Comparison of outcomes between metaplastic and triple-negative breast cancer patients

A comprehensive overview of metaplastic breast cancer: Features and treatments

Metaplastic breast cancer is a rare, aggressive, and chemotherapy-resistant subtype of breast cancers, accounting for less than 1% of invasive breast cancers, characterized by adenocarcinoma with spindle cells, squamous epithelium, and/or mesenchymal tissue differentiation. The majority of metaplastic breast cancers exhibit the characteristics of triple-negative breast cancer and have unfavorable prognoses with a lower survival rate. This subtype often displays gene alterations in the PI3K/AKT pathway, Wnt/β-catenin pathway, and cell cycle dysregulation and demonstrates epithelial-mesenchymal transition, immune response changes, TP53 mutation, EGFR amplification, and so on. Currently, the optimal treatment of metaplastic breast cancer remains uncertain. This article provides a comprehensive review on the clinical features, molecular characteristics, invasion and metastasis patterns, and prognosis of metaplastic breast cancer, as well as recent advancements in treatment strategies.

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.

Chemotherapy is of prognostic significance to metaplastic breast cancer

This study aimed to evaluate the significance of chemotherapy (CT) among metaplastic breast cancer (MpBC), and to compare the survival outcomes between triple negative MpBC (MpBC-TNBC) and triple negative invasive ductal carcinoma (IDC-TNBC). SEER database was indexed to identify female unilateral primary MpBC diagnosed from 2010 to 2017. Patients were classified into neoadjuvant chemotherapy (NAC) with response (NAC-response), NAC-no response, adjuvant chemotherapy, and no CT. Breast cancer-specific survival (BCSS) and overall survival (OS) was estimated using the Kaplan-Meier method and compared by log-rank test. Cox regression was used to evaluate the independent prognostic factors. A 1:4 propensity score matching method was adopted to balance baseline differences. Altogether 1186 MpBC patients were enrolled, among them 181 received NAC, 647 received adjuvant CT and 358 did not receive any CT. Chemotherapy was an independent favorable prognostic factor. NAC-response and adjuvant CT had a significant or an obvious trend of survival improvement compared with NAC-no response or no CT. MpBC-TNBC was an independent unfavorable prognostic factor compared with IDC-TNBC. Among them, there was significant or trend of survival improvement among all TNBCs receiving NAC or adjuvant CT compared with no CT. Chemotherapy was of important significance to MpBC prognosis and should be integrated in comprehensive treatment for MpBC.

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.

Trends of incidence and mortality in metaplastic breast cancer and the effect of contralateral prophylactic mastectomy: A population-based study

INTRODUCTION

Metaplastic breast cancer (MBC) is considered rare and aggressive. We examined the epidemiology of and prognostic factors for MBC and investigated the effect of contralateral prophylactic mastectomy (CPM), because neither had been thoroughly examined previously.

METHODS

We obtained data from the Surveillance, Epidemiology, and End Results (SEER)-18(2000-2018) for epidemiological and survival analysis.

RESULTS

The age-adjusted incidence per 100,000 persons of MBC increased significantly from 0.12 to 0.35 [annual percent change (APC):2.95%, 95% confidence interval [CI], 1.73-4.19]. The incidence-based mortality increased from 0.01 to 0.12 (APC: 5.01%, 95% CI: 2.50-7.58). The incidence of MBC patients who underwent CPM significantly increased from 0.003 to 0.039 with an APC of 10.96% (95%CI, 7.26-14.78). Older patients and those with higher T classification were less likely to receive CPM. The multivariate Cox model showed that CPM was not an independent predictor of good prognosis for both overall survival (OS) and breast cancer-specific survival (BCSS) (pre-propensity score matching (PSM): OS: P = 0.331; BCSS: P = 0.462. post-PSM: OS: P = 0.916; BCSS: P = 0.967). Subgroup analysis showed that CPM still did not provide a survival benefit to any risk groups.

CONCLUSION

In this study, we demonstrated that the incidence and incidence-based mortality of MBC have increased over the past decades. Although the number of MBC patients who underwent CPM has significantly increased recently, CPM did not confer a survival benefit compared with unilateral mastectomy, indicating that the decision to undergo CPM should be considered carefully.

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.

Metaplastic Breast Carcinoma: Clinicopathologic Features and Recurrence Score Results From a Population-based Database

OBJECTIVES

Metaplastic breast carcinoma (MBC) is a rare, aggressive form of cancer comprising epithelial and mesenchymal elements. The purpose of this study was to use population-based data to review the clinicopathologic, molecular features, and outcomes of MBC.

METHODS

Surveillance, Epidemiology, and End Results Program (SEER) data were used to identify MBC and invasive ductal carcinoma (IDC), no special type (NOS) between 2004 and 2015. Results from Oncotype DX's 21-gene assay linked to SEER registries were included for hormone receptor (HR)-positive tumors. χ 2 analysis was performed to determine the differences between MBC and IDC. Kaplan-Meier curves and multivariate Cox proportional hazards models were used for breast cancer specific death (BCSD).

RESULTS

Compared with IDC, NOS (n=509,864), MBC (n=3876) were more likely to present at an older age, be black, have negative lymph nodes, be >2 cm, grade 3, and triple negative (TN). All subtypes [HR-positive/human epidermal growth receptor 2 (HER2)-negative, HR-positive/HER2-positive, HR-negative/HER2-positive, and TN] had higher BCSD than IDC, NOS. 22.3% of MBC cases were HR-positive. HR-positive MBCs tested for a recurrence score (RS) 65% were high-risk compared with 16.8% of IDC, NOS. Within the MBC cohort, no significant differences in BCSD were identified with respect to different molecular subtypes. In a fully adjusted model, TN or HER2-positive status did not adversely affect BCSD compared with HR-positive MBC.

CONCLUSIONS

All molecular subtypes of MBC had a poorer prognosis compared with IDC, NOS. The different molecular subtypes of MBC did not affect the BCSD. HR-positive MBC patients had a significantly higher high-risk RS than IDC, NOS patients.

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.

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.

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.

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.

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.

Clinical Characteristics and Prognosis of Metaplastic Breast Cancer Compared with Invasive Ductal Carcinoma: A Propensity-Matched Analysis

BACKGROUND

Metaplastic breast cancer (MpBC) is an aggressive histologic type of breast cancer. Although MpBC has a poor prognosis and is responsible for a large proportion of breast cancer mortalities, the clinical features of MpBC compared with invasive ductal carcinoma (IDC) are not well known, and the optimal treatment has not been identified.

METHODS

We retrospectively reviewed medical records of 155 MpBC patients and 16,251 IDC cases who underwent breast cancer surgery in a single institution between January 1994 and December 2019. The two groups were matched 1:4 by age, tumor size, nodal status, hormonal receptor status, and HER2 status using propensity-score matching (PSM). Finally, 120 MpBC patients were matched with 478 IDC patients. Disease-free survival and overall survival of MpBC and IDC patients both before and after PSM were analyzed by Kaplan-Meier survival, and multivariable Cox regression analysis was performed to identify variables affecting long-term prognosis.

RESULTS

The most common subtype of MpBC was triple-negative breast cancer, and nuclear and histologic grades were higher than those of IDC. Pathologic nodal staging of the metaplastic group was significantly lower than that of the ductal group, and more frequent adjuvant chemotherapy was performed in the metaplastic group. Multivariable Cox regression analysis indicated that MpBC was an independent prognostic factor for disease-free survival (HR = 2.240; 95% CI, 1.476-3.399, p = 0.0002) and overall survival (HR = 1.969; 95% CI, 1.147-3.382, p = 0.0140). However, survival analysis revealed no significant difference between MpBC and IDC patients in disease-free survival (HR = 1.465; 95% CI, 0.882-2.432, p = 0.1398) or overall survival (hazard ratio (HR) = 1.542; 95% confidential interval (CI), 0.875-2.718, p = 0.1340) after PSM.

CONCLUSION

Although the MpBC histologic type had poor prognostic factors compared with IDC, it can be treated according to the same principles as aggressive IDC.

Metastatic Metaplastic Breast Cancer Successfully Treated with Adriamycin and Cisplatin

Metaplastic breast cancer (MBC) is characterized by the histological presence of a mixture of epithelial and mesenchymal-like elements. However, MBC responds poorly to chemotherapy. Due to its rarity, there is no well-defined treatment for MBC. Herein, we report the case of a 56-year-old woman who underwent a mastectomy and was diagnosed with MBC with osseous differentiation classified as pT4N0M1. After the operation, she was treated with adriamycin and cisplatin, which are standard osteosarcoma treatments, resulting in a partial response. However, to determine the proper chemotherapy treatment, knowledge of the metaplastic elements of the tumor is required.

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.

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.

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.

Molecular Characterization and Prospective Evaluation of Pathologic Response and Outcomes with Neoadjuvant Therapy in Metaplastic Triple-Negative Breast Cancer

PURPOSE

Metaplastic breast cancer (MpBC) is a rare subtype of breast cancer that is commonly triple-negative and poorly responsive to neoadjuvant therapy in retrospective studies.

EXPERIMENTAL DESIGN

To better define clinical outcomes and correlates of response, we analyzed the rate of pathologic complete response (pCR) to neoadjuvant therapy, survival outcomes, and genomic and transcriptomic profiles of the pretreatment tumors in a prospective clinical trial (NCT02276443). A total of 211 patients with triple-negative breast cancer (TNBC), including 39 with MpBC, received doxorubicin-cyclophosphamide-based neoadjuvant therapy.

RESULTS

Although not meeting the threshold for statistical significance, patients with MpBCs were less likely to experience a pCR (23% vs. 40%; P = 0.07), had shorter event-free survival (29.4 vs. 32.2 months, P = 0.15), metastasis-free survival (30.3 vs. 32.4 months, P = 0.22); and overall survival (32.6 vs. 34.3 months, P = 0.21). This heterogeneity is mirrored in the molecular profiling. Mutations in PI3KCA (23% vs. 9%, P = 0.07) and its pathway (41% vs. 18%, P = 0.02) were frequently observed and enriched in MpBCs. The gene expression profiles of each histologically defined subtype were distinguishable and characterized by distinctive gene signatures. Among nonmetaplastic (non-Mp) TNBCs, 10% possessed a metaplastic-like gene expression signature and had pCR rates and survival outcomes similar to MpBC.

CONCLUSIONS

Further investigations will determine if metaplastic-like tumors should be treated more similarly to MpBC in the clinic. The 23% pCR rate in this study suggests that patients with MpBC should be considered for NAT. To improve this rate, a pathway analysis predicted enrichment of histone deacetylase (HDAC) and RTK/MAPK pathways in MpBC, which may serve as new targetable vulnerabilities.

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.

Partial Response After Toripalimab Plus Anlotinib for Advanced Metaplastic Breast Carcinoma: A Case Report

Metaplastic breast carcinoma (MBC) is an aggressive subtype of breast cancer, accounting for <1%. The clinical outcome is unknown due to the lack of treatment options. Here, we present the case of a 58-year-old woman with advanced MBC, in which standard adjuvant chemotherapy was unsuccessful. In the second-line therapy, she received anti-angiogenic(anlotinib) therapy plus chemotherapy. Finally, she was subsequently treated with immunotherapy (toripalimab) combined anlotinib and achieved partial response (PR); thus, immunotherapy plus anti-angiogenic therapy might be a novel option for advanced MBC patients.

The Effect of HER2 Status on Metaplastic Breast Cancer A Propensity Score-Matched Analysis

BACKGROUND

The role of human epidermal growth factor receptor 2 (HER2) in metaplastic breast cancer (MBC) patients remains unclear. The present study aimed to evaluate the effect of HER2 status on MBC patients by propensity-score matching (PSM).

METHODS

The SEER data from 2010 to 2016 were extracted. The breast cancer-specific survival (BCSS) of MBC patients, diagnosed from 2001 to 2016, was compared using Kaplan-Meier analysis. The multivariate Cox proportional model between groups was performed. PSM was used to make 1:1 case-control matching.

RESULTS

We included 1887 patients with a median follow-up time of 28 months (range 1-83 months). 1749 (92.7%) and 138 (7.3%) patients presented in the HER2-negative group and HER2-positive group. 833 (44.1%) patients received post-mastectomy radiotherapy (PMRT). The HER2-positive group had younger patients, lower tumor grades, and more advanced tumor stages. The prognoses were related to age of diagnosis, race/ethnicity, TNM stage, and PMRT in multivariate Cox analysis. ER status and HER2 status had no impact on BCSS. In the Kaplan-Meier analysis, PMRT was associated with a better prognosis. Importantly, patients with HER2-negative status can benefit from PMRT, but not those with HER2-positive status. After PSM, on multivariate Cox analysis, the prognosis was related to HER2 status and PMRT. In the Kaplan-Meier analysis, PMRT was related to a better prognosis for HER2-negative patients.

CONCLUSIONS

Our findings supported that PMRT and HER2-positive status were associated with a better prognosis after PSM. However, HER2-negative, but not HER2-positive patients could benefit from PMRT.

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.

Presentation and survival by hormonal receptor status in metaplastic breast cancer: A propensity score-matched analysis

Background

Metaplastic breast cancer (MBC) is a rare and aggressive form of breast cancer. The effectiveness of chemotherapy (CT) for MBC remains controversial. The present study aimed to evaluate the efficacy of CT combined hormone receptor (HR) status on MBC patients with high risk (T1-4N2-3M0 and T4N0-1M0) by propensity-score matching (PSM).

Methods

A retrospective study was performed to analyze MBC from the SEER database. Breast cancer-specific survival (BCSS) was analyzed using the Kaplan–Meier curve. Cox proportional hazard models were used to assess BCSS. PSM was used to make 1:1 case-control matching.

Results

This study identified 3116 patients. The median follow-up time was 44 months (range, 1–321 months). About 62.5 % of patients received CT. 23.0 % of patients were HR-positive. Recurrence risk had a significant difference between the HR-negative and HR-positive groups. In the multivariable Cox regression model, CT had no benefit for MBC patients. HR status was not associated with a better prognosis. In subgroup analysis, the Kaplan–Meier analysis showed that HR-negative MBC with intermediate-risk benefited from CT. For HR-positive MBC, patients with intermediate and high risk also benefited from CT. After PSM, neither CT nor HR status was not related to better BCSS. Moreover, the use of CT could only improve the survival of HR-positive MBC patients with high risk.

Conclusion

PSM analysis showed that HR status was not associated with a better prognosis. CT was not a significant prognostic factor for prognosis. However, HR-positive MBC patients with high risk might benefit from CT.

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Metaplastic breast cancer (MBC) is a rare and aggressive form of breast cancer.

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Hormone receptor (HR) status was not associated with a better prognosis.

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Chemotherapy (CT) was not a significant prognostic factor for prognosis.

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HR-positive MBC patients with high risk might benefit from CT.

Clinicopathologic Characteristics and Outcome Descriptors of Metaplastic Breast Carcinoma

CONTEXT.—

Metaplastic breast carcinoma is an aggressive form of breast cancer that accounts for 0.5% to 3% of all breast cancers.

OBJECTIVE.—

To study the clinicopathologic characteristics and outcomes of this rare disease.

DESIGN.—

Retrospective study of patients with a diagnosis of metaplastic breast carcinoma between 2000 and 2019. Hematoxylin-eosin-stained slides were reviewed and additional clinical data were obtained from electronic medical records. Univariable and multivariable Cox proportional hazard regression analyses were used to determine associations between overall survival and several clinicopathologic variables.

RESULTS.—

Of the 125 patients with metaplastic breast carcinoma identified, only patients with high-grade disease (N = 115) were included in the data analysis. A total of 38 participants (33%) were white, 66 (57%) were African American, and 11 (10%) belonged to other ethnicities. The median age at diagnosis was 57 years. The median tumor size was 3 cm. Heterologous histology was seen in 30% of cases. Multivariable analyses showed that patients with a larger tumor size had worse overall survival (hazard ratio [HR], 1.25; 95% CI, 1.10-1.44; P < .001). Distant metastatic disease was also associated with worse overall survival on multivariable analysis (HR, 10.27; 95% CI, 2.03-55.54; P = .005). In addition to treatment with either partial or complete mastectomies, 84 patients (73%) received chemotherapy. Multivariable analyses showed that chemotherapy had no effect on overall survival (HR, 0.53; 95% CI, 0.09-6.05; P = .55).

CONCLUSIONS.—

A larger tumor size and distant metastatic disease are associated with worse overall survival in patients with metaplastic breast carcinoma. Additional studies are needed to further characterize our findings.

Benefit of adjuvant chemotherapy in patients with special histology subtypes of triple-negative breast cancer: a systematic review

PURPOSE

Breast cancer (BC) is a leading cause of morbidity, disability, and mortality in women, worldwide; triple-negative BC (TNBC) is a subtype traditionally associated with poorer prognosis. TNBC special histology subtypes present distinct clinical and molecular features and sensitivity to antineoplastic treatments. However, no consensus has been defined on the best adjuvant therapy. The aim of the review is to study the evidence from literature to inform the choice of adjuvant treatments in this setting.

METHODS

We systematically searched literature assessing the benefit of adjuvant chemotherapy in patients with TNBC special histotypes (PROSPERO: CRD42020153818).

RESULTS

We screened 6404 records (15 included). All the studies estimated the benefit of different chemotherapy regimens, in retrospective cohorts (median size: 69 patients (range min-max: 17-5142); median follow-up: 51 months (range: 21-268); mostly in Europe and USA). In patients with early-stage adenoid cystic TNBC, a marginal role of chemotherapy was reported. Similar for apocrine TNBC. Medullary tumors exhibited an intrinsic good prognosis with a limited role of chemotherapy, suggested to be modulated by the presence of tumor-infiltrating lymphocytes. A significant impact of chemotherapy on the overall survival was estimated in patients with metaplastic TNBC. Limitations were related to the retrospective design of all the studies and heterogeneous treatments received by the patients.

CONCLUSIONS

There is potential opportunity to consider treatment de-escalation and less intense therapies in some patients with early, special histology-type TNBC. International efforts are indispensable to validate prospective clinical decision models.

Metaplastic breast cancer with chondroid differentiation-case report and literature review

Metaplastic breast cancer (MBC) comprises less than 1% of all breast cancers, and it is defined by a mixture of adenocarcinoma plus mesenchymal and epithelial components. It is more common in older and black female patients. It has a larger size and faster growth, and it is frequently node-negative and triple-negative when compared with invasive ductal carcinoma. The authors report the case of a 72-year-old female patient, presenting with a breast lump, whose biopsy revealed a probable MBC with chondroid differentiation. She underwent a breast conservative surgery (BCS) and axillary sentinel lymph node dissection (SLND). The pathological report was concordant with the biopsy, and the patient was proposed to chemoradiotherapy. Despite its rarity and more severe features at diagnosis, BCS plus SLND plus radiotherapy should be offered to these patients, associated with chemotherapy. Chondroid differentiation is the rarest of all histological subtypes.

Metaplastic Breast Carcinoma: Experience of a Tertiary Cancer Center in the Middle East

Background:

Metaplastic breast cancer (MetBC) represents a therapeutic challenge. We evaluated the impact of clinicopathological characteristics and treatment modalities on outcomes among MetBC patients treated at our center.

Methods:

Women with stage I-III MetBC were reviewed from our database from 2005-2018. Kaplan-Meier method was used to calculate locoregional-failure-free survival (LRFFS), overall-survival (OS) and distant-metastases-free survival (DMFS). We assessed associations with survival outcomes by log-rank tests. Multivariate Cox proportional-hazards models were used to identify independent predictors of LRFFS, OS and DMFS.

Results:

81 patients were eligible for the study. Median age at diagnosis was 48 years. 90.1% had G-III tumors, 64.2% were pathologically node negative and lympho-vascular invasion (LVI) was absent in 72.8%. 67.8% were triple negative, and 7.4% were HER2-neu positive. Most (66.7%) patients underwent mastectomy. Free margins were achieved in the entire cohort, however, 17.3% had close margin (<2 mm). Almost all patients received chemotherapy. 75.3% received radiotherapy, 23.5% received hormonal therapy and 6.2% received Trastuzumab. With a median follow-up of 54 months, 18.5% developed loco-regional recurrence and 34.6% relapsed distally. Five-year OS was 66.0%. On multivariate analysis: adjuvant radiotherapy correlated with better OS (P < .0001), and tumor size >5 cm, nodal involvement and LVI correlated with worse OS, (P = .019, P = .021, P = .028, respectively). There were no survival differences with respect to age, triple negativity, and morphologic subtype.

Conclusion:

We report the largest single institutional series on MetBC in the Middle East region. MetBC confers worse survival outcomes, and more aggressive local and systemic treatment strategies should be investigated.

Clinical and Demographic Factors, Treatment Patterns, and Overall Survival Associated With Rare Triple-Negative Breast Carcinomas in the US

IMPORTANCE

Triple-negative breast cancers are known collectively to demonstrate a more aggressive clinical course and earlier recurrence than cancers of other histological subtypes. However, the literature on rare triple-negative breast cancers and the association of histological type with survival and risk of metastasis is sparse.

OBJECTIVE

To present the clinical and demographic characteristics, treatment patterns, and overall survival (OS) for histologically rare (<10% of breast cancers) triple-negative breast cancer types: medullary carcinoma, adenoid cystic carcinoma, and metaplastic breast carcinoma.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was performed in the US using data reported by the National Cancer Database between 2010 and 2016. Confirmed cases of medullary carcinoma, adenoid cystic carcinoma, and metaplastic breast cancer were analyzed. Univariable analyses and multivariable Cox regression models were performed. Data analysis was performed from April to May 2020.

MAIN OUTCOMES AND MEASURES

The primary outcome was 5-year OS. Secondary outcomes included site of metastasis, effect of immunohistochemistry, management, and 2-year mortality.

RESULTS

A total of 8479 patients with breast cancer (mean [SD] age; 62.6 [14.3] years; 8435 women [99.48%]) were analyzed. Metaplastic carcinoma was the most commonly diagnosed histological type in this cohort, with 6867 patients (81%), followed by 1357 (16%) with adenoid cystic carcinoma and only 255 (3%) with medullary carcinoma. Medullary carcinoma presented earlier in life, at a median (interquartile range) age of 53 (45-62) years, compared with 62 (53-72) years for patients with adenoid cystic carcinoma and 63 (52-74) years for patients with metaplastic carcinoma. The proportion of tumors with triple-negative immunohistochemistry varied by histological type for medullary carcinoma (57 patients [22.4%]), adenoid cystic carcinoma (653 patients [48.1%]), and metaplastic carcinoma (3637 patients [53.0%]). Patients with adenoid cystic carcinoma were less likely to receive radiotherapy (711 patients [52.4%]) and chemotherapy (175 patients [12.9%]) compared with patients with medullary carcinoma (radiotherapy, 156 patients [61.2%]; chemotherapy, 190 patients [74.5%]) and metaplastic carcinoma (radiotherapy, 3416 patients [49.7%]; chemotherapy, 4709 patients [68.6%]). The 5-year OS rate was superior for patients with medullary (91.7%) and adenoid cystic carcinoma (88.4%) compared with patients with metaplastic carcinoma (63.1%). The 5-year mortality rate for adenoid cystic carcinoma was 8.33% vs 36.91% for metaplastic carcinoma.

CONCLUSIONS AND RELEVANCE

Nationally, over the course of 7 years, medullary carcinoma was most common and metaplastic carcinoma had the worst 5-year OS among the rare histological breast cancer subtypes analyzed. Factors associated with a poor prognosis for metaplastic carcinoma included advanced stage, lung metastasis, older age, and not receiving chemotherapy or radiation therapy. Future research focusing on rare subtypes of breast cancer is desirable and could inform the optimal management of these relatively understudied carcinomas.

Survival Outcomes for Metaplastic Breast Cancer Differ by Histologic Subtype

BACKGROUND

Metaplastic breast carcinoma (MBC) is a rare, aggressive subtype of breast cancer associated with poorer overall survival than other triple-negative breast cancers. This study sought to compare survival outcomes among histologic subtypes of MBC with those of non-metaplastic triple-negative breast cancer.

METHODS

Clinicopathologic and treatment data for all patients with non-metastatic, pure MBC undergoing surgery from 1995 to 2017 and for a large cohort of patients with other types of triple-negative breast cancer during that period were collected from an institutional database. The MBC tumors were classified as having squamous, spindle, heterologous mesenchymal, or mixed histology. Survival outcomes were compared using the Kaplan-Meier method.

RESULTS

Of 132 MBC patients, those with heterologous mesenchymal MBC (n = 45) had the best 5-year overall and breast cancer-specific survival (BCSS, 88%; 95% confidence interval [CI], 0.78-0.99), whereas those with squamous MBC had the worst survival (BCSS, 56%; 95% CI, 0.32-0.79). Overall survival, BCSS, and recurrence-free survival were worse for the patients with MBC than for the patients who had non-MBC triple-negative breast cancer, with a clinicopathologically adjusted recurrence hazard ratio of 2.4 (95% CI, 1.6-3.3; p < 0.001). Of the 10 MBC patients who received neoadjuvant chemotherapy, 4 progressed while receiving treatment, and 3 had no response.

CONCLUSIONS

Metaplastic breast carcinoma is associated with worse survival than other triple-negative breast cancers. The heterologous mesenchymal subtype is associated with the best survival, whereas the squamous subtype is associated with the worst survival. These data call for research to identify therapies tailored to MBC's unique biology.

Metaplastic breast cancer: Prognostic and therapeutic considerations

INTRODUCTION

Metaplastic breast cancer (MBC) is a rare condition of breast tumor with different subtypes, considered a disease with worse prognosis; treatments and survival are often unclear and conflicting.

METHODS

We consecutively collected 153 primary MBCs of different subtypes. Breast surgery, neoadjuvant or adjuvant treatment, clinic-pathological factors, number and type of events during follow-up were considered to evaluate overall survival (OS) and invasive disease-free survival (IDFS).

RESULTS

The majority of MBC was triple-negative (TN) subtype (88.7%), G3 (95.3%), pN0 (70.6%), and with high levels of Ki-67 (93.5%). For OS and IDFS, no significant associations were seen between the different MBC subtypes. The matched triple-negative MBC (TNMBC) and ductal TNBC cohorts had similar prognosis both in terms of OS (p = .411) and IDFS (p = .981). We observed a positive trend for TNMBC patients treated in the adjuvant setting with the cyclofosfamide, methotrexate, 5-fluorouracil protocol for better OS (p = .090) and IDFS (p = .087). A poor or absent response rate was observed in the neoadjuvant setting.

CONCLUSION

Our results demonstrate that metaplastic and ductal breast cancers with TN phenotype are similar in terms of overall and disease-free survival. Metaplastic cancers are poorly responsive to neoadjuvant treatment, and in the absence of novel targeted therapies, surgical treatment remains the first choice.

Clinicopathological characteristics and prognosis of breast cancer with special histological types: A surveillance, epidemiology, and end results database analysis

Objectives

To explore the clinicopathological features and prognosis of breast cancer with special histological types.

Materials and methods

The information of breast cancer patients was obtained from the Surveillance, Epidemiology, and End Results (SEER) database (2010–2016). Comparative analyses were performed to explore the difference in clinicopathological characteristics and propensity score matching (PSM) was used to weaken the effects from clinical profiles. Survival analysis was conducted to investigate the prognostic effects from histological types, and the prognostic factors of this group of patients were identified with the univariate COX proportional model.

Results

A total of 242863 breast cancer patients were eligible, of which 230213 individuals were ductal breast cancer (IDC) and 12650 individuals were special breast lesions, respectively. Comparatively, special breast cancer had a lower histological grade, a smaller tumor size, a lower proportion of nodal involvement and distant metastasis, in addition to a higher proportion of triple-negative subtype. The overall prognosis of special histological breast cancer was comparable to IDC, while the survival of HER2 enriched breast cancer was in favor of special breast cancer. With the PSM performance, the prognosis exhibited an inferior profile in the metaplastic breast cancer and was significantly favorable to apocrine, medullary, micropapillary, and papillary breast cancer.

Conclusion

This study revealed that the special histological breast cancer presented distinct clinicopathological characteristics and great heterogeneity in the prognosis among diverse histological subtypes.

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Breast cancer is a heterogenous disease with diverse histological subtypes.

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Special histological breast cancer exhibits distinct clinicopathological profiles.

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Prognosis of special histological breast cancer is profoundly heterogenous.

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Histological subtype is an independent prognostic indicator of breast cancer.