Pleomorphic lobular carcinoma of the breast: is it a prognostically significant pathological subtype independent of histological grade?

The Challenges of Lobular Carcinomas from a Surgeon's Point of View

Invasive lobular breast cancer (ILC) presents unique challenges and considerations in the realm of surgical management. Characterized by its distinct histological features, including the loss of E-cadherin expression and dys-cohesive growth pattern, ILC often poses diagnostic and therapeutic dilemmas for clinicians. This abstract explores the surgical landscape of ILC, focusing on its epidemiology, clinical presentation, diagnostic modalities, and surgical interventions. Emphasizing the importance of individualized treatment strategies, this narrative delves into the nuances of surgical decision-making, including the role of breast-conserving surgery versus mastectomy, axillary staging, and the significance of margin status. Additionally, advancements in surgical techniques, such as oncoplastic approaches and sentinel lymph node biopsy, are examined in the context of optimizing oncologic outcomes and preserving cosmesis. Through a comprehensive review of current literature and clinical guidelines, this overview aims to provide a nuanced understanding of the surgical considerations inherent to the management of invasive lobular breast cancer.

Deciphering the Clinical Behaviour of Invasive Lobular Carcinoma of the Breast Defines an Aggressive Subtype

BACKGROUND

Invasive lobular carcinoma (ILC), the most common special type of breast cancer (BC), has unique clinical behaviour and is different from invasive ductal carcinoma of no special type (IDC-NST). However, ILC further comprises a diverse group of tumours with distinct features. This study aims to examine the clinicopathological and prognostic features of different variants of ILC, with a particular focus on characterising aggressive subtypes.

METHODS

A large (n = 7140) well-characterised and histologically reviewed BC cohort with treatment and long-term follow-up data was investigated. The cohort was classified based on the WHO classification of tumours into main histological subtypes, including ILC and IDC-NST. ILCs were further classified into variants. Clinicopathological parameters and patient outcomes in terms of BC-specific survival (BCSS) and disease-free survival (DFS) were evaluated.

RESULTS

ILC constituted 11% of the cohort. The most common non-classic ILC variants were pleomorphic (pILC) and solid (sILC), constituting 19% of ILC. Compared to classic and related variants (alveolar, trabecular, papillary, and tubulolobular; cILC), pILC and sILC variants were associated with aggressive tumour characteristics. The histologic grade of ILC was an important prognostic variable. The survival patterns identified an aggressive ILC subtype encompassing pILC and high-grade sILC. These tumours, which comprised 14% of the cases, were associated with clinicopathological characteristics of poor prognosis and had high BC-specific death and recurrence rates compared not only to cILC (p < 0.001) but also to IDC-NST (p = 0.02) patients. Contrasting this, cILC patients had significantly longer BCSS and DFS than IDC-NST patients in the first 10 to 15 years of follow-up. Adjuvant chemotherapy did not improve the outcome of patients with aggressive ILC subtypes.

CONCLUSIONS

pILC and high-grade sILC variants comprise an aggressive ILC subtype associated with poor prognostic characteristics and a poor response to chemotherapy. These results warrant confirmation in randomised clinical trials.

Comparison of Clinicopathological Features of Pleomorphic and Invasive Lobular Breast Carcinomas

PURPOSE

Accounting for about 15% of invasive lobular carcinomas and 1% of breast carcinomas, pleomorphic lobular carcinoma is known to be a rare histological subtype of invasive lobular carcinoma. Yet, it is more aggressive and produces a worse prognosis than other breast cancers. Ultimately, the present study compares the clinicopathological features of pleomorphic and invasive lobular breast carcinomas.

METHODS

In the study, we retrospectively evaluated the data of 262 patients with histological subtypes of classical and pleomorphic lobular cancers having been recruited for surgical operations. After resorting to Kolmogorov-Smirnov and Shapiro-Wilk tests to check the normality of distribution, the categorical and continuous variables were compared between the groups using the chi-square test and independent samples t test, respectively. In all analyses, we considered a P-value of <.05 to be statistically significant.

RESULTS

Our findings revealed that the groups with lobular and pleomorphic groups significantly differed by Ki-67 value, estrogen receptor negativity, grade, multicentricity, multifocality, surgical margin positivity, completion mastectomy, and metachronous contralateral tumor (P < .05).

CONCLUSION

We discovered that pleomorphic type was associated with higher grades, estrogen receptor negativity, and Ki-67 expression. The incidence of metachronous breast cancer was high in the pleomorphic group, which may be a noteworthy finding to be considered in follow-ups. In addition, the high rates of multicentricity and multifocality of tumors in the pleomorphic group may be associated with increased surgical margin positivity and a higher likelihood of mastectomy. In a nutshell, our findings may guide patients and surgeons regarding the type of intervention and reconstruction options to be adopted in prospective surgeries.

Lobular Carcinoma of the Breast: A Comprehensive Review with Translational Insights

The second most common breast carcinoma, invasive lobular carcinoma, accounts for approximately 15% of tumors of breast origin. Its incidence has increased in recent times due in part to hormone replacement therapy and improvement in diagnostic modalities. Although believed to arise from the same cell type as their ductal counterpart, invasive lobular carcinomas (ILCs) are a distinct entity with different regulating genetic pathways, characteristic histologies, and different biology. The features most unique to lobular carcinomas include loss of E-Cadherin leading to discohesion and formation of a characteristic single file pattern on histology. Because most of these tumors exhibit estrogen receptor positivity and Her2 neu negativity, endocrine therapy has predominated to treat these tumors. However novel treatments like CDK4/6 inhibitors have shown importance and antibody drug conjugates may be instrumental considering newer categories of Her 2 Low breast tumors. In this narrative review, we explore multiple pathological aspects and translational features of this unique entity. In addition, due to advancement in technologies like spatial transcriptomics and other hi-plex technologies, we have tried to enlist upon the characteristics of the tumor microenvironment and the latest associated findings to better understand the new prospective therapeutic options in the current era of personalized treatment.

Biomarker profile of invasive lobular carcinoma: pleomorphic versus classic subtypes, clinicopathological characteristics and prognosis analyses

PURPOSE

To compare the clinicopathologic features and prognosis of pleomorphic invasive lobular carcinoma (P-ILC) and classic ILC (C-ILC) according to the biomarker profile.

METHODS

A total of 667 C-ILCs and 133 P-ILCs between 2011 and 2021 were included. Clinicopathologic features and stromal tumor-infiltrating lymphocytes (sTILs) status were evaluated. P-ILCs were divided into subtypes based on ER/PR and HER2 expression. The overall survival and disease-free survival (DFS) of patients were compared among matched P-ILCs, C-ILCs, and invasive ductal carcinomas (IDCs) with biomarker subtypes.

RESULTS

Compared to C-ILCs, P-ILCs had greater tumor sizes and stages, fewer ER-positive, more HER2-positive, triple negative (TN), and Ki-67 > 20% tumors (P < 0.05). P-ILCs were subdivided into ER+ (63.1%), HER2+ (21.1%) and TN (15.8%). ER+ P-ILCs were mainly showed trabecular and solid growth patterns. Apocrine and solid features were more strongly associated with HER2+ P-ILCs and TN-P-ILCs, respectively. The prognosis of each biomarker group (ER+, HER2+ and TN) differed by subtype. The P-ILC biomarker subtypes had worse prognosis than the same subtypes in the IDC group, while there was no difference between the P-ILC and the C-ILC counterparts. Solid variants of P-ILC had the worst prognosis. Bone was the most common metastatic site in ER+ P-ILCs and TN-P-ILCs. HER2+ P-ILCs tended to metastasize to the brain and liver. DFS of HER2+ P-ILCs and TN-P-ILCs were worse than that of ER+ P-ILCs. Lacking lobular carcinoma in situ and sTILs ≤ 10% were associated with worse survival of ER+ P-ILCs and TN-P-ILCs, respectively. For HER2+ P-ILCs, Ki-67 > 20% and sTILs ≤ 10% were significant factors for lower DFS.

CONCLUSION

P-ILCs is an aggressive subtype of ILCs. Analyzing the prognostic factors of P-ILCs with heterogeneous morphological and biomarker characteristics is helpful for creating an individualized treatment.

The positive predictive value of vacuum assisted biopsy (VAB) in predicting final histological diagnosis for breast lesions of uncertain malignancy (B3 lesions): A systematic review & meta-analysis

INTRODUCTION

High-risk or B3 breast lesions are considered lesions of uncertain malignant potential and comprise between 5 and 12% of initial biopsy results. We sought to perform a systematic review and meta-analysis of studies published within the last twenty years to determine the pooled Positive Predictive Value (PPV) of VAB in selected B3 lesions.

METHODS

The study report is based on the guidelines of PRISMA and Meta-Analysis of Observational Studies in Epidemiology.

OUTCOMES

The primary outcome of this study was to determine the PPV of VAB in determining final histological diagnosis in B3 breast lesions using pooled estimates. The secondary outcomes were to determine if needle gauge or the re-classification of Lobular Carcinoma in Situ(LCIS) introduced in 2012 influenced pooled estimates.

RESULTS

78 studies incorporating 6,377 B3 lesions were included in this review, 1214 of which were upgraded to DCIS or invasive malignancy following surgical excision(19%). The pooled PPV of VAB in Atypical Ductal Hyperplasia(ADH) and Lobular Neoplasia(LN) were 0.79(CI 0.76-0.83) and 0.84(CI 0.8-0.88). VAB of Flat Epithelial Atypia(FEA), radial scar and papillary lesions with/without atypia all had a pooled PPV >90% (underestimation rates 7%, 1%, 5% and 3% respectively). Needle gauge size and the change in LCIS classification did not appear to influence underestimation rates on subgroup analysis.

CONCLUSION

Results from this meta-analysis suggests it is reasonable to perform VAB as definitive treatment for certain B3 lesions, specifically LN, FEA, radial scar, and papillary lesions when specific criteria are fulfilled. Surgical excision should continue as the mainstay of treatment for ADH.

Assessment of Digital Pathology Imaging Biomarkers Associated with Breast Cancer Histologic Grade

Background: Evaluating histologic grade for breast cancer diagnosis is standard and associated with prognostic outcomes. Current challenges include the time required for manual microscopic evaluation and interobserver variability. This study proposes a computer-aided diagnostic (CAD) pipeline for grading tumors using artificial intelligence. Methods: There were 138 patients included in this retrospective study. Breast core biopsy slides were prepared using standard laboratory techniques, digitized, and pre-processed for analysis. Deep convolutional neural networks (CNNs) were developed to identify the regions of interest containing malignant cells and to segment tumor nuclei. Imaging-based features associated with spatial parameters were extracted from the segmented regions of interest (ROIs). Clinical datasets and pathologic biomarkers (estrogen receptor, progesterone receptor, and human epidermal growth factor 2) were collected from all study subjects. Pathologic, clinical, and imaging-based features were input into machine learning (ML) models to classify histologic grade, and model performances were tested against ground-truth labels at the patient-level. Classification performances were evaluated using receiver-operating characteristic (ROC) analysis. Results: Multiparametric feature sets, containing both clinical and imaging-based features, demonstrated high classification performance. Using imaging-derived markers alone, the classification performance demonstrated an area under the curve (AUC) of 0.745, while modeling these features with other pathologic biomarkers yielded an AUC of 0.836. Conclusion: These results demonstrate an association between tumor nuclear spatial features and tumor grade. If further validated, these systems may be implemented into pathology CADs and can assist pathologists to expeditiously grade tumors at the time of diagnosis and to help guide clinical decisions.

Lobular Breast Cancer: Histomorphology and Different Concepts of a Special Spectrum of Tumors

Simple Summary

Invasive lobular breast cancer (ILC) is a special type of breast cancer (BC) that was first described in 1941. The diagnosis of ILC is made by microscopy of tumor specimens, which reveals a distinct morphology. This review recapitulates the developments in the microscopic assessment of ILC from 1941 until today. We discuss different concepts of ILC, provide an overview on ILC variants, and highlight advances which have contributed to a better understanding of ILC as a special histologic spectrum of tumors.

Abstract

Invasive lobular breast cancer (ILC) is the most common special histological type of breast cancer (BC). This review recapitulates developments in the histomorphologic assessment of ILC from its beginnings with the seminal work of Foote and Stewart, which was published in 1941, until today. We discuss different concepts of ILC and their implications. These concepts include (i) BC arising from mammary lobules, (ii) BC growing in dissociated cells and single files, and (iii) BC defined as a morpho-molecular spectrum of tumors with distinct histological and molecular characteristics related to impaired cell adhesion. This review also provides a comprehensive overview of ILC variants, their histomorphology, and differential diagnosis. Furthermore, this review highlights recent advances which have contributed to a better understanding of the histomorphology of ILC, such as the role of the basal lamina component laminin, the molecular specificities of triple-negative ILC, and E-cadherin to P-cadherin expression switching as the molecular determinant of tubular elements in CDH1-deficient ILC. Last but not least, we provide a detailed account of the tumor microenvironment in ILC, including tumor infiltrating lymphocyte (TIL) levels, which are comparatively low in ILC compared to other BCs, but correlate with clinical outcome. The distinct histomorphology of ILC clearly reflects a special tumor biology. In the clinic, special treatment strategies have been established for triple-negative, HER2-positive, and ER-positive BC. Treatment specialization for patients diagnosed with ILC is just in its beginnings. Accordingly, ILC deserves greater attention as a special tumor entity in BC diagnostics, patient care, and cancer research.

Comprehensive Review of Molecular Mechanisms and Clinical Features of Invasive Lobular Cancer

Invasive lobular carcinoma (ILC) accounts for 10% to 15% of breast cancers in the United States, 80% of which are estrogen receptor (ER)-positive, with an unusual metastatic pattern of spread to sites such as the serosa, meninges, and ovaries, among others. Lobular cancer presents significant challenges in detection and clinical management given its multifocality and multicentricity at presentation. Despite the unique features of ILC, it is often lumped with hormone receptor-positive invasive ductal cancers (IDC); consequently, ILC screening, treatment, and follow-up strategies are largely based on data from IDC. Despite both being treated as ER-positive breast cancer, querying the Cancer Genome Atlas database shows distinctive molecular aberrations in ILC compared with IDC, such as E-cadherin loss (66% vs. 3%), FOXA1 mutations (7% vs. 2%), and GATA3 mutations (5% vs. 20%). Moreover, compared with patients with IDC, patients with ILC are less likely to undergo breast-conserving surgery, with lower rates of complete response following therapy as these tumors are less chemosensitive. Taken together, this suggests that ILC is biologically distinct, which may influence tumorigenesis and therapeutic strategies. Long-term survival and clinical outcomes in patients with ILC are worse than in stage- and grade-matched patients with IDC; therefore, nuanced criteria are needed to better define treatment goals and protocols tailored to ILC's unique biology. This comprehensive review highlights the histologic and clinicopathologic features that distinguish ILC from IDC, with an in-depth discussion of ILC's molecular alterations and biomarkers, clinical trials and treatment strategies, and future targets for therapy. IMPLICATIONS FOR PRACTICE: The majority of invasive lobular breast cancers (ILCs) are hormone receptor (HR)-positive and low grade. Clinically, ILC is treated similar to HR-positive invasive ductal cancer (IDC). However, ILC differs distinctly from IDC in its clinicopathologic characteristics and molecular alterations. ILC also differs in response to systemic therapy, with studies showing ILC as less sensitive to chemotherapy. Patients with ILC have worse clinical outcomes with late recurrences. Despite these differences, clinical trials treat HR-positive breast cancers as a single disease, and there is an unmet need for studies addressing the unique challenges faced by patients diagnosed with ILC.

Invasive pleomorphic lobular carcinoma of the breast with multiple metastases: A case report

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Invasive Pleomorphic Lobular Carcinoma(IPLC) accounts for less than 1% of breast cancer.

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This paper reports a case of IPLC with multiple metastases and gives review literature.

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The patient’s general condition improved after our specific treatment options, which has a certain reference for the treatment of this kind of patients in the future.

Introduction and importance

IPLC (Invasive Pleomorphic Lobular Carcinoma) accounts for less than 1% of breast cancer. To the best of our knowledge, this is one of the few reported cases in the IPLC with multiple metastases. The patient's general condition got improved after our treatment, which has a certain reference for the treatment of this kind of patient in the future.

Case presentation

A 42-year-old female with IPLC and multiple metastases. The IPLC malignant cells were positive for p120 (cytoplasmic) and human epidermal growth factor receptor 2, negative for estrogen receptor, progesterone receptor, and E-cadherin. There were nodular enhancement foci in the liver, which are considered the metastatic lesions of the breast, and the liver function was abnormal. Multiple metastatic lesions of the vertebral body, appendage of the whole spine, and sternum. And C7, T1, and T9 vertebrae showed compression fractures.

Clinical discussion

IPLC has systemic metastasis which molecular typing by immunohistochemistry is HER-2 overexpression can choose chemotherapy combined with targeted therapy to prolong the survival time and improve the quality of life of patients. The patient was followed up.

Conclusions

This paper reports a case of IPLC with multiple metastases and gives review literature. Our treatment of the patient can be a reference for other clinicians.

Clinicopathological and Molecular Characteristics of Pleomorphic Invasive Lobular Carcinoma

Pleomorphic invasive lobular carcinoma (PILC) is a distinct morphological and biologically aggressive variant of invasive lobular carcinoma (ILC). We hypothesized that was due to de novo activation of PI3K/Akt/mTOR pathway in PILC resulting in higher proliferation rate and markers of cell cycle activation. We identified PILC and ILC tumors and tested for PI3K/Akt/mTOR pathway activation by immunohistochemistry (PTEN and pS6K1) and gene expression analysis (by Nanostring nCounter system). Proliferation index (Ki67) was elevated in 85% of PILCs compared to 20% of ILCs (p < 0.007). PTEN expression was high in all while pS6K1 was high in 8/9 PILCs compared to 3/9 ILCs (p < 0.007). Gene expression analysis shows that PILCs have overexpression of genes involved in cell cycle proliferation, cellular proliferation, DNA damage, and repair genes but no difference in PI3K/Akt/mTOR pathway genes. PILCs are a biologically distinct group of ILC, and clinicopathological characteristics suggest they would have a more clinically aggressive behavior. In addition, our results indicate that PI3k/Akt/mTOR pathway and cell cycle proliferation are activated in majority of these tumors. Further studies are needed to investigate these mechanisms as there are approved therapies available that may benefit PILCs.

Differential impact of prognostic parameters in hormone receptor-positive lobular breast cancer

BACKGROUND

Invasive lobular breast cancer (BC) is the second most common BC subtype. Prognostic parameters (tumor classification, lymph node status, histologic grade, Oncotype DX recurrence score [RS], progesterone receptor status, and Ki67 index) were retrospectively studied in a large, prospective clinical trial encompassing 2585 patients who had hormone receptor-positive early BC (the West German Study Group PlanB trial).

METHODS

BCs were centrally reviewed and classified as lobular (n = 353; 14%) or nonlobular (n = 2232; 86%). The median follow-up was 60 months. Five-year disease-free survival (DFS) estimates were obtained using the Kaplan-Meier method. Prognostic parameters were evaluated using Cox proportional hazard models.

RESULTS

Lobular BC was associated with higher tumor classification, higher lymph node status, lower histologic grade, lower Ki67 index, and low or intermediate RS. The prevalence of high RS (RS range, 26-100) was 3-fold lower in patients who had lobular BC compared with those who had nonlobular BC (8% vs 24%; P < .001). However, 5-year DFS estimates for lobular and nonlobular BC were similar (92.1% and 92.3%, respectively; P = .673). In multivariate analyses, prognostic parameters for DFS in lobular BC included grade 3 (hazard ratio, 5.06; 95% CI, 1.91-13.39) and a pathologic lymph node status (pN) of pN3 (hazard ratio, 12.16; 95% CI, 3.87-38.24), but not RS. By contrast, prognostic parameters in nonlobular BC included grade 3 (hazard ratio, 1.65; 95% CI, 1.11-2.44), pN3 (hazard ratio, 3.68; 95% CI, 1.60-8.46), and high RS (hazard ratio, 2.49; 95% CI, 1.69-3.68).

CONCLUSIONS

Lobular BC is associated with low and intermediate RS, although 5-year DFS is similar to that of nonlobular BC. The effect of the RS in lobular BC appears to be distinct from that in nonlobular BC. For risk assessment, the RS needs to be complemented by clinicopathologic parameters for therapy decision making.

Mitotic score and pleomorphic histology in invasive lobular carcinoma of the breast: impact on disease-free survival

PURPOSE

Pleomorphic invasive lobular carcinoma (ILC) has long been thought to have worse outcomes than classic ILC and is therefore often treated with chemotherapy. However, recent data question the utility of the pleomorphic designation, as the poor outcomes seen may be related to other associated high-risk features. Importantly, mitotic count may better define a subset of ILC with high risk of recurrence. We sought to determine the impact of pleomorphic histology versus mitotic count on disease-free survival (DFS) in pure ILC. Additionally, we evaluated whether pleomorphic histology was associated with receipt of chemotherapy when adjusting for other factors.

METHODS

We analyzed a cohort of 475 patients with stage I-III pure ILC. We used Kaplan-Meier estimates, and Cox proportional hazards and logistic regression for multivariate analyses. Pleomorphic histology was confirmed by central pathology review.

RESULTS

In a multivariate model, pleomorphic histology was not associated with reduced DFS. Only mitotic score, receptor subtype, and pathologic stage were independently and significantly associated with DFS. Patients with pleomorphic ILC were significantly more likely to receive chemotherapy than patients with classic ILC (adjusted odds ratio 2.96, p = 0.026).

CONCLUSIONS

The pleomorphic designation in ILC does not have clinical utility and should not be used to determine therapy. Rather, mitotic count identified clear prognostic groups in this cohort of pure ILC.

Invasive Lobular Carcinoma With Extensive Clear Cells: A Pitfall in Diagnosis

Carcinomas in the breast with a predominantly clear cytoplasm are rare. In this article, we review the differential diagnosis of clear cell breast neoplasms and report a case of invasive lobular carcinoma with extensive clear cell morphology that was diagnosed as invasive ductal carcinoma, not otherwise specified, on ultrasound-guided biopsy. Lobular carcinomas with extensive clear cell change are unusual, but must be considered when evaluating a clear cell neoplasm in the breast.

Lobular neoplasia and invasive lobular breast cancer: Inter-observer agreement for histological grading and subclassification

Lobular neoplasia (LN), invasive lobular breast cancer (ILBC) and related pleomorphic variants represent a distinct group of neoplastic mammary gland lesions. This study assessed the inter-observer agreement of histological grading in a series of ILBC and LN. 54 cases (36x ILBC, 18x LN) were evaluated by 17 observers. 3978 classification calls on various histological features, including nuclear grade, proliferative activity (Ki67 immunohistochemistry, categorical scoring), histological grade and pleomorphism were obtained. Pairwise Cohen's kappa values were calculated and compared between various features and different observer subsets with variable histomorphological experience. In ILBC, pairwise inter-observer agreement for histological grade ranged from poor to almost perfect concordance and was higher in advanced and experienced histopathologists compared with beginners (P < 0.001). Agreement for proliferation (Ki67) ranged from slight to almost perfect concordance and was also higher in advanced and experienced histopathologists (P < 0.001). Considering different features, agreement for proliferation (Ki67) was superior to agreement for histological grade and nuclear grade, even among advanced and experienced histopathologists (P < 0.001). In LN, agreement for B-classification ranged from poor to almost perfect concordance and was higher in advanced and experienced histopathologists (P < 0.001). Considering different features, agreement for proliferation (Ki67 in LN) was superior to subclassification agreement based on conventional features, such as acinar distention and nuclear grade (P < 0.001). In summary, pairwise inter-observer concordance of histological grading of ILBC and LN is dependent on histomorphological experience. Assessment of proliferation by Ki67 immunohistochemistry is associated with favorable inter-observer agreement and can improve histological grading of ILBC as well as LN.

Scandenolone from Cudrania tricuspidata fruit extract suppresses the viability of breast cancer cells (MCF-7) in vitro and in vivo

Scandenolone, an isoflavone, has shown anti-cancer potential. In this study, we extracted scandenolone from Cudrania tricuspidata fruit and evaluated its anti-breast cancer effects as well as toxicity in cell and animal models. In cell model, scandenolone suppressed the breast cancer MCF-7 cells viability, ceased mitotic cell cycle, decreased mitochondrial membrane potential, up-regulated cleaved caspase-3 and promoted the phosphorylation of p53. Additionally, this isoflavone promoted cell apoptosis and induced a sustained activation of the phosphorylation of p38 and ERK, but not JNK and Akt. The effects were further verified in a human MCF-7 breast cancer xenograft model, where scandenolone efficiently suppressed the cancer growth and increased apoptotic cells in tumor tissue. However scandenolone has also shown certain toxicity to normal hepatocytes and breast epithelial cells. It could be concluded that scandenolone suppressed the growth of breast cancer cells, but its toxicity towards normal cells might limit its potential clinical use.

Long-Term Survival Differences Between T1-2 Invasive Lobular Breast Cancer and Corresponding Ductal Carcinoma After Breast-Conserving Surgery: A Propensity-Scored Matched Longitudinal Cohort Study

BACKGROUND

The role of histology subtype on the prognosis of T1-2 breast cancer patients receiving breast-conserving surgery (BCS) is not clear.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) Program was used to compare overall survival, second primary cancer-free survival (CFS), and local recurrence risk (LR) for patients with invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC), both receiving BCS.

RESULTS

The study enrolled 196,688 patients with T1-2 disease receiving BCS, including 12,906 with ILC and 183,782 with IDC. Patients with IDC showed higher unadjusted annual rates of BCS than ILC. Five- and 10-year estimated survival rates were, respectively, 92.06% and 86.14% in ILC, compared to 90.50% and 85.26% in IDC (P = .12). In multivariable Cox regression, ILC patients showed advantage over IDC in overall survival (hazard ratio [HR] = 0.93, P = .001), whereas no significant differences in CFS (HR = 1.03, P = .33) and LR (HR = 1.17, P = .06) were found, which were consistent with results from matched cohort. In subgroup analyses, patients with grade III ILC had poorer CFS (HR = 1.23, P = .009) and higher LR (HR = 1.59, P = .01) than IDC.

CONCLUSION

Histologic type is of prognostic importance in T1-2 patients receiving BCS, and surgeons should be cautious in performing BCS for individuals with grade III ILC.

Evaluating agreement, histological features, and relevance of separating pleomorphic and florid lobular carcinoma in situ subtypes

Morphological variants of lobular carcinoma in situ (LCIS) include classical (CLCIS), pleomorphic (PLCIS) and florid type (FLCIS). Treatment guidelines suggest managing PLCIS and FLCIS like ductal carcinoma in situ (DCIS); therefore accurate identification of LCIS subtypes is critical. However, the significance of separating PLCIS from FLCIS is not clear. Also, interobserver agreement in identifying LCIS subtypes, using contemporary criteria, is not known. We aimed to evaluate interobserver agreement amongst breast pathologists in diagnosing LCIS subtypes and use the agreement data to justify LCIS classification for management purposes. Six breast pathologists independently reviewed 50 hematoxylin and eosin-stained slides comprised of a mix of LCIS subtypes. After reviewing published criteria, participants diagnosed PLCIS, CLCIS and apocrine change in a marked region of interest and FLCIS based on entire section. PLCIS was identified in 8 to 37 slides with overall moderate agreement (Fleiss' κ = 0.565) and pairwise κ (Cohen's) ranging from -.008 to 0.492. FLCIS was diagnosed in 15-26 slides with overall substantial agreement (Fleiss' κ = 0.687) and pairwise κ ranging from -.068 to 0.706. Both FLCIS and PLCIS coexisted in 45% of slides with consensus on non-classical LCIS. Comedo-type necrosis (odds ratio = 5.5) and apoptosis (odds ratio = 1.8) predicted FLCIS. We found moderate and substantial agreement in diagnosing PLCIS and FLCIS respectively. Objective histological features linked with aggressive behavior were more frequent with FLCIS. PLCIS and FLCIS patterns frequently coexist, contain similar molecular aberrations, and are managed similarly (like DCIS); therefore, combining FLCIS and PLCIS into one category (non-classical LCIS) should be considered.

Associations between genomic stratification of breast cancer and centrally reviewed tumour pathology in the METABRIC cohort

The integration of genomic and transcriptomic profiles of 2000 breast tumours from the METABRIC [Molecular Taxonomy of Breast Cancer International Consortium] cohort revealed ten subtypes, termed integrative clusters (IntClust/s), characterised by distinct genomic drivers. Central histopathology (N = 1643) review was undertaken to explore the relationship between these ten molecular subtypes and traditional clinicopathological features. IntClust subtypes were significantly associated with histological type, tumour grade, receptor status, and lymphocytic infiltration (p < 0.0001). Lymph node status and Nottingham Prognostic Index [NPI] categories were also significantly associated with IntClust subtype. IntClust 3 was enriched for tubular and lobular carcinomas, the latter largely accounting for the association with CDH1 mutations in this cluster. Mucinous carcinomas were not present in IntClusts 5 or 10, but did not show an association with any of the remaining IntClusts. In contrast, medullary-like cancers were associated with IntClust 10 (15/26). Hormone receptor-positive tumours were scattered across all IntClusts. IntClust 5 was dominated by HER2 positivity (127/151), including both hormone receptor-positive (60/72) and hormone receptor-negative tumours (67/77). Triple-negative tumours comprised the majority of IntClust 10 (132/159) and around a quarter of IntClust 4 (52/217). Whilst the ten IntClust subtypes of breast cancer show characteristic patterns of association with traditional clinicopathological variables, no IntClust can be adequately identified by these variables alone. Hence, the addition of genomic stratification has the potential to enhance the biological relevance of the current clinical evaluation and facilitate genome-guided therapeutic strategies.

A nationwide registry-based cohort study of the MammaPrint genomic risk classifier in invasive breast cancer

AIM

To evaluate the use of the MammaPrint assay, a 70-gene risk signature for early breast cancers, and to correlate genomic risk stratification with individual clinicopathological parameters and clinical risk as assessed by Adjuvant! Online.

METHODS

A Dutch Pathology Registry (PALGA)-based cohort study consisting of 1916 patients for which 1946 MammaPrint assay results were synoptically reported from 2013 to 2016. We could retrospectively assess clinical risk for 1146 tumors (58.9%) using Adjuvant! Online (version 8.0 with HER2 status) and for 1155 tumors (59.4%) using PREDICT (version 2.0).

RESULTS

Adjuvant! Online classified 718 tumors (62.7%) as clinical low risk and 428 tumors (37.3%) as clinical high risk. MammaPrint classified 1206 tumors (62.0%) as genomic low risk and 740 tumors (38.0%) as genomic high risk. Genomic risk stratification was significantly associated with histological subtype and grade (P < .001), hormonal receptor status (P < .001), presence of lymphovascular invasion (P = .001) and nodal status (P = .002), whereas no association was found with tumor size (P = .541). MammaPrint classified 52.6% of clinical high risk tumors (N = 428) as genomic low risk. This percentage was highest (67.3%) in clinical high risk ER-positive/HER2-negative grade 1-2 tumors (N = 282). Correlation between predicted overall survival benefit from adjuvant chemotherapy (PREDICT V2.0) and genomic risk distribution was almost linear.

CONCLUSIONS

This study showed that MammaPrint classified 52.6% of clinical high risk tumors as genomic low risk. In the Netherlands, 62.7% of the MammaPrint assays from 2013 to 2016 were performed on clinical low risk tumors, although recent International Guidelines recommend its use in clinical high and intermediate risk tumors.

Clinicopathological characteristics and survival outcomes in pleomorphic lobular breast carcinoma of the breast: a SEER population-based study

The purpose of this study was to explore the clinicopathological features and survival outcome of pleomorphic lobular carcinoma (PLC) of breast, we identified 131 PLC patients and 460,109 invasive ductal carcinoma (IDC) patients in the Surveillance, Epidemiology, and End Result (SEER) database. PLCs presented with increased lymph node involvement, older age, higher AJCC stage and grade, and lower median survival months (PLC 84 ± 51.03 vs. IDC 105.2 ± 64.39 P < 0.01). Compared to IDC patients, PLC patients were more inclined to be treated with mastectomy. In univariate analysis, PLC patients showed a worse disease-specific survival (DSS) than that of IDC patients (hazard ratio = 0.691, 95% confidence interval 0.534-0.893, P < 0.01). In multivariate analysis, we took into account other prognostic factors and found that the histology types were no longer an independent prognostic factor (P = 0.120). DSS have no difference between matched IDC and PLC groups (P = 0.615). This result may be due to PLCs presenting higher tumor stage, higher tumor grade, and higher rate of LN metastasis than IDCs. Our conclusion is that PLC and IDC have many different characteristics, but there is not enough difference on the DSS.

Transcriptomic and genomic features of invasive lobular breast cancer

Accounting for 10-15% of all breast neoplasms, invasive lobular breast cancer (ILC) is the second most common histological subtype of breast cancer after invasive ductal breast cancer (IDC). Understanding ILC biology, which differs from IDC in terms of clinical presentation, treatment response, relapse timing and patterns, is essential in order to adopt novel, disease-specific management strategies. While the contribution of the histological subtypes to tumour biology has been poorly investigated and acknowledged in the past, recently several major, independent efforts have led to the assembly and molecular characterization of well-annotated ILC case sets. In this review, we provide a critical overview of the literature exploring ILC, through comprehensive and multiomic methods. The first part specifically focuses on ILC transcriptomic features by reviewing the intrinsic molecular subtypes, the application of gene expression scores for the prediction of recurrence, and the identification of gene expression subtypes. The second part describes the main research efforts that lead to the identification of the genomic landscape of ILC, with a special focus to findings that differentiate ILC from IDC and carry potential clinical relevance.

Invasive Pleomorphic Lobular Histology is an Adverse Prognostic Factor on Survival in Patients with Breast Cancer

Invasive pleomorphic lobular carcinoma (IPLC) is defined to be an uncommon and different subtype of classical invasive lobular carcinoma (ILC). This special variant is characterized by significant cytological atypia and pleomorphism which differs from the cytological uniformity of ILC. IPLC has been shown to have some poor prognostic factors such as axillary node metastasis and higher histological grade which may lead to poor clinical courses including a short relapse time, increased risk of recurrence and a decreased survival. The aim of this study is to investigate the clinicopathological characteristics and prognosis of IPLC in comparison with ILC and also to evaluate if IPLC is a different clinical entity compared to ILC. A total number of 4418 breast cancer patients treated between 1996 and 2015 in Hacettepe University Cancer Institute, were retrospectively analyzed. Among 4418 patients, 210 were diagnosed with ILC and 23 patients diagnosed with pure IPLC. In this present study, clinicopathological characteristics, disease free survival (DFS) and overall survival (OS) of patients with ILC and IPLC were compared. This study design is one of the rare face to face comparison of pure IPLC and ILC. Patients with IPLC had an increased rate of higher histologic grade, extracapsular extension, lymphovascular invasion and lower percentage of hormone positivity than those of patients with ILC. During the follow-up time, IPLC group experienced 4 cases (17.3%) of recurrence, 5 cases (21.7%) of death and 2 cases (8.7%) of progression in 3 metastatic patients compared to that of 27 cases (12.9%) of recurrence, 29 cases (13,8%) of death and 14 cases (6.7%) of progression in 19 metastatic patients in the ILC group. Patients with IPLC had a worse DFS and OS duration than patients with ILC (P = 0.02 for OS, P = 0.04 for DFS). In conclusion, IPLC is a different and a special breast cancer subtype. This study suggests that IPLC is a distinct clinical entity with an advanced stage and more aggressive clinical course. Patients with IPLC reveal poorer prognostic factors such as higher histological grade, relative lower percentages of hormone positivity, and increased rate of recurrences resulting in poor clinical outcomes and worse survival. Nowadays, it is observed that current treatment methods for IPLC do not seem as successful as in ILC and failed to be effective. Thence, individual therapies including more aggressive surgery and adjuvant or neoadjuvant chemotherapy even in the earlier stages of breast cancer should be performed for this distinct variant.

Pleomorphic lobular carcinoma of the breast: a comparison of cytopathological features with other lobular carcinoma variants

OBJECTIVE

Pleomorphic lobular carcinoma (PLC) is a subtype of breast cancer with unique morphological features, but it remains controversial whether PLC should be considered an independent disease entity. The aim of this study was to illustrate cytopathological characteristics of PLC in comparison with other lobular carcinoma variants.

METHODS

We investigated clinicopathological features of PLC (n = 11) compared with those of other variants of invasive lobular carcinoma (ILC, non-PLC) (n = 32). Histological variants of the non-PLC group consisted of classic (n = 25), solid (n = 2), alveolar (n = 1) and a tubulolobular type (n = 4). A review of cytological reports and fine needle aspiration (FNA) smear samples was performed for the PLC (n = 9) and non-PLC (n = 27) groups.

RESULTS

Patients with PLC were older, and had a higher nuclear grade and a higher incidence of axillary lymph node metastasis and triple negative phenotype than non-PLC patients (P = 0.007, P < 0.001, P = 0.02 and P < 0.001, respectively). Cytological findings in PLC included medium- to large-sized nuclei, prominent nucleoli, a moderate-to-severe degree of pleomorphism, apocrine change and background necrosis, none of which were evident in the smears of the non-PLC group (P < 0.001, P = 0.002, P < 0.001, P < 0.001, and P = 0.03, respectively). Despite these differences, patients with PLC and non-PLC showed similar clinical outcomes in our follow-up period.

CONCLUSIONS

Based on our results, a cytological diagnosis of PLC should be proposed if there are moderate- to large-sized nuclei, prominent nucleoli, a moderate-to severe degree of nuclear pleomorphism, apocrine change and necrosis in the background in FNA biopsy samples.

Invasive Pleomorphic Lobular Carcinoma of the Breast: Pathologic, Clinical, and Therapeutic Considerations

Pleomorphic lobular carcinoma is an uncommon form of breast cancer and a subtype of invasive lobular carcinoma. It has unique histopathologic features that translate to a more aggressive phenotype with an associated poor prognosis. Unlike classical invasive lobular carcinoma, it can lose estrogen and progesterone receptor expression and demonstrate HER-2/neu amplification. It remains to be determined, however, whether the pleomorphic histology independently predicts a worse outcome or whether other known associated negative prognostic factors such as larger tumor size, increased metastatic disease, and associated worse molecular subtypes commonly present in pleomorphic carcinoma account for the poor prognosis. Here we present an updated review of the unique pathologic and clinical features of pleomorphic lobular carcinoma needed to guide management for women with this subtype of cancer.

Invasive lobular carcinoma of the breast: morphology, biomarkers and 'omics

Invasive lobular carcinoma of the breast is the most common 'special' morphological subtype of breast cancer, comprising up to 15% of all cases. Tumours are generally of a good prognostic phenotype, being low histological grade and low mitotic index, hormone receptor positive and HER2, p53 and basal marker negative, and with a generally good response to endocrine therapy. Despite this, clinicians face countless challenges in the diagnosis and long-term management of patients, as they encounter a tumour that can be difficult to detect through screening, elicits a very invasive nature, a propensity for widespread metastatic colonisation and, consequently, in some studies a worse long-term poor outcome compared with invasive carcinoma of no special type. Here we review the morphological and molecular features that underpin the disparate biological and clinical characteristics of this fascinating tumour type.

Invasive lobular breast cancer and its variants: how special are they for systemic therapy decisions?

The WHO classification of breast tumors distinguishes, besides invasive breast cancer 'of no special type' (former invasive ductal carcinoma, representing 60-70% of all breast cancers), 30 special types, of which invasive lobular carcinoma (ILC) is the most common (5-15%). We review the literature on (i) the specificity and heterogeneity of ILC biology as documented by various analytical techniques, including the results of molecular testing for risk of recurrence; (ii) the impact of lobular histology on prediction of prognosis and effect of systemic therapies in patients. Though it is generally admitted that ILC has a better prognosis than IDC, is endocrine responsive, and responds poorly to chemotherapy, currently available data do not unanimously support these assumptions. This review demonstrates some lack of specific data and a need for improving clinical research design to allow oncologists to make informed systemic therapy decisions in patients with ILC. Importantly, future studies should compare various endpoints in ILC breast cancer patients among the group of hormonosensitive breast cancer.

Molecular classification of breast cancer

Breast cancer is a complex, multifaceted disease encompassing a great variety of entities that show considerable variation in clinical, morphological and molecular attributes. Traditional classifications including histological assessment and clinical staging are used to guide patient management. In recent years, there has been exponential progress in molecular analysis with profound implications for our understanding of breast cancer biology and, hence, classification. There are now genome-based frameworks for the molecular categorisation of breast cancer including the development of prognostic and predictive signatures that potentially allow individualisation of treatment. Here we review the current state of the molecular classifications of in situ and invasive breast cancer including special subtypes. Future perspectives are also provided.