Lobular Carcinoma In Situ Lesions Research Articles

Abstract PO5-13-11: Quantitative Assessment of HER2 Expression in Intraductal Neoplasms of the Breast

Abstract HER2 (ERBB2) is an established prognostic and predictive marker for patients with invasive breast cancer and used in HER2-targeted therapy. The clinical and biological significance of expression of HER2 protein in patients with intraductal neoplasms of the breast is not well characterized. In this study, we used our HS-HER2 (High Sensitivity-HER2) which is a CAP/CLIA certified laboratory derived test (LDT) using quantitative immunofluorescence (QIF). We evaluated HER2 expression in DCIS (ductal carcinoma in situ), LCIS (lobular carcinoma in situ) and benign lesions to correlate with their clinicopathologic characteristics. Thirty- eight cases of DCIS, and fourteen cases of LCIS and thirty benign cases were selected from the Yale Pathology department archives and 252 ROIs (regions of interest) were annotated by a board-certified pathologist. DCIS is classified according to the three-tier nuclear grading system: low, intermediate, and high-nuclear grade. LCIS is classified as PLCIS (pleomorphic variant) and CLCIS (classic LCIS) according to the WHO classification of breast tumors. Serial sections of FFPE tumor specimens were used to accurately quantify the HER2 expression by the HS-HER2 assay and the acquisition by QuPath v.04 with Qymia extension. According to the LOD (limit of detection,3 amol/mm2), LOQ (limit of quantification, 9 amol/mm2) and LOL (limit of linearity, 23 amol/mm2) of the optimized HS-HER2 assay as performed in our CLIA lab shows a broad range of HER2 expression in both DCIS and LCIS lesions, ranging from 0.7 amol/mm2 to 111.4 amol/mm2 in DCIS and 3.6 amol/mm2 to 49.9 amol/mm2 in LCIS. High grade DCIS lesions express higher average HER2 levels (111.4 + 0.7 amol/mm2) than combined low and intermediate grade DCIS (77.9 +1.9 amol/mm2) with no significant difference between low/intermediate and high-grade DCIS. CLCIS lesions express higher average HER2 level (49.9 + 3.6 amol/mm2) than PLCIS (35.1 + 5.4amol/mm2) but again this is not statistically significant. HER protein expression is relatively low in benign lesions ranging from 0.8 to 8.4 amol/mm2. Using the HS-HER2 assay, our results show quantitative level HER2 levels in DCIS and LCIS breast lesions. These findings may be important as HER2 targeted therapies that work in gene-unamplified cancer (HER2 conjugated ADCs) gain broader usage in the clinic. Citation Format: Nay Nwe Nyein Chan, Haiying Zhan, Revekka Khaimova, Thazin Aung, Charles Robbins, Patricia Gaule, David Rimm. Quantitative Assessment of HER2 Expression in Intraductal Neoplasms of the Breast [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-13-11.

Immediate and delayed risk of breast cancer associated with classic lobular carcinoma in situ and its variants.

To determine the risk of breast cancer due to lobular carcinoma in situ (LCIS). This retrospective IRB-approved study identified cases of LCIS after percutaneous breast biopsy from 7/2005 to 7/2022. Excluded were cases with less than 2years of imaging surveillance or a concurrent ipsilateral breast cancer diagnosis within 6months of the LCIS diagnosis. Final outcomes of cancer versus no cancer were determined by pathology at surgical excision or the absence of cancer on imaging surveillance. A total of 116 LCIS lesions were identified. The primary imaging findings targeted for percutaneous biopsy included calcifications (50.0%, 58/116), MR enhancing lesions (25.0%, 29/116), noncalcified mammographic architectural distortions (10.3%, 12/116), or masses (14.7%, 17/116). Surgical excision was performed in 49.1% (57/116) and imaging surveillance was performed in 50.9% (59/116) of LCIS cases. There were 22 cancers of which 11 cancers were discovered at immediate excision [19.3% (11/57) immediate upgrade] and 11 cancers developed later while on imaging surveillance [18.6% (11/59) delayed risk for cancer]. Among all 22 cancers, 63.6% (14/22) occurred at the site of LCIS (11 at immediate excision and 3 at surveillance) and 36.4% (8/22) occurred at a location away from the site of LCIS (6 in a different quadrant and 2 in the contralateral breast). LCIS has both an immediate risk (19.3%) and a delayed risk (18.6%) for cancer with 90.9% occurring in the ipsilateral breast (63.6% at and 27.3% away from the site of LCIS) and 9.1% occurring in the contralateral breast.

Lobular Carcinomas In Situ Display Intralesion Genetic Heterogeneity and Clonal Evolution in the Progression to Invasive Lobular Carcinoma.

Lobular carcinoma in situ (LCIS) is a preinvasive lesion of the breast. We sought to define its genomic landscape, whether intralesion genetic heterogeneity is present in LCIS, and the clonal relatedness between LCIS and invasive breast cancers.Experimental Design: We reanalyzed whole-exome sequencing (WES) data and performed a targeted amplicon sequencing validation of mutations identified in 43 LCIS and 27 synchronous more clinically advanced lesions from 24 patients [9 ductal carcinomas in situ (DCIS), 13 invasive lobular carcinomas (ILC), and 5 invasive ductal carcinomas (IDC)]. Somatic genetic alterations, mutational signatures, clonal composition, and phylogenetic trees were defined using validated computational methods. WES of 43 LCIS lesions revealed a genomic profile similar to that previously reported for ILCs, with CDH1 mutations present in 81% of the lesions. Forty-two percent (18/43) of LCIS were found to be clonally related to synchronous DCIS and/or ILCs, with clonal evolutionary patterns indicative of clonal selection and/or parallel/branched progression. Intralesion genetic heterogeneity was higher among LCIS clonally related to DCIS/ILC than in those nonclonally related to DCIS/ILC. A shift from aging to APOBEC-related mutational processes was observed in the progression from LCIS to DCIS and/or ILC in a subset of cases. Our findings support the contention that LCIS has a repertoire of somatic genetic alterations similar to that of ILCs, and likely constitutes a nonobligate precursor of breast cancer. Intralesion genetic heterogeneity is observed in LCIS and should be considered in studies aiming to develop biomarkers of progression from LCIS to more advanced lesions.

Role of breast magnetic resonance imaging in predicting residual lobular carcinoma in situ after initial excision

Breast magnetic resonance (MR) imaging is a useful screening modality in detecting suspicious lesions in patients with a history of lobular carcinoma in situ (LCIS). This study aimed to evaluate the effectiveness of breast MR imaging in detecting remnant LCIS lesions after initial excision. Between 2011 and 2015, 29 patients with LCIS who underwent initial excision were enrolled. Breast ultrasonography and breast MR imaging was conducted after initial excision. Imaging findings were compared with pathologic results. There were nine (31.0%) cases with positive margins after initial excision; they were LCIS (n=8) and atypical lobular hyperplasia (n=1). Residual lesions were identified in 12 cases; they were invasive lobular carcinoma (n=1; 3.4%), LCIS (n=9; 31.0%), atypical lobular hyperplasia (n=1; 3.4%), and papillary carcinoma in situ (n=1; 3.4%). Prior to the second operation, these lesions could be detected in seven cases using ultrasonography (sensitivity, 53.3%; specificity, 100%) and in 10 cases using breast MR imaging (sensitivity, 83.3%; specificity, 100%). Breast MR imaging showed higher sensitivity than breast ultrasonography in detecting remnant LCIS lesions. If a suspicious lesion was found using breast MR imaging, a second operation should be considered because of the possibility of multifocality, even if LCIS was confirmed at the initial operation.

Features of Pure Lobular Carcinoma In Situ on Magnetic Resonance Imaging Associated with Immediate Re-Excision after Lumpectomy.

PurposeTo evaluate imaging features of pure lobular carcinoma in situ (LCIS) on magnetic resonance imaging (MRI) in patients who underwent immediate re-excision after lumpectomy.MethodsTwenty-six patients (46.1±6.7 years) with 28 pure LCIS lesions, who underwent preoperative MRI and received curative surgery at our institution between 2005 and 2013, were included in this study. Clinicopathologic features associated with immediate re-excision were reviewed and analyzed using Fisher exact test or the Wilcoxon signed rank test.ResultsOf the 28 lesions, 21.4% (6/28, six patients) were subjected to immediate re-excision due to resection margin involvement by LCIS. Nonmass lesions and moderate-to-marked background parenchymal enhancement on MRI were more frequently found in the re-excision group than in the single operation group (100% [6/6] vs. 40.9% [9/22], p=0.018; 83.3% [5/6] vs. 31.8% [7/22], p=0.057, respectively). The median lesion size discrepancy observed between magnetic resonance images and histopathology was greater in the re-excision group than in the single operation group (-0.82 vs. 0.13, p=0.018). There were no differences in the mammographic or histopathologic findings between the two groups.ConclusionNonmass LCIS lesions or moderate-to-marked background parenchymal enhancements on MRI can result in an underestimation of the extent of the lesions and are associated with subsequent re-excision due to resection margin involvement.

Molecular drivers of lobular carcinoma in situ.

Lobular carcinoma in situ (LCIS) is considered to be a risk factor for the development of invasive breast carcinoma, but it may also be a non-obligate precursor to invasive lobular carcinoma (ILC). Many LCIS lesions do not progress to ILC, and the molecular changes that are necessary for progression from LCIS to ILC are poorly understood. Disruption in the E-cadherin complex is the hallmark of lobular lesions, but other signaling molecules, such as PIK3CA and c-src, are consistently altered in LCIS. This review focuses on the molecular drivers of lobular carcinoma, a more complete understanding of which may give perspective on which LCIS lesions progress, and which will not, thus having immense clinical implications.

Underestimation of Atypical Lobular Hyperplasia and Lobular Carcinoma in Situ at Stereotaxic 11-Gauge Vacuum-Assisted Breast Biopsy

The aims of this study are to determine the frequency of diagnosis of atypical lobular hyperplasia (ALH) and lobular carcinoma in situ (LCIS) at stereotaxic-guided 11-gauge vacuum-assisted breast biopsy (VABB) and to assess the rate of underestimation of these at subsequent surgical excision and follow-up. Moreover, we aimed to define clinical, radiological and histological features of nonpalpable lesions in core biopsies that predict the lesion upgrade. Retrospective review of 11-gauge VABB was performed to identify the underestimation rate of nonpalpable lesions diagnosed as ALH or LCIS at VABB. Thirteen cases of ALH and 36 cases of LCIS were sent to surgery, 29 cases of ALH and 14 cases of LCIS were sent to follow-up. The clinical, mammographic and histologic features were assessed. The correlation between mammographic BI-RADS score and histological B-classification for both ALH and LCIS lesions were performed by Pearson's test. Of 1,765 patients enrolled, lobular lesions (ALH and/or LCIS) occurred in 82 cases, and underestimation arose in 9 (10.9%). Two cases of underestimated ALH were upgraded to invasive lobular carcinoma and one to invasive ductal carcinoma. One case of underestimated LCIS was upgraded to ductal carcinoma in situ, two to invasive ductal carcinoma and three to invasive lobular carcinoma. The histology of the core and surgical specimens were compared. A significant difference was seen in the BI-RADS score (4–5 in 91% of underestimated lesions), and the size of the lesions (≥ 1.5 cm) for underestimated cases versus accurately diagnosed cases (p<0.001). Further significant parameters predictive for malignancy were the incomplete lesion removal by VABB and the presence of associated different breast lesions in the specimen. In conclusion, as far as ALH is concerned, we propose surgery as first choice when at least one of the following condition is respected: positive history for breast carcinoma, lesion >1.5cm, co-presence of high-risk lesions in the sample, signs of ductal involvement, high histological grading for atypia and follow-up in the other cases. Surgery is recommended in all cases of LCIS:

Abstract PD05-02: Novel mutations in lobular carcinoma in situ (LCIS) as uncovered by targeted parallel sequencing

Abstract Background: LCIS has traditionally been recognized as a marker of increased risk for the subsequent development of breast cancer, of either the lobular or ductal phenotype, yet due to the incidental nature of LCIS little is known about its underlying biology. Here we describe the first report of novel mutations in LCIS using targeted exome sequencing of fresh frozen tissue samples. Methods: Fresh frozen tissue samples from patients with a prior history of LCIS undergoing therapeutic or risk-reducing mastectomy from 2003–08 were harvested and systematically reviewed to identify LCIS. Cells from individual LCIS lesions +/− associated cancers were collected by laser capture microdissection. For the purposes of this study, germline DNA (blood) and DNA from 12 unique LCIS lesions were subject to targeted parallel sequencing of exons corresponding to 230 cancer genes using the Illumina HiSeq 2000 platform. DNA from an associated ductal carcinoma in situ (DCIS) and/or an invasive ductal (IDC) or lobular (ILC) lesion was also available for 7 of these cases resulting in 41 samples from 12 pts for mutational analysis. Normalized (RMA) Affymetrix U133A gene expression data were also available. Results: DNA profiling reliably identified 7 somatic mutations in 5/12 LCIS samples (41.7%). Of these, 4/7 mutations were base substitutions (missense mutations); and the others included: 1 deletion; 1 silent and 1 splice-site mutation. Mutations in LCIS were identified in 5/230 cancer genes analyzed, including: PIK3CA, CDH1, NOTCH4, PREX2 and ARAF. PIK3CA and CDH1 mutations were each identified in two samples, representing 4/7 (57.1%) mutations. Specific mutations found in LCIS and their frequencies are listed (table). Among 3 LCIS-ILC pairs, one shared the G914R mutation in PIK3CA, and 1/3 LCIS-IDC pairs exhibited an identical point mutation (R373W) in the NOTCH4 gene. No shared mutations were observed in 3 LCIS-DCIS pairs. Both CDH1 mutated cases were associated with decreased e-cadherin mRNA levels when compared to non-mutated cases (mean 9.88 vs 11.01), as was the NOTCH4 mutation (mean 6.02 vs 6.47). Mutations in ARAF and PREX2 were associated with increased mRNA levels, mean 7.07 vs 6.52 and 4.82 vs 4.22, respectively. The hotspot PIK3CA mutation (E545K) was also associated with increased gene expression (mean 5.15 vs 4.64) whereas the G914R mutant was associated with decreased expression (mean 4.13 vs 4.64). Conclusions: This study represents the first targeted exon sequencing analysis of fresh frozen LCIS. Although LCIS has been regarded as a rather genetically stable lesion, somatic mutations were detected in 41.7% of lesions in this small cohort. While CDH1 mutations are expected in lobular neoplasia, this is the first report of mutations in ARAF, NOTCH4, PIK3CA and PREX2. Given the shared relevance of PIK3CA and PREX2 in the PI3K/AKT pathway, these findings suggest novel mechanisms for new chemoprevention strategies among women with LCIS. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD05-02.

Surgical Outcome of Biopsy-Proven Lobular Neoplasia: Is There Any Difference Between Lobular Carcinoma In Situ and Atypical Lobular Hyperplasia?

The aims of our study were to determine the frequency of malignancy after surgical excision of biopsy-proven lobular carcinoma in situ (LCIS) or atypical lobular hyperplasia (ALH) lesions, to assess any difference between pure LCIS and pure ALH lesions regarding their radiologic presentation and the malignancy upgrade rate after surgical excision, and to evaluate the outcome of lesions that were not excised surgically but were followed up. Radiologic and pathologic records of 14,435 imaging-guided needle biopsies of the breast performed between 2004 and 2008 in three different institutions were retrospectively reviewed. A total of 126 patients (0.9%) had biopsy-proven LCIS or ALH, or both, as the highest-risk lesion. Among the 126 patients, 89 (71%) continued to surgery, and 14 were followed up for more than 24 months. The Mantel-Haensel chi-square test was used for statistical analysis. Cancer upgrade was documented in 17 of the 43 LCIS (40%), 11 of the 40 ALH (27%), and two of the six combined ALH and LCIS lesions (33%) surgically excised, for a total malignancy upgrade rate of 34% (30/89). Both LCIS and ALH lesions presented mammographically in most cases as microcalcifications (p = 0.078). None of the 14 patients followed up for a mean period of 51 months showed development of malignancy. No statistically significant difference was found between mammographic presentation and postsurgical outcome of LCIS versus ALH lesions. Surgical excision of these lesions is recommended as long as no evident criteria are provided to differentiate those that might be associated with an underlying malignancy.

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.

Hsa‐miR‐375 is differentially expressed during breast lobular neoplasia and promotes loss of mammary acinar polarity

Invasive lobular carcinoma (ILC) of the breast, characterized by loss of E-cadherin expression, accounts for 5-15% of invasive breast cancers and it is believed to arise via a linear histological progression. Genomic studies have identified a clonal relationship between ILC and concurrent lobular carcinoma in situ (LCIS) lesions, suggesting that LCIS may be a precursor lesion. It has been shown that an LCIS diagnosis confers a 15-20% risk of progression to ILC over a lifetime. Currently no molecular test or markers can identify LCIS lesions likely to progress to ILC. Since microRNA (miRNA) expression changes have been detected in a number of other cancer types, we explored whether their dysregulation might be detected during progression from LCIS to ILC. Using the Illumina miRNA profiling platform, designed for simultaneous analysis of 470 mature miRNAs, we analysed the profiles of archived normal breast epithelium, LCIS lesions found alone, LCIS lesions concurrent with ILC, and the concurrent ILCs as a model of linear histological progression towards ILC. We identified two sets of differentially expressed miRNAs, the first set highly expressed in normal epithelium, including hsa-miR-224, -139, -10b, -450, 140, and -365, and the second set up-regulated during lobular neoplasia progression, including hsa-miR-375, -203, -425-5p, -183, -565, and -182. Using quantitative RT-PCR, we validated a trend of increasing expression for hsa-miR-375, hsa-miR-182, and hsa-miR-183 correlating with ILC progression. As we detected increased expression of hsa-miR-375 in LCIS lesions synchronous with ILC, we sought to determine whether hsa-miR-375 might induce phenotypes reminiscent of lobular neoplasia by expressing it in the MCF-10A 3D culture model of mammary acinar morphogenesis. Increased expression of hsa-miR-375 resulted in loss of cellular organization and acquisition of a hyperplastic phenotype. These data suggest that dysregulated miRNA expression contributes to lobular neoplastic progression.

MicroRNA expression patterns in lobular neoplasia.

10551 Background: Lobular carcinoma in situ (LCIS) is a marker of increased risk for subsequent development of invasive breast cancer. Molecular studies have identified a clonal relationship between LCIS and concurrent invasive lobular carcinoma (ILC), suggesting that LCIS may be a precursor lesion of ILC. We hypothesized that differences in miRNA expression patterns might exist in LCIS lesions with concurrent ILC compared with LCIS lesions found alone. Methods: RNA was collected from matched frozen and archival formalin fixed paraffin embedded (FFPE) breast tissue using TRIZOL extractions. MiRNA expression profiling was performed using the Illumina miRNA DASL assay, in duplicate experiments, allowing simultaneous profiling of 735 miRNAs. MiRNAs of interest were further validated and analyzed by quantitative RT-PCR (qrt-PCR) in triplicate. To verify our data by localizing specific miRNA sequences of interest, in situ hybridization was performed on FFPE sections using a one-day protocol with locked nucleic acid (LNA) detection probes for miR-375 and miR-182, the U6 small nuclear RNA probe as a positive control and a scrambled miRNA probe as a negative control. Results: qrt-PCR analysis of the miR-183/182/96 cluster and miR-375 was performed using normal breast tissue, LCIS alone, and matched synchronous LCIS and ILC. A trend of increasing miRNA expression correlating with a model of histological progression toward invasive disease was observed. Results of in-situ hybridization confirmed this trend, showing the weakest signal intensity for both miR-375 and miR-182 in normal breast tissue, a stronger signal in LCIS alone, and the strongest signal in LCIS associated with synchronous ILC. Localization of signal to the nucleus was observed in normal breast tissue and LCIS alone, while a more diffuse cytoplasmic localization pattern was observed in LCIS associated with ILC, possibly suggesting nucleocytoplasmic transport for further processing of these miRNAs during progression to a more invasive phenotype. Conclusions: Upregulation of miR-375 and the miR-183/182/96 cluster in LCIS may correlate with risk for progression to ILC. These novel biomarkers may also be potential targets for treatment.

The Florid Subtype of Lobular Carcinoma In Situ: Marker or Precursor for Invasive Lobular Carcinoma?

Lobular carcinoma in situ (LCIS) is considered a risk factor-not a precursor-for both invasive lobular and ductal carcinoma. Florid LCIS (F-LCIS) is an architectural subtype of LCIS that does not express E-cadherin, yet has the histologic and often radiographic appearance of solid-type ductal carcinoma in situ (DCIS). Since DCIS is considered a precursor to invasive ductal carcinoma, should F-LCIS be considered a precursor to invasive lobular carcinoma (ILC)? Review of an institutional database identified cases of LCIS and solid-type DCIS diagnosed by excisional biopsy, segmentectomy, or mastectomy between 1991 and 2000 to determine the prevalence of associated invasive breast cancer. Archival specimens were evaluated for florid and nonflorid LCIS, nuclear grade of LCIS, and the presence and subtype of invasive breast cancer. Solid-type DCIS that lacked E-cadherin expression was classified as F-LCIS. Of 210 consecutive specimens of LCIS examined, 171 had nonflorid LCIS (81%) and 39 had F-LCIS (19%). Nonflorid LCIS had a diffuse pattern, whereas F-LCIS appeared as discrete foci adjacent to ILC. An invasive component was identified with 87% of F-LCIS lesions versus 73% of nonflorid LCIS lesions (P = 0.064); this component was lobular in 100% of F-LCIS lesions versus 82% of nonflorid LCIS lesions, a significant difference (P = 0.0044) that persisted when the analysis was adjusted for nuclear grade (P = 0.0082). Its close spatial relationship to an invasive component and increased association with ILC suggest that F-LCIS may be a precursor for ILC.

Abstract P3-07-01: Clonal Relatedness between Lobular Carcinoma In Situ and Synchronous Malignant Lesions: Analysis of Fresh Frozen Tissue Using SNP Array

Abstract INTRODUCTION: Lobular carcinoma in situ (LCIS) confers one of the greatest risks for subsequent development of invasive breast carcinoma yet historical data suggests that LCIS is not a precursor to invasive disease. Emerging evidence of shared molecular alterations between LCIS and co-existing invasive lesions in a small number of archival samples have reopened the debate regarding the true significance of LCIS and its malignant potential. METHODS: We investigated clonality between LCIS and adjacent malignant lesions in 26 patients using fresh frozen samples harvested from mastectomy specimens. Laser Capture Microdissection was used to isolate pure cell populations and DNA was subject to Affymetrix SNP 6.0 array. Data were converted for copy number analysis and the closeness of identified paired copy number changes was measured to determine the probability of clonality. RESULTS: After excluding cases with low DNA yield/quality and noise signals, 14 LCIS with seven patient matched invasive lobular carcinomas (ILC), 6 matched ductal carcinoma in situ (DCIS) and 3 matched invasive ductal carcinomas with lobular features (IDCLF) were considered adequate for statistical comparison. The immunohistochemical profile of invasive cancer showed: 10 cases ER+/PR+/Her-2(-), 2 cases ER-/PR-/Her-2(+), 1 ER-/PR-/Her2(-) and 1 case non-available for staining (microinvasive carcinoma). The results suggest that the tumor pairs are more likely to be of clonal than independent origin between LCIS and DCIS in 4/6 samples (66.6%), between LCIS and low-grade IDCLF in 3/3 (100%) samples and between LCIS and classic ILC in 5/7 (71.4%) samples. Independent LCIS/DCIS samples were seen in association with Her2+ cancers. In LCIS/DCIS samples favoring a clonal origin the DCIS were low-grade cribriform type associated with ER+ cancers. CONCLUSION: Clonal relatedness was detected in the majority of LCIS and adjacent malignancies, including cases of low-grade DCIS and IDCLF. These results support a true precursor role for LCIS and provide additional evidence to the concept of a low-grade malignancy pathway as opposed to the classic lobular versus ductal dichotomy. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-07-01.

Dissociation of the E-Cadherin-Catenin-Complex (CCC) Is an Early and Progressive Event in Lobular Neoplasia.

Abstract Recent data suggests that some lobular carcinoma in situ (LCIS) lesions may behave as precursors to invasive lobular carcinoma (ILC). Loss of E-cadherin (E-CD) mediated cell adhesion is characteristic of both LCIS and ILC and is reflected in the dis-cohesive appearance of the individual cells. Subsequent dissociation of the intracellular E-cadherin-catenin-complex (CCC) facilitates tumor progression, invasion and migration. Whether disruption of the CCC plays a role in the progression of select LCIS lesions to ILC remains unclear. The aim of this study was to evaluate the relation between loss of E-CD and dissociation of the CCC in pure LCIS and LCIS with concurrent ILC (LCIS w/ILC). Methods Thirty patients undergoing mastectomy for LCIS alone or LCIS w/ ILC were prospectively enrolled to an IRB-approved protocol. FFPE blocks were retrieved and sections prepared for IHC. 18 cases had LCIS w/ ILC, 12 cases had pure-LCIS. IHC was performed for ER, PR, E-CD, N-cadherin (N-CD), and α-, β- and phospho-β-catenin. ER/PR positivity was scored as any nuclear staining, and E-CD and N-CD by any membranous staining. a- and β-catenin expression was scored by site (membranous/cytoplasmic/nuclear) of staining compared to normal. Dissociation of the CCC was defined by loss of membranous α- and β-catenin expression.Results Median age at surgery was 51yrs (range 40-79); patients with pure LCIS were younger than those with LCIS w/ ILC (median 48yrs vs 57yrs, p=.0002). Among 18 cases of LCIS w/ ILC, the median tumor size was 2cm (range 1.4-5.7), 9 patients had N1 disease and 1 had M1 disease. All pure LCIS, LCIS w/ ILC and ILC lesions were ER/PR positive and E-CD negative. N-CD expression was also absent in all pure LCIS, LCIS w/ ILC and ILC lesions. Normal α-catenin membranous expression was confirmed in all normal epithelial cells but decreased with the transition from in-situ to invasive disease: pure-LCIS lesions 83%; LCIS w/ ILC 28%; ILC 0%. Loss of membranous α-catenin expression was accompanied by cytoplasmic α-catenin expression in all lesions. A similar trend of decreasing membranous staining from in-situ to invasive disease was observed for β-catenin, however in contrast to α-catenin, cytoplasmic β-catenin expression decreased from 67% in pure LCIS to 11% in LCIS w/ ILC and 6% in ILC. Active β-catenin (nuclear staining) was not seen in pure LCIS lesions and was only present in one case of LCIS w/ ILC. Inactive (phospho) β-catenin expression was present in all lesions.Conclusion Loss of E-CD expression is an early event in lobular neoplasia however subsequent dissociation of the intracellular CCC a a ppears to be a progressive process with complete dissociation occurring only in invasive lesions. This finding suggests that complete disruption of the CCC may be required to facilitate maintenance of the invasive phenotype; however, the absence of N-CD expression and predominance of inactive β-catenin in both in situ and invasive lesions suggests that alternate mechanisms are also required to mediate the pro-invasive effects of CCC dissociation. Further studies into the mechanisms of CCC dissociation and downstream events in lobular carcinoma are needed to define the role of this process in the transition from in-situ to invasive disease. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6149.

Uncommon high-risk lesions of the breast diagnosed at stereotactic core-needle biopsy: clinical importance.

To assess the outcome of papillary lesions, radial scars, or lobular carcinoma in situ (LCIS) diagnosed at stereotactic core-needle biopsy (SCNB). Retrospective review of 1,236 lesions sampled with SCNB yielded 22 papillary lesions, nine radial scars, and five LCIS lesions. Diffuse lesions such as papillomatosis, papillary ductal hyperplasia, papillary ductal carcinoma in situ (DCIS), and atypical lobular hyperplasia were not included. The mammographic findings, associated histologic features, and outcome were assessed for each case. Sixteen papillary lesions were diagnosed as benign at SCNB. Of these, five were benign at excision, and 10 were unremarkable at mammographic follow-up. At excision of an unusual lesion containing a microscopic papillary lesion, DCIS was found. Three of four papillary lesions suspicious at SCNB proved to be papillary carcinomas; the fourth had no residual carcinoma at excision. Eight of nine radial scars were excised, which revealed atypical hyperplasia in four scars but no malignancies. One LCIS lesion was found at excision to contain DCIS. Benign or malignant papillary lesions were accurately diagnosed with SCNB in the majority of cases. Cases diagnosed as suspicious for malignancy or with atypia or unusual associated histologic findings should be excised. No malignancies were found at excision of radial scars diagnosed at SCNB. Surgical removal of these lesions following SCNB may not be routinely necessary. DCIS was found in one lesion diagnosed as LCIS at SCNB, which suggests that removal of these lesions may be prudent.

Lobular carcinoma in situ at percutaneous breast biopsy: surgical biopsy findings.

The purpose of this study was to review surgical histologic findings in women with lobular carcinoma in situ (LCIS) at percutaneous breast biopsy. Retrospective review was performed of 1315 consecutive lesions that underwent percutaneous breast biopsy. Percutaneous biopsy yielded LCIS in 16 (1.2%) lesions. Subsequent surgical biopsy was performed in 14 lesions in 13 women. Histologic findings were reviewed. In five of the 14 lesions, percutaneous biopsy yielded LCIS and a high-risk lesion (radial scar in three and atypical ductal hyperplasia in two); in one (20%) of these five lesions, surgery revealed ductal carcinoma in situ (DCIS). In four of the 14 lesions, the LCIS in the percutaneous biopsy had features that overlapped with those of DCIS; in two (50%) of these four lesions, surgery revealed DCIS (n = 1) or infiltrating lobular carcinoma (n = 1). In the remaining five of the 14 lesions, surgery revealed no DCIS or infiltrating carcinoma. Five (38%) of 13 women with LCIS lesions had synchronous or metachronous infiltrating carcinoma (three ductal, one lobular, one mixed) in the ipsilateral (n = 1) or contralateral (n = 4) breast. Surgical excision was warranted in lesions in which LCIS was found at percutaneous breast biopsy when the percutaneous biopsy histologic features overlapped with those of DCIS, when a high-risk lesion was present, or when there was imaging-histologic discordance. LCIS without these factors was not shown to require surgical excision in our small series, but a larger study is needed. Diagnosis of LCIS at percutaneous biopsy is a marker for women who are at increased risk of ductal or lobular carcinoma in either breast.