Metaplastic Breast Carcinoma: Update on Histopathology and Molecular Alterations

Differential diagnosis of primary mesenchymal neoplasms of the breast

OBJECTIVE

While the majority of breast neoplasms originate from epithelial cells, a rare part of them originate from mesenchymal breast tissue. This study aims to present the histomorphological and clinicoradiological features of our series of primary mesenchymal breast tumors and to discuss the features of these tumors in light of the literature.

MATERIALS AND METHODS

Cases diagnosed as primary mesenchymal breast tumor in breast resection materials evaluated in our center between 2010 and 2023 were included.

RESULTS

Of the 26 tumors included, 57.7% were diagnosed as benign and 42.3% as malignant mesenchymal tumor. Cases diagnosed as benign mesenchymal tumor were hemangioma, lipoma, extra-abdominal fibromatosis, leiomyoma, angiofibroma, lipomatosis, benign fibrous histiocytoma and granular cell tumor. Histopathological study results were compatible with angiosarcoma in 5 (45.4%), undifferentiated sarcoma in 3 (27.3%), myxofibrosarcoma in 2 (18.2%) cases and rhabdomyosarcoma in 1 (9.1%) case.

CONCLUSION

Primary breast sarcomas are rarely seen compared to benign mesenchymal tumors and constitute less than 0.1% of all malignant breast tumors. When histomorphological findings suggestive of a mesenchymal tumor are observed in breast specimens, sufficient sampling should be performed to exclude a possible phyllodes tumor, and clinicoradiological findings should be examined to exclude the possibility of a metastasis.

Better Local Disease Control With Mastectomy in Metaplastic Breast Carcinoma: Findings of a Retrospective Cohort

BACKGROUND

Metaplastic breast cancer (MBC) is a rare type of breast carcinoma with clinicopathological differences. The prognosis and treatment strategies for MBC are usually conflicting. In this study, we aim to present the clinicopathologic features, treatment strategies, and prognosis of our MBC patients.

MATERIAL AND METHODS

In our retrospective study, 18 metaplastic breast cancer patients treated in our institution between January 2005 and December 2022 were evaluated. Demographic and clinicopathological characteristics, surgical and systemic treatment options, locoregional recurrences, distant metastases, and overall survival (OS) of the MBC patients were retrieved from the patient files.

RESULTS

All patients were female; the median age was 54.42 ± 12.37 years. Most of the patients (n = 15, 83.33%) presented with palpable masses. Tumors were mostly triple-negative, with a high grade and a high Ki‑67 proliferation index. Spindle cell carcinoma and MBC with mesenchymal differentiation were the most common subtypes. Most of the patients underwent mastectomy (n = 11, 61.11%); breast-conserving surgery (BCS) was performed on seven (38,88%) patients. Lymph node positivity was detected in six of 18 patients (33.33%). Fewer patients (n = 4, 22.22%) received neoadjuvant chemotherapy. While local recurrence developed in two out of seven patients (28.57%) who underwent BCS, there was no local recurrence in patients who had mastectomy. The OS time varied according to tumor size and the presence of lymph node metastases (p <0.001; p = 0.005).

CONCLUSION

Metaplastic breast cancer is genetically heterogeneous and resistant to conventional treatment strategies. Mastectomy is still the surgical treatment method that is performed more frequently and provides better local control for patients with metaplastic breast cancer.

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.

Translational Aspects in Metaplastic Breast Carcinoma

Breast cancer is the most common cancer among women. Metaplastic breast carcinoma (MpBC) is a rare, heterogeneous group of invasive breast carcinomas, which are classified as predominantly triple-negative breast carcinomas (TNBCs; HR-negative/HER2-negative). Histologically, MpBC is classified into six subtypes. Two of these are considered low-grade and the others are high-grade. MpBCs seem to be more aggressive, less responsive to neoadjuvant chemotherapy, and have higher rates of chemoresistance than other TNBCs. MpBCs have a lower survival rate than expected for TNBCs. MpBC treatment represents a challenge, leading to a thorough exploration of the tumor immune microenvironment, which has recently opened the possibility of new therapeutic strategies. The epithelial-mesenchymal transition in MpBC is characterized by the loss of intercellular adhesion, downregulation of epithelial markers, underexpression of genes with biological epithelial functions, upregulation of mesenchymal markers, overexpression of genes with biological mesenchymal functions, acquisition of fibroblast-like (spindle) morphology, cytoskeleton reorganization, increased motility, invasiveness, and metastatic capabilities. This article reviews and summarizes the current knowledge and translational aspects of MpBC.

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.

A Single-Center 18-Year Series of 73 Cases of Metaplastic Carcinoma of the Breast

Aim

To examine the clinical management of metaplastic breast cancer (MeBC), particularly the role of chemotherapy.

Methods

This retrospective study included patients with MeBC (n = 73) from a tertiary breast cancer center: the "Centre des Maladies du Sein of the CHU de Québec-Université Laval." The specimens were reviewed by two pathologists. Patient and tumor characteristics, systemic therapy (neoadjuvant and adjuvant), disease-free survival (DFS), and overall survival (OS) were recorded.

Results

The median follow-up was 57.2 months. The mean tumor size was 39.5 ± 32.1 (range, 1-200) mm. Most were in grade 3 (75.3%), without evidence of clinical nodal involvement (75.3%), and triple-negative (79.5%). Chemotherapy was given to 49 (67.1%) patients. Thirty-seven patients (50.7%) underwent a mastectomy, and 22/37 (59.5%) received radiotherapy. Adjuvant chemotherapy was given to 36 patients (49.3%), and nine (12.3%) patients were treated with neoadjuvant chemotherapy. The 5-year OS and DFS rates were 60.2% and 66.8%. Among the nine patients who received neoadjuvant chemotherapy, three (33.3%) achieved a partial response, three (33.3%) had stable disease, and three (33.3%) had disease progression. The use of chemotherapy, especially in the adjuvant setting, had a significant positive effect on 5-year OS (P=0.003) and 5-year DFS (P=0.004). Nodal involvement was associated with worse OS (P=0.049) but similar DFS (P=0.157). Lumpectomy was associated with better 5-year OS (P < 0.0001) and DFS (P=0.0002) compared with mastectomy.

Conclusion

MeBC represents a rare heterogeneous group of malignancies with poor prognosis. Adjuvant chemotherapy was associated with improved OS and DFS. Patients should be carefully selected for neoadjuvant chemotherapy.

Discrepancy between Tumor Size Assessed by Full-Field Digital Mammography or Ultrasonography (cT) and Pathology (pT) in a Multicenter Series of Breast Metaplastic Carcinoma Patients

Metaplastic breast cancer (BC-Mp) presents diagnostic and therapeutic complexities, with scant literature available. Correct assessment of tumor size by ultrasound (US) and full-field digital mammography (FFDM) is crucial for treatment planning.

METHODS

A retrospective cohort study was conducted on databases encompassing records of BC patients (2012-2022) at the National Research Institutes of Oncology (Warsaw, Gliwice and Krakow Branches). Inclusion criteria comprised confirmed diagnosis in postsurgical pathology reports with tumor size details (pT) and availability of tumor size from preoperative US and/or FFDM. Patients subjected to neoadjuvant systemic treatment were excluded. Demographics and clinicopathological data were gathered.

RESULTS

Forty-five females were included. A total of 86.7% were triple-negative. The median age was 66 years (range: 33-89). The median pT was 41.63 mm (6-130), and eight patients were N-positive. Median tumor size assessed by US and FFDM was 31.81 mm (9-100) and 34.14 mm (0-120), respectively. Neither technique demonstrated superiority (p > 0.05), but they both underestimated the tumor size (p = 0.002 for US and p = 0.018 for FFDM). Smaller tumors (pT1-2) were statistically more accurately assessed by any technique (p < 0.001). Only pT correlated with overall survival.

CONCLUSION

The risk of underestimation in tumor size assessment with US and FFDM has to be taken into consideration while planning surgical procedures for BC-Mp.

Genetic analysis of low-grade adenosquamous carcinoma of the breast progressing to high-grade metaplastic carcinoma

PURPOSE

Low-grade adenosquamous carcinoma (LGASC) is a rare type of metaplastic carcinoma of the breast (MBC) with an indolent clinical course. A few LGASC cases with high-grade transformation have been reported; however, the genetics underlying malignant progression of LGASC remain unclear.

METHODS

We performed whole-genome sequencing analysis on five MBCs from four patients, including one case with matching primary LGASC and a lymph node metastatic tumor consisting of high-grade MBC with a predominant metaplastic squamous cell carcinoma component (MSC) that progressed from LGASC and three cases of independent de novo MSC.

RESULTS

Unlike de novo MSC, LGASC and its associated MSC showed no TP53 mutation and tended to contain fewer structural variants than de novo MSC. Both LGASC and its associated MSC harbored the common GNAS c.C2530T:p.Arg844Cys mutation, which was more frequently detected in the cancer cell fraction of MSC. MSC associated with LGASC showed additional pathogenic deletions of multiple tumor-suppressor genes, such as KMT2D and BTG1. Copy number analysis revealed potential 18q loss of heterozygosity in both LGASC and associated MSC. The frequency of SMAD4::DCC fusion due to deletions increased with progression to MSC; however, chimeric proteins were not detected. SMAD4 protein expression was already decreased at the LGASC stage due to unknown mechanisms.

CONCLUSION

Not only LGASC but also its associated high-grade MBC may be genetically different from de novo high-grade MBC. Progression from LGASC to high-grade MBC may involve the concentration of driver mutations caused by clonal selection and inactivation of tumor-suppressor genes.

Spindle cell carcinoma of male breast: Report of a rare case

ABSTRACT

We report a rare case of spindle cell carcinoma, a histological subtype of metaplastic breast carcinoma, in a 40-year-old male who presented with an ulcero-proliferative lump in the right breast. Fine-needle aspiration cytology of the lesion showed poorly cohesive clusters of pleomorphic spindle-shaped cells, suggestive of malignant spindle cell tumor. Right mastectomy along with ipsilateral lymph node dissection was performed. Microscopic evaluation revealed a neoplasm comprising interlacing fascicles of oval to spindled pleomorphic cells with brisk mitosis and areas of necrosis. There was no nodal metastasis. Immunohistochemistry revealed a triple-negative phenotype along with diffuse positivity for CK5/6, vimentin, and smooth muscle actin. p63, beta-catenin, and CD34 were negative. The patient subsequently received adjuvant chemotherapy with 5-fluorouracil, adriamycin, and cyclophosphamide regimen and was disease-free at 1-year follow-up.

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.

Metaplastic breast carcinoma: Analysis of clinical and pathologic features, a five-year study

Background

Metaplastic carcinoma breast (MCB) is a rare tumor comprising of both glandular and non-glandular patterns with epithelial and or mesenchymal components. Due to their varied clinicomorphological features, diagnosis has been challenging.

Aim

To study the clinicopathological and histomorphology of cases of metaplastic carcinoma breast diagnosed in a tertiary care hospital along with literature review.

Materials and Methods

This is a retrospective study including data of 11 patients who were diagnosed with MCB either on trucut or mastectomy specimens conducted between January 2014 and December 2018.

Results

The study includes 11 patients, out of which 10 were diagnosed on mastectomy while one on trucut specimen. All the patients were women with the mean age of presentation being 43.8 years. The most common presentation was palpable breast lump with mean tumor size of 7.3 cm in greatest dimension. Skin involvement was seen in 36.3% of cases. While eight cases (72.7%) were classified as epithelial, three (27.2%) were classified as mixed. Amongst epithelial variety, in eight cases, squamous component was seen along with infiltrating ductal carcinoma (IDC) while one was pure squamous type. In mixed variety, one case showed spindled areas along with squamous areas and areas of IDC. Other two showed focal sarcomatous and cartilaginous areas in one and angiosarcomatous, bone and cartilage formation admixed with areas of IDC in other case.

Conclusion

MCB are rare breast tumors with aggressive course and are characterized by their large size and rapid growth rate. Recently, there has been an upsurge in the cases of MCB due to increase in recognition of this entity. It has to be distinguished from other tumors by the pathologists so as to guide proper treatment.

The conundrum of metaplastic breast cancer: a single Egyptian institution retrospective 10-year experience (2011-2020)

BACKGROUND

Metaplastic breast cancer (MetBC) still represents a conundrum owing to its peculiar histogenesis and molecular drivers that render it extremely resistant to standard chemotherapy with ultimate dismal survival.

AIM

Describe the Egyptian National Cancer Institute's (NCI-E) experience with MetBC regarding its clinicopathologic features, treatment, and survival outcomes.

PATIENTS AND METHODS

Between 2011 and 2020, all MetBC patients presented to NCI-E were retrospectively evaluated. Original clinicopathologic data, therapeutic modalities, pathologic response to neoadjuvant chemotherapy (NACT), recurrence, and date of last follow-up/death were obtained from archived charts.

RESULTS

A cohort of 135 females, the median age was 52 years, and median follow-up period was 40 months (range: 2.6-130.8). Two-thirds were triple negative (TN). Squamous carcinoma was prevalent in 74.8% followed by carcinoma with osseous/chondroid differentiation, spindle cell, and low-grade adenosquamous carcinoma encountered in 13.3, 7.4, and 4.5%, respectively. Modified radical mastectomy was done in 59.3%, and positive nodes (pN+) were depicted in 37.7%. Median Ki-67 was 45% (range: 10-88); grade III and lymphovascular invasion (LVI) were observed in 83.7 and 43.7%, respectively. Stage II was the most common (49%), whereas initial stage IV was encountered in 8.1%. Anthracyclines/taxane combinations were rampant in adjuvant/neoadjuvant settings. The latter was employed in 41 patients, with only 3 cases (7.3%) achieving pathologic complete response (pCR), while moderate/significant residual tumor burden was found in 83%. The 5-year DFS and OS were 56.4 and 57.6%, respectively. Spindle cell carcinoma showed the worst survival parameters in univariate analysis. On the multivariate level, higher tumor stage (pT3 & 4), Ki-67 ≥ 45%, and TN subtype were independent variables for worse DFS and OS; age ≥ 52 years and the presence of LVI were independent features for worse DFS, whereas pN+ was an independent parameter for worse OS.

CONCLUSIONS

This study further solidifies the dreadful response of MetBC to conventional chemotherapy regimens employed in common non-metaplastic pathologies. A radical shift in treatment standards tailored to combat the molecular landscape of this distinctive tumor is urgently needed. Immunotherapy and molecularly targeted agents demonstrated promising results in phase I and II trials with hopeful sooner implementation in phase III studies.

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.

Metaplastic breast cancer: A review

Metaplastic breast cancer (MpBC) is an uncommon aggressive malignancy that is associated with a poor prognosis. Due to its rarity, the relationships between the clinical and pathological features of MpBC, treatment approach, and clinical outcomes remain underexplored. In the following review article, we synthesize the existing data on the clinical, pathological and genomic features, management, and outcomes of MpBC. We also identify potential targets for future clinical trials.

Molecular Classification of Breast Cancer: Relevance and Challenges

CONTEXT.—

Appropriate patient management requires precise and meaningful tumor classification. Breast cancer classification continues to evolve from traditional morphologic evaluation to more sophisticated systems with the integration of new knowledge from research being translated into practice. Breast cancer is heterogeneous at the molecular level, with diversified patterns of gene expression, which is presumably responsible for the difference in tumor behavior and prognosis. Since the beginning of this century, new molecular technology has been gradually applied to breast cancer research on issues pertinent to prognosis (prognostic signature) and therapeutic prediction (predictive signature), and much progress has been made.

OBJECTIVE.—

To summarize the current state and the prospective future of molecular classification of breast cancer.

DATA SOURCES.—

Sources include recent medical literature on molecular classification of breast cancer.

CONCLUSIONS.—

Identification of intrinsic tumor subtypes has set a foundation for refining the breast cancer molecular classification. Studies have explored the genetic features within the intrinsic cancer subtypes and have identified novel molecular targets that led to the innovation of clinical assays to predict a patient's prognosis and to provide specific guidelines for therapeutic decisions. With the development and implication of these molecular tools, we have remarkably advanced our knowledge and enhanced our power to provide optimal management to patients. However, challenges still exist. Besides accurate prediction of prognosis, we are still in urgent need of more molecular predictors for tumor response to therapeutic regimes. Further exploration along this path will be critical for improving a patient's prognosis.

Differences between complex epithelial neoplasms of the ovary and high-grade serous ovarian cancer: a retrospective observational cohort study

BACKGROUND

Complex epithelial neoplasms of the ovary (CENO), an uncommon pathological histotype in ovarian cancer, comprises adenosquamous carcinoma and adenocarcinoma with metaplasia. Owing to the rarity of relevant reports, there are currently no statistics on outcomes based on large samples. Meanwhile high-grade serous ovarian cancer (HGSOC) is the most common histotype in ovarian cancer which has a recognized first-line treatment regimen and poor prognosis. Thus, we aimed to determine the characteristics, prognosis, and independent predictors of survival for CENO, compare them with those of HGSOC and construct prognostic predictive models and nomograms.

METHODS

We used the Surveillance, Epidemiology, and End Results (SEER) database to determine patients diagnosed with CENO or HGSOC from 2000 to 2017. Clinical, demographic, and treatment characteristics were compared between these groups. Propensity score matching, Cox risk regression analysis, Kaplan-Meier survival curves, and the Least Absolute Shrinkage and Selection Operator regression analysis were employed for analyzing the data.

RESULTS

Here, 31,567 patients with HGSOC and 216 patients with CENO between 2000 and 2017 in the SEER database were enrolled. Age < 57 years, unmarried, and early-stage diseases were more common in patients with CENO than in those with HGSOC. Women with CENO were less likely to receive adjuvant chemotherapy (65.7% vs. 79.4%) but more likely to receive radiotherapy (6.0% vs. 0.8%; both p < 0.001) than those with HGSOC. Year of diagnosis, surgery status, number of primary tumors, grade, and FIGO stage were independent prognostic factors for overall and cancer-specific survival in CENO. Overall survival rates were significantly lower for CENO than for more malignant HGSOC.

CONCLUSIONS

In summary, CENO was rare in ovarian cancer, while the year of diagnosis, surgery status, number of primary tumors, grade, and FIGO stage were independent prognostic factors. Compared with other common malignant ovarian tumors, CENO had a poor prognosis. Prognostic predictive models and nomograms had been determined to predict the individual survival rates of patients with CENO. These methods could improve evaluations of survival and therapeutic decisions for patients.

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.

Prognostic relevance of mixed histological subtypes in invasive breast carcinoma: a retrospective analysis

Purpose

The prognostic and therapeutic power of special histological subtypes in breast cancer in pure form or in combination with other histological subtypes is still not established, and diagnostic guidelines are cautious regarding prognostic power based on the histological subtype alone. Therapy decisions are guided in most cases independently of the histological subtype and are directed by biomarkers and tumor stage. In this study, we analyzed a comprehensive large retrospective breast cancer cohort with a special focus on histological subtype (other than ductal non-special type or lobular carcinoma) and correlated pure or mixed histological forms with pathological tumor stage and overall disease-free survival.

Materials and methods

A total of 827 breast cancer cases with pure or mixed special histological types were retrospectively analyzed. Survival information was available in 645 of 827 cases.

Results

A total of 293 cases had pure forms, and 534 cases had mixed histological subtypes. The most common pure special types were mucinous (23.9%), micropapillary (21.2%), high-grade metaplastic (13%), male breast cancer (8.2%), cribriform (6.8%), metastases (6.1%), apocrine and papillary (each 5.46%), NST with medullary and clear cell pattern (up to 3.4%) and high-grade neuroendocrine carcinomas (2.7%). Mixed forms were most frequently encountered in NST carcinomas with micropapillary components (41.8%), followed by mucinous (9.93%) and cribriform (6.74%) mixed patterns. In univariate analysis, no pure form had prognostic relevance compared with any mixed form with the basic pure element. Pooling pure histological subtypes with tumor stage and age in a linear random-effects model, the cribriform subtype had the most favorable prognosis, while male breast cancer showed the poorest outcome (p < 0.001). All other frequent pure forms had intermediate prognostic power (p < 0.001).

Conclusion

Our results show that the analyzed special histological breast cancer subtypes (other than ductal and lobular carcinomas) do not carry prognostic information alone, either in pure form or in any combination with other subtypes. Prognostic groups including special subtypes, however, can strongly stratify breast cancer if tumor stage, age and biomarkers are included in the prognostic measurements.

Clinicopathologic Features of Metaplastic Breast Carcinoma: Experience From a Tertiary Cancer Center of North India

Introduction

Metaplastic breast cancer (MBC) is a rare malignancy that accounts for < 1% of all breast cancers. The aim of this study is to evaluate the clinicopathologic characteristics of MBC patients treated at a tertiary cancer center.

Materials and methods

In this study, the authors retrospectively analyzed the prospectively maintained data of MBC patients treated at a tertiary cancer care center in North India between January 2019 and July 2022.

Results

A total of 28 MBCs were identified. The median age of presentation was 47 years (range 27-81 years). Seventeen patients (60.7%) presented with clinical T3/T4 disease, and axillary nodal involvement was detected in 11 patients (39.3%) at presentation. Two patients had metastatic disease at presentation. A preoperative diagnosis of MBC on core biopsy was attained in five patients (17.9%), and the most common histologic subtype was sarcomatoid carcinoma. Triple-negative receptor status was observed in 15 patients (53.6%). Six patients (21.4%) underwent upfront breast conservation surgery and another six (21.4%) upfront mastectomy. Thirteen patients (46.4%) underwent mastectomy following neoadjuvant therapy. Definitive axillary nodal metastasis was found in eight patients (32%). Following neoadjuvant chemotherapy, five patients (35.7%) had stable disease, disease progression was evident in five patients (35.7%), partial response in four patients (28.6%), and no patient evinced complete response. Adjuvant postoperative radiation therapy was administered in 16 patients (57.1%). At a median follow-up of 13.2 months (range 4-26 months), 16 patients (57.1%) were alive with no evidence of disease, one patient (3.6%) was alive with disease, nine patients (32.1%) died of disease, and two patients (7.2%) died of other causes. One patient suffered from locoregional recurrence and nine patients developed distant metastasis.

Conclusion

MBC is an infrequent entity among breast carcinomas in India, which is similar to the reports of MBC worldwide. The diagnosis of MBC is difficult and requires the use of immunohistochemistry. Most of the cases in our study presented with a larger tumor size; however, they displayed a relatively lower incidence of nodal involvement as well as hormone receptor negativity. Being a rare and heterogeneous disease, large-scale studies are essential for better understanding and management of these tumors.

Metaplastic breast cancers and triple-negative breast cancers of no special type: are they prognostically different? A systematic review and meta-analysis

BACKGROUND AND AIMS

Metaplastic breast cancer (MBC) and triple-negative (TN) BC of no special type are often confounded with each other in terms of survival and prognosis. In this systematic study and meta-analysis, we evaluated the prognosis of each of these two different diagnoses.

METHODS

We conducted a systematic literature search and review using the MOOSE guidelines, through PUBMED database, the Ovid MEDLINE database, and the ISI Web of Science Citation Index Expanded (SCI Expanded). Overall survival (OS) and disease-free survival (DFS) were the main outcomes considered.

RESULTS

Our review eventually selected six independent studies, with a total of more than 59 519 patients. MBC was found to associate with worse OS compared to TNBC of no special type, with a significant 40% increased risk of death [summary hazard ratio (SHR) = 1.40, 95% confidence interval (CI): 1.30-1.50]. We found neither heterogeneity ( I2 = 0%) nor evidence of publication bias ( P = 0.82 and P = 0.49 by Begg's and Egger's test, respectively) between studies. No statistically significant difference was found between MBC and TNBC of no special type in terms of DFS (SHR = 1.17, 95% CI: 0.80-1.71).

CONCLUSION

This study demonstrates that TNBC of no special type and MBC have comparable DFS, although the latter presents a significantly worse prognosis in terms of OS. Despite DFS being similar in both subtypes, this did not result in significant OS benefits, with MBC score being the worse of the two diseases.

Metaplastic Breast Carcinoma in a 37-Year-Old Female: A Case Report

Metaplastic breast carcinoma (MBC) is a rare and aggressive histologic subtype of cancer. Because of its rarity and heterogeneity, the management of these patients is challenging. Here, we present the case of a rapidly progressive MBC with mesenchymal differentiation in a 37-year-old female, treated with trimodal therapy consisting of neoadjuvant chemotherapy with paclitaxel and carboplatin, followed by dose-dense cyclophosphamide and doxorubicin (ddAC), modified radical left mastectomy, and adjuvant radiotherapy. Despite the need to anticipate the surgery after the first cycle of ddAC, because of a life-treating adverse event, there was a pathologic complete response. Nevertheless, 6.2 months after completing adjuvant radiotherapy, the patient had a recurrence on the central nervous system (CNS) (two lesions), which was managed with excisional biopsy and stereotactic body radiation therapy. The patient also started “complementary” chemotherapy with capecitabine. Still, 18 months after being diagnosed, she died due to CNS disease progression.

Breast Metaplastic Carcinoma With Osteosarcomatous Differentiation: A Case Report and literature Review

Metaplastic breast carcinoma (MBCs) is a rare heterogeneous group of malignancies. Herein, we report a case of metaplastic breast carcinoma, which had 2 components. One of them was typical invasive ductal carcinoma (IDC), the other one was presenting as osteosarcoma with lots of immature trabeculae. The results of immunohistochemistry showed different presentations between them. The majority of MBCs show triple-negativity for ER, PR, and HER-2 and are thus associated with poor prognosis. Our report shows that, it is necessary to describe the proportion of the components and the presentations of immunohistochemistry in the diagnosis, which will be important to develop specific and effective therapies.

Survival in metaplastic breast carcinoma: A case series

BACKGROUND

Metaplastic breast carcinoma (MBC) is a rare type of breast cancer (0.20-1.00% of all cases). With a more aggressive clinical course, MBC frequently presents as a triple-negative subtype.

OBJECTIVE

To describe a case series, analyzing patients survival in four MBC cases.

METHODS

The cases were obtained from 532 medical records of breast cancer patients (0.7% of the total).

RESULTS

All patients were female. Mean patient age was 49 years (range: 38-60 years). Mean tumor size was 8.9 cm (range: 3.0-15.5 cm). Mastectomy was performed in three cases. One patient had axillary nodal metastasis. All underwent chemotherapy and three received radiation therapy after surgery.

CONCLUSIONS

With a mean follow-up of 36 months (range: 10-60 months), one case had a tumor recurrence (25%). Three patients (75%) died from metastatic disease and one (25%) is still alive and free of disease.

The CCN axis in cancer development and progression

Since the authors first reviewed this subject in 2016 significant progress has been documented in the CCN field with advances made in the understanding of how members of the CCN family of proteins, CCN1-6, contribute to the pathogenesis and progression, positive and negative, of a larger variety of cancers. As termed matricellular proteins, and more recently the connective communication network, it has become clearer that members of the CCN family interact complexly with other proteins in the extracellular microenvironment, membrane signaling proteins, and can also operate intracellularly at the transcriptional level. In this review we expand on this earlier information providing new detailed information and insights that appropriate a much greater involvement and importance of their role in multiple aspects of cancer. Despite all the new information many more questions have been raised and intriguing results generated that warrant greater investigation. In order to permit the reader to smoothly integrate the new information we discuss all relevant CCN members in the context of cancer subtypes. We have harmonized the nomenclature with CCN numbering for easier comparisons. Finally, we summarize what new has been learned and provide a perspective on how our knowledge about CCN1-6 is being used to drive new initiatives on cancer therapeutics.

Metaplastic breast carcinoma with extensive osseous differentiation

Metaplastic breast carcinoma is a rare subtype of invasive breast carcinoma. Metaplastic carcinoma with osseous differentiation is exceptionally uncommon. Because of the heterogenous microscopy of the lesion, various clinical and radiological features are observed, leading to diagnostic difficulty. Herein, we present a case of a 43-year-old female with a recurrent breast lump, who was clinically diagnosed as a phyllodes tumor. However, histopathological examination revealed metaplastic carcinoma with extensive osseous differentiation.

Metaplastic carcinoma of the breast: Clinicopathological features and treatment outcomes with long-term follow up

Metaplastic breast carcinoma is an uncommon subtype of invasive ductal carcinoma with a tendency towards poorer clinical outcomes. Following ethical approval, the current study reviewed the institutional records of ~2,500 women with breast cancer. A total of 14 cases of metaplastic breast cancer were reviewed for management and treatment outcomes. The results demonstrated that patients had median follow up of 30 months, a 5-year disease-free survival of 57.1% and 5-year overall survival of 57.1%. The majority of patients had at least T2 disease and all tumours were high grade. Additionally, most patients were triple negative and nodal metastases were uncommon. Metaplastic breast cancer is an aggressive variant of invasive breast cancer. Most patients can be treated with breast conservation and survival parameters tend to be worse than more common breast cancer subtypes.

Role of Matricellular CCN Proteins in Skeletal Muscle: Focus on CCN2/CTGF and Its Regulation by Vasoactive Peptides

The Cellular Communication Network (CCN) family of matricellular proteins comprises six proteins that share conserved structural features and play numerous biological roles. These proteins can interact with several receptors or soluble proteins, regulating cell signaling pathways in various tissues under physiological and pathological conditions. In the skeletal muscle of mammals, most of the six CCN family members are expressed during embryonic development or in adulthood. Their roles during the adult stage are related to the regulation of muscle mass and regeneration, maintaining vascularization, and the modulation of skeletal muscle fibrosis. This work reviews the CCNs proteins' role in skeletal muscle physiology and disease, focusing on skeletal muscle fibrosis and its regulation by Connective Tissue Growth factor (CCN2/CTGF). Furthermore, we review evidence on the modulation of fibrosis and CCN2/CTGF by the renin-angiotensin system and the kallikrein-kinin system of vasoactive peptides.

Metaplastic breast cancer: an old histotype but a current therapeutic problem

Metaplastic breast cancer (MPBC) is a rare and aggressive tumor type in great need of satisfactory therapies. Although most cases of MPBC are 'triple negative', they are nonetheless related to worse outcomes compared with other triple-negative invasive tumors. MPBC presents high levels of genetic and molecular heterogeneity, suggesting that novel targeted therapies can be exploited. Overexpression of PD-L1 and high levels of tumor-infiltrating lymphocytes have also been observed in these tumors, suggesting a role for immunotherapy. We present an updated literature revision on clinical, histopathological and molecular features of MPBC and their significance to prognosis and therapy options. We discuss emerging efforts to improve and personalize prognostic and therapeutic approaches, exploiting the molecular signature of MPBC with targeted therapies and immunotherapies.

Subcellular localization of EZH2 phosphorylated at T367 stratifies metaplastic breast carcinoma subtypes

BACKGROUND

Metaplastic carcinoma is an aggressive, triple-negative breast cancer (TNBC) with differentiation towards squamous, spindle, or mesenchymal cell types. The molecular underpinnings of the histological subtypes are unclear. Our lab discovered a cytoplasmic function of EZH2, a transcriptional repressor, whereby pEZH2 T367 binds to cytoplasmic proteins in TNBC cells and enhances invasion and metastasis. Here, we investigated the expression and subcellular localization of pEZH2 T367 protein in metaplastic carcinomas.

METHODS

Thirty-five metaplastic carcinomas (17 squamous, 10 mesenchymal, and 8 spindle) were evaluated and immunostained with anti-pEZH2 T367. We analyzed staining intensity (score 1-4), subcellular localization (nuclear/cytoplasmic), and localization within the tumor (center/invasive edge). Protein expression of pEZH2 T367-binding partners was measured from a quantitative multiplex proteomics analysis performed in our lab.

RESULTS

Cytoplasmic pEZH2 T367 was significantly upregulated in squamous (14 of 17, 82%) compared to mesenchymal (4 of 10, 40%) and spindle (2 of 6, 33%) subtypes (p = 0.011). Twenty-five of 34 (73%) tumors with available tumor-normal interface showed accentuated cytoplasmic pEZH2 T367 at the infiltrative edge. Cytoplasmic pEZH2 T367 was upregulated in 9 of 10 (90%) tumors with lymph node metastasis (p = 0.05). Bioinformatics analyses identified an EZH2 protein network in metaplastic carcinomas (p value: < 1.0e-16). Using quantitative proteomics, we found significantly increased expression of cytoplasmic EZH2-binding partners in squamous compared to spindle and mesenchymal subtypes.

CONCLUSIONS

pEZH2 T367 expression and subcellular localization may be useful to distinguish metaplastic carcinoma subtypes. pEZH2 T367 may play a role in the histological diversity and behavior of these tumors.

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

Metaplastic breast cancer (MpBC) is an exceedingly rare breast cancer variant that is therapeutically challenging and aggressive. MpBC is defined by the histological presence of at least two cellular types, typically epithelial and mesenchymal components. This variant harbors a triple-negative breast cancer (TNBC) phenotype, yet has a worse prognosis and decreased survival compared to TNBC. There are currently no standardized treatment guidelines specifically for MpBC. However, prior studies have found that MpBC typically has molecular alterations in epithelial-to-mesenchymal transition, amplification of epidermal growth factor receptor, PI3K/Akt signaling, nitric oxide signaling, Wnt/β-catenin signaling, altered immune response, and cell cycle dysregulation. Some of these molecular alterations have been studied as therapeutic targets, in both the preclinical and clinical setting. This current review discusses the histological organization and cellular origins of MpBC, molecular alterations, the role of radiation therapy, and current clinical trials for MpBC.

Descriptive study of the histopathological subtypes and programmed death-ligand 1 in metaplastic breast carcinoma

Metaplastic Breast Carcinoma (MBC) is a rare heterogeneous group of tumors, the incidence of which is less than 1% of breast tumors. These are a unique set of tumors with varying subtypes, poor prognosis, and an increased chance of distant metastasis. We aimed to study the clinical, histomorphological, and immunohistochemical (IHC) features of Metaplastic Breast Carcinoma (MBC). This was a descriptive study of cases diagnosed as MBC at a tertiary care center in Southern India from January 2015 to December 2019. A total of 20 cases were diagnosed whose clinical, histomorphological, and IHC features were studied. PD-L1and CD8 IHC were performed and analyzed in 12 cases. The median age of presentation was 50 years. Seventy percent (14/20) patients were postmenopausal women. On excision, 75% (15/20) showed mixed typed MBC, the remainder showing epithelial type MBC. Metastasis to axillary lymph node was seen only in 20% (4/20) of the cases. Thirty percent (6/20) of the cases belonged to stage 3 disease and 5% (1/20) of the cases belonged to stage 4 disease with liver metastasis. Estrogen receptor (ER), Progesterone receptor (PR) were negative in all the cases, Her2neu was positive in three cases. Ki67 labeling index was greater than 14% in all the cases. PD-L1was positive in 41.5% of the cases and intratumoral CD8 positive lymphocytes were increased in 83.3% of the cases. MBCs are tumors occurring in elderly postmenopausal women, presenting with large tumor size, have lesser chances of lymph node metastasis, and a higher chance of recurrence and hematogenous spread. They are negative for ER, PR, Her-2 neu, with a high Ki67 index and a strong PDL-1 expression.

Best Practice (Efficient) Immunohistologic Panel for Diagnosing Metaplastic Breast Carcinoma

Immunohistochemistry (IHC) plays a key role in the diagnosis of metaplastic breast carcinomas (MBCs), particularly the spindle cell variant. The most efficient immunopanel has yet to be developed. We studied the immunoprofile of 45 MBCs including 23 matrix-producing MBCs, 11 squamous cell carcinomas, 6 spindle cell carcinomas, and 5 mixed-subtypes (2 cases including spindle cell components). Representative sections from mastectomy or core biopsy specimens were subject to IHC using a list of antibodies including OSCAR, a recently developed antibody against pooled cytokeratins. The staining was interpreted as positive when >1% of tumor cells demonstrated unequivocal staining. As a result, OSCAR showed similar sensitivity to AE1/AE3 and CAM 5.2 (89.1% vs. 89.4% vs. 89.4%) for MBCs, but the former showed more diffuse pattern of staining, particularly in spindle cell carcinomas. High molecular weight cytokeratin CK14, CK5, and CK17 were positive in 91.3%, 87.2%, and 73.3% of MBCs, respectively. CK7 was much less likely to be positive in spindle cell carcinomas (37.5%) than in other variants of MBCs (97.4%). P63 and CK14 were the most useful markers for spindle cell carcinomas, positive in 87.5% and 85.7% of cases, respectively. GATA 3 was positive in 63% MBCs, and nonspecific staining for vimentin and smooth muscle actin were common. Random combination of up to 3 antibodies against keratins including p63 showed sensitivities ranging from 80.9% to 97.9%. Our results suggested the combination of OSCAR, CK14 and p63 is the most efficient panel (sensitivity 97.9%) for diagnosing MBCs.

When Something Seems Amiss: Radiology-Pathology Correlation of Metaplastic Breast Cancer

Metaplastic breast cancer is difficult to diagnose, resistant to conventional treatment, and biologically aggressive. A suspicious timeline and discordance between imaging findings and histopathologic tissue diagnosis should trigger additional workup. New, large lesions or rapidly growing lesions with complex echogenicity on ultrasound warrant correlation with image-guided biopsy for a definitive diagnosis. Lesions that appear aggressive on imaging, with negative biopsy findings, may represent false negatives due to sampling bias from intratumoral heterogeneity. In such cases, it may be advisable to obtain an excisional biopsy. These tumors are known to progress even with neoadjuvant chemotherapy. Immunotherapy, however, may be effective even for metastatic disease. A multidisciplinary approach and a high index of suspicion may, therefore, confer survival benefits in circumstances where the imaging phenotype does not fit with the timeline or pathologic diagnosis. This report describes five cases of metaplastic breast cancer diagnosed at our institution to highlight the importance of a timely and accurate diagnosis of this rare but aggressive breast malignancy.