A comprehensive overview of metaplastic breast cancer: clinical features and molecular aberrations

Curative Approaches for Metaplastic Breast Cancer: A Retrospective Cohort Outcome Review

PURPOSE

Metaplastic breast cancer (MBC) is a rare and heterogeneous breast cancer subtype, and there are critical gaps in our understanding of its long-term outcomes. This retrospective cohort study aimed to address these gaps by scrutinizing the pathologic and clinical aspects of MBC to enhance clinical decision-making and refine patient care strategies.

METHODS AND MATERIALS

This registry-based retrospective cohort study included women aged ≥21 years diagnosed with MBC or matrix-producing carcinoma. The data were obtained from January 2001 to August 2020 from the Joint Breast Cancer Registry of Singapore Health Services, which included 23,935 patients. Demographic and clinicopathologic characteristics, neoadjuvant chemotherapy responses, and survival outcomes were analyzed. Statistical assessments involved univariate and multivariate Cox proportional hazards models and Kaplan-Meier survival analyses.

RESULTS

This study enrolled 170 patients; 87.1% had non-metastatic disease, and 12.9% had metastatic disease. The age of patients at diagnosis ranged from 46 to 65 years (median, 56 years). The cohort's predominant characteristics were triple negative breast cancer (64%), advanced clinical stage (77.6%), node negativity (67.6%), and grade 3 disease (74.1%). In patients receiving neoadjuvant chemotherapy with curative intent treatment (17.6%), neoadjuvant chemotherapy yielded a pathologic complete response of 19.2% and a disease progression rate of 46.2%. Multivariate analysis showed that adjuvant radiation therapy significantly improved overall survival and disease-free survival, with hazard ratios of 0.29 (95% CI, 0.13-0.62; P < .005) and 0.23 (95% CI, 0.10-0.50; P < .005), respectively. Clinical T3 and T4 stages and nodal involvement were associated with poor outcomes. Stable disease after neoadjuvant chemotherapy was associated with poor overall survival and disease-free survival.

CONCLUSIONS

This study sheds light on the complex landscape of MBC and emphasizes the pivotal role of adjuvant radiation therapy in enhancing patient outcomes. Despite advancements, challenges persist that warrant continued research to refine neoadjuvant chemotherapy strategies and delve into the nuanced factors that influence treatment responses.

Comparative Evaluation of Machine Learning Models for Subtyping Triple-Negative Breast Cancer: A Deep Learning-Based Multi-Omics Data Integration Approach

Objective: Triple-negative breast cancer (TNBC) poses significant diagnostic challenges due to its aggressive nature. This research develops an innovative deep learning (DL) model based on the latest multi-omics data to enhance the accuracy of TNBC subtype and prognosis prediction. The study focuses on addressing the constraints of prior studies by showcasing a model with substantial advancements in data integration, statistical performance, and algorithmic optimization. Methods: Breast cancer-related molecular characteristic data, including mRNA, miRNA, gene mutations, DNA methylation, and magnetic resonance imaging (MRI) images, were retrieved from the TCGA and TCIA databases. This study not only compared single-omics with multi-omics machine learning models but also applied Bayesian optimization to innovatively optimize the neural network structure of a DL model for multi-omics data. Results: The DL model for multi-omics data significantly outperformed single-omics models in subtype prediction, achieving a 98.0% accuracy in cross-validation, 97.0% in the validation set, and 91.0% in an external test set. Additionally, the MRI radiomics model showed promising performance, especially with the training set; however, a decrease in performance during transfer testing underscored the advantages of the DL model for multi-omics data in data consistency and digital processing. Conclusion: Our multi-omics DL model presents notable innovations in statistical performance and transfer learning capability, bearing significant clinical relevance for TNBC classification and prognosis prediction. While the MRI radiomics model proved effective, it requires further optimization for cross-dataset application to enhance accuracy and consistency. Our findings offer new insights into improving TNBC classification and prognosis through multi-omics data and DL algorithms.

Breast conservation versus mastectomy for metaplastic breast cancer: A systematic review and meta-analysis

Metaplastic breast cancer is a rare aggressive subtype of breast cancer for which there are no clear treatment guidelines regarding the optimal surgical approach. This systematic review and meta-analysis aimed to evaluate survival outcomes of patients with metaplastic breast cancer undergoing breast conservation compared with mastectomy. We identified studies from MEDLINE, Pubmed, EMBASE, Google Scholar, the Cochrane Library Register of Controlled Trials and the EBM Reviews Register. Studies were deemed suitable for inclusion where they compared breast-conserving surgery to mastectomy with the primary outcome of overall survival. Survival data were pooled using a random-effects model. From the 456 citations screened by our search, three studies were assessed as eligible for inclusion. There were a total of 2995 patients who underwent mastectomy and 1909 who underwent breast conservation. The median follow-up time was 43 months. Meta-analysis demonstrated no significant difference between breast conservation and mastectomy (pooled HR 0.89, 95% CI, 0.56-1.42, p = 0.631). Wide local excision, in conjunction with adjuvant radiation and judicious use of chemotherapy, may be a reasonable alternative to mastectomy as surgical management of metaplastic breast cancer as part of an individualized, multidisciplinary approach.

Therapeutic vulnerabilities in triple negative breast cancer: Stem-like traits explored within molecular classification

Triple Negative Breast Cancer (TNBC) is the most aggressive type of breast cancer (BC). Despite advances in the clinical management of TNBC, recurrence-related mortality remains a challenge. The stem-like phenotype of TNBC plays a significant role in the persistence of minimal disease residue after therapy. Individuals exhibiting stem-like characteristics are particularly prone to inducing malignant relapse accompanied by strong resistance. Therefore, stem-like traits have been broadly proposed as therapeutic vulnerabilities to treat TNBC and reduce recurrence. However, heterogeneity within TNBC often generally restricts the stability of the therapeutic efficacy. To understand the heterogeneity and manage TNBC more precisely, multiple TNBC subtyping categories have been reported, providing the basis for profile-according therapeutic regimens. To provide more insight into targeting stem-like traits to ablate TNBC and reduce recurrence in the context of heterogeneity, this paper reviewed the molecular subtyping of TNBC, identified the consensus subtypes with distinct stem-like phenotypes, characterized the stemness hierarchy of TNBC, outlined the biological models for stem-like TNBC subtypes, summarized the therapeutic vulnerabilities in stem-like traits of the subtypes, and proposed potential therapeutic regimens targeting stem-like characteristics to improve TNBC prognosis.

High tumor infiltrating lymphocytes are significantly associated with pathological complete response in triple negative breast cancer treated with neoadjuvant KEYNOTE-522 chemoimmunotherapy

INTRODUCTION

For patients with locally advanced triple negative breast cancer (TNBC), the standard of care is to administer the KEYNOTE-522 (K522) regimen, including chemotherapy and immunotherapy (pembrolizumab) given in the neoadjuvant setting. Pathological complete response (pCR) is more likely in patients who receive the K522 regimen than in patients who receive standard chemotherapy. Studies have shown that pCR is a strong predictor of long-term disease-free survival. However, factors predicting pCR to K522 are not well understood and require further study in real-world populations.

METHODS

We evaluated 76 patients who were treated with the K522 regimen at our institution. Twenty-nine pre-treatment biopsy slides were available for pathology review. Nuclear grade, Nottingham histologic grade, Ki-67, lymphovascular invasion, and tumor infiltrating lymphocytes (TIL) were evaluated in these 29 cases. For the cases that did not have available slides for review from pre-treatment biopsies, these variables were retrieved from available pathology reports. In addition, clinical staging, race, and BMI at the time of biopsy were retrieved from all 76 patients' charts. Binary logistic regression models were used to correlate these variables with pCR.

RESULTS

At the current time, 64 of 76 patients have undergone surgery at our institution following completion of K522 and 31 (48.4%) of these achieved pCR. In univariate analysis, only TIL was significantly associated with pCR (p = 0.014) and this finding was also confirmed in multivariate analysis, whereas other variables including age, race, nuclear grade, Nottingham grade, Ki-67, lymphovascular invasion, BMI, pre-treatment tumor size, and lymph node status were not associated with pCR (p > 0.1).

CONCLUSION

Our real-world data demonstrates high TIL is significantly associated with pCR rate in the K522 regimen and may potentially serve as a biomarker to select optimal treatment. The pCR rate of 48.4% in our study is lower than that reported in K522, potentially due to the smaller size of our study; however, this may also indicate differences between real-world data and clinical trial results. Larger studies are warranted to further investigate the role of immune cells in TNBC response to K522 and other treatment regimens.

Carcinosarcoma of breast - A chimera among breast neoplasms

Malignant phyllodes, along with ductal carcinoma, is known as metaplastic cancer of the breast. This tumor is additionally known as breast carcinosarcoma. Malignant phyllodes in conjunction with ductal carcinoma is a rare finding in routine clinical practice. We describe the case report of a 47-year-old female patient who arrived with a large right breast mass. A core biopsy was performed, and histopathological examination indicated that the tumor was a malignant phyllodes tumor. A positron emission tomography (PET) scan revealed hyper-metabolic and hypo-metabolic tumors with perilesional stranding and satellite nodularity. There were a few metastatic right axillary nodes visible. There was no indication of distant metastases. Due to the presence of both components, a modified radical mastectomy surgery with axillary dissection was undertaken for this patient. Histopathological analysis of paraffin sections revealed ductal carcinoma in situ (DCIS) comedo-epithelial component and spindle-shaped cells with hyper-chromatic oval nuclei and scanty cytoplasm.

Clinical analysis of metaplastic breast carcinoma with distant metastases: A multi‑centre experience

Metaplastic breast cancer (BC-Mp), which includes a range of epithelial and mixed epithelial-mesenchymal tumours, are rare malignancies with an unfavourable prognosis. The limited literature on BC-Mp focuses mainly on retrospective data for radically treated patients. Notably absent are studies dedicated to the palliative treatment of BC-Mp with distant metastases. The present retrospective study investigated treatment modalities and prognosis in a multi-centre cohort of 31 female participants diagnosed with distant metastatic BC-Mp, including 7 patients with de novo metastatic disease. The median age of the patients was 61 years (range, 33-87 years), with 38.7% presenting local lymph node involvement. Lungs were the most common site for the metastatic disease (61.3%). Median Ki-67 index was 50% (range, 35-70%), and 80.7% of cases were classified as grade 3. Human epidermal growth factor receptor 2 (HER2)+ and estrogen receptor+ were detected in 12.9 and 6.5% of cases, respectively. A total of 62.4% of patients received first-line palliative systemic treatment. The 1- and 2-year overall survival (OS) were 38.5 and 19.2%, respectively. Receiving ≥1 line of palliative treatment was significantly associated with improved OS (P<0.001). Factors such as age, Ki-67 index, HER2 or hormonal status, presence of specific epithelial or mesenchymal components, location of metastases or chemotherapy regimen type did not influence OS. The present study provided insights into the clinicopathological profile, systemic treatment experience, prognostic factors and OS data of BC-Mp with distant metastases, emphasizing the imperative for clinical trials in this population.

Significance of Estrogen/Progesterone Receptor Expression in Metaplastic Breast Carcinoma

Introduction

Metaplastic breast carcinoma (MBC) is a rare subgroup of breast neoplasms associated with adverse outcomes because of its aggressive nature. Typically, MBCs show triple-negative hormone receptor (HR) status. Determining the HR status of breast cancer is an integral part because it is an important prognostic factor and helps in the treatment course of the disease. This study aimed to determine the HR status of MBC, its significance, and its association with various clinicopathological parameters.

Methods

This was a retrospective study conducted at the Department of Histopathology, Liaquat National Hospital. A total of 140 biopsy-proven cases of MBC were enrolled in the study. Clinical and pathological data were retrieved from the institutes' archives. Immunohistochemical studies were conducted to determine the estrogen receptor (ER) and progesterone receptor (PR) status.

Results

The mean age of MBC in our population was found to be 52.18 ± 12.19 years. The HR positivity rate in our population was found to be 32.9%. A significant association was found between HR status and tumor laterality, tumor size, tumor grade, tumor stage, and recurrence. ER/PR-negative MBCs were most probably associated with higher grade and higher tumor stage and were larger in size (6.62 ± 3.43 cm) than ER/PR-positive MBCs (4.20 ± 1.88 cm). Moreover, ER/PR-positive MBCs showed a higher recurrence rate than ER/PR-negative MBCs (43.5% vs. 25.5%, respectively). No statistically significant relationship was found between HR status and patient age, histological subtype, or survival rate.

Conclusion

MBC is a rare breast neoplasm. MBC was found to be triple negative in most cases, but a significant percentage were HR (ER/PR) positive. Moreover, we found an association between HR status and various clinicopathological features, indicating that HR status is a significant predictor of MBC prognosis.

Bilateral metaplastic squamous cell breast cancer

ABSTRACT

Metaplastic breast cancer is a rare and heterogeneous breast cancer group that encompasses both malign epithelial and mesenchymal tissue components. Squamous cell breast cancer (SCC) is one of the types of metaplastic breast cancer, and diagnosis is established when more than 90% of the malignant cells are of squamous cell origin. Squamous cell metaplastic breast carcinoma is considered an aggressive tumor because of the risk of distant metastases, and there are limited data on treatment patterns. In this study, we report patient characteristics and treatment results of one patient with bilateral metaplastic squamous cell breast cancer.

Starfysh integrates spatial transcriptomic and histologic data to reveal heterogeneous tumor-immune hubs

Spatially resolved gene expression profiling provides insight into tissue organization and cell-cell crosstalk; however, sequencing-based spatial transcriptomics (ST) lacks single-cell resolution. Current ST analysis methods require single-cell RNA sequencing data as a reference for rigorous interpretation of cell states, mostly do not use associated histology images and are not capable of inferring shared neighborhoods across multiple tissues. Here we present Starfysh, a computational toolbox using a deep generative model that incorporates archetypal analysis and any known cell type markers to characterize known or new tissue-specific cell states without a single-cell reference. Starfysh improves the characterization of spatial dynamics in complex tissues using histology images and enables the comparison of niches as spatial hubs across tissues. Integrative analysis of primary estrogen receptor (ER)-positive breast cancer, triple-negative breast cancer (TNBC) and metaplastic breast cancer (MBC) tissues led to the identification of spatial hubs with patient- and disease-specific cell type compositions and revealed metabolic reprogramming shaping immunosuppressive hubs in aggressive MBC.

A Rare and Intriguing Case Report of Metaplastic Breast Carcinoma

Metaplastic breast carcinoma (MBC) is a rare and aggressive subtype of breast cancer characterized by the presence of both epithelial and mesenchymal components within the tumor. Its clinical and radiological appearance is comparable to other types of breast cancer, but it grows rapidly. The diagnosis of metaplastic carcinoma is largely based on the epithelial origin of the cells confirmed by immunohistochemistry (IHC). Compared to invasive ductal carcinoma, metaplastic carcinoma has a worse overall survival rate. Any patient with a rapidly growing breast mass should be assessed with suspicion of sarcomatoid or metaplastic malignant neoplasm. We report this case due to its rarity and the complex nature of the disease.

A rare case of metaplastic breast carcinoma from India: Towards precision oncology

BACKGROUND

Metaplastic Breast Cancer (MpBC) is an exceedingly rare entity, accounting for less than 1% of all malignant breast tumours. Predominantly triple-negative, they are notorious for their chemoresistance, high rates of recurrence and decreased disease-free survival (DFS). All this contributes significantly to BC mortality and results in poor prognostic implications. Limited evidence has led to a lacuna of specific treatment guidelines for this entity and hence remains an uncharted territory for clinicians.

CASE

We report a case of a 46 year old premenopausal female with left-sided metaplastic triple negative T3N2aM0 BC with mesenchymal differentiation (high grade) whom we treated with neoadjuvant chemotherapy, primary surgery in the form of extreme oncoplasty and adjuvant radiotherapy by Telecobalt machine. Contrary to the expected aggressive course of the disease and poor prognosis of treatment, the patient is presently in remission without progression for over 2 years of follow up.

CONCLUSION

Limited experience in management of this pathological entity warrants the need for more research on it, with a special focus on targeted therapy. Discussing possibilities of a tailored approach, rather than a one-size-fits-all approach may aid in paving the path for the future of MpBC treatment.

Long-Lasting Complete Remission in a Patient With Metastatic Metaplastic Breast Cancer Treated With Immune Checkpoint Inhibitor and Chemotherapy: A Case Report and a Review of the Literature

Metaplastic breast cancer (MpBC) is a rare form of breast cancer known for suboptimal response to chemotherapy, high recurrence rate, poor prognosis, and limited treatment options. Recent studies have reported that MpBC has high expression of programmed death ligand 1 and tumor-infiltrating lymphocytes, indicating the potential effectiveness of immunotherapy (IO) in MpBC. In addition, several reports have demonstrated the activity of IO in MpBC. In this case report, we present a case of recurrent MpBC that achieved durable, rapid, complete remission with atezolizumab (anti-PD-L1) and nab-paclitaxel with a continued response even after discontinued therapy.

The Use of Schisandrin B to Combat Triple-Negative Breast Cancers by Inhibiting NLRP3-Induced Interleukin-1β Production

Triple-negative breast cancer (TNBC) is the most aggressive and fatal breast cancer subtype. Nowadays, chemotherapy remains the standard treatment of TNBC, and immunotherapy has emerged as an important alternative. However, the high rate of TNBC recurrence suggests that new treatment is desperately needed. Schisandrin B (Sch B) has recently revealed its anti-tumor effects in cancers such as cholangiocarcinoma, hepatoma, glioma, and multi-drug-resistant breast cancer. However, there is still a need to investigate using Sch B in TNBC treatment. Interleukin (IL)-1β, an inflammatory cytokine that can be expressed and produced by the cancer cell itself, has been suggested to promote BC proliferation and progression. In the current study, we present evidence that Sch B can significantly suppress the growth, migration, and invasion of TNBC cell lines and patient-derived TNBC cells. Through inhibition of inflammasome activation, Sch B inhibits interleukin (IL)-1β production of TNBC cells, hindering its progression. This was confirmed using an NLRP3 inhibitor, OLT1177, which revealed a similar beneficial effect in combating TNBC progression. Sch B treatment also inhibits IL-1β-induced EMT expression of TNBC cells, which may contribute to the anti-tumor response.

Compartmental Syndecan-1 (CD138) expression as a novel prognostic marker in triple-negative metaplastic breast cancer

BACKGROUND

Metaplastic breast cancer (MpBC) is rare, aggressive, and mostly triple-negative (TN) subtype of BC. We aimed to investigate the potential prognostic significance of Syndecan-1 (SDC1/CD138) expression in this unique tumor.

METHODS

Archived charts of 50 TNBC patients [21 MpBC and 29 invasive ductal carcinoma (IDC)] were retrospectively evaluated. Corresponding paraffin blocks were used for immunohistochemical (IHC) staining of SDC1. Compartmental (epithelial membranous, stromal, and cytoplasmic) staining scores were expressed in quartiles (Q) and correlated with disease-free survival (DFS) and overall survival (OS).

RESULTS

The median follow-up period was 54.6 months (range: 2.2-112.7). MpBC patients showed significantly worse DFS and OS than IDC (p = 0.007 and 0.004, respectively). MpBC demonstrated significantly higher Q4 stromal and membranous SDC1 compared to IDC (p = 0.016 and 0.021, respectively), whereas IDC exhibited significantly higher cytoplasmic Q4 SDC1 than MpBC (p = 0.015). Stromal Q4 SDC1 expression was found to be an independent factor associated with MpBC relative to IDC (OR: 6.7, 95% CI: 1.24-36.90; p = 0.028). Stromal Q4 SDC1 expression was also an independent prognostic parameter for worse DFS and OS compared to Q1-3 in the whole cohort (HR: 4.2, 95% CI: 1.6-10.5; p = 0.003 and HR: 5.8; 95% CI: 2.2-15.3; p < 0.001, respectively). In MpBC, cytoplasmic Q1-3 SDC1 expression was an independent prognostic indicator for worse OS compared with their IDC counterparts (HR: 2.837, 95% CI: 1.048-7.682; p = 0.04).

CONCLUSION

This study suggests, for the first time, that differential expression and localization of SDC1 may contribute to the pathogenesis and prognosis of TN-MpBC. Therefore, targeting SDC1 (CD138) could emerge as a novel therapeutic approach for this devastating disease.

Epithelial to mesenchymal transition (EMT) in metaplastic breast cancer and phyllodes breast tumors

Epithelial-mesenchymal transition (EMT), a transdifferentiation program whereby epithelial cells acquire mesenchymal phenotype, is essential during embryonic development. EMT has also been implicated in cancer progression by conferring migratory and metastatic potential, as well as cell plasticity and stem cell like traits, to cancer cells. Metaplastic breast carcinoma (MBC) is a rare aggressive type of breast cancer characterized by the presence of heterologous elements, typically by the existence of epithelial and mesenchymal components. Phyllodes tumors (PTs) are uncommon fibroepithelial neoplasms consisting of epithelial and mesenchymal elements. Although various hypotheses have been proposed on the pathogenesis of these biphasic tumors, there is growing evidence supporting the theory that PTs and MBC could both correlate with cancer related EMT. This review summarizes the existing literature on the emerging role of EMT in the pathogenesis of MBC and PTs. Both malignant PTs and MBC are characterized by poor prognosis. Therefore, several anti-EMT targeting strategies such as blocking upstream signaling pathways, targeting the molecular drivers of EMT and targeting mesenchymal cells and the extracellular matrix, could potentially represent a promising therapeutic approach for patients suffering from these aggressive neoplasms.

Outcomes of Metaplastic Breast Cancer Versus Triple-Negative Breast Cancer: A Propensity Score Matching Analysis

PURPOSE

This study aims to compare the survival outcomes of metaplastic breast cancer (MPBC) with triple-negative breast cancer (TNBC) and identify prognostic factors that influence the survival outcomes of MPBC patients and TNBC patients.

METHODS

Patients with nonmetastatic MPBC or TNBC were reviewed from our database. Patients' clinicopathologic and molecular features were analyzed with respect to outcomes, including disease-free survival (DFS) and overall survival (OS). Propensity score matching (PSM) with a one-to-three matching between MPBC patients and TNBC patients was performed.

RESULTS

A total of 857 female patients (76 MPBC patients and 781 TNBC patients) were included in this study. A subgroup of triple-negative MPBC (n  =  60) was matched with TNBC (n  =  180) cases based on patient characteristics and treatments. Kaplan-Meier analysis indicated that the MPBC group was associated with worse OS and DFS before (P  =  0.0046 both) and after (P  =  0.011 and P  =  0.0046, respectively) PSM. Multivariable analysis revealed that a higher T stage (T > 2) (P  =  0.032) and higher lymph node stage (N3 vs. N0-2, P  =  0.012) were associated with worse OS after PSM. For DFS, the MPBC group (P  =  0.012), higher T stage (T > 2) (P  =  0.032), and higher lymph node stage (N3 vs. N0-2, P  =  0.045) were associated with worse DFS. Among the 76 MPBC patients, a higher T stage and mesenchymal differentiation were associated with worse OS (pT1/2 vs. pT3/4 and mesenchymal differentiation vs. other subtypes, P  =  0.007 and P  =  0.011, respectively).

CONCLUSIONS

Compared with TNBC, MPBC was associated with worse OS and DFS. Mesenchymal differentiation has a worse DFS than other subtypes of MPBC.

Spatial Transcriptomics Reveal Pitfalls and Opportunities for the Detection of Rare High-Plasticity Breast Cancer Subtypes

Breast cancer is one of the most prominent types of cancers, in which therapeutic resistance is a major clinical concern. Specific subtypes, such as claudin-low and metaplastic breast carcinoma (MpBC), have been associated with high nongenetic plasticity, which can facilitate resistance. The similarities and differences between these orthogonal subtypes, identified by molecular and histopathological analyses, respectively, remain insufficiently characterized. Furthermore, adequate methods to identify high-plasticity tumors to better anticipate resistance are lacking. Here, we analyzed 11 triple-negative breast tumors, including 3 claudin-low and 4 MpBC, via high-resolution spatial transcriptomics. We combined pathological annotations and deconvolution approaches to precisely identify tumor spots, on which we performed signature enrichment, differential expression, and copy number analyses. We used The Cancer Genome Atlas and Cancer Cell Line Encyclopedia public databases for external validation of expression markers. By focusing our spatial transcriptomic analyses on tumor cells in MpBC samples, we bypassed the negative impact of stromal contamination and identified specific markers that are neither expressed in other breast cancer subtypes nor expressed in stromal cells. Three markers (BMPER, POPDC3, and SH3RF3) were validated in external expression databases encompassing bulk tumor material and stroma-free cell lines. We unveiled that existing bulk expression signatures of high-plasticity breast cancers are relevant in mesenchymal transdifferentiated compartments but can be hindered by abundant stromal cells in tumor samples, negatively impacting their clinical applicability. Spatial transcriptomic analyses constitute powerful tools to identify specific expression markers and could thus enhance diagnosis and clinical care of rare high-plasticity breast cancers.

Nitrogen isotopic composition as a gauge of tumor cell anabolism-to-catabolism ratio

Studies have suggested that cancerous tissue has a lower 15N/14N ratio than benign tissue. However, human data have been inconclusive, possibly due to constraints on experimental design. Here, we used high-sensitivity nitrogen isotope methods to assess the 15N/14N ratio of human breast, lung, and kidney cancer tissue at unprecedented spatial resolution. In lung, breast, and urothelial carcinoma, 15N/14N was negatively correlated with tumor cell density. The magnitude of 15N depletion for a given tumor cell density was consistent across different types of lung cancer, ductal in situ and invasive breast carcinoma, and urothelial carcinoma, suggesting similar elevations in the anabolism-to-catabolism ratio. However, tumor 15N depletion was higher in a more aggressive metaplastic breast carcinoma. These findings may indicate the ability of certain cancers to more effectively channel N towards growth. Our results support 15N/14N analysis as a potential tool for screening biopsies and assessing N metabolism in tumor cells.

Germline pathogenic variants in metaplastic breast cancer patients and the emerging role of the BRCA1 gene

Metaplastic breast cancer (MpBC) is a rare, aggressive breast cancer (BC) histotype. Scarce information is available about MpBC genetic predisposition. Previous studies, mainly consisting of case reports, retrospective reviews and others on target therapies, pointed to a possible involvement of the BRCA1 gene in increasing MpBC risk, without ever confirming it. In this study, we retrospectively reviewed all BC patients counseled at our Institute for genetic testing of at least BRCA1 or BRCA2 (BRCA) genes and we found that 23 (23/5226 = 0.4%) were affected by MpBC. About 65% (15/23) of MpBC patients harbored a germline pathogenic variant (PV): 13 in BRCA1 (86.7%), including two patients who received genetic testing for known familial PV, one in TP53 (6.7%), and one in MLH1 (6.7%). We observed a statistically different frequency of MpBC in patients who carried a PV in the BRCA genes (13/1114 = 1.2%) vs. all other BC patients (10/4112 = 0.2%) (p = 0.0002). BRCA carriers proved to have an increased risk of developing MpBC compared to all other BC patients who were tested for BRCA genes (OR = 4.47; 95% CI: 1.95-10.23). Notably, MpBCs were diagnosed in 2.1% (13/610) of BRCA1 carriers. No MpBCs were observed in BRCA2 carriers (0/498 = 0%), revealing a statistically significant difference between the prevalence of MpBCs in BRCA1 and BRCA2 carriers (p = 0.0015). Our results confirmed that BRCA1 is involved in MpBC predisposition. Further studies on unselected patients are needed to elucidate the authentic role of BRCA1 and to explore the possible implication of other genes in MpBC predisposition.

Presentation and treatment of a rare case of metaplastic breast cancer: A case report

Breast carcinosarcoma, also known as metaplastic breast cancer, is one of the rarest types of breast cancer. It is an aggressive and poor prognostic breast cancer compared to triple-negative breast cancer. Due to the lack of specific and prescribed treatment, it could threaten patients' lives, especially women worldwide. There are various diagnostic methods, such as multiple imaging and pathology methods, to diagnose breast cancers. Still, considering the common appearance characteristic of this type of breast cancer with other types, histopathology is the most definitive way. There is no standard neoadjuvant or adjuvant chemotherapy for this rare type of breast cancer. In this article, we reported the case of a 62-year-old female with a final diagnosis of metaplastic breast carcinoma and her surgical and medical treatment method.

Human basal-like breast cancer is represented by one of the two mammary tumor subtypes in dogs

BACKGROUND

About 20% of breast cancers in humans are basal-like, a subtype that is often triple-negative and difficult to treat. An effective translational model for basal-like breast cancer is currently lacking and urgently needed. To determine whether spontaneous mammary tumors in pet dogs could meet this need, we subtyped canine mammary tumors and evaluated the dog-human molecular homology at the subtype level.

METHODS

We subtyped 236 canine mammary tumors from 3 studies by applying various subtyping strategies on their RNA-seq data. We then performed PAM50 classification with canine tumors alone, as well as with canine tumors combined with human breast tumors. We identified feature genes for human BLBC and luminal A subtypes via machine learning and used these genes to repeat canine-alone and cross-species tumor classifications. We investigated differential gene expression, signature gene set enrichment, expression association, mutational landscape, and other features for dog-human subtype comparison.

RESULTS

Our independent genome-wide subtyping consistently identified two molecularly distinct subtypes among the canine tumors. One subtype is mostly basal-like and clusters with human BLBC in cross-species PAM50 and feature gene classifications, while the other subtype does not cluster with any human breast cancer subtype. Furthermore, the canine basal-like subtype recaptures key molecular features (e.g., cell cycle gene upregulation, TP53 mutation) and gene expression patterns that characterize human BLBC. It is enriched in histological subtypes that match human breast cancer, unlike the other canine subtype. However, about 33% of canine basal-like tumors are estrogen receptor negative (ER-) and progesterone receptor positive (PR+), which is rare in human breast cancer. Further analysis reveals that these ER-PR+ canine tumors harbor additional basal-like features, including upregulation of genes of interferon-γ response and of the Wnt-pluripotency pathway. Interestingly, we observed an association of PGR expression with gene silencing in all canine tumors and with the expression of T cell exhaustion markers (e.g., PDCD1) in ER-PR+ canine tumors.

CONCLUSIONS

We identify a canine mammary tumor subtype that molecularly resembles human BLBC overall and thus could serve as a vital translational model of this devastating breast cancer subtype. Our study also sheds light on the dog-human difference in the mammary tumor histology and the hormonal cycle.

Metaplastic breast carcinoma with mesenchymal differentiation: A case series

ABSTRACT

The metaplastic breast carcinoma is a rare malignancy with an incidence of 5% of all breast tumors. Metaplastic carcinoma of the breast with mesenchymal differentiation (MCMD), previously known as carcinosarcoma, is a very rare and aggressive tumor that has been recently classified as a subtype of metaplastic breast carcinoma. It accounts for 0.08%-0.2% of all breast cancers, with only a few cases reported in the literature. Metaplastic breast carcinoma most often affects women over 50 years of age, with an average age between 55 and 60 years. We report three cases of metaplastic breast carcinoma with mesenchymal differentiation presented at our hospital. Patients were in their 4th decade. All patients presented with a fast-growing large mass and were treated surgically (mastectomy), with the final histopathological diagnosis of MCMD.

PRMT5 triggers glucocorticoid-induced cell migration in triple-negative breast cancer

Triple-negative breast cancers (TNBCs) are the most aggressive breast cancers, and therapeutic options mainly rely on chemotherapy and immunotherapy. Although synthetic glucocorticoids (GCs) are given to alleviate the side effects of these treatments, GCs and their receptor, the glucocorticoid receptor (GR), were recently associated with detrimental effects, albeit the mechanisms involved remain elusive. Here, we identified the arginine methyltransferase PRMT5 as a master coregulator of GR, serving as a scaffold protein to recruit phospho-HP1γ and subsequently RNA polymerase II, independently of its methyltransferase activity. Moreover, the GR/PRMT5/HP1γ complex regulated the transcription of GC-target genes involved in cell motility and triggering cell migration of human TNBC cells in vitro and in a zebrafish model. Of note, we observed that GR/PRMT5 interaction was low in primary tumors but significantly increased in residual tumors treated with chemotherapy and GCs in neoadjuvant setting. These data suggest that the routine premedication prescription of GCs for early TNBC patients should be further assessed and that this complex could potentially be modulated to specifically target deleterious GR effects.

Triple-Negative Breast Cancer: Histopathologic Features, Genomics, and Treatment

Triple-negative breast cancer (TNBC) is a heterogeneous and aggressive group of tumors that are defined by the absence of estrogen and progesterone receptors and lack of ERBB2 (formerly HER2 or HER2/neu) overexpression. TNBC accounts for 8%-13% of breast cancers. In addition, it accounts for a higher proportion of breast cancers in younger women compared with those in older women, and it disproportionately affects non-Hispanic Black women. TNBC has high metastatic potential, and the risk of recurrence is highest during the 5 years after it is diagnosed. TNBC exhibits benign morphologic imaging features more frequently than do other breast cancer subtypes. Mammography can be suboptimal for early detection of TNBC owing to factors that include the fast growth of this cancer, increased mammographic density in young women, and lack of the typical features of malignancy at imaging. US is superior to mammography for TNBC detection, but benign-appearing features can lead to misdiagnosis. Breast MRI is the most sensitive modality for TNBC detection. Most cases of TNBC are treated with neoadjuvant chemotherapy, followed by surgery and radiation. MRI is the modality of choice for evaluating the response to neoadjuvant chemotherapy. Survival rates for individuals with TNBC are lower than those for persons with hormone receptor-positive and human epidermal growth factor receptor 2-positive cancers. The 5-year survival rates for patients with localized, regional, and distant disease at diagnosis are 91.3%, 65.8%, and 12.0%, respectively. The early success of immunotherapy has raised hope regarding the development of personalized strategies to treat TNBC. Imaging and tumor biomarkers are likely to play a crucial role in the prediction of TNBC treatment response and TNBC patient survival in the future. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

MYC Deregulation and PTEN Loss Model Tumor and Stromal Heterogeneity of Aggressive Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) patients have a poor prognosis and few treatment options. Mouse models of TNBC are important for development of new therapies, however, few mouse models represent the complexity of TNBC. Here, we develop a female TNBC murine model by mimicking two common TNBC mutations with high co-occurrence: amplification of the oncogene MYC and deletion of the tumor suppressor PTEN. This Myc;Ptenfl model develops heterogeneous triple-negative mammary tumors that display histological and molecular features commonly found in human TNBC. Our research involves deep molecular and spatial analyses on Myc;Ptenfl tumors including bulk and single-cell RNA-sequencing, and multiplex tissue-imaging. Through comparison with human TNBC, we demonstrate that this genetic mouse model develops mammary tumors with differential survival and therapeutic responses that closely resemble the inter- and intra-tumoral and microenvironmental heterogeneity of human TNBC, providing a pre-clinical tool for assessing the spectrum of patient TNBC biology and drug response.

Predicting breast cancer-specific survival in metaplastic breast cancer patients using machine learning algorithms

Metaplastic breast cancer (MpBC) is a rare and aggressive subtype of breast cancer, with data emerging on prognostic factors and survival prediction. This study aimed to develop machine learning models to predict breast cancer-specific survival (BCSS) in MpBC patients, utilizing a dataset of 160 patients with clinical, pathological, and biological variables. An in-depth variable selection process was carried out using gain ratio and correlation-based methods, resulting in 10 variables for model estimation. Five models (decision tree with bagging; logistic regression; multilayer perceptron; naïve Bayes; and, random forest algorithms) were evaluated using 10-fold cross-validation. Despite the constraints posed by the absence of therapeutic information, the random forest model exhibited the highest performance in predicting BCSS, with an ROC area of 0.808. This study emphasizes the potential of machine learning algorithms in predicting prognosis for complex and heterogeneous cancer subtypes using clinical datasets, and their potential to contribute to patient management. Further research that incorporates additional variables, such as treatment response, and more advanced machine learning techniques will likely enhance the predictive power of MpBC prognostic models.

Metaplastic breast carcinoma with osseous differentiation: A report of a rare case and literature review

Metaplastic matrix-producing breast carcinoma is a type of metaplastic breast carcinoma (MBC), which is a rare malignancy, accounting for 0.2-1% of breast carcinomas. A 52-year-old female visited a hospital because of a palpable painless mass in the right breast and was diagnosed with Breast Imaging Reporting and Data System (BI-RADS) category 4A via ultrasound (US) with a suspected positive lymph node at the right axillary region. Excision of the breast mass was performed and histopathologically confirmed that it was MBC with osseous differentiation. No distant metastasis was revealed before a modified radical mastectomy; however, metastasis to a lymph node of the right axillary region was observed (1/22). She received six cycles of TEC scheme chemotherapy (docetaxel, epirubicin, and cyclophosphamide, 21 days) and 5 weeks of radiotherapy (48 Gy/25 f/5 days a week), but without any follow-up examinations since radiotherapy. Twenty-four months after surgery, distant metastases to lungs and liver were confirmed and died 3 months later. This case provides valuable information for clinicians on MBC and suggests that further examination or biopsy should be performed to US BI-RADS 4A masses before surgery. In addition, regular postoperative follow-up plays important roles in detecting metastases early and improving prognosis.

Development and validation of competitive risk model for older women with metaplastic breast cancer

BACKGROUND

Metaplastic breast cancer (MpBC) is a rare histological subtype of breast cancer. This study aims to establish a competitive risk model for older women with MpBC to predict patients' survival accurately.

METHODS

Data on patients diagnosed with MpBC from 2010 to 2019 are from the Surveillance, Epidemiology and End Results (SEER) program in the United States. All patients were randomly assigned to the training set and validation set. The proportional sub-distribution risk model was used in the training set to analyze the risk factors affecting patient death. Based on the risk factors for cancer-specific mortality (CSM) in patients, we constructed a competitive risk model to predict patients' 1-, 3-, and 5-year cancer-specific survival. Then we used the concordance index (C-index), the calibration curve and the area under the receiver operating characteristic curve (AUC) to validate the discrimination and accuracy of the model.

RESULTS

One thousand, four hundred twelve older women with MpBC were included in this study. Age, T stage, N stage, M stage, tumor size, surgery and radiotherapy were risk factors for CSM. We established a competitive risk model to predict 1-, 3-, and 5-year cancer-specific survival in older women with MpBC. The C-index of the model was 0.792 in the training set and 0.744 in the validation set. The calibration curves in the training and validation sets showed that the model's predicted values were almost consistent with the actual observed values. The AUC results show that the prediction model has good accuracy.

CONCLUSION

We developed a competitive risk model based on these risk factors to predict cancer-specific survival in older women with MpBC. The validation results of the model show that it is a very effective and reliable prediction tool. This predictive tool allows doctors and patients to make individualized clinical decisions.

Metaplastic breast cancer: an all-round multidisciplinary consensus

Metaplastic breast cancer (MpBC) is a rare and aggressive histologic subtype of breast cancer (BC) characterized by the presence of at least two cellular types, commonly epithelial and mesenchymal components. Despite growing evidence that MpBC is a unique entity, it has long been treated as a variant of nonspecial type (NST) BC. MpBC typically shows the phenotype of triple-negative breast cancer (TNBC), but compared to NST-TNBC, it is a relatively chemorefractory tumor associated with worse outcomes. Therefore, there is an urgent need to develop management guidelines specifically for MpBC to improve the prognosis of patients with early MpBC. This expert consensus aims to guide diagnosis and standardize clinical management of early MpBC among treating physicians. We provide guidance on the challenging radiological and pathological diagnosis of MpBC. Evidence on the involvement of genetic predisposition in the development of MpBC is also explored. We emphasize the importance of a multidisciplinary approach for the treatment of patients with early MpBC. The optimal surgery and radiotherapy approach is presented, as well as the opportunity offered by novel therapeutic approaches to increase treatment response in this chemoresistant subtype. Appropriate management of patients with MpBC is critical to reduce the high risk of local and distant recurrence that characterizes this disease.

Mammary Spindle Cell Proliferations on Core Needle Biopsy: Is Excision Always Necessary?

Mammary spindle cell proliferations (SCPs) encompass a wide range of lesions and can be challenging to accurately diagnose on core needle biopsies (CNBs). Most SCPs are excised for definitive diagnosis. In the era of minimally invasive therapy, some SCP may be followed conservatively. We aim to examine the spectrum of SCP diagnosed on CNB and evaluate if excision of benign/indeterminate SCP is always required. We identified patients with SCP across 3 institutions. The CNB were classified into benign, indeterminate, or malignant. Available excisional specimens were used to classify the lesion as benign or malignant. Clinical variables were reviewed. A total of 197 SCP met the inclusion criteria, including 100 (53%) CNB classified as benign, 52 (26%) indeterminate, and 36 (19%) malignant. Nine patients had excisions without a preceding CNB. Excision was performed in 47% of benign, 87% of indeterminate, and 86% malignant CNB. Of 123 excised SCP, 77 (63%) were benign, while 44 (36%) were malignant. Most benign lesions were not suspicious radiologically (67%), while indeterminate and malignant lesions were more likely to be suspicious (44% and 75%, respectively; P <0.001). Malignant lesions tended to present as larger, rapidly growing, masses. Most mammary SCP are benign (63% of excisions). Appropriate ancillary tests can safely exclude some malignant entities. We encourage narrowing down the differential diagnosis to pertinent entities based on clinical presentation, imaging, histology, immunohistochemistry, and molecular studies, if applicable. Patients with mammary SCP may be spared surgery provided accurate pathologic diagnosis and appropriate correlation with imaging and clinical data.

Metaplastic Breast Carcinoma Revisited; Subtypes Determine Outcomes: Comprehensive Pathologic, Clinical, and Molecular Review

Metaplastic breast carcinoma (MpBC) is a heterogeneous group of tumors that clinically could be divided into low risk and high risk. It is important to recognize the different types of MpBC, as the high-risk subtypes have worse clinical outcomes than triple-negative breast cancer. It is important for the pathologist to be aware of the MpBC entities and use the proposed algorithms (morphology and immunohistochemistry) to assist in rendering the final diagnosis. Few pitfalls are discussed, including misinterpretation of immunohistochemistry and certain histomorphologies, particularly spindle lesions associated with complex sclerosing lesions.

Metaplastic Breast Carcinoma in U.S. Population: Racial Disparities, Survival Benefit of Adjuvant Chemoradiation and Future Personalized Treatment with Genomic Landscape

PURPOSE

In this population-based study, we aim to identify factors that are influential on the survival outcome in MBC and investigate novel molecular approaches in personalized disease management.

METHODS

The data of this study were collected from the SEER database from 2000-2018. A total of 5315 cases were extracted from the database. The data were evaluated for demographics, tumor characteristics, metastasis, and treatment. Survival analysis was completed by using SAS software for multivariate analysis, univariate analysis, and non-parametric survival analysis. The molecular data with the most common mutations in MBC were extracted from the Catalogue of Somatic Mutations in Cancer (COSMIC) database.

RESULTS

The mean age at the time of presentation was 63.1 with a standard deviation (SD) of 14.2 years. Most patients were White (77.3%) with 15.7% Black patients, 6.1% Asian or Pacific Islander, and 0.5% American Indian. Histologically, most of the reported tumors were grade III (74.4%); 37% of the cases were triple negative (ER-, PR- and HER2-), whereas the hormone status was unknown in 46% of the cases. Spread was localized in 67.3% of patients while 26.3% had regional spread and 6.3% had distant metastases. Most tumors were unilateral (99.9%) and between 20-50 mm in size (50.6%). The lungs were the most common site for distant metastasis at diagnosis (3.42%) followed by bone (1.94%), liver (0.98%), and brain (0.56%). A combination of surgery, chemotherapy, and radiation therapy was the most common treatment with a cause-specific survival rate of 78.1% (95% CI = 75.4-80.4). The overall survival rate at 5 years was 63.6% (95% confidence interval (CI) = 62.0-65.1) with a cause-specific survival of 71.1% (95% CI = 69.5-72.6). Cause-specific survival was found to be 63.2% (95% CI = 58.9-67.1) in Black patients as compared to 72.4% (95% CI = 70.1-74.1) in White patients. Black patients also presented with higher rates of grade III disease, distant metastasis, and larger tumor size. On multivariate analysis, age > 60, grade III+, metastasis, and tumor size > 50 mm were associated with worse survival. The most common mutations in MBC identified in COSMIC data were TP53, PIK3CA, LRP1B, PTEN, and KMT2C.

CONCLUSION

Though rare, MBC is aggressive, with poor prognosis associated with high-grade tumors, metastasis, tumor size over 50 mm, and advanced age at the time of presentation. Overall, Black women had worse clinical outcomes. MBC is difficult to treat and carries a poor prognosis that affects various races disproportionately. Continued enhancement of treatment strategies to foster more individualized care as well as continued enrollment in clinical trials are needed to improve outcomes among patients with MBC.

The mixed subtype has a worse prognosis than other histological subtypes: a retrospective analysis of 217 patients with metaplastic breast cancer

OBJECTIVE

Metaplastic breast cancer (MpBC) is an aggressive subtype of all breast cancer. We aimed to investigate the clinicopathological features, treatments and prognoses of MpBC patients.

METHODS

We collected the data from MpBC patients diagnosed at Tianjin Medical University Cancer Hospital from 2010 to 2017. Kaplan Meier curves and Cox regression model were used to evaluating clinical outcomes and prognostic factors. After removing baseline differences by propensity score matching (PSM), we analyzed the prognosis between MpBC patients and invasive ductal carcinomas of no special type (IDC-NST) patients.

RESULTS

A total of 217 MpBC patients were subsumed. Of all histological subtypes, 45.1% were mixed subtypes, followed by with mesenchymal differentiation (27.2%), pure squamous (15.2%) and pure spindle (12.4%) subtypes. 69.6% of MpBC were triple-negative, 25.3% and 6.5% were HR-positive and HER2-positive. MpBC patients had worse survival compared to IDC-NST patients, with 5-year RFS of 73.8 and 83.6% (HR = 1.177 95%CI (1.171-2.676) P = 0.0068), and 5-year BCSS of 79.0% and 89.7% (HR = 2.187 95%CI (1.357-3.523) P = 0.0013). In the multivariate COX model, AJCC stage, mixed subtype and chemotherapy were independent prognostic factors. Mixed MpBC is more aggressive than pure and with heterologous mesenchymal differentiation subtypes. And whether squamous or spindle MpBC, mixed forms have shorter outcomes than pure forms.

CONCLUSIONS

MpBCs are associated with poorer prognoses than IDC-NSTs. They are heterogeneous with different clinicopathological features and clinical outcomes between histological subtypes. Pure and with heterologous mesenchymal differentiation subtypes have more survival benefits than the mixed subtype.

Current therapeutic approaches and promising perspectives of using bioengineered peptides in fighting chemoresistance in triple-negative breast cancer

Breast cancer is a collation of malignancies that manifest in the mammary glands at the early stages. Among breast cancer subtypes, triple-negative breast cancer (TNBC) shows the most aggressive behavior, with apparent stemness features. Owing to the lack of response to hormone therapy and specific targeted therapies, chemotherapy remains the first line of the TNBC treatment. However, the acquisition of resistance to chemotherapeutic agents increase therapy failure, and promotes cancer recurrence and distant metastasis. Invasive primary tumors are the birthplace of cancer burden, though metastasis is a key attribute of TNBC-associated morbidity and mortality. Targeting the chemoresistant metastases-initiating cells via specific therapeutic agents with affinity to the upregulated molecular targets is a promising step in the TNBC clinical management. Exploring the capacity of peptides as biocompatible entities with the specificity of action, low immunogenicity, and robust efficacy provides a principle for designing peptide-based drugs capable of increasing the efficacy of current chemotherapy agents for selective targeting of the drug-tolerant TNBC cells. Here, we first focus on the resistance mechanisms that TNBC cells acquire to evade the effect of chemotherapeutic agents. Next, the novel therapeutic approaches employing tumor-targeting peptides to exploit the mechanisms of drug resistance in chemorefractory TNBC are described.

Peptide-functionalized therapeutic nanoplatform for treatment orthotopic triple negative breast cancer and bone metastasis

Epidermal Growth Factor Receptor (EGFR) is a promising therapeutic target for triple-negative breast cancer (TNBC). Recently, specific EGFR-targeting peptide GE11-based delivery nano-system shows excellent potential because of its chemical versatility and good targeting ability. However, no further research focusing on the downstream of EGFR after binding with GE11 was explored. Hence, we tailor-designed a self-assembled nanoplatform named GENP using amphiphilic molecule of stearic acid-modified GE11. After loading doxorubicin (DOX), the resulted nanoplatform GENP@DOX demonstrated high loading efficiency and sustainable drug release. Importantly, our findings proved that GENP alone significantly suppressed the proliferation of MDA-MB-231 cells via EGFR-downstream PI3K/AKT signaling pathways, contributing to the synergistic treatment with its DOX release. Further work illustrated remarkable therapeutic efficacy both in orthotopic TNBC and its bone metastasis models with minimal biotoxicity. Together, the results highlight that our GENP-functionalized nanoplatform is a promising strategy for the synergistic therapeutic efficacy targeting EGFR-overexpressed cancer.

Human basal-like breast cancer is represented by one of the two mammary tumor subtypes in dogs

Background

About 20% of breast cancers in humans are basal-like, a subtype that is often triple negative and difficult to treat. An effective translational model for basal-like breast cancer (BLBC) is currently lacking and urgently needed. To determine if spontaneous mammary tumors in pet dogs could meet this need, we subtyped canine mammary tumors and evaluated the dog-human molecular homology at the subtype level.

Methods

We subtyped 236 canine mammary tumors from 3 studies by applying various subtyping strategies on their RNA-seq data. We then performed PAM50 classification with canine tumors alone, as well as with canine tumors combined with human breast tumors. We investigated differential gene expression, signature gene set enrichment, expression association, mutational landscape, and other features for dog-human subtype comparison.

Results

Our independent genome-wide subtyping consistently identified two molecularly distinct subtypes among the canine tumors. One subtype is mostly basal-like and clusters with human BLBC in cross-species PAM50 classification, while the other subtype does not cluster with any human breast cancer subtype. Furthermore, the canine basal-like subtype recaptures key molecular features (e.g., cell cycle gene upregulation, TP53 mutation) and gene expression patterns that characterize human BLBC. It is enriched histological subtypes that match human breast cancer, unlike the other canine subtype. However, about 33% of canine basal-like tumors are estrogen receptor negative (ER-) and progesterone receptor positive (PR+), which is rare in human breast cancer. Further analysis reveals that these ER-PR+ canine tumors harbor additional basal-like features, including upregulation of genes of interferon-γ response and of the Wnt-pluripotency pathway. Interestingly, we observed an association of PGR expression with gene silencing in all canine tumors, and with the expression of T cell exhaustion markers (e.g., PDCD1 ) in ER-PR+ canine tumors.

Conclusions

We identify a canine mammary tumor subtype that molecularly resembles human BLBC overall, and thus could serve as a vital spontaneous animal model of this devastating breast cancer subtype. Our study also sheds light on the dog-human difference in the mammary tumor histology and the hormonal cycle.

Mixed metaplastic carcinoma of the breast: a case report

A 68 year-old woman with no significant medical history discovered a lump incidentally in her left breast. The patient's initial imaging revealed a 4.6-cm irregular mass at 11:00 categorized as a BI-RADS 5 as well as an enlarged axillary lymph node and an area of 2.5 cm of heterogeneous calcifications in the 3 o'clock position. The 4.6-cm lesion was revealed to be infiltrating ductal carcinoma with a squamous component, mixed metaplastic carcinoma, which was strongly ER (100+)/PR (100+) positive, HER-2/Neu negative on FISH. The 2.5-cm calcifications were ductal carcinoma in situ. The patient completed neoadjuvant chemotherapy, and had an excellent response. After further discussion, the patient elected for breast conservation therapy and underwent a left wireless localized partial mastectomy with a left axillary dissection. Surgical pathology revealed a near complete pathologic response with only 8-mm residual tumour as well as a negative conversion of the clipped axillary node.

Deep learning in digital pathology for personalized treatment plans of cancer patients

Over the past decade, many new cancer treatments have been developed and made available to patients. However, in most cases, these treatments only benefit a specific subgroup of patients, making the selection of treatment for a specific patient an essential but challenging task for oncologists. Although some biomarkers were found to associate with treatment response, manual assessment is time-consuming and subjective. With the rapid developments and expanded implementation of artificial intelligence (AI) in digital pathology, many biomarkers can be quantified automatically from histopathology images. This approach allows for a more efficient and objective assessment of biomarkers, aiding oncologists in formulating personalized treatment plans for cancer patients. This review presents an overview and summary of the recent studies on biomarker quantification and treatment response prediction using hematoxylin-eosin (H&E) stained pathology images. These studies have shown that an AI-based digital pathology approach can be practical and will become increasingly important in improving the selection of cancer treatments for patients.

Recurrent Metaplastic Breast Cancer with Subtype Converted from Triple-Negative to HER2-Positive: A Case Report and Literature Review

Background

Metaplastic breast cancer (MBC) is an extremely rare malignant breast disease that has rarely been reported. The molecular subtype of MBC is mostly triple-negative, with a high recurrence rate and a worse prognosis. Due to its low HR- and HER2-positive rate, reports on endocrine and targeted therapy are very limited.

Case report

We report a case of infrequent triple-negative MBC, which, although at an early stage, quickly developed multiple recurrent lesions in the chest wall. The tumor relapsed repeatedly after comprehensive treatment, including surgery, chemotherapy and radiotherapy. However, pathological results after the third surgery suggested that the molecular subtype had changed from triple-negative to HER2-positive. The previous comprehensive treatment had not been able to effectively control the disease, but the patient achieved a long progression-free survival time through chemotherapy and trastuzumab targeted therapy after the subtype change. To date, there has been no recurrence for over eight years.

Conclusion

Among repeatedly relapsed MBC patients, further investigation should be taken into consideration. As in the case presented in our study, it is possible that the HER2 status can convert from negative to overexpression. Moreover, for HER2-positive MBC patients, anti-HER2 therapy is recommended. The decision-making process requires multidisciplinary involvement.

Novel markers in breast pathology

Breast pathology is an ever-expanding database of information which includes markers, or biomarkers, that detect or help treat the disease as prognostic or predictive information. This review focuses on these aspects of biomarkers which are grounded in immunohistochemistry, liquid biopsies and next-generation sequencing.

Clinical characteristics and overall survival prognostic nomogram for metaplastic breast cancer

Background

Metaplastic breast cancer (MBC) is a rare breast tumor and the prognostic factors for survival in patients still remain controversial. This study aims to develop and validate a nomogram to predict the overall survival (OS) of patients with MBC.

Methods

We searched the Surveillance, Epidemiology, and End Results (SEER) database for data about patients including metaplastic breast cancer and infiltrating ductal carcinoma (IDC) from 2010 to 2018. The survival outcomes of patients between MBC and IDC were analyzed and compared with the Kaplan-Meier (KM) method. MBC patients were randomly allocated to the training set and validation I set by a ratio of eight to two. Meanwhile, the performance of this model was validated again by the validation II set, which consisted of MBC patients from the Union Hospital of Fujian Medical University between 2010 and 2018. The independent prognostic factors were selected by univariate and multivariate Cox regression analyses. The nomogram was constructed to predict individual survival outcomes for MBC patients. The discriminative power, calibration, and clinical effectiveness of the nomogram were evaluated by the concordance index (C-index), the receiver operating characteristic (ROC) curve, and the decision curve analysis (DCA).

Results

MBC had a significantly higher T stage (T2 and above accounting for 75.1% vs 39.9%), fewer infiltrated lymph nodes (N0 accounted for 76.2% vs 67.7%), a lower proportion of ER (22.2% vs 81.2%), PR (13.6% vs 71.4%), and HER-2(6.7% vs 17.7%) positive, radiotherapy(51.6% vs 58.0%) but more chemotherapy(67.5% vs 44.7%), and a higher rate of mastectomy(53.2% vs 36.8%), which was discovered when comparing the clinical baseline data between MBC and IDC. Age at diagnosis, T, N, and M stage, as well as surgery and radiation treatment, were all significant independent prognostic factors for overall survival (OS). In the validation I cohort, the nomogram's C-index (0.769 95% CI 0.710 -0.828) was indicated to be considerably higher than the standard AJCC model's (0.700 95% CI 0.644 -0.756). Nomogram's great predictive capability capacity further was supported by the comparatively high C-index of the validation II sets (0.728 95%CI 0.588-0.869).

Conclusions

Metaplastic breast cancer is more aggressive, with a worse clinical prognosis than IDC. This nomogram is recommended for patients with MBC, both American and Chinese, which can help clinicians make more accurate individualized survival analyses.

Complete Response of Triple-Negative Metaplastic Carcinoma of the Breast Using Pembrolizumab

Metaplastic breast cancer (MpBC) is a rare form of breast malignancy with a poor prognosis and limited treatment guidance. Here, we report on a case of triple-negative MpBC that was successfully treated following the Keynote-522 clinical algorithm using pembrolizumab, paclitaxel, carboplatin, adriamycin, and cyclophosphamide in a neo-adjuvant fashion. The radiographic and histologic findings of the tumor are reviewed here along with the treatment regimen and response. No major toxicities associated with pembrolizumab were observed in this case. This case report serves as an example of complete pathological response of triple-negative MpBC with pembrolizumab plus chemotherapy and demonstrates the need for further research on chemoimmunotherapy for MpBC.

Correlation of TROP-2 expression with clinical-pathological characteristics and outcome in triple-negative breast cancer

Limited data exist regarding the associations between TROP-2 protein expression, clinical-pathological characteristics, and outcome in triple-negative breast cancer (TNBC). TROP-2 expression was determined for patients diagnosed with TNBC between 2000 and 2017 by immunohistochemistry (IHC) (ab227689, Abcam) on whole slide tumor sections, and assessed as continuous and categorical variables (H-score high, 201-300, medium 100-200 and low < 100). We investigated the prognostic value of TROP-2 expression for relapse and survival, associations between TROP-2 expression and baseline patient and tumor characteristics, stromal tumor-infiltrating lymphocytes (sTILs), androgen receptor (AR), standardized mitotic index (SMI) and pathological complete response (pCR, in patients with neoadjuvant chemotherapy) were assessed. We included 685 patients with a median age at diagnosis of 54 years (range 22-90 years). After median follow-up of 9.6 years, 17.5% of patients experienced distant relapse. TROP-2 expression was high, medium and low in 97 (16.5%), 149 (25.3%) and 343 (58.2%) of patients, respectively. The presence of LVI, associated DCIS, nodal involvement, apocrine histology and AR expression were correlated with higher TROP-2 levels. There were no associations between TROP-2 expression and sTILs, time-to-event outcomes, or pCR rate after neoadjuvant chemotherapy. TROP-2 expression is not associated with sTILs level and has no prognostic value in our cohort of stage 1-3 TNBC. However, an association with histotype and AR expression was found, suggesting a histotype specific TROP-2 expression pattern with highest expression in apocrine subtype, warranting further research.

Metaplastic Breast Cancer: Mesenchymal Subtype Has Worse Survival Outcomes

Background

Metaplastic breast carcinoma (MBC) is a rare type of breast cancer that accounts for 0.2-1% of all breast cancers. To date, there are only few institutional studies comparing survival rates between different subtypes. In this retrospective cohort study, we aim to evaluate factors effecting survival rates of different subtypes of MBC.

Methods

This retrospective cohort study observed 118 nonmetastatic MBC patient records extracted from 15,244 breast cancer cases between December 2000 and December 2020. In order to analyze factors effecting survival rates of mesenchymal subtype of MBC, all cases are classified as mesenchymal (n = 45) and other (n = 48). Twenty-five cases could not be sub-classified due to the missing data. Univariate and multivariate logistic regression analyses were performed to define factors associated with survival rates.

Results

Of the 15,244 cases, 118 (0.8%) were nonmetastatic MBC. 105 were triple negative and 12 were nonluminal HER2. There was no significant difference between mesenchymal and other subgroups for age, median tumor size, AJCC staging, and type of surgery. Of the five local recurrences with known subgroup, four of them had mesenchymal subtype. It is demonstrated that mesenchymal subtype was significantly associated with worse 5-year disease-free survival and disease-specific survival (HR: 2.35 [1.01-5.48], p = 0.049, and HR: 3.16 [1.06-9.47], p = 0.040 with 95% CI, respectively).

Conclusion

This study is one of the few studies presenting the survival outcomes of subtypes of MBCs. Nonetheless, it is the only study demonstrating that mesenchymal subtype had worse survival outcomes. Further studies are needed to determine the outcome of different subtypes of MBCs.

Current Molecular Combination Therapies Used for the Treatment of Breast Cancer

Breast cancer is the second leading cause of death for women worldwide. While monotherapy (single agent) treatments have been used for many years, they are not always effective, and many patients relapse after initial treatment. Moreover, in some patients the response to therapy becomes weaker, or resistance to monotherapy develops over time. This is especially problematic for metastatic breast cancer or triple-negative breast cancer. Recently, combination therapies (in which two or more drugs are used to target two or more pathways) have emerged as promising new treatment options. Combination therapies are often more effective than monotherapies and demonstrate lower levels of toxicity during long-term treatment. In this review, we provide a comprehensive overview of current combination therapies, including molecular-targeted therapy, hormone therapy, immunotherapy, and chemotherapy. We also describe the molecular basis of breast cancer and the various treatment options for different breast cancer subtypes. While combination therapies are promising, we also discuss some of the challenges. Despite these challenges, the use of innovative combination therapy holds great promise compared with traditional monotherapies. In addition, the use of multidisciplinary technologies (such as nanotechnology and computer technology) has the potential to optimize combination therapies even further.

Mesoporous Silica Nanoparticles Loaded with Resveratrol Are Used for Targeted Breast Cancer Therapy

Objective

The characteristics of poor pharmacokinetics, stability, and low solubility seriously limited the clinical application of resveratrol (Res) in breast cancer. Thus, this study intends to develop a delivery system for Res which could be better used in breast cancer therapy.

Methods

Resveratrol-modified mesoporous silica nanoparticles (MSN-Res) were chemically constructed. Their shape and encapsulation were detected by transmission electron microscope, Fourier transforms infrared spectrometer, and UV spectroscopy, respectively. MGF-7 tumor-bearing mice were established by subcutaneous injection, and the pathological changes were detected by hematoxylin-eosin staining. CCK-8 and Ki-67 immunohistochemical staining were used for proliferation evaluation in vitro and in vivo. Flow cytometry, TUNEL, wound healing, and transwell assay detected cell apoptosis, invasion, and migration.

Results

MSN-Res was successfully prepared with high biosafety. MSN-Res inhibited MGF-7 cell proliferation, invasion, and migration and promoted apoptosis in vitro. Furthermore, MSN-Res showed better performance compared Res in breast cancer mouse models. In addition, we found that MSN-Res inhibited tumor growth via inhibiting the NF-κB signaling pathway.

Conclusion

MSN-Res inhibited breast cancer progression with better efficacy compared with Res treatment alone by inhibiting the NF-κB signaling pathway, suggesting that MSN-Res is a more effective adjuvant treatment method for breast cancer. Thus, our findings may provide a new and safer means of using phytochemicals in combinatorial therapy of breast cancer.