Genomics and premalignant breast lesions: clues to the development and progression of lobular breast cancer

Atypical Lobular Hyperplasia and Classic Lobular Carcinoma In Situ Can Be Safely Managed Without Surgical Excision

BACKGROUND

Based on modern series demonstrating low upgrade rates for pure lobular neoplasia (LN) diagnosed on core needle biopsy (CNB), our institution no longer recommends routine excision, provided imaging is concordant. This study describes outcomes in patients managed without surgical excision.

METHODS

From an institutional database, we identified all patients with a diagnosis of pure atypical lobular hyperplasia and/or classic lobular carcinoma in situ on CNB managed without surgical excision (i.e., conservative management) from 2015 to 2019. The primary outcome of interest was failure of conservative management, defined as development of ipsilateral same-quadrant ductal carcinoma in situ or invasive breast cancer within 2 years of CNB, or need for ipsilateral same-quadrant excisional biopsy. We also evaluated rates of ipsilateral same-quadrant CNB during follow-up.

RESULTS

Among 96 pure LN lesions on CNB since 2015, 80 (83%) were managed without surgical excision. Median follow-up was 27 months (IQR: 16-28), with only 2 (2%) patients lost to follow-up. No patients developed an ipsilateral, same-quadrant breast cancer. The 3-year risk of conservative management failure was 6.2% (95% CI 2.3-15.7%). All failures were a result of need for excisional biopsy due to progressive imaging abnormalities at the initial CNB site, with benign final pathology. The 3-year risk of ipsilateral same-quadrant CNB was 9.2% (95% CI 3.8-21.5%).

CONCLUSION

Non-surgical management of pure LN is safe, and the likelihood of requiring subsequent surgical excision or repeat CNB during follow-up is low. These data provide reassurance that routine excision of pure LN in the setting of radiologic-pathologic concordance is not required.

Rifaximin, a pregnane X receptor (PXR) activator regulates apoptosis in a murine model of breast cancer

The present study was proposed to investigate the effect of rifaximin (RFX) on methyl nitrosourea (MNU) induced mammary gland carcinoma in albino wistar rats.

Gene expression profiling of lobular carcinoma in situ reveals candidate precursor genes for invasion

PURPOSE

Lobular carcinoma in situ (LCIS) is both a risk indicator and non-obligate precursor of invasive lobular carcinoma (ILC). We sought to characterize the transcriptomic features of LCIS and ILC, with a focus on the identification of intrinsic molecular subtypes of LCIS and the changes involved in the progression from normal breast epithelium to LCIS and ILC.

METHODS

Fresh-frozen classic LCIS, classic ILC, and normal breast epithelium (N) from women undergoing prophylactic or therapeutic mastectomy were prospectively collected, laser-capture microdissected, and subjected to gene expression profiling using Affymetrix HG-U133A 2.0 microarrays.

RESULTS

Unsupervised hierarchical clustering of 40 LCIS samples identified 2 clusters of LCIS distinguished by 6431 probe sets (p < 0.001). Genes identifying the clusters included proliferation genes and other genes related to cancer canonical pathways such as TGF beta signaling, p53 signaling, actin cytoskeleton, apoptosis and Wnt-Signaling pathway. A supervised analysis to identify differentially expressed genes (p < 0.001) between normal epithelium, LCIS, and ILC, using 23 patient-matched triplets of N, LCIS, and ILC, identified 169 candidate precursor genes, which likely play a role in LCIS progression, including PIK3R1, GOLM1, and GPR137B. These potential precursor genes map significantly more frequently to 1q and 16q, regions frequently targeted by gene copy number alterations in LCIS and ILC.

CONCLUSION

Here we demonstrate that classic LCIS is a heterogeneous disease at the transcriptomic level and identify potential precursor genes in lobular carcinogenesis. Understanding the molecular heterogeneity of LCIS and the potential role of these potential precursor genes may help personalize the therapy of patients with LCIS.

Aberrant Proliferation of Differentiating Alveolar Cells Induces Hyperplasia in Resting Mammary Glands of SV40-TAg Transgenic Mice

WAP-T1 transgenic mice express SV40-TAg under control of the whey acidic protein (WAP) promoter, which directs activity of this strong viral oncogene to luminal cells of the mammary gland. Resting uniparous WAP-T1 glands develop hyperplasia composed of TAg positive cells prior to appearance of advanced tumor stages. We show that cells in hyperplasia display markers of alveolar differentiation, suggesting that TAg targets differentiating cells of the alveolar compartment. The glands show significant expression of Elf5 and milk genes (Lalba, Csn2, and Wap). TAg expressing cells largely co-stain with antibodies to Elf5, lack the epithelial marker Sca1, and are hormone receptor negative. High expression levels of Elf5 but not of milk genes are also seen in resting glands of normal BALB/c mice. This indicates that expression of Elf5 in resting WAP-T1 glands is not specifically induced by TAg. CK6a positive luminal cells lack TAg. These cells co-express the markers prominin-1, CK6a, and Sca1, and are positive for hormone receptors. These hormone sensitive cells localize to ducts and seem not to be targeted by TAg. Despite reaching an advanced stage in alveolar differentiation, the cells in hyperplasia do not exit the cell cycle. Thus, expression of TAg in conjunction with regular morphogenetic processes of alveologenesis seem to provide the basis for a hormone independent, unscheduled proliferation of differentiating cells in resting glands of WAP-T1 transgenic mice, leading to the formation of hyperplastic lesions.

Lobular Breast Cancer in a Male Patient with a Previous History of Irradiation Due to Hodgkin's Disease

BACKGROUND

Male breast cancer is rare and represents less than 1% of all breast cancers. Considering the fact that the male breast most often does not consist of lobules and acini, lobular carcinoma of the male breast is exceptionally rare.

CASE REPORT

In this paper we present a unique case of alveolar variant of lobular male breast cancer in a 56-year-old patient.

CONCLUSION

According to our knowledge this is the first presentation of an alveolar variant of lobular male breast cancer that appeared 14 years after chemo- and radiotherapy for the treatment of Hodgkin's disease.

Cadherin-catenin complex dissociation in lobular neoplasia of the breast

E-cadherin (E-CD) inactivation with loss of E-CD-mediated cell adhesion is the hallmark of lesions of the lobular phenotype. E-CD is typically absent by immunohistochemistry in both lobular carcinoma in situ (LCIS) and invasive lobular lesions, suggesting it occurs early in the neoplastic process. In laboratory models, downstream post-transcriptional modifiers such as TWIST and SNAIL contribute to the dissociation of the intracellular component of the cadherin-catenin complex (CCC), resulting in tumor progression and invasion. We hypothesized that complete CCC dissociation may play a role in lobular neoplasia progression. Here we explore the relationship between loss of E-CD and dissociation of the CCC in pure LCIS and LCIS associated with invasive cancer. Fresh-frozen tissues were obtained from 36 patients undergoing mastectomy for pure LCIS (n = 11), LCIS with ILC (n = 18) or LCIS with IDC (n = 7). Individual lesions were subject to laser-capture microdissection and gene-expression analysis (Affymetrix HG-U133A 2.0). Immunohistochemistry for ER,PR,HER2, E-CD,N-CD,α-,β-, and phosphoβ-catenin, TWIST, and SNAIL were evaluated in normal, in situ, and invasive components from matched formalin-fixed paraffin-embedded samples (n = 36). CCC-dissociation was defined as negative membranous E-CD, α- and β-catenin expression. E-CD was negative in all LCIS and ILC lesions, and positive in all normal and IDC lesions. Membranous α and β-catenin expressions decreased with the transition from LCIS to ILC (pure LCIS 82%; LCIS w/ILC 28%; ILC 0%), while TWIST expression increased (pure LCIS low; LCIS w/ILC moderate; ILC high). Gene expression paralleled IHC-staining patterns with a stepwise downregulation of E-CD, α and β-catenins from normal to LCIS to invasive lesions, and increasing expression of TWIST from normal to LCIS to ILC. Loss of E-CD expression is an early event in lobular neoplasia. Decreasing membranous catenin expression in tandem with increasing levels of TWIST across the spectrum of lobular lesions suggests that CCC dissociation is a progressive process.

Amplification of the prolactin receptor gene in mammary lobular neoplasia

The identification of lobular carcinoma in situ (LCIS) in a patient's specimen confers an appreciable increased risk of development of future invasive mammary carcinoma. However, the study of LCIS presents a challenge as it is usually only recognized in fixed specimens. Recent advances in high throughput genomics have made possible comprehensive copy number analysis of lesions such as this. Using array comparative genomic hybridization (aCGH), we characterized eight cases of lobular carcinoma (four invasive and four non-invasive) from microdissected samples of archival specimens and validated our results by quantitative real-time PCR (qRT-PCR). Immunohistochemistry (IHC) was performed on an independent set of 80 in situ ductal (DCIS) and lobular breast lesions to confirm our results. Amplification of the prolactin receptor gene (PRLr) was identified in 4/4 cases of LCIS by aCGH. We confirmed this amplification by qRT-PCR and demonstrated PRLr expression in 29/40 (73%) cases of lobular neoplasia by IHC. Amplification of PRLr was neither detected in 10 cases of DCIS nor in 5 areas of normal breast tissue by qRT-PCR and only 14/40 (35%) cases of DCIS showed PRLr expression by IHC (P = 0.0008). Our study suggests the prolactin receptor gene is a molecular target that may be important in the pathogenesis and progression of lobular neoplasia. Investigation of the status of this gene in cases of DCIS has indicated that it may not be as important in the progression of this type of breast cancer, supporting the view that lobular and ductal carcinomas may evolve along separate pathways.

Lobular neoplasia: morphology, biological potential and management in core biopsies

Lobular neoplasia has been traditionally recognized as a marker of increased risk for subsequent breast carcinoma development; however, molecular studies suggest that it also behaves in a non-obligate precursor manner. We do not know, as yet, how to identify the subgroup of cases that is most likely to progress, but the epidemiological data would indicate that this progression occurs after a long period of time. Thus, the current approach of conservative management of these lesions when identified in excision specimens is justified. Recently, several variants of lobular carcinoma in situ (LCIS), most notably pleomorphic LCIS, have been recognized and these can be difficult to differentiate from ductal carcinoma in situ. Application of strict diagnostic criteria and the judicial use of immunohistochemistry, particularly E-cadherin, can be helpful in this differential diagnosis. Another challenging issue is the management of lobular neoplasia when diagnosed on core biopsy. This controversial issue will be discussed in detail. The goals of this review are (1) to describe the morphological criteria used to diagnose the spectrum of lobular neoplastic lesions, including atypical lobular hyperplasia, LCIS and variants of LCIS; (2) to discuss the data exploring the biological potential of lobular neoplasia from an epidemiological and molecular viewpoint; and (3) to outline the recommendations for management of lobular neoplasia when encountered in core biopsies.

Gene expression in histologically normal epithelium from breast cancer patients and from cancer-free prophylactic mastectomy patients shares a similar profile

INTRODUCTION

We hypothesised that gene expression in histologically normal (HN) epithelium (NlEpi) would differ between breast cancer patients and usual-risk controls undergoing reduction mammoplasty (RM), and that gene expression in NlEpi from cancer-free prophylactic mastectomy (PM) samples from high-risk women would resemble HN gene expression.

METHODS

We analysed gene expression in 73 NlEpi samples microdissected from frozen tissue. In 42 samples, we used microarrays to compare gene expression between 18 RM patients and 18 age-matched HN (9 oestrogen receptor (ER)+, 9 ER-) and 6 PM patients. Data were analysed using a Bayesian approach (BADGE), and validated with quantitative real-time PCR (qPCR) in 31 independent NlEpi samples from 8 RM, 17 HN, and 6 PM patients.

RESULTS

A total of 98 probe sets (86 genes) were differentially expressed between RM and HN samples. Performing hierarchical analysis with these 98 probe sets, PM and HN samples clustered together, away from RM samples. qPCR validation of independent samples was high (84%) and uniform in RM compared with HN patients, and lower (58%), but more heterogeneous, in RM compared with PM patients. The 86 genes were implicated in many processes including transcription and the MAPK pathway.

CONCLUSION

Gene expression differs between the NlEpi of breast cancer cases and controls. The profile of cancer cases can be discerned in high-risk NlEpi from cancer-free breasts. This suggests that the profile is not an effect of the tumour, but may mark increased risk and reveal the earliest genomic changes of breast cancer.

Lobular neoplasia of the breast: an update

CONTEXT

Lobular neoplasias (LNs) of the breast include atypical lobular neoplasia and lobular carcinoma in situ. Recent evidence suggests that LN is not only a risk factor for invasive lobular carcinoma, but is also a nonobligate precursor. Pleomorphic lobular carcinoma in situ (PLCIS) is a subtype of LN that has high-grade nuclei and other features that may mimic high-grade ductal carcinoma in situ. The management and follow-up of patients diagnosed with LN on core biopsy is a current issue of debate. However, recent genomic and molecular studies have identified candidate genes that may be important in understanding the pathogenesis of atypical lobular neoplasia and lobular carcinoma in situ, and thus may lead to other therapeutic interventions.

OBJECTIVE

To review the literature on LN of the breast and discuss current issues in the diagnosis and management of this entity, with particular attention to the relatively newly recognized lesion PLCIS. Because the management of PLCIS varies from the other LN lesions, the recognition of PLCIS by the pathologist is necessary. Current issues in the molecular pathogenesis of LN are also presented.

DATA SOURCES

Extensive review of the literature. Hematoxylin-eosin-stained and immunohistochemical-stained tissue from the author's personal collection.

CONCLUSIONS

Although morphology and immunohistochemical stains, such as E-cadherin, are important in the diagnosis and understanding of LN, genomic and molecular studies may guide the way these lesions are handled in the future. Recognizing PLCIS is important both for patient management and for our future understanding of LN pathogenesis.

Increased levels of active c-Src distinguish invasive from in situ lobular lesions

Introduction

Mounting molecular evidence suggests that invasive lobular carcinoma (ILC) is developing from in situ lesions, atypical lobular hyperplasia (ALH), and lobular carcinoma in situ (LCIS). However, little is known about the mechanisms promoting the progression of lobular breast cancer (LBC) to invasive disease. Here, we investigated whether c-Src kinase, an established inducer of invasive states, contributes to the progression from ALH/LCIS to ILC.

Methods

Immunochemistry for c-Src and other cancer-related molecules was performed on archived tissue specimens from 57 LBC patients. Relative c-Src activity was estimated by comparing fluorescence intensity of ILC with that of adjacent ALH/LCIS and nonneoplastic epithelia after staining with an antibody against active c-Src. Expression of active c-Src was correlated with markers of invasion and malignancy and with relapse among LBC patients.

Results

Levels of activated c-Src were increased in ILC relative to ALH/LCIS (1.63-fold ± 0.24 SD) and nonneoplastic epithelia (1.47 ± 0.18 SD). Increased c-Src levels correlated with the activation of c-Src downstream targets (Fak, Stat-3) and the expression of mesenchymal markers. ILC cells with activated c-Src co-expressed metastatic markers (Opn, Cxcr4) and included cells positive for the cancer stem cell marker Aldh1. A tendency for high c-Src levels (P = 0.072) was observed among the seven LBC patients with relapsed disease.

Conclusions

Our data indicate elevated c-Src activity in ILC relative to noninvasive neoplastic tissue. The associated molecular changes suggest that c-Src promotes LBC invasiveness by inducing an epithelial-mesenchymal transition. Therefore, c-Src antagonists might counteract the acquisition of invasiveness during LBC progression. Inhibition of c-Src may also affect ILC cells thought to have a high metastatic potential and to be capable of initiating/maintaining tumor growth. Together with the possible association between high c-Src levels and disease recurrence, our findings encourage the evaluation of c-Src antagonists for the treatment of LBC.

Epigenetic silencing in non-neoplastic epithelia identifies E-cadherin (CDH1) as a target for chemoprevention of lobular neoplasia

Invasive lobular carcinoma (ILC) of the breast is believed to develop from in situ lesions, atypical lobular hyperplasia (ALH), and lobular carcinoma in situ (LCIS). Down-regulation of the cell-cell adhesion protein E-cadherin is a defining feature of lobular breast cancer (LBC) and already occurs in ALH and LCIS. Apart from mutational mechanisms, epigenetic silencing of the E-cadherin gene (CDH1) is thought to be involved in E-cadherin down-regulation and has been observed at a high frequency in ILC. Whether CDH1 promoter methylation is already present in in situ lesions and thus contributes to the initiation of LBC is not established. We thus examined microdissected archived tissue from 20 LBCs by methylation-specific PCR to determine the CDH1 methylation status of lobular lesions. Nineteen of the 20 LBCs had a hypermethylated CDH1 promoter, including 13/14 ILCs and 13/13 ALHs or LCIS. Bisulphite sequencing indicated that methylation was complete within the investigated promoter fragment. Intriguingly, CDH1 methylation was likewise present in 8/8 adjacent non-neoplastic epithelia, but not in 6/6 mammary epithelia from healthy subjects. E-cadherin protein and mRNA were down-regulated in in situ lesions relative to adjacent epithelia. Together, these results indicate that CDH1 promoter methylation occurs in LBC prior to E-cadherin down-regulation and neoplastic formation. We thus propose that epigenetic silencing represents the first of the two hits required to silence both CDH1 alleles for LBC to develop. Because promoter methylation is in principle reversible, our findings suggest that chemoprevention of LBC by epigenetic drugs should be feasible. Furthermore, the presence of CDH1 methylation in pre-neoplastic epithelia suggests the existence of mammary regions with increased disease susceptibility, providing an explanation for the often multifocal presentation of LBC.

Lobular and ductal intraepithelial neoplasia

Lobular and ductal intraepithelial neoplasias reflect proliferations of immunophenotypically variable, biologically and morphologically diverse cells with a potential, not always realized, for progression to carcinoma by breaking through the barriers of the myoepithelial cell layer and basement membrane, ultimately invading the stroma. Starting with the lobular and then the ductal proliferations, this review will address the evolution of our understanding of these lesions; the problems associated with the conventional terminology of ductal hyperplasia, atypical hyperplasia, and carcinoma in situ; and reasons for and advantages of the intraepithelial neoplasia terminology.

Atypical lobular hyperplasia and classic lobular carcinoma in situ in core biopsy specimens: routine excision is not necessary

Standardized recommendations for the management of lobular neoplasia in core biopsy specimens are not established. The aim of our study was to define morphologic features of lobular neoplasia in core biopsies that predict the finding of ductal carcinoma in situ or invasive carcinoma in the subsequent excisional specimen. We reviewed 333 cases of atypical lobular hyperplasia or lobular carcinoma in situ without ductal carcinoma in situ or invasive carcinoma diagnosed in core biopsies from 1996 to 2006. Subsequent excision was performed in 41% (136/333) of cases, including atypical lobular hyperplasia (n=48), lobular carcinoma in situ (n=39), and lobular neoplasia associated with atypical ductal hyperplasia (n=49). Upgrades were identified in 2% (1/48) of atypical lobular hyperplasia, 23% (9/39) of lobular carcinoma in situ, and 27% (13/49) of lobular neoplasia associated with atypical ductal hyperplasia cases. When further analyzed, the upgraded cases of lobular carcinoma in situ were associated with radiologic-pathologic discordance in 6/9 cases and with nonclassic pathology (two lobular carcinoma in situ with necrosis and one pleomorphic lobular carcinoma in situ) in the remaining three cases. The frequency of upgrade was 11% (3/26) in classic lobular carcinoma in situ, and 46% (6/13) in nonclassic types (pleomorphic or with necrosis). After excluding cases with discordant imaging/pathology, there was a 5% upgrade in our excisional specimens. After excluding cases where the upgrade was associated with nonclassic morphology, the upgrade in our study was 1%. Our results suggest that atypical lobular hyperplasia and classic lobular carcinoma in situ with concordant radiology and pathology can be appropriately managed with clinical follow-up without surgery.