor status (83% vs. 50%) and the progesterone receptor status (87% vs. 58%). The pattern persisted in the other factors examined (p53, c-erbB2, bcl-2 and Ki67), although it was less pronounced. The overall high rate of concordance in the characteristics between the primary DCIS and the subsequent ipsilateral tumours suggests that, in most cases, they represent true local recurrences. Subsequent contralateral tumours are more likely to be new primary cancers.

HER2 protein overexpression in estrogen receptor-positive ductal carcinoma in situ of the breast: frequency and implications for tamoxifen therapy

Recent clinical data have suggested that the efficacy of tamoxifen in reducing the risk of local recurrence following lumpectomy and radiation therapy in patients with ductal carcinoma in situ (DCIS) is limited to patients with estrogen receptor (ER)-positive lesions. However, it is currently not known if HER2 protein overexpression might be associated with reduced tamoxifen benefit in patients with ER-positive DCIS, as has been suggested in patients with ER-positive invasive breast cancer and in preclinical models. Moreover, the frequency of HER2 overexpression in ER-positive ductal carcinoma in situ has not been previously evaluated in detail. To address this issue, we studied ER expression and HER2 overexpression in 148 cases of DCIS using a sensitive double immunostaining technique and assessed the frequency of ER expression and HER2 overexpression in relation to each other and in relation to DCIS grade. Overall, ER expression was seen in 114 cases (77%) and HER2 protein overexpression was seen in 42 cases (28%). Of 114 ER-positive ductal carcinoma in situ, 14 (12%) showed concurrent HER2 protein overexpression, and all 14 of these DCIS lesions were of high nuclear grade. In addition, in all 14 ER-positive DCIS cases that showed HER2 overexpression, double immunostaining demonstrated that ER and HER2 protein were coexpressed by the same neoplastic cells. We conclude that a subset of ER-positive DCIS show concomitant overexpression of HER2 protein. Whether or not HER2 overexpression is associated with a diminished response to tamoxifen in patients with ER-positive DCIS will require investigation in clinical outcome studies.

Aspects of molecular phenotype and its correlations with breast cancer behaviour and taxonomy

The assessment of breast cancer morphology remains an important element in the evaluation of prognosis and therapeutic planning for this disease. The tumour morphology reflects the molecular profile that produced it and consequently each can be predictive of the other.

Testing for HER2 in breast cancer

HER2 is a paradigm of a molecular target whose appropriate assessment is pivotal in the targeting of novel therapies for breast cancer, notably including Herceptin/Trastuzumab. Determining the correct levels requires immunohistochemical and molecular biological skills that are reproducible and measurable, coupled with a knowledge of the appropriate morphological and pathobiological context. Attaining these goals is not easy and laboratories testing for HER2 should maintain a high level of throughput of tests and engage in a recognized external quality assurance scheme. Fluorescence in-situ hybridization testing remains a particular challenge and there is a range of testing strategies. This testing forms the model for the identification of other novel molecular targets. In the future rapid throughput techniques such as real-time quantitative polymerase chain reaction (rqPCR), tissue microarrays or both should bring significant economies of cost and scale.

Conservation of Breast Cancer Molecular Subtypes and Transcriptional Patterns of Tumor Progression Across Distinct Ethnic Populations

PURPOSE

Breast cancers can display distinct clinical characteristics in different ethnic populations. Previous studies involving European and United States patients have shown that breast tumors can be divided by their gene expression profiles into distinct "molecular subtypes." In this report, we surveyed a series of invasive and preinvasive breast tumors from Asian-Chinese patients to investigate whether similar subtypes could also be observed in this ethnic group.

EXPERIMENTAL DESIGN AND RESULTS

An analysis of expression profiles generated from 11 nonmalignant breast tissues, 17 ductal carcinomas in situ (DCIS) and 98 invasive carcinomas identified three broad molecular subtypes of breast [estrogen receptor (ER)+, ERBB2+ and ER-] in the Asian-Chinese population. These subtypes were highly similar to the "Luminal," "ERBB2+," and "Basal" molecular subtypes defined in previous studies, and the subtype-specific expression signatures were also observed in preinvasive DCIS tumors. By comparing the expression profiles of nonmalignant DCIS and invasive breast cancers for two subtypes (ER+ and ERBB2+), we identified several genes that were regulated in both a common and subtype-specific manner during the normal/DCIS and DCIS/invasive carcinoma transitions. Several of these genes were validated by comparison with another recently published similar, but not identical, study.

CONCLUSIONS

Our results suggest that molecularly similar subtypes of breast cancer are indeed broadly conserved between Asian and Caucasian patients, and that these subtypes are already present at the preinvasive stage of carcinogenesis. To our knowledge, this study is among the first to directly compare the expression profiles of breast tumors across two different ethnic populations.

Molecular Characterization of the Transition to Malignancy in a Genetically Engineered Mouse-Based Model of Ductal Carcinoma In situ

A transplantable model of human ductal carcinoma in situ that progresses to invasive carcinoma was developed from a genetically engineered mouse (GEM). Additional lines were established using early mammary premalignant lesions from transgenic MMTV-PyV-mT mice. These lines were verified to be premalignant and transplanted repeatedly to establish stable and predictable properties. Here, we report the first in-depth molecular analysis of neoplastic progression occurring in one premalignant transplantable GEM-derived line. Oligonucleotide microarrays showed that many genes are differentially expressed between the quiescent and prelactating mammary gland and the premalignant GEM outgrowth. In contrast, a small but consistent group of genes was associated with the transformation from premalignancy to tumor. This suggests that the majority of gene expression changes occur during the premalignant transition from normal to premalignancy, whereas many fewer changes occur during the malignant transition from premalignancy to invasive carcinoma. The premalignant transition is associated with several cell cycle–related genes and the up-regulation of oncogenes is associated with various cancers (Ccnd11, Cdk4, Myb, and Ect2). The changes identified in the malignant transition included genes previously associated with human breast cancer progression. Misregulation of the insulin-like growth factor and transforming growth factor-β signaling pathways and the stromal-epithelial interaction were implicated. Our results suggest that this transplantable GEM-based model recapitulates human ductal carcinoma in situ at both histologic and molecular levels. With consistent tumor latency and molecular profiles, this model provides an experimental platform that can be used to assess functional genomics and molecular pharmacology and to test promising chemoprevention strategies.

Ductal carcinoma in situ, complexities and challenges

The incidence of ductal carcinoma in situ (DCIS), a noninvasive form of breast cancer, has increased markedly in recent decades, and DCIS now accounts for approximately 20% of breast cancers diagnosed by mammography. Laboratory and patient data suggest that DCIS is a precursor lesion for invasive cancer. The appropriate classification of DCIS has provoked much debate; a number of classification systems have been developed, but there is a lack of uniformity in the diagnosis and prognostication of this disease. Further investigation of molecular markers should improve the classification of DCIS and our understanding of its relationship to invasive disease. Controversy also exists with regard to the optimal management of DCIS patients. In the past, mastectomy was the primary treatment for patients with DCIS, but as with invasive cancer, breast-conserving surgery has become the standard approach. Three randomized trials have reported a statistically significant decrease in the risk of recurrence with radiation therapy in combination with lumpectomy compared with lumpectomy alone, but there was no survival advantage with the addition of radiotherapy. Two randomized trials have suggested an additional benefit, in terms of recurrence, with the addition of adjuvant tamoxifen therapy, although in one trial the benefit was not statistically significant. Current data suggest that tamoxifen use should be restricted to patients with estrogen receptor-positive DCIS. Neither trial demonstrated a survival benefit with adjuvant tamoxifen. Ongoing and recently completed studies should provide information on outcomes in patients treated with lumpectomy alone and on the effectiveness of aromatase inhibitors as an alternative to tamoxifen.

Partially unspliced and fully spliced ELF3 mRNA, including a new Alu element in human breast cancer

Using modified representational difference analysis, a DNA fragment (GC3) was isolated as a difference between a breast cancer and a normal cell line from the same patient. GC3 proved to be a fragment of intron 7 of the ELF3 gene, an ets family transcription factor, amplified in the breast cancer cell line. Using genomic walking technology, a new Alu (Alu(kwd)) was found downstream of GC3 in an antisense position between nt 8762 and nt 8763 within intron 8 of the ELF3 gene. This ELF3 intron fragment(GC3) was expressed in human breast cancer cell lines and four of six breast cancer tissues, but not in matched normal cell lines and tissues. Similarly, Alu(kwd) was also found in the same breast cancer cell lines and five of eight other breast cancer tissues, but not in matched normal cell lines and tissue. This was confirmed by RNase and DNase digestion analysis. Moreover, GC3 and Alu(kwd) were detected in both the nuclear and cytoplasmic RNA fractions of breast cancer cell lines. The finding of cytoplasmic intron retention was verified with northern blotting and the 5' and 3' rapid amplification cDNA ends procedure (5' and 3'RACE) to search for cDNA sequences in RNA from these cancer cell lines. Partially unspliced ELF3 mRNA and fully spliced ELF3 mRNA was found in the same breast cancer cell line. Partially unspliced ELF3 mRNA contained introns 4-7 without any nucleotide mutation at intron/exon splice junction borders. Fully spliced 1959 bp ELF3 mRNA showed a different 5'UTR from the published ELF3 mRNA, and was predicted to encode a 371 amino acid protein sharing 98% homology with the ELF3 protein sequence. This is the first report of intron retention of ELF3 as well as the pathological appearance of both spliced and unspliced cytoplasmic ELF3 mRNA in human breast cancer cells.

HER-2/neu (c-erbB-2) Evaluation in Primary Breast Carcinoma by Fluorescent In Situ Hybridization and Immunohistochemistry With Special Focus on Intratumor Heterogeneity and Comparison of Invasive and In Situ Components

We have studied the intratumor HER-2/neu heterogeneity in 78 consecutive and population-based primary invasive breast carcinomas. Within the invasive component, heterogeneity was detected in only 1 of 78 tumors. In 48 tumors (62%), we found both in situ and invasive components in analyzed tissue sections. Twelve of these 48 tumors had a difference of at least 2 arbitrary units in the in situ compared with the invasive part of the tumor with regard to the HER-2/neu status analyzed by HercepTest (immunohistochemistry). Eight of these 12 tumors were reanalyzed with fluorescent in situ hybridization and immunohistochemistry with and without a new Automated Cellular Imaging System. In this limited material, immunohistochemistry in combination with the Automated Cellular Imaging System seemed to have a better correlation with fluorescent in situ hybridization than immunostaining analyzed manually. In conclusion, HER-2/neu expression is not seldom heterogeneous in invasive compared with in situ components within a tumor. This finding should be considered in the choice of evaluation method. To avoid heterogeneity as a confounding factor in HER-2/neu analyses, detection methods such as immunohistochemistry and fluorescent in situ hybridization, which can provide evaluation in a preserved tissue architecture, should be used. Perhaps the intratumor HER-2/neu heterogeneity can explain some of the unexpected failures of trastuzumab therapy.

Molecular analysis of metastasis in a polyomavirus middle T mouse model: the role of osteopontin

INTRODUCTION

In order to study metastatic disease, we employed the use of two related polyomavirus middle T transgenic mouse tumor transplant models of mammary carcinoma (termed Met and Db) that display significant differences in metastatic potential.

METHODS

Through suppression subtractive hybridization coupled to the microarray, we found osteopontin (OPN) to be a highly expressed gene in the tumors of the metastatic mouse model, and a lowly expressed gene in the tumors of the lowly metastatic mouse model. We further analyzed the role of OPN in this model by examining sense and antisense constructs using in vitro and in vivo methods.

RESULTS

With in vivo metastasis assays, the antisense Met cells showed no metastatic tumor formation to the lungs of recipient mice, while wild-type Met cells, with higher levels of OPN, showed significant amounts of metastasis. The Db cells showed a significantly reduced metastasis rate in the in vivo metastasis assay as compared with the Met cells. Db cells with enforced overexpression of OPN showed elevated levels of OPN but did not demonstrate an increase in the rate of metastasis compared with the wild-type Db cells.

CONCLUSIONS

We conclude that OPN is an essential regulator of the metastatic phenotype seen in polyomavirus middle T-induced mammary tumors. Yet OPN expression alone is not sufficient to cause metastasis. These data suggest a link between metastasis and phosphatidylinositol-3-kinase-mediated transcriptional upregulation of OPN, but additional phosphatidylinositol-3-kinase-regulated genes may be essential in precipitating the metastasis phenotype in the polyomavirus middle T model.

Detailed gene copy number and RNA expression analysis of the 17q12-23 region in primary breast cancers

Chromosome region 17q12-23 commonly shows an increase in DNA copy number in breast cancers, suggesting that several oncogenes are located at this site. We performed a high-resolution expression array and comparative genomic hybridization analysis of genes mapped to the entire 17q12-23 region, to identify novel candidate oncogenes. We identified 24 genes that showed significant overexpression in breast cancers with gain of 17q12-23, compared to cancers without gain. These genes included previously identified oncogenes, together with several novel candidate oncogenes. FISH analysis using specific gene probes hybridized to tissue arrays confirmed the underlying amplification of overexpressed genes. This high-resolution analysis of the 17q12-23 region indicates that several established and novel candidate oncogenes, including a Wnt-signaling pathway member, are amplified and overexpressed within individual primary breast cancer samples. We were also able to confirm the presence of two apparently separate and reciprocally amplified groups of genes within this region. Investigation of these genes and their functional interactions will facilitate our understanding of breast oncogenesis and optimal management of this disease.

Biological markers that predict clinical recurrence in ductal carcinoma in situ of the breast

The optimal management of ductal carcinoma in situ (DCIS) is controversial, due in part to our poor understanding of its natural history. We undertook to identify subgroups of DCIS based on the expression of biomarkers, which were related to the likelihood of clinical recurrence. Biomarker expression of a total of 95 DCIS lesions in a nested case-control study within a population-based cohort with up to 135 months follow-up data (median 101 months) was analysed using immunohistochemistry. ERBB2-positivity and bcl-2-, oestrogen receptor (ER)- and progesterone receptor (PR)-negativity were individually associated with the risk of clinical recurrence. The predictive value of these biomarkers was independent of cytonuclear grade. ERBB2, bcl-2, ER and PR expression were conserved in the recurrent lesions, including subsequent invasive cancers. p21-positive DCIS was also associated with clinical recurrence, independently of the associations with ERBB2/bcl-2/ER/PR expression. These data identify clinically and biologically relevant subcategories of DCIS lesions, an essential basis for improving management.

Pathway pathology: histological differences between ErbB/Ras and Wnt pathway transgenic mammary tumors

To study phenotype-genotype correlations, ErbB/Ras pathway tumors (transgenic for ErbB2, c-Neu, mutants of c-Neu, polyomavirus middle T antigene (PyV-mT), Ras, and bi-transgenic for ErbB2/Neu with ErbB3 and with progesterone receptor) from four different institutions were histopathologically compared with Wnt pathway tumors [transgenes Wnt1, Wnt10b, dominant-negative glycogen synthase kinase 3-beta, beta-Catenin, and spontaneous mutants of adenomatous polyposis coli gene (Apc)]. ErbB/Ras pathway tumors tend to form solid nodules consisting of poorly differentiated cells with abundant cytoplasm. ErbB/Ras pathway tumors also have scanty stroma and lack myoepithelial or squamous differentiation. In contrast, Wnt pathway tumors exhibit myoepithelial, acinar, or glandular differentiation, and, frequently, combinations of these. Squamous metaplasia is frequent and may include transdifferentiation to epidermal and pilar structures. Most Wnt pathway tumors form caricatures of elongated, branched ductules, and have well-developed stroma, inflammatory infiltrates, and pushing margins. Tumors transgenic for interacting genes such as protein kinase CK2alpha (casein kinase IIalpha), and the fibroblast growth factors (Fgf) Int2/Fgf3 or keratinocyte growth factor (Kgf/Fgf7) also have the Wnt pathway phenotype. Because the tumors from the ErbB/Ras and the Wnt pathway are so distinct and can be readily identified using routine hematoxylin and eosin sections, we suggest that pathway pathology is applicable in both basic and clinical cancer research.

Presence of ductal carcinoma in situ confers an improved prognosis for patients with T1N0M0 invasive breast carcinoma

We have retrospectively analyzed a series of 155 sequential cases of T1N0M0 ductal carcinomas of which 51 tumors had a ductal carcinoma in situ (DCIS) component for correlation between the presence of DCIS and clinicopathological variables, recurrence and patient survival. No correlations between the presence of DCIS and age, menopausal status, size, estrogen or progesterone receptors were found. High-grade infiltrative tumors tended not to present a DCIS component (P = 0.08). Patients with tumors associated with DCIS form a subgroup with few recurrences (P = 0.003) and good survival (P = 0.008). When tumors were classified by size, an association between large tumors (>1.0 cm) and increased recurrence and shortened overall survival was found. The presence of DCIS in this subgroup significantly reduced the relative risk of death.

Molecular and biologic markers of premalignant lesions of human breast

There is currently great interest in the detection and characterization of putative precursor breast cancer lesions because of the possibility of chemoprevention. Knowledge of the biologic features of premalignant lesions, although limited, is rapidly evolving. Premalignant breast lesions have been examined for the presence of genetic alterations and for the expression of biomarkers such as the estrogen receptor (ER), Ki67, p53, and HER2/neu. Data obtained from genetic studies of precursor breast lesions clearly support the contention that genetic alterations begin quite early in selected subsets of histologically benign lesions. Although the results of biomarker expression profiles have been contradictory, most studies agree that precursor lesions significantly overexpress ER and that progressive alterations in ER expression accompany the transition of normal cells to hyperplastic lesions and carcinoma in situ. So far, the collected evidence indicates that precursor lesions in the breast demonstrate biomarker expression profiles and genetic abnormalities that are distinct from those of terminal ductal lobular units but share some of these features with invasive tumors. Future research in this field is urgently needed to identify specific biomarkers of prognostic and predictive value, which can help not only in the selection of patients for chemopreventive therapy but in monitoring the progression of high-risk lesions.

HER2 overexpression in various tumor types, focussing on its relationship to the development of invasive breast cancer

To date, poor standardization in HER2 status evaluation has precluded reliable comparison of overexpression rates in different tumors. However, standardized methodologies have been introduced recently for these analyses, and have identified frequencies of 51%, 44%, 26% and 25% in Wilm's tumor, bladder, pancreatic and breast carcinoma, respectively. Other tumors tested had frequencies below 20%. The frequency was greater than that predicted by gene amplification data in some tumor types, which may indicate overexpression due to gene deregulation, rather than gene amplification. Analysis of a large retrospective series of breast carcinomas demonstrated an association between HER2 positivity and a number of other prognostic markers. Together, these variables identify a subset of tumors with poor prognosis and early relapse post-surgery. HER2 expression is relatively stable, with 95% concordance between the HER2 status of primary and metastatic lesions. However, contralateral tumors are unrestricted with regard to HER2 status. Preliminary data indicate that the HER2 status of a hormone receptor-positive tumor may fluctuate according to the menstrual cycle. It is anticipated that the emerging wealth of standardized data for HER2 status will help to elucidate the role of HER2 in tumor progression.

HER2 as a prognostic and predictive marker for breast cancer

In recent years investigators have looked at the human epidermal growth factor receptor-2 (HER2), which is overexpressed in 20%-30% of breast cancer patients, with regard to its role as a prognostic and predictive factor. Although many studies have suggested that HER2 overexpression may be associated with a poor clinical outcome, other studies have not fully supported this observation. The inconsistencies between studies may be due in part to discrepancies between different HER2 testing methods. To overcome this problem, a radioimmunohistochemical method was developed to quantitatively measure HER2 overexpression levels in breast tumor samples. The application of this method demonstrated that 85% of all breast tumor samples expressed HER2 at levels greater than normal. Of these, 23% expressed HER2 at levels between 45 and 480 times greater than normal, and this was associated with poor clinical outcome. The investigation of HER2 status as a predictor of response to therapy has also yielded many conflicting results. Overall, it appears that HER2 overexpression may correlate with resistance to hormonal therapy, sensitivity to anthracycline-based chemotherapy and resistance to CMF. With the development of targeted anti-HER2 therapies, assessment of HER2 status will be important in stratifying patients to the most appropriate treatment regimens.

A new model for ductal carcinoma in situ suggests strategies for treatment

Human ductal carcinoma in situ (DCIS) of the breast is now diagnosed quite frequently, due largely to the introduction of mammographic screening. It has been shown in a cell culture system that activation of c-erbB-2, but not the epidermal growth factor receptor, results in a DCIS-like phenotype. Since overexpression of c-erbB-2 occurs in 60% of DCIS, this suggests that it could be a target for treatment in this disease.

Immunohistochemical analysis on biological markers in ductal carcinoma in situ of the breast

BACKGROUND

The increasing use of mammographic screening has led to an increased detection of ductal carcinoma in situ (DCIS) of the breast. The detailed biological characteristics of DCIS and a new classification of DCIS based on these characteristics are needed.

METHODS

Immunohistochemical studies were performed to assess the expression of c-erbB-2 (ErbB-2), estrogen receptor (ER), p53 and proliferative activity (Ki-67) in 65 patients with pure DCIS and 60 with invasive ductal carcinoma (IDC). We classified pure DCIS tumors using three classifications, the architectural, Nottingham, and Van Nuys classifications.

RESULTS

ErbB-2, ER and p53 staining was positive in 34%, 66% and 21% of patients with DCIS, respectively, and 58%, 42% and 33% in patients with IDC, respectively. Ki-67 stained positively in 1.5% of patients with DCIS and 11.2% of patients with IDC. The comedo type showed a high rate of positive ErbB-2 and p53 staining. The cribriform and papillary types showed a high rate of positive ER staining. Under the Van Nuys classification, ErbB-2, p53 and Ki-67 expression were highest in the group with high nuclear grade and lowest in the group with non-high nuclear grade without necrosis.

CONCLUSION

Although the biological markers of IDC tended to suggest aggressive behavior more so than those of DCIS, these differences were based on the histological sub-type, comedo or non-comedo. The Van Nuys classification best defined the subgroups of DCIS with a distinct expression pattern of biological markers, and the best candidates for breast-conserving surgery.

Cell biological factors in ductal carcinoma in situ (DCIS) of the breast-relationship to ipsilateral local recurrence and histopathological characteristics

All cases of ductal carcinoma in situ (DCIS) diagnosed from 1987 to 1991 in the Southern Health Care Region of Sweden, and operated upon with breast conserving treatment (BCT) with (n=66) or without (n=121) postoperative radiation (RT) were clinically followed, morphologically re-evaluated and analysed for cell biological factors (immunohistochemical assays or DNA flow cytometry). Median age at diagnosis was 58 years (range 29--83 years) and median follow-up was 62 months. Oestrogen (ER)- and progesterone receptor (PR)-negativity, c-erbB-2 overexpression, low bcl-2 expression, p53 accumulation, DNA non-diploidy and high Ki67, were strongly associated with high grade DCIS, and comedo-type necrosis. In contrast, significant associations to growth pattern (not diffuse versus diffuse) were seen only for c-erbB-2 and PgR. There was also a strong relationship between the cell biological factors, and a summary cell biological index based on principal component analysis was introduced (CBI-7). In the group that had not received postoperative RT, 31 ipsilateral local recurrences occurred (13 invasive, 18 DCIS). Ipsilateral recurrence-free interval (IL-RFI) was in univariate analyses significantly, or almost significantly, shorter for patients showing p53 accumulation, high Ki67 or low bcl-2, compared with patients with normal p53, low Ki67 and high bcl-2. The prognostic importance of the remaining cell biological factors was less pronounced. On the other hand, the index CBI-7, was a strong predictor for recurrence.

Regulation of MUC1 expression in human mammary cell lines by the c-ErbB2 and ras signaling pathways

The MUC1 protein is a highly O-glycosylated transmembrane molecule that is expressed at the luminal surface of most glandular epithelial cells and is upregulated in carcinomas. Here, we report the effect of the activation of the c-ErbB2 --> Ras pathway on the expression of the MUC1 gene in the nontumorigenic mammary cell lines MTSV1-7 and HB2 and in the malignant cell lines T47D and ZR75. Endogenous levels of MUC1 mRNA and protein in HB2 clones permanently overexpressing c-ErbB2 or V12-H-Ras were markedly reduced compared with levels in the parental cell lines. Furthermore, in transient transfection assays, the transcription of a CAT reporter construct driven by the MUC1 promoter was inhibited when cotransfected with a c-ErbB2 or a V12-H-ras expressing vector. Transient transfections using mutant forms of the ras oncogene, and the inhibitor chemical wortmannin, indicated that the pathway activated by c-ErbB2 proceeds via activation of Ras and that the Raf and phosphoinositide 3-kinase pathways are involved. Finally, cotransfection assays using a reporter gene driven by the MUC1 promoter carrying abolishing mutations in some of the cis-acting elements showed that a GC box at -99/-91 is crucial for responsiveness to c-ErbB2 inhibition of transcription.

Molecular mechanisms underlying ErbB2/HER2 action in breast cancer

Overexpression of ErbB2, a receptor-like tyrosine kinase, is shared by several types of human carcinomas. In breast tumors the extent of overexpression has a prognostic value, thus identifying the oncoprotein as a target for therapeutic strategies. Already, antibodies to ErbB2 are used in combination with chemotherapy in the treatment of metastasizing breast cancer. The mechanisms underlying the oncogenic action of ErbB2 involve a complex network in which ErbB2 acts as a ligand-less signaling subunit of three other receptors that directly bind a large repertoire of stroma-derived growth factors. The major partners of ErbB2 in carcinomas are ErbB1 (also called EGFR) and ErbB3, a kinase-defective receptor whose potent mitogenic action is activated in the context of heterodimeric complexes. Why ErbB2-containing heterodimers are relatively oncopotent is a function of a number of processes. Apparently, these heterodimers evade normal inactivation processes, by decreasing the rate of ligand dissociation, internalizing relatively slowly and avoiding the degradative pathway by returning to the cell surface. On the other hand, the heterodimers strongly recruit survival and mitogenic pathways such as the mitogen-activated protein kinases and the phosphatidylinositol 3-kinase. Hyper-activated signaling through the ErbB-signaling network results in dysregulation of the cell cycle homeostatic machinery, with upregulation of active cyclin-D/CDK complexes. Recent data indicate that cell cycle regulators are also linked to chemoresistance in ErbB2-dependent breast carcinoma. Together with D-type cyclins, it seems that the CDK inhibitor p21waf1 plays an important role in evasion from apoptosis. These recent findings herald a preliminary understanding of the output layer which connects elevated ErbB-signaling to oncogenesis and chemoresistance.

Biological features of premalignant disease in the human breast

Most human invasive breast cancers (IBCs) arise from preexisting benign lesions. There are many types of benign lesions in the human breast and only a few appear to have significant premalignant potential (atypical hyperplasias and in situ carcinomas). These lesions are relatively common and only a small proportion progress to IBC. They are currently defined by their histological features and their prognosis is imprecisely estimated from indirect evidence based on epidemiological studies. Although lesions within specific categories look alike, they must possess morphologically silent biological differences motivating some to remain stable and others to progress. Understanding the biological changes responsible for the development and progression of premalignant disease is a very active area of medical research. Progress in this area may provide new opportunities for breast cancer prevention by providing strategies to treat premalignant lesions before they develop or become cancerous. A large number of biological features have been evaluated in this setting during the past decade. This review discusses a few features that appear to be particularly important and have been studied in a relatively comprehensive manner.

Ductal carcinoma in situ. Implications for screening mammography

Ductal carcinoma in situ (DCIS) now represents 20% of all newly diagnosed breast cancers because of increased detection by screening mammography. Twenty year relative survival rates are 97%. Postsurgical and histological studies and recent molecular biological studies indicate that most cases of DCIS will progress to invasive carcinoma if not detected by mammography. Screening mammography studies support the need for annual versus less frequent screenings to detect DCIS before further progression.

The hyperplasia-to-carcinoma sequence in the breast. Immunohistochemical-histologic correlations

Breast cancer is probably the result of a series of genetic events, each with its own histopathologic correlate in the hyperplasia to carcinoma sequence. The expression of breast cancer markers in hyperplasia and tumors are well known, but few studies have investigated their sequential expression among hyperplastic and cancerous lesions within the same breast. Using breast tissue obtained from a single procedure, we correlated the immunohistochemical expression of several breast cancer markers with the histopathologic stage of proliferative breast disease. We selected 14 cases in which various degrees of hyperplasia coexisted with carcinoma. Serial sections were reacted with antibodies to DF3, c-erbB-2, p53 (DO7 and CM1), B72.3, and cyclin D1. We found that within an individual breast, the number of breast cancer markers expressed increased with progression from hyperplasia to atypical hyperplasia to carcinoma. Cytoplasmic DF3 was first expressed at the level of simple hyperplasia, followed by c-erbB-2 in atypical hyperplasia. Overexpression of p53 was confined to carcinomas, and thus appeared to be a late event. B72.3 was expressed in three carcinomas and in one atypical hyperplasia, although the associated carcinoma was negative. Carcinomas that expressed cytoplasmic DF3 and c-erbB-2 were associated with atypical hyperplasias that also expressed cytoplasmic DF3 and c-erbB-2, with one and two exceptions, respectively. No specific cyclin D1 staining pattern was observed.