Mucinous carcinoma of the breast is genomically distinct from invasive ductal carcinomas of no special type

Clinicopathological characteristics of mucinous breast cancer: a retrospective analysis of a 6-years study from national cancer center in Vietnam

PURPOSE

To evaluate clinicopathological features in women with mucinous breast cancer (MBC), distinguishing between pure (PMC) and mixed (MMC) subtype.

METHODS

A retrospective analysis of all 358 women with MBC treated at Vietnam National Cancer hospital from June 2015 to December 2020. PMC was defined by ≥ 90% mucinous components.

RESULTS

We identified 358 women with MBC (245 PMC and 113 MMC) representing 2.7% of all 13,254 BC patients. The proportions of stage I, II, III and IV were 34.9%, 50.8%, 10.4% and 3.9% respectively. The rate of HER2 overexpression was 12%, and only 1.4% of patients was treated with anti-HER2. 193 patients (53.9%) had chemotherapy, including 55 patients (15.4%) treated in the neoadjuvant setting. Only 3 patients (5.5%) achieved pCR. PMC patients were older (54.4 ± 13.3 vs 51.1 ± 13.1 years), had lower Ki67 expression, lower incidence of nodal metastasis (N +) (p values < 0.05). At a median follow-up of 58 months, the 5-year overall survival rate of non-metastatic patients was 86.6%. Multivariate analysis showed N + to be the most significant prognostic factor (HR = 3.3; 95%CI 1.5-7.1), followed by T-stage (HR = 2.9; 95%CI 1.4-6.3), HER2 + (HR = 2.5; 95%CI 1.2-5.3) and MMC subtype (HR = 1.9; 95%CI 1.0-3.9).

CONCLUSION

Poor prognostic factors of MBC include high T-stage, N-positivity, HER2 overexpression and MMC subtype. Given the low response rate to neoadjuvant CT, upfront surgery is appropriate for MBC patients.

Clinicopathological features and prognosis of mucinous breast carcinoma with a micropapillary structure

OBJECTIVE

To conduct a comparative analysis of clinicopathological data between mucinous micropapillary breast carcinoma (MUMPC) and pure mucinous carcinoma (PMC) without a micropapillary structure to elucidate the distinctive clinicopathological characteristics of MUMPC and their impact on prognosis.

METHODS

This retrospective analysis included 325 patients diagnosed with mammary mucinous carcinoma admitted to Tianjin Cancer Hospital between July 2014 and December 2019, including 197 patients with MUMPC and 128 patients with PMC without a micropapillary structure. Clinicopathological features were compared, and factors influencing the prognosis of MUMPC were analyzed. Survival analysis was conducted using the Kaplan-Meier method, and univariate and multivariate prognostic analyses for MUMPC were performed using the Cox proportional hazard regression model.

RESULTS

The median follow-up period was 76 months. In the MUMPC and PMC groups, the disease-free survival (DFS) rates at 3, 5, and 7 years were 95.4%, 90.4%, 89.8%, and 100%, 98.4%, and 96.9%, respectively, with a statistically significant difference between the two groups (p = 0.009). Tumor, node, and metastasis (TNM) stage, lymph node metastasis, and endocrine treatment were significant factors influencing the prognosis of the MUMPC group (p < 0.001). Multivariate analysis revealed that lymph node metastasis and endocrine therapy were independent prognostic factors in patients with MUMPC (p < 0.001). Compared with PMC, the MUMPC group exhibited a higher prevalence of HER2 (11.2% vs. 3.1%, p = 0.009) and Ki-67 overexpression (79.7% vs. 60.2%, p < 0.001).

CONCLUSION

The lymph node stage is the most crucial clinicopathological feature of MUMPC. Endocrine treatment strategy is an independent risk factor affecting the prognosis of MUMPC.

An Effective Ultrasound Features-Based Diagnostic Model via Principal Component Analysis Facilitated Differentiating Subtypes of Mucinous Breast Cancer From Fibroadenomas

BACKGROUND

Mucinous breast carcinoma (MBC) is often misdiagnosed as fibroadenoma (FA),which can lead to inappropriate or delayed treatments. This study aimed to establish an efficient ultrasound (US)-based diagnostic model to distinguish MBC subtypes from FAs.

METHODS

Between January 2017 and February 2024, 240 lesions were enrolled, comprising 65 cases of pure mucinous breast carcinoma (PMBC), 47 cases of mixed mucinous breast carcinoma (MMBC), and 128 cases of FAs. Ten US feature variables underwent principal component analysis (PCA). Models were constructed based on components explaining over 75% of the total variation, with varimax rotation applied for interpretability. Comprehensive models were developed to distinguish PMBCs and MMBCs from FAs.

RESULTS

Six principal components were selected, achieving a cumulative contribution rate of 77.46% for PMBCs vs. FAs and 78.62% for MMBCs vs. FAs. The principal component of cystic-solid composition and posterior acoustic enhancement demonstrated the highest diagnostic value for distinguishing PMBCs from FAs (AUC: 0.86, ACC: 80.31%). Features including vascularization, irregular shape, ill-defined border, and larger size exhibited the highest diagnostic value for distinguishing MMBCs from FAs (AUC: 0.90, ACC: 87.43%). The comprehensive models showed excellent clinical value in distinguishing PMBCs (AUC = 0.86, SEN = 86.15%, SPE = 73.44%, ACC = 77.72%) and MMBCs (AUC = 0.92, SEN = 80.85%, SPE = 95.31%, ACC = 91.43%) from FAs.

CONCLUSION

This diagnostic model holds promise for effectively distinguishing PMBCs and MMBCs from FAs, assisting radiologists in mitigating diagnostic biases and enhancing diagnostic efficiency.

Mucinous Carcinoma of the Breast With Neuroendocrine Differentiation: A Case Report of Cyto-Histopathology Findings

Mucinous breast carcinoma is a rare neoplasm. A minority of breast neoplasms exhibit a mucinous component, with purely mucinous cases being less frequent. It is more typically found in postmenopausal women. The etiology is multifactorial and involves dietary factors, reproductive factors, and hormonal factors. Mucinous carcinoma can grow to a large size at the time of diagnosis, although it typically grows slowly and palpable. Transcriptomic genetic studies have explained that mucinous tumors are of luminal A molecular subtype. Mucinous A tumors have different transcriptome characteristics than mucinous B tumors, which have a gene expression pattern resembling neuroendocrine (NE) carcinomas. Diagnosis of mucinous carcinoma with NE differentiation by fine needle aspiration cytology (FNAC) is reported infrequently. Histopathology is mandatory in the evaluation of mucinous breast carcinoma. NE carcinoma of the breast is an underestimated subtype of BC which has characteristics of heterogenicity, rarity, and poor differentiation. In this instance, we present a case of breast carcinoma exhibiting NE differentiation. A postmenopausal woman aged 63, with no family history of breast cancer, presented with a firm mass in the upper lateral quadrant of her right breast. This lump, causing discomfort for the past two years, was accompanied by nipple retraction and the discharge of bloody fluid. The clinical examination revealed the palpable presence of the lump. Ultrasonography-guided FNAC suggested Mucinous breast carcinoma with NE differentiation. The patient underwent a modified radical mastectomy, and the tissue was evaluated by immunohistochemistry which confirmed the diagnosis.

Clinicopathological characteristics and genomic profiling of pure mucinous breast cancer

PURPOSE

Pure mucinous breast cancer (PMC) is a rare histological type with a favourable prognosis. However, cases with recurrence have been reported and diagnosed in clinical practice. The mechanisms underlying PMC recurrence remain unknown. In this study, we aimed to identify the prognostic factors associated with PMC.

MATERIALS AND METHODS

A total of 166 patients diagnosed with PMC were included. We compared the clinicopathological characteristics between patients with and without recurrence. The 21-gene assay was performed in 10 patients with recurrence and 20 TNM stage-matched patients without recurrence. Whole-exon sequencing was performed in 12 PMC primary tumours and four positive lymph nodes (LNs).

RESULTS

Tumour size, lymph node status and TNM staging differed significantly between recurrent group and non-recurrent group. And the 21-gene recurrence scores did not differ significantly between recurrent group and its TNM stage-matched non-recurrent group. The most frequently mutated genes in the primary tumours of regional LN-positive PMCs were ADCY10 (3/6) and SHANK3 (3/6), and they more recurrently harboured gains of 15q23, 17q23.2 and 20p11.21, and loss of 21p11.2. And these alterations were not detected in primary tumours of regional LN-negative PMCs.

CONCLUSION

TNM stage is an important prognostic factor in PMC. Although we revealed that regional LN-positive PMCs show increased occurrence of duplication variants at 15q23, 17q23.2 and 20p11.21, and deletion variants at 21p11.2. Further investigation, including multi-omics studies, are needed and may provide additional insights into the nature of PMC.

Pathological response in mucinous carcinoma of breast after neoadjuvant therapy - a multi-institutional study

Although mucinous carcinoma (MC) is considered a favorable histologic subtype of invasive breast cancer (BC), a subset of MC is managed with neoadjuvant therapy (NAT). The clinical and pathologic features of MC following NAT are not well characterized. The aim of this study is to characterize pathologic response in patients with MC treated with NAT, including neoadjuvant endocrine therapy (NET), neoadjuvant chemotherapy (NCT), and Herceptin-targeted NCT (H-NCT). We conducted a retrospective cohort study of 28 patients with MC who received preoperative adjuvant therapy followed by resection from three institutions between 2010 and 2020. Demographic and clinical information were retrieved from the medical records. Pathologic review of the post NAT resection specimens was performed including tumor grading, tumor size, staging, residual tumor cellularity, estrogen receptor (ER) and HER2 status. Nine (32 %) patients with ER+/HER2- MC received NET, 8 (29 %) ER+/HER2- MC were treated with NCT only and 11 (39 %) HER2+ MC received HER2-targeted NCT (H-NCT). The HER2+ MC patients were younger (45 vs. 64 years; p = 0.006). The HER2+ MC were of higher grade (p = 0.03) and more likely to be multifocal (p = 0.008). Only 2 of 28 (7 %) MC (both HER2+) showed complete pathologic response with residual acellular mucin pools. Persistent mass-forming mucin pools were present in 26 (93 %) cases. The residual tumor cellularity was markedly reduced (≤5 %) in H-NCT treated MC (11/11, 100 %), followed by NET group (6/9, 67 %) and NCT only group (4/8, 50 %) (p = 0.011). Similarly, a higher rate of pathologic response (pCR/RCB-I) was observed in H-NCT (7/11, 64 %), followed by NET group (5/9, 56 %), and NCT only group (1/7, 13 %) (p = 0.053). Post-therapy, all HER2+ MC were smaller than 2 cm and ypT size was significantly smaller in H-NCT group (11/11, 100 %) versus combined NET (5/9, 55 %) and NCT only groups (4/8, 50 %) (p = 0.029). We conclude that ER-/HER2+ and ER+/HER2-mucinous carcinomas of the breast show robust pathological response to neoadjuvant HER2 targeted and endocrine therapy, respectively. Our findings suggest that MC may show good response to endocrine therapy.

Molecular Classification of Breast Cancer

Breast carcinomas classified based on traditional morphologic assessment provide useful prognostic information. Although morphology is still the gold standard of classification, recent advances in molecular technologies have enabled the classification of these tumors into four distinct subtypes based on its intrinsic molecular profile that provide both predictive and prognostic information. This article describes the association between the different molecular subtypes with the histologic subtypes of breast cancer and illustrates how these subtypes may affect the appearance of tumors on imaging studies.

Spectrum of Mucin-containing Lesions of the Breast: Multimodality Imaging Review with Pathologic Correlation

Mucin-containing lesions of the breast encompass a wide range of benign and malignant processes. The spectrum of histologic findings includes incidental mucus-filled benign cysts or ducts, mucocele-like lesions (MLLs), mucin-producing ductal carcinoma in situ, and invasive mucinous carcinoma. MLL is characterized by the presence of mucin-containing cysts that are typically associated with extravasated stromal mucin. MLL is often benign but can be associated with epithelial atypia or malignancy. Mucinous carcinoma represents the malignant end of the spectrum of mucinous lesions of the breast. Evidence-based literature supports a conservative approach for benign MLLs without associated atypia or malignancy, reserving excision for those lesions exhibiting such pathologic features. The most common imaging finding for MLL is microcalcifications at mammography. No specific imaging feature is predictive of malignant outcome at surgical excision. Invasive mucinous carcinoma is a heterogeneous breast tumor subtype, as defined according to the World Health Organization criteria. Mucinous carcinomas are categorized into pure (>90% mucinous component) or mixed (10%-90% mucinous component) subtypes. Pure mucinous carcinomas are generally associated with excellent prognosis and survival, with a few exceptions. Mixed mucinous carcinomas do not have the same favorable prognosis and instead behave similarly to invasive breast carcinomas of no special type. Characteristic diagnostic imaging features can be identified for mucinous carcinoma based on its mucinous and nonmucinous contents. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Comparison of clinicopathological characteristics and survival outcomes between gallbladder mucinous adenocarcinoma and gallbladder adenocarcinoma: A propensity score-matched study

BACKGROUND

Gallbladder mucinous adenocarcinoma (GBMAC) is a rare subtype of gallbladder adenocarcinoma (GBAC), with limited knowledge of its survival outcomes from small case series and single-center retrospective analysis.

AIM

To compare the clinicopathological characteristics of GBMAC with typical GBAC and its prognostic factors to gain insights into this field.

METHODS

This study was conducted using data from the Surveillance, Epidemiology, and End Results database, including cases of GBMAC and typical GBAC diagnosed from 2010 to 2017. The Pearson chi-square test or Fisher exact test was used to examine the differences in clinicopathological features between these two cohorts. In addition, propensity score matching (PSM) analysis was performed to balance the selection biases. Univariate and multivariate Cox hazards regression analyses were performed to determine independent prognostic factors for cancer-specific survival (CSS) and overall survival (OS). The Kaplan-Meier curves and log-rank tests were used to assess the OS and CSS of GBMAC and typical GBAC patients.

RESULTS

The clinicopathological and demographic characteristics of GBMAC were different from typical GBAC. They included a larger proportion of patients with unmarried status, advanced American Joint Committee on Cancer (AJCC) stage, higher T stage, higher N1 stage rate and lower N0 and N2 stage rates (P < 0.05). Multivariate analyses demonstrated that surgery [OS: Hazard ratio (HR) = 2.27, P = 0.0037; CSS: HR = 2.05, P = 0.0151], chemotherapy (OS: HR = 6.41, P < 0.001; CSS: HR = 5.24, P < 0.001) and advanced AJCC stage (OS: Stage IV: HR = 28.99, P = 0.0046; CSS: Stage III: HR = 12.31, P = 0.015; stage IV: HR = 32.69, P = 0.0015) were independent prognostic indicators for OS and CSS of GBMAC patients. Furthermore, after PSM analysis, there was no significant difference between GBMAC and matched typical GBAC patients regarding OS (P = 0.82) and CSS (P = 0.69).

CONCLUSION

The biological behaviors of GBMAC are aggressive and significantly different from that of typical GBAC. However, they show similar survival prognoses. Surgery, chemotherapy, and lower AJCC stage were associated with better survival outcomes. Further research is needed in the future to verify these results.

Pure Mucinous Carcinoma of the Breast: Radiologic-Pathologic Correlation

Mucinous carcinoma (MC) of the breast is a rare, specialized subtype of invasive breast carcinoma (IBC) accounting for approximately 1% to 4% of all primary breast malignancies. Mucinous carcinoma occurs predominantly in patients who are postmenopausal or elderly. It is usually detected on screening mammography, but occasionally the patient may present with a palpable mass. The most common mammographic appearance is an equal to high density, oval or round mass with circumscribed or indistinct margins; MC can mimic a benign lesion. Histologically, MC is a well-differentiated cancer characterized by pools of mucin around neoplastic cells. Depending on mucin content, the tumor is classified as pure (≥90% mucin) or mixed (>10% and <90% mucin). Pure MCs (PMCs) are of low or intermediate nuclear grade, and the vast majority are hormone receptor-positive and human epidermal growth factor-2 receptor-negative (luminal A subtype). Pure MCs may be classified as hypocellular (type A) or hypercellular (type B) and have a lower rate of axillary lymph node involvement and more favorable prognosis than IBCs, no special type. The purpose of this article is to review the clinical features, imaging appearances, associated histopathology, and management of PMC.

Novel markers in breast pathology

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

Gross Cystic Disease Fluid Protein-15 (GCDFP-15) Expression Characterizes Breast Mucinous Carcinomas in Older Women

The predominant histological subtype of breast mucinous carcinoma in older women is type B (hypercellular type), and, in younger women, it is type A (hypocellular type). The characteristics of mucinous carcinomas of the same histological subtype may differ between older and younger women. This study aims to systematically clarify the pathological/immunohistochemical features of mucinous carcinomas. A total of 21 surgical cases of mucinous carcinoma (type A/B: 9/12 cases) in the older group (≥65 years) and 16 cases (type A/B: 14/2 cases) in the younger group (≤55 years) (n = 37) were included. Gross cystic disease fluid protein-15 (GCDFP-15) and eight other markers were used for immunostaining. The GCDFP-15-positive rate in the older group was high regardless of the histological subtype (type A, 77.8%; type B, 91.7%). The GCDFP-15 positivity in the older group was significantly higher than that in the younger group (p < 0.001 for Allred score). Among type A, GCDFP-15 positivity was significantly higher in the older group than in the younger group (p = 0.042 for the Allred score and p = 0.007 for the positivity rate). The present results suggest that GCDFP-15 expression characterizes mucinous carcinomas in older women.

Mucinous carcinoma of the breast: distinctive histopathologic and genetic characteristics

Mucinous carcinoma is a rare histologic type of breast cancer that, when classified with favorable histology, can be treated with different therapeutic options. This study reviews the histologic findings of mucinous carcinoma that support or exclude favorable histology and emphasizes the necessity of an appropriate gross examination with radiologic findings for an accurate diagnosis. In addition, unusual findings such as micropapillary arrangements and lobular differentiation in mucinous carcinoma and their implications for prognosis and treatment are reviewed. Mucinous carcinoma involves upregulation of MUC2, a mucus-associated gene common in mucinous carcinoma of the breast as well as various other organs. In mucinous carcinoma, the fraction of genome altered and tumor mutation burden are lower than those of invasive carcinoma of no special type, the most common histology of breast cancer. In addition, the genetic alterations found in mucinous carcinoma are diverse, unlike the pathognomonic genetic alterations observed in other histologic types of breast cancer. These genetic features support the importance of conventional microscopic evaluations for the pathologic differential diagnosis of mucinous carcinoma of the breast in routine practice. A variety of breast lesions, including mucinous cystadenocarcinoma and mucocele-like lesions, as well as mucinous carcinoma from other organs, can mimic mucinous carcinoma of the breast. In order to obtain an accurate pathologic diagnosis, careful evaluation of the overall histopathologic characteristics and ancillary testing are required to provide information on appropriate treatment and prognosis.

Effect of postoperative radiotherapy in women with localized pure mucinous breast cancer after lumpectomy: a population-based study

Purpose

Pure mucinous breast cancer is a rare subtype of invasive breast cancer with favorable prognosis, in which the effect of postoperative radiotherapy remains unclear. We aimed to investigate the prognostic value of postoperative radiotherapy in women with localized pure mucinous breast cancer after lumpectomy.

Methods

We conducted a retrospective cohort study to compare the effectiveness of postoperative radiotherapy (RT) and omitting postoperative radiotherapy (non-RT) in patients with first primary T1-2N0M0 (T ≤ 3 cm) pure mucinous breast cancer who underwent lumpectomy between 1998 and 2015 using the Surveillance, Epidemiology, and End Results (SEER) database. Breast cancer-specific survival (BCSS) was compared between RT and non-RT groups using Kaplan–Meier method and Cox proportional hazards regression model. Propensity score matching (PSM) was carried out to balance cohort baselines. In addition, an exploratory analysis was performed to verify the effectiveness of RT in subgroup patients.

Results

Of 7832 eligible patients, 5352 (68.3%) underwent lumpectomy with postoperative RT, 2480 (31.7%) received lumpectomy without postoperative RT. The median follow-up duration was 92 months. The median age was 66 years in the RT group and 76 years in the non-RT group.The 15-year BCSS was 94.39% (95% CI, 93.08% to 95.35%) in the RT group versus 91.45%(95% CI, 88.93% to 93.42%) in the non-RT group (P < 0.001). The adjusted hazard ratio for BCSS was 0.64 (95% CI, 0.49 to 0.83; P = 0.001) for RT group versus non-RT group. After propensity score matching, similar results were yielded. Adjuvant RT reduced the 15-year risk of breast cancer death from 7.92% to 6.15% (P = 0.039). The adjusted hazard ratio for BCSS were 0.66 (95%CI, 0.47 to 0.92; P = 0.014) for RT group versus non-RT group. The benefit of RT was well consistent across subgroup patients.

Conclusion

Among women with T1-2N0M0 (tumor size ≤ 3 cm) pure mucinous breast cancer, the addition of RT after lumpectomy was significantly associated with a reduced incidence of breast cancer death compared with non-RT, and the magnitude of benefit may be modest. This suggests that postoperative RT is recommended in the treatment of localized pure mucinous breast cancer.

Clinical and genomic analyses of neuroendocrine neoplasms of the breast

Breast neuroendocrine neoplasms (NENs) constitute a rare histologic subtype that includes both neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs). In this study, we aimed to gain insight into the clinical and molecular characteristics of NENs of the breast. NEN and paired distant normal fresh tissues and clinicopathological data were obtained from 17 patients with NENs, and clinicopathological data were collected from 755 patients with invasive breast carcinomas of no special type (IBCs-NST). We compared the clinicopathological characteristics of NENs and IBCs-NST and performed whole-exome sequencing (WES) of both NEN and paired normal tissues. Compared with the IBC-NST patients, the NEN patients had a higher mean age, lower clinical stage, and lower pathological nodal (pN) stage (P < 0.001, P < 0.001, and P = 0.017, respectively). The most frequently mutated gene in NENs was KMT2C (3/17, 17.6%). NENs had copy number variations (CNVs) of 8q, 11q, and 17q amplification and 17q and 11q deletion and harbored the following specific genes related to tumorigenesis: (i) suppressor genes with loss of heterozygosity (LOH) such as ACE (2/17, 11.8%); (ii) tumor driver genes such as GATA3 (2/17, 11.8%); and (iii) susceptibility genes such as MAP3K4 (17/17, 100%) and PDE4DIP (17/17, 100%). The oncogenic/likely oncogenic mutations of NETs in PI3K pathway genes (50.0%, 18.2%; P < 0.001) and MAPK signaling pathway genes (83.3%, 18.2%; P = 0.035) affected higher proportions than those of NECs. In conclusion, this study provides certain clinical and molecular evidence supporting NENs as a distinct subtype of breast cancer and provides some potential molecular features for distinguishing NETs from NECs.

Identifying Clinicopathological Risk Factors of the Regional Lymph Node Metastasis in Patients with T1-2 Mucinous Breast Cancer: A Population-Based Study

Background

Pure mucinous breast cancer (PMBC) has a better prognosis than other types of invasive breast cancer. However, regional lymph node metastasis (LNM) might reverse this outcome. We aim to determine the independent predictive factors for regional LNM and further develop a nomogram model for clinical practice.

Method

Data of PMBC patients from the Surveillance, Epidemiology, and End Results (SEER) program between Jan 2010 and Dec 2015 were retrospectively reviewed. Univariate and multivariate logistic regression analyses were used to determine the risk factors for LNM in T_1-2 MBC. The nomogram was constructed and further evaluated by an internal validation cohort. The receiver operating characteristic (ROC) curves, decision curve analysis (DCA), and calibration curves were performed to evaluate the accuracy of this model.

Result

Five variables, including age, race, tumor size, grade, and breast subtype, were identified to be significantly associated with regional LNM in female patients with T_1-2 PMBC. A nomogram was successfully established with a favorable concordance index (C-index) of 0.780, supported by an internal validation cohort with a C-index of 0.767.

Conclusion

A nomogram for predicting regional LNM in female patients with T_1-2 PMBC was successfully established and validated via an internal cohort. This visualized model would assist surgeons to make appropriate clinical decisions in the management of primary PMBC, especially in terms of whether axillary lymph node dissection (ALND) is warranted.

Clinicopathological significance of WT1 expression in invasive breast carcinoma with >90% mucinous component

AIMS

This study was aimed to investigate the clinicopathological significance of immunohistochemical (IHC) Wilm's tumour 1 (WT1) expression in invasive breast carcinoma with >90% mucinous components.

METHODS

One hundred specimens of invasive breast carcinoma with >90% mucinous component were collected. All H&E-stained slides were reviewed, and the clinicopathological data, including sex, age, tumour size, nuclear grade, histological grade, growth pattern and lymph node (LN) status, were collected. IHC staining of WT1, oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and Ki-67 was performed. Fluorescence in situ hybridisation was used to verify the amplification of the HER2 gene. The relationship between WT1 expression and clinicopathological features was analysed statistically.

RESULTS

WT1 expression was detected in 67% (67/100) of invasive breast carcinoma with >90% mucinous components. WT1 expression was significantly associated with low-to-intermediate nuclear grade/histological grade, ER and PR positivity, HER2 negativity, Ki-67 proliferation index <30% and noLN metastasis (all p<0.001). Micropapillary architecture was observed in 80% of cases. WT1 expression was not significantly correlated with different percentage of micropapillary components (p=0.422). None of the histological grade 3 tumours, tumours with HER2 overexpression/amplification and triple-negative specimens showed WT1 expression.

CONCLUSIONS

WT1 expression was significantly related with low-intermediate nuclear/histological grade, ER positivity, HER2 negativity, a lower Ki-67 proliferation index and no LN metastasis in invasive breast carcinoma with >90% mucinous component. The micropapillary growth pattern in this type of tumour did not show a specific relationship with WT1 expression.

Breast cancer with neuroendocrine differentiation: an update based on the latest WHO classification

Breast cancers with neuroendocrine (NE) differentiation are very heterogeneous, comprising broadly cancers that are morphologically similar to NE tumors (NET) of other anatomic sites, infiltrating breast carcinomas, no special type (IBC-NST) and other special subtypes with NE morphology and/or NE markers expression. Depending on the classification schemes, they are variably included into "NE breast cancers". The latest WHO classification harmonized NE breast cancers with NE neoplasms (NEN) of other organ systems, defined NEN into well-differentiated NET (low Nottingham grade) and poorly-differentiated NE carcinoma (NEC) (high Nottingham grade). Other IBC with NE differentiation are diagnosed based on solely the non-NEN component. Due to the changes in diagnostic criteria, variable results were obtained in the previous studies on NE breast cancers. Hence, the clinical value of NE differentiation in breast cancers is not well investigated and understood. In this review, the current understanding in the pathogenesis, clinical, prognostic, immunhistochemical, and molecular features of "NE breast cancers" is summarized. Controversial issues in their diagnosis and classification are also discussed.

The genomic landscape of carcinomas with mucinous differentiation

Mucinous carcinomas can arise in any organ with epithelial cells that produce mucus. While mucinous tumors from different organs are histologically similar, it remains to be elucidated whether they share molecular alterations. Here we analyzed a total of 902 patients across six cancer types by comparing mucinous and non-mucinous samples, integrating text mining of pathology reports, gene expression, methylation, mutational and copy-number profiling. We found that, in addition to genes involved in mucin processing and secretion, MUC2 up-regulation is a multi-cancer biomarker of mucinous histology and is regulated by DNA methylation in colorectal, breast and stomach cancer. The majority of carcinomas with mucinous differentiation had fewer DNA copy-number alterations than non-mucinous tumors. The tumor mutational burden was lower in breast and lung with mucinous differentiation compared to their non-mucinous counterparts. We found several differences in the frequency of oncogenic gene and pathway alterations between mucinous and non-mucinous carcinomas, including a lower frequency of p53 pathway alterations in colorectal and lung cancer, and a lower frequency of PI-3-Kinase/Akt pathway alterations in breast and stomach cancer with mucinous differentiation. This study shows that carcinomas with mucinous differentiation originating from different organs share transcriptomic and genomic similarities. These results might pave the way for a more biologically relevant taxonomy for these rare cancers.

Clinicopathological and Molecular Analysis of 45 Cases of Pure Mucinous Breast Cancer

Pure mucinous breast carcinoma (PMBC) is characterized by clusters of tumor cells floating in abundant extracellular mucin and can be classified into paucicellular (Type A) and hypercellular (Type B) subtypes. However, the clinicopathological and genomic differences between these two subtypes have not been well characterized. We retrospectively investigated the clinicopathologic features of 45 cases of surgically removed PMBC (31 Type A and 14 Type B). We also performed whole-exome sequencing (WES) in eight cases of PMBC. We found that Type B PMBC occurs at an older age and shows more aggressive clinical behavior than Type A. WES analysis revealed that HYDIN was the most frequently mutated gene in both types of PMBC. Although Type B PMBC showed a tendency toward more frequent genetic alterations, there were no statistically significant differences between the two subtypes in single nucleotide variants or insertions or deletions of bases associated with moderate or high effects. Our results provide additional evidence that PMBCs are clinicopathologically and genetically heterogeneous and lack pathognomonic genetic alterations. Further, Type B PMBC is more frequently associated with lymph node metastasis than Type A.

Evaluation of efficacy of chemotherapy for mucinous carcinoma: a surveillance, epidemiology, and end results cohort study

Background

In this study, we investigated the impact of chemotherapy on breast cancer-specific survival (BCSS) in patients with mucinous carcinoma using the surveillance, epidemiology, and end results (SEER) database.

Methods

A large-scale SEER-based retrospective analysis was conducted; 13,329 patients with mucinous carcinoma from 1994 to 2014 were identified. Clinicopathological characteristics were compared using the chi-square test. BCSS curves were generated using the Kaplan-Meier method. The prognostic significance of all demographic and clinicopathological characteristics and treatment patterns were calculated using univariate and multivariate regression analyses.

Results

Mucinous carcinoma was demonstrated to be less aggressive than invasive ductal carcinoma and predicted a better prognosis in the Kaplan-Meier analysis (hazard ratios = 0.336, 95% confidence interval: 0.308-0.368, p < 0.001). Univariate and multivariate analyses revealed that chemotherapy did not provide any additional benefit for patients with mucinous carcinoma. Predictors for receiving chemotherapy were younger age, estrogen receptor-negative, progesterone receptor-negative, and human epidermal growth factor receptor 2-positive status, higher grade, larger tumor size, lymph node involvement, radiation reception, and mastectomy. Further subgroup analysis verified that regardless of the hormone receptor (HR) and lymph node (LN) status, patients did not benefit from chemotherapy.

Conclusion

Our study showed that patients with HR+/LN- mucinous carcinoma did not benefit from chemotherapy and that chemotherapy could not improve the survival of all subtypes of mucinous carcinoma based on large-scale SEER data. These results support that patients with mucinous carcinoma could be exempt from chemotherapy. Additional research is needed to further evaluate the impact of adjuvant treatments, particularly in patients with favorable histology.

Epidemiology of Mucinous Adenocarcinomas

Simple Summary

Mucinous adenocarcinomas are a very uncommon type of cancer that is poorly studied. These cancers overexpress a jelly-like substance called mucin outside their cells. These cancers share characteristics to another group of cancers called signet ring cell adenocarcinomas, which express mucin inside their cells, and these cancers almost invariability have a worse outcome compared to conventional adenocarcinomas. In our study, we show that patient outcomes with mucinous adenocarcinomas depend largely on the site of the cancer, with both similarities and differences to cancers arising from signet ring cells. This work, along with our recent study on signet ring cell cancers, provides a solid epidemiological reference for future work to motivate investigations as to how recognizing this tumor histology should lead to more tailored cancer treatments in order to improve patient outcomes.

Abstract

Mucinous (colloid) adenocarcinomas (MAs) are a rare histological subtype of adenocarcinomas where extracellular mucin comprises more than 50% of the tumor. Most literature on MAs relate to cancers from colorectal and breast sites; however, the literature lacks a standardized overview of the MA disease entity. Particularly in colorectal cancer, some MAs may have signet ring cells floating within the mucin, which may represent a highly metastatic phenotype. MAs and signet ring cell adenocarcinomas represent a spectrum of mucin-producing neoplastic conditions where in the latter most mucin is intracellular rather than extracellular. We recently published a standardized overview of signet ring cells, and in this companion work, using a retrospective cohort approach, we summarize the clinicodemographic and mortality outcomes of MAs in sixteen primary sites, comprising 95.6% of all MAs in the Surveillance, Epidemiology, and End Results Program (SEER), a population-level cancer database covering nearly one-third of the United States population. Compared to matching nonvariant adenocarcinomas, MAs have a slightly earlier age of onset with increased rates of regional and distant disease at presentation. Survival outcomes are highly dependent on tumor location, illustrating our poor understanding of MA tumor biology. The clinical significance of MA histology depends largely on tumor site.

The genomic landscape of metastatic histologic special types of invasive breast cancer

Histologic special types of breast cancer (BC) account for ~20% of BCs. Large sequencing studies of metastatic BC have focused on invasive ductal carcinomas of no special type (IDC-NSTs). We sought to define the repertoire of somatic genetic alterations of metastatic histologic special types of BC. We reanalyzed targeted capture sequencing data of 309 special types of BC, including metastatic and primary invasive lobular carcinomas (ILCs; n = 132 and n = 127, respectively), mixed mucinous (n = 5 metastatic and n = 14 primary), micropapillary (n = 12 metastatic and n = 8 primary), and metaplastic BCs (n = 6 metastatic and n = 5 primary), and compared metastatic histologic special types of BC to metastatic IDC-NSTs matched according to clinicopathologic characteristics and to primary special type BCs. The genomic profiles of metastatic and primary special types of BC were similar. Important differences, however, were noted: metastatic ILCs harbored a higher frequency of genetic alterations in TP53, ESR1, FAT1, RFWD2, and NF1 than primary ILCs, and in CDH1, PIK3CA, ERBB2, TBX3, NCOR1, and RFWD2 than metastatic IDC-NSTs. Metastatic ILCs displayed a higher mutational burden, and more frequently dominant APOBEC mutational signatures than primary ILCs and matched metastatic IDC-NSTs. ESR1 and NCOR mutations were frequently detected in metastatic mixed mucinous BCs, whereas PIK3CA and TP53 were the most frequently altered genes in metastatic micropapillary and metaplastic BCs, respectively. Taken together, primary and metastatic BCs histologic special types have remarkably similar repertoires of somatic genetic alterations. Metastatic ILCs more frequently harbor APOBEC mutational signatures than primary ILCs and metastatic IDC-NSTs.

Mucinous carcinoma with micropapillary features is morphologically, clinically and genetically distinct from pure mucinous carcinoma of breast

Micropapillary features are seen in pure mucinous carcinoma of breast (PMC), which is termed mucinous carcinoma with micropapillary features (MPMC). However, whether MPMC can be identified as a morphologically, clinically or genetically distinct entity from PMC remains controversial. In this study, a retrospective review of 161 cases of breast mucinous carcinoma was conducted to assess the clinicopathologic features, prognostic implications, and genomic alterations of MPMC and PMC. MPMCs were identified in 32% of mucinous carcinomas showing an excellent interobserver agreement (ICC = 0.922). MPMCs occurred at a younger age and exhibited higher nuclear grade, more frequent lymph nodal metastasis, lymphovascular invasion, and HER2 amplification compared with PMCs. Survival analyses revealed that MPMCs show decreased progression-free survival compared with PMCs in both unmatched and matched cohorts. A similar outcome of distant disease-free survival was observed only in the unmatched cohort. However, no statistical difference in recurrence score was observed between MPMC and PMC using a 21-gene assay. Notably, both MPMCs and PMCs displayed low mutation burden, common mutations affecting TTN, GATA3, SF3B1, TP53, recurrent 6q14.1-q27 losses, and 8p11.21-q24.3 gains. GATA3, TP53, and SF3B1 were recurrently mutated in MPMCs, while PIK3CA mutations were exclusively detected in PMCs. Moreover, MPMCs harbored 17q and 20q gains as well as 17p losses, while PMCs displayed gains at 6p. PI3K-Akt, mTOR, ErbB, and focal adhesion pathways were more frequently deregulated in MPMCs than in PMCs, which may responsible for the aggressive tumor behavior of MPMCs. Our findings suggest that MPMC is morphologically, clinically, and genetically distinct from PMC.

Visual histological assessment of morphological features reflects the underlying molecular profile in invasive breast cancer: a morphomolecular study

AIMS

Tumour genotype and phenotype are related and can predict outcome. In this study, we hypothesised that the visual assessment of breast cancer (BC) morphological features can provide valuable insight into underlying molecular profiles.

METHODS AND RESULTS

The Cancer Genome Atlas (TCGA) BC cohort was used (n = 743) and morphological features, including Nottingham grade and its components and nucleolar prominence, were assessed utilising whole-slide images (WSIs). Two independent scores were assigned, and discordant cases were utilised to represent cases with intermediate morphological features. Differentially expressed genes (DEGs) were identified for each feature, compared among concordant/discordant cases and tested for specific pathways. Concordant grading was observed in 467 of 743 (63%) of cases. Among concordant case groups, eight common DEGs (UGT8, DDC, RGR, RLBP1, SPRR1B, CXorf49B, PSAPL1 and SPRR2G) were associated with overall tumour grade and its components. These genes are related mainly to cellular proliferation, differentiation and metabolism. The number of DEGs in cases with discordant grading was larger than those identified in concordant cases. The largest number of DEGs was observed in discordant grade 1:3 cases (n = 1185). DEGs were identified for each discordant component. Some DEGs were uniquely associated with well-defined specific morphological features, whereas expression/co-expression of other genes was identified across multiple features and underlined intermediate morphological features.

CONCLUSION

Morphological features are probably related to distinct underlying molecular profiles that drive both morphology and behaviour. This study provides further evidence to support the use of image-based analysis of WSIs, including artificial intelligence algorithms, to predict tumour molecular profiles and outcome.

Clinicopathological Study of Mucinous Carcinoma of Breast with Emphasis on Cytological Features: A Study at Tertiary Care Teaching Hospital of South India

Introduction  Mucinous carcinoma (MC) is a rare form of breast cancer. It accounts for 1 to 7% of the cases and characterized by the presence of extracellular mucin (ECM). Depending on the amount of mucin, it is classified into pure mucinous carcinoma (> 90%, PMC) and mixed mucinous carcinoma (MMC; < 90%). In comparison to most common subtypes, MC is having better prognosis. There exist clinicopathological differences among PMC and MMC and also MC and IDC-NOS.

Materials and Methods  MCs diagnosed between January 2012 and December 2017 were included. Fine needle aspiration cytology smears were screened for cellularity, ECM, nuclear pleomorphism, signet ring cells (SRC), mucinophages, and myxovascular fragments (MVF). Histopathology slides were screened to confirm the diagnosis. Immunohistochemistry slides were graded as per the standard protocol. Statistical analyses were performed by SPSS software.

Results  In the present study, MC constituted 3.3%. The mean age of the patients was 50.9 years. ECM, mucinophages, and SRC were the key diagnostic cytological features. The PMC and MMC were clinicopathologically distinct with respect to gross findings and lymph node status. MMCs were highly proliferative. The mean duration of follow-up was 24.5 months. Complications were more common in MMC than PMC. Lymph node involvement is the key prognostic factor and it is independent of other prognostic factors like age, size, and hormonal receptor status.

Conclusion  PMC are rare subtype of breast cancer. The diagnostic cytological features are ECM, MVF, and SRC. MMC and PMC are clinicopathologically and genetically distinct.

Clinicopathological and genomic features of breast mucinous carcinoma

Introduction

Mucinous carcinoma (MC) of the breast is a special histological type of breast cancer. Clinicopathological characteristics and genomic features of MC is not fully understood.

Materials and methods

186,497 primary breast cancer patients from SEER database diagnosed with invasive ductal carcinoma (IDC) or MC were included. 801 primary IDC or MC patients from TCGA cohort were included for transcriptomic and genomic analysis.

Results

MC patients were older, had lower tumor grade and T and N stage, higher hormone receptor positive proportions and lower HER2 positive proportions than IDC patients. Kaplan-Meier plots showed that the breast cancer-specific survival (BCSS) of MC patients was significantly better than IDC patients (P < 0.001). However, after adjusting for clinicopathological factors, survival advantage of MC disappeared. In terms of genomic features of MC, representative upregulated genes of MC in transcriptomic level were MUC2, TFF1 and CARTPT. Upregulated pathways of MC included neurotransmitter-related pathways. Moreover, MC was featured by the amplification of 6p25.2, 6q12 and 11q12.3.

Conclusion

MC is a distinct histological subtype compared with IDC in terms of clinicopathological characteristics and genomic features. Further investigation need to be conducted to explore the formation of this specific histological subtype.

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Mucinous breast carcinoma is a distinct histological subtype with better prognosis.

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The clinicopathological characteristics of mucinous breast carcinoma contributed to its good prognosis.

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Transcriptomic and genomic features of mucinous breast carcinoma contributed to its formation.

The Genomic Landscape of Mucinous Breast Cancer

Mucinous carcinoma of the breast (MCB) is a rare histologic form of estrogen receptor (ER)-positive/HER2-negative breast cancer (BC) characterized by tumor cells floating in lakes of mucin. We assessed the genomic landscape of 32 MCBs by whole-exome sequencing and/or RNA-sequencing. GATA3 (23.8%), KMT2C (19.0%), and MAP3K1 (14.3%) were the most frequently mutated genes in pure MCBs. In addition, two recurrent but not pathognomonic fusion genes, OAZ1-CSNK1G2 and RFC4-LPP, were detected in 3/31 (9.7%) and 2/31 (6.5%) samples, respectively. Compared with ER-positive/HER2-negative common forms of BC, MCBs displayed lower PIK3CA and TP53 mutation rates and fewer concurrent 1q gains and 16q losses. Clonal decomposition analysis of the mucinous and ductal components independently microdissected from five mixed MCBs revealed that they are clonally related and evolve following clonal selection or parallel evolution. Our findings indicate that MCB represents a genetically distinct ER-positive/HER2-negative form of BC.

Genomic, Transcriptomic, Epigenetic, and Immune Profiling of Mucinous Breast Cancer

Although invasive ductal breast cancer (IDC) represents the most common histological type of breast cancer, minor subtypes exist such as mucinous breast cancer (MuBC). MuBC are distinguished by tumor cells floating in extracellular mucin. MuBC patients are generally older and associated with a favorable prognosis. To unravel the molecular architecture of MuBC, we applied low-pass whole-genome sequencing and microscopic evaluation of stromal tumor infiltrating lymphocytes to 30 MuBC from a retrospective institutional cohort. We further analyzed two independent datasets from the International Cancer Genomics Consortium and The Cancer Genome Atlas. Genomic data (n = 26 MuBC, n = 535 estrogen receptor [ER] positive/HER2-negative IDC), methylation data (n = 28 MuBC, n = 529 ER-positive/HER2-negative IDC), and transcriptomic data (n = 27 MuBC, n = 467 ER-positive/HER2-negative IDC) were analyzed. MuBC was characterized by low tumor infiltrating lymphocyte levels (median = 0.0%, average = 3.4%, 95% confidence interval = 1.9% to 4.9%). Compared with IDC, MuBC had a lower genomic instability (P = .01, two-sided Mann-Whitney U test) and a decreased prevalence of PIK3CA mutations (39.7% in IDC vs 6.7% in MuBC, P = .01 in the International Cancer Genomics Consortium; and 34.8% vs 0.0%, P = .02 in The Cancer Genome Atlas, two-sided Fisher's exact test). Finally, our report identifies aberrant DNA methylation of MUC2 as a possible cause of extracellular production of mucin in MuBC.

Pathologic evaluation of response to neoadjuvant therapy drives treatment changes and improves long-term outcomes for breast cancer patients

Systemic therapy for breast cancer may be given before (neoadjuvant) or after (adjuvant) surgery. When neoadjuvant systemic therapy is given, response to treatment can be evaluated. However, some prognostic information (for example, pathologic tumor size pretreatment) is then lost and pathologic evaluation of breast specimens after neoadjuvant therapy is more difficult. Pathologic complete response (pCR), defined as no invasive disease in the breast (ypT0/is or ypT0) and no disease in all sampled lymph nodes (ypN0), identifies patients with a lower risk of recurrence or death compared to those with residual disease. Multidisciplinary collaboration, marking of the tumor site and any lymph node involvement pretreatment, and access to specimen imaging to facilitate correlation of gross and microscopic findings are critical for accurate determination of pCR. For HER2-positive and triple negative tumors requiring systemic therapy, giving the treatment before surgery identifies a high-risk group of patients that can receive additional adjuvant therapy after surgery if a pCR is not achieved. Recent clinical trials have demonstrated that this approach reduced recurrence risk. More than ever, pathologic evaluation of response to neoadjuvant systemic therapy directs treatment received after surgery. Using a single standardized protocol for sampling of the post-neoadjuvant surgical specimen allows pathologists to ensure accurate determination of pCR or residual disease and quantify residual disease. Residual cancer burden (RCB) and AJCC stage provide complementary quantitative information about residual disease and prognosis.

Genotype-phenotype associations in breast pathology: Achievements of the past quarter century

The first genotype-phenotype relationship in breast pathology developed in 1994 with the discovery of the CDH1 gene. This finding eventually provided biological insight into the characteristic morphology of invasive lobular carcinoma. Subsequent investigative efforts have uncovered additional molecular alterations largely responsible for the histology of several breast neoplasms including secretory carcinoma, adenoid cystic carcinoma, tall cell carcinoma with reversed polarity, fibroepithelial lesions, and most recently, adenomyoepithelioma. Evaluation of the genomic landscape of other special types of breast cancer with distinctive growth patterns, such as invasive mucinous carcinoma, have yet to uncover recurring cytogenetic and/or molecular alterations. Despite the lack of a hallmark alteration in mucinous carcinoma, it is important to note the relative decrease in PIK3CA mutations compared with invasive carcinoma of no special type. In this review, we describe the clinical and pathologic features of breast tumors with recognized genotype-phenotype correlations and summarize the molecular alterations of mucinous carcinoma.

New Advances in Molecular Breast Cancer Pathology

Breast cancer (BC) comprises a diverse spectrum of diseases featuring distinct presentation, morphological, biological, and clinical phenotypes. BC behaviour and response to therapy also vary widely. Current evidence indicates that traditional prognostic and predictive classification systems are insufficient to reflect the biological and clinical heterogeneity of BC. Advancements in high-throughput molecular techniques and bioinformatics have contributed to the improved understanding of BC biology, refinement of molecular taxonomies and the development of novel prognostic and predictive molecular assays. Molecular testing has also become increasingly important in the diagnosis and treatment of BC in the era of precision medicine. Despite the enormous amount of research work to develop and refine BC molecular prognostic and predictive assays, it is still in evolution and proper incorporation of these molecular tests into clinical practice to guide patient's management remains a challenge. With the increasing use of more sophisticated high throughput molecular techniques, large amounts of data will continue to emerge, which could potentially lead to identification of novel therapeutic targets and allow more precise classification systems that can accurately predict outcome and response to therapy. In this review, we provide an update on the molecular classification of BC and molecular prognostic assays. Companion diagnostics, contribution of massive parallel sequencing and the use of liquid biopsy are also highlighted.

The prognostic value of HER2 status and efficacy of anti-HER2 therapy in patients with HR-positive mucinous breast cancer: a nationwide study from the Korean Breast Cancer Society

PURPOSE

The effect of human epidermal growth factor receptor 2 (HER2) status on mucinous carcinoma (MC) of the breast is unknown due to the rarity of HER2-positive cases. We evaluated the prognostic value of HER2 status and the efficacy of anti-HER2 therapy in patients with hormone receptor (HR)-positive MC.

METHODS

From the data of 154,661 patients recorded in the Korean Breast Cancer Registry between January 1990 and August 2016, 3076 (2.0%) were diagnosed with MC. Overall survival (OS) according to HER2 status and anti-HER2 therapy was analyzed using Kaplan-Meier estimates. Multivariate analysis was performed using the Cox proportional hazards model to estimate the adjusted hazards ratio (HR) for clinicopathologic factors.

RESULTS

A total of 2716 HR-positive MC patients were enrolled and followed up for a median 100.1 months. Of these, 2094 (77.1%) were HER2-negative and 228 (8.4%) were HER2-positive. HR-positive, HER2-positive MC patients had more advanced pathologic tumor stages (T3 or T4) (p = 0.001), more axillary lymph node involvement (p < 0.001), higher nuclear grade (p < 0.001), and more lymphovascular invasion (p = 0.012) than HER2-negative patients. Subgroup analysis of HR-positive, node-positive MC showed that HER2-positive MC was an independent prognostic factor for OS (HR = 2.657; 95% CI, 1.665-4.241; p < 0.001). HR-positive, node-positive, and HER2-negative MC had significantly longer OS than HER2-positive MBC (p = 0.017). The node-positive subgroup that received anti-HER2 therapy had increased OS, although not significantly (p = 0.224).

CONCLUSION

Our nationwide database study revealed that HER2-positive status was associated with worse prognosis in HR-positive and node-positive MC. Anti-HER2 therapy might be beneficial in HR-positive, node-positive, and HER2-positive MC.

Aggressive behavior of Her-2 positive colloid breast carcinoma: A case report in a metastatic breast cancer

INTRODUCTION

Colloid breast carcinoma is a rare form of invasive ductal cancer characterized by large amount of mucous deposition. It is considered as an indolent cancer that usually affects older women. Colloid breast carcinoma generally expresses estrogen and progesterone receptors but negative for Her-2. Recommended surgery and adjuvant treatment of colloid breast carcinoma is not well-established.

PRESENTED CASE

A 46 years-old woman presented as an aggressive colloid breast carcinoma showing skin ulceration, enlargement of multiple axillary lymph nodes and a metastasis in the pleura at diagnosis. The primary tumor showed strong positive expression of estrogen, progesterone as well as Her-2 receptors. The patient was treated with 6 cycles of paclitaxel and carboplatin followed by mastectomy, radiotherapy, and hormonal therapy. Patient tolerated the treatment course and showed improvement both in the locoregional control and pleural metastasis.

DISCUSSION

Colloid breast carcinoma with aggressive clinical course is rarely found. Nodal involvement as a sign of poor prognosis in colloid breast carcinoma ranges only between 12 and 19%. Therefore, axillary node clearance is usually excluded during the surgery of colloid breast carcinomas. However, in the presence of high-risk characteristics, mastectomy involving axillary lymph node dissection is still contentious. In patients with Her-2 overexpression, treatment using anti-Her2 (trastuzumab) is also still disputed in colloid breast carcinoma because of the higher resistance rates.

CONCLUSION

Although clinically aggressive colloid breast carcinoma is rare, thorough clinical assessment and immediate treatment initiation will be beneficial for patients with high risk of relapse and metastatic spread.

Breast Cancer: A Molecularly Heterogenous Disease Needing Subtype-Specific Treatments

Breast cancer is the most commonly occurring cancer in women. There were over two-million new cases in world in 2018. It is the second leading cause of death from cancer in western countries. At the molecular level, breast cancer is a heterogeneous disease, which is characterized by high genomic instability evidenced by somatic gene mutations, copy number alterations, and chromosome structural rearrangements. The genomic instability is caused by defects in DNA damage repair, transcription, DNA replication, telomere maintenance and mitotic chromosome segregation. According to molecular features, breast cancers are subdivided in subtypes, according to activation of hormone receptors (estrogen receptor and progesterone receptor), of human epidermal growth factors receptor 2 (HER2), and or BRCA mutations. In-depth analyses of the molecular features of primary and metastatic breast cancer have shown the great heterogeneity of genetic alterations and their clonal evolution during disease development. These studies have contributed to identify a repertoire of numerous disease-causing genes that are altered through different mutational processes. While early-stage breast cancer is a curable disease in about 70% of patients, advanced breast cancer is largely incurable. However, molecular studies have contributed to develop new therapeutic approaches targeting HER2, CDK4/6, PI3K, or involving poly(ADP-ribose) polymerase inhibitors for BRCA mutation carriers and immunotherapy.

Mucinous versus medullary breast carcinoma: mammography, ultrasound, and MRI findings

Mucinous and medullary breast cancers (BCs) have different histological substrates that manifest as different imaging features on mammography, ultrasound, and MRI. The aim of the present review is to demonstrate the differences between these two rare BC subtypes and to describe the microscopic features, review the imaging methods for detection of both cancer subtypes, illustrate the imaging findings and present useful pearls and pitfalls. Out of a total of 30 patients with mucinous BC and nine with medullary BC, we have selected typical and also unusual imaging features that best represent these cancers. The patients underwent a mammography and breast ultrasound followed by magnetic resonance imaging. We briefly exhibit histological characteristics for a better understanding of the imaging aspects.

Omission of Chemotherapy for the Treatment of Mucinous Breast Cancer: A Nationwide Study from the Korean Breast Cancer Society

PURPOSE

Mucinous breast carcinoma (MBC) is a rare type of breast cancer. Although patients with MBC may have a better prognosis than that of patients with invasive ductal carcinoma, many clinicians administer adjuvant chemotherapy regimens similar to those for other breast tumors. Using data from a nationwide clinical database, this study evaluated the significance of adjuvant systemic chemotherapy and whether it can be omitted in MBC patients.

METHODS

We included 3,076 patients with a diagnosis of MBC recorded in the Korean Breast Cancer Registry between January 1990 and August 2016. We used the Kaplan-Meier method to analyze breast cancer-specific survival (BCCS) and overall survival (OS). Multivariate analysis was performed using a Cox proportional hazard ratio (HR) model to estimate the adjusted HR for each prognostic factor.

RESULTS

A total of 2,988 MBC patients were enrolled and followed-up for a median of 100 months (range, 2-324 months). Multivariate analysis revealed that axillary lymph node (ALN) metastasis and estrogen receptor (ER) negativity were significant prognostic factors for BCSS. Meanwhile, old age, pathologic tumor stage, and ALN metastasis were significant prognostic factors for OS. Subgroup analysis of ER-positive MBC showed that ALN metastasis was a significant prognostic factor for BCSS. Additionally, old age, pathologic tumor stage, and ALN metastasis were prognostic factors for OS. Ultimately, ALN metastasis was the most statistically significant prognostic factor for MBC. However, chemotherapy had no significant effect on BCSS and OS. The Kaplan-Meier curves of BCSS and OS based on pathologic tumor and nodal stages and age revealed that chemotherapy did not statistically significantly improve prognosis, except for the N3 stage.

CONCLUSION

Our large retrospective analysis revealed that adjuvant chemotherapy provided little benefit to improve the prognosis of most ER-positive MBC patients. Therefore, chemotherapy can be omitted in the treatment of most ER-positive MBC.

Clinicopathologic characteristics of HER2-positive pure mucinous carcinoma of the breast

BACKGROUND

Pure mucinous carcinoma (PMC) is a rare type of breast cancer, estimated to represent 2% of invasive breast cancer. PMC is typically positive for estrogen receptors (ER) and progesterone receptors (PR) and negative for human epidermal growth factor receptor 2 (HER2). The clinicopathologic characteristics of HER2-positive PMC have not been investigated.

METHODS

Pathology archives were searched for PMC diagnosed from January 1999 to April 2018. Clinicopathologic data and microscopic findings were reviewed and compared between HER2-positive PMC and HER2-negative PMC. We also analyzed the differences in disease-free survival (DFS) and overall survival according to clinicopathologic parameters including HER2 status in overall PMC cases.

RESULTS

There were 21 HER2-positive cases (4.8%) in 438 PMCs. The average tumor size of HER2-positive PMC was 32.21 mm (± 26.55). Lymph node metastasis was present in seven cases. Compared to HER2-negative PMC, HER2-positive PMC presented with a more advanced T category (p < .001), more frequent lymph node metastasis (p = .009), and a higher nuclear and histologic grade (p < .001). Microscopically, signet ring cells were frequently observed in HER2-positive PMC (p < .001), whereas a micropapillary pattern was more frequent in HER2-negative PMC (p = .012). HER2-positive PMC was more frequently negative for ER (33.3% vs. 1.2%) and PR (28.6% vs. 7.2%) than HER2-negative PMC and showed a high Ki-67 labeling index. During follow-up, distant metastasis and recurrence developed in three HER2-positive PMC patients. Multivariate analysis revealed that only HER2-positivity and lymph node status were significantly associated with DFS.

CONCLUSIONS

Our results suggest that HER2-positive PMC is a more aggressive subgroup of PMC. HER2 positivity should be considered for adequate management of PMC.

Mucinous breast cancer: A narrative review of the literature and a retrospective tertiary single-centre analysis

Mucinous carcinoma (MC) is a rare breast cancer characterized by the presence of large extracellular mucin amount. Two main subtypes can be distinguished: pure (PMC) and mixed (MMC). We conducted a retrospective MC analysis in our prospective maintained database, calculating disease-free survival (DFS) and 5-year overall survival (OS). We found a global 92.1% OS (higher in MMC group and statistically significative) and a DFS of 95.3% (higher in MMC group but not statistically significative).

Imaging features of pure mucinous breast carcinoma: correlation with extracellular mucus content

AIM

To analyse the correlation between imaging features using multiple techniques and extracellular mucus content in pure mucinous breast carcinoma (PMBC).

MATERIALS AND METHODS

A retrospective review of available images from 25 patients with 25 PMBC tumours was conducted, with ultrasonography (US), ultrasonic elastography (USE), mammography, and breast-specific gamma imaging (BSGI) available for 25, 15, 11, and eight patients, respectively. Microscopic slides from each tumour were evaluated for extracellular mucus content. The correlation between imaging features and mucus content was analysed using linear-by-linear association chi-square tests or Spearman's rank correlation analyses.

RESULTS

On US images, a significant correlation was found between mucus content and echo pattern (p=0.042) and colour Doppler blood flow (p=0.032), with a trend that the lower mucus content present in tumours, the more likely they were detected with isoechoic echo and high blood flow. On USE images, a moderate negative correlation (r=-0.60, p=0.029) was observed between mucus content and tumour stiffness. On BSGI images, a strong negative correlation (r=-0.92, p=0.001) was shown between mucus content and lesion to non-lesion ratio (L/N) values of radioactivity counts. No significant correlation was found between mucus content and mammography imaging features (all p>0.05).

CONCLUSION

Imaging features at US, USE, and BSGI correlated with extracellular mucus content in PMBC tumours, among which the L/N value using BSGI imaging is the most relevant feature.

Micropapillary variant of mucinous carcinoma of the breast shows genetic alterations intermediate between those of mucinous carcinoma and micropapillary carcinoma

AIMS

Micropapillary variant of mucinous carcinoma of the breast (MPMC) is a rare histological form of oestrogen receptor (ER)-positive invasive carcinoma that is characterised by micropapillary clusters of tumour cells in lakes of extracellular mucin. The aims of this study were to determine the genetic alterations underpinning MPMCs, and to determine whether they overlap with those of mucinous carcinomas and/or invasive micropapillary carcinomas.

METHODS AND RESULTS

DNA from five MPMCs was subjected to whole-exome sequencing. Somatic mutations, copy number alterations and mutational signatures were determined with state-of-the-art bioinformatics methods. No mutations in genes significantly mutated in breast cancer, including TP53, PIK3CA, GATA3, and MAP3K1, were detected. We identified copy number alterations that have been reported in invasive micropapillary carcinomas, such as recurrent gains in 1q, 6p, 8q, and 10q, and recurrent losses in 16q, 11q, and 13q, as well as a recurrent 8p12-8p11.2 amplification encompassing FGFR1. Like mucinous carcinomas, three of the five MPMCs analysed lacked PIK3CA mutations, 1q gains, and 16q losses, which are the hallmark genetic alterations of ER-positive breast cancers, whereas two MPMCs harboured 16q losses and/or a complex pattern of copy number alterations similar to those found in breast-invasive micropapillary carcinomas.

CONCLUSIONS

MPMCs are heterogeneous at the genetic level; some tumours show a pattern of somatic genetic alterations similar to those of mucinous carcinomas, whereas others resemble invasive micropapillary carcinomas at the genetic level. These findings suggest that MPMCs may not constitute one histological subtype, but rather a convergent phenotype that can stem from mucinous carcinomas or invasive micropapillary carcinomas.

Exploring Collagen Parameters in Pure Special Types of Invasive Breast Cancer

One of the promising tools to evaluate collagen in the extracellular matrix is the second-harmonic generation microscopy (SHG). This approach may shed light on the biological behavior of cancers and their taxonomy, but has not yet been applied to characterize collagen fibers in cases diagnosed as invasive breast carcinoma (BC) of histological special types (IBC-ST). Tissue sections from 99 patients with IBC-ST and 21 of invasive breast carcinoma of no special type (IBC-NST) were submitted to evaluation of collagen parameters by SHG. Tissue microarray was performed to evaluate immunohistochemical-based molecular subtype. In intratumoral areas, fSHG and bSHG (forward-SHG and backward-SHG) collagen parameters achieved their lowest values in mucinous, papillary and medullary carcinomas, whereas the highest values were found in classic invasive lobular and tubular carcinomas. Unsupervised hierarchical cluster analysis and minimal spanning tree using intratumoral collagen parameters allowed the identification of three main groups of breast cancer: group A (classic invasive lobular and tubular carcinomas); group B (IBC-NST, metaplastic, invasive apocrine and micropapillary carcinomas); and group C (medullary, mucinous and papillary carcinomas). Our findings provide further characterization of the tumor microenvironment of IBC-ST. This understanding may add information to build more consistent tumor categorization and to refine prognostication.

Copy number alterations associated with clinical features in an underrepresented population with breast cancer

Background

As the most incident tumor among women worldwide, breast cancer is a heterogeneous disease. Tremendous efforts have been made to understand how tumor characteristics as histological type, molecular subtype, and tumor microenvironment collectively influence disease diagnosis to treatment, which impact outcomes. Differences between populations and environmental and cultural factors have impacts on the origin and evolution of the disease, as well as the therapeutic challenges that arise due to these factors. We, then, compared copy number variations (CNVs) in mucinous and nonmucinous luminal breast tumors from a Brazilian cohort to investigate major CNV imbalances in mucinous tumors versus non‐mucinous luminal tumors, taking into account their clinical and pathological features.

Methods

48 breast tumor samples and 48 matched control blood samples from Brazilian women were assessed for CNVs by chromosome microarray. Logistic regression and random forest models were used in order to assess CNVs in chromosomal regions from tumors.

Results

CNVs that were identified in chromosomes 1, 5, 8, 17, 19, and 21 classify tumors according to their histological type, ethnicity, disease stage, and familial history.

Conclusion

Copy number alterations described in this study provide a better understanding of the landscape of genomic aberrations in mucinous breast cancers that are associated with clinical features.

Clinical Implication of HER2 Status in Hormone Receptor-Positive Mucinous Breast Cancer

PURPOSE

Mucinous carcinoma (MC) is a rare breast cancer with favorable outcome. Unlike typical breast cancer, the current guidelines do not recommend chemotherapy or anti-human epidermal growth factor receptor 2 (HER2) therapy for hormone receptor (HR)-positive MC, regardless of HER2 status. We evaluated the prognostic implication of HER2 status in HR-positive MC.

METHODS

We retrospectively reviewed the data of 471 patients with pure MC (stages I-III) who underwent curative surgery. We analyzed 5-year disease-free survival (DFS) and distant metastasis-free survival (DMFS), according to clinicopathological characteristics.

RESULTS

The median follow-up duration was 79.0 months. Overall, the 5-year DFS rate was 95.7% and the 5-year DMFS rate was 96.2%. Nodal status was the only significant factor for DFS (relative risk [RR], 3.40; 95% confidence interval [CI] 3.40-9.67, p = 0.021). Among HR-positive/node-negative patients with tumor size ≥ 3 cm, HER2-positive patients showed significantly worse DFS (RR, 8.76; 95% CI 1.45-52.76, p = 0.018) and DMFS (RR, 11.37; 95% CI 1.37-74.70, p = 0.011). This finding was consistently significant, when combining both "HR-positive/node-negative/tumor size ≥ 3 cm" and "HR-positive/node-positive" MC (n = 125) for DFS (RR, 4.30; 95% CI 1.43-12.97, p = 0.009) and DMFS (RR, 4.93; 95% CI 1.63-14.90, p = 0.005). Intriguingly, within this subgroup, among HER2-positive tumors, whereas 5-year DFS was 60.2% in patients who did not receive trastuzumab, 100% of those who received trastuzumab were disease free (p = 0.053).

CONCLUSIONS

In HR-positive, node-negative MC with tumor size ≥ 3 cm, patients with HER2-positive MC showed worse survival, suggesting a potential role of an anti-HER2 strategy in this subgroup.

Human Epidermal Growth Factor Receptor 2-positive Mucinous Carcinoma with Signet Ring Cell Differentiation, Which Showed Complete Response after Neoadjuvant Chemotherapy

Mucinous carcinoma (MC) is a rare subtype of breast cancer, which is composed of tumor cells floating in the abundant extracellular mucin. This form of cancer is usually estrogen receptor/progesterone receptor positive and human epidermal growth factor receptor 2 (HER2) negative. Here, we present a case of HER2-positive MC with an unusual signet ring cell differentiation. It is very rare that a breast tumor consists entirely of signet ring cells. The tumor showed pathologic complete response (pCR) after neoadjuvant chemotherapy with trastuzumab and pertuzumab. pCR of HER2-positive MC has rarely been described in literature. It is important to consider the biological heterogeneity of MCs for effective management.

Breast Carcinoma: Updates in Molecular Profiling 2018

The most significant contribution of molecular subtyping of breast carcinomas has been the identification of estrogen-positive and estrogen-negative tumor subtypes. Knowledge of genetic alterations in these tumors will help clinicians identify novel therapeutic targets. Understanding the progression pathways involved in the transition of in situ carcinoma to invasive carcinoma might lead to efficient risk stratification in these patients. The Cancer Genome Analysis Network has collected genomic and epigenomic data to provide comprehensive information regarding carcinogenesis and pathway interactions. Such information improves understanding of the disease process and also provides more accurate information toward identifying targetable mutations for treatment.

Role of columnar cell lesions in breast carcinogenesis: analysis of chromosome 16 copy number changes by multiplex ligation-dependent probe amplification

Columnar cell lesions have been proposed as precursor lesions of low-grade breast cancer. The molecular characteristic of low-grade breast neoplasia is whole-arm loss of chromosome 16q. Copy number changes of 6 genes on 16p and 20 genes on 16q were analysed by multiplex ligation-dependent probe amplification in 165 lesions of 103 patients. Twenty-three columnar cell lesions and 19 atypical ducal hyperplasia lesions arising in columnar cell lesions were included, as well as cases of usual ductal hyperplasia, blunt duct adenosis, ductal carcinoma in situ, lobular neoplasia and invasive carcinoma. Usual ductal hyperplasia and blunt duct adenosis lacked whole-arm losses of 16q. In contrast, columnar cell lesions without atypia, columnar cell lesions with atypia, atypical ductal hyperplasia, low-grade ductal carcinoma in situ and low-grade invasive carcinomas increasingly harboured whole-arm losses of 16q (17%, 27%, 47% and 57%, respectively). However, no recurrent losses in specific genes could be identified. In several patients, columnar cell lesions and atypical ductal hyperplasia harboured similar losses as related ductal carcinoma in situ or invasive carcinomas within the same breast. There were indications for 16q breakpoints near the centromere. Whole-arm gains on 16p were relatively scarce and there was no relation between whole-arm gains of 16p and progression of lesions of the low-grade breast neoplasia family. In conclusion, columnar cell lesions (with and without atypia) often harbour whole-arm losses of 16q, which underlines their role as precursors in low-grade breast carcinogenesis, in contrast with usual ductal hyperplasia and blunt duct adenosis. However, no recurrent losses in specific genes could be identified, pointing to minor events in multiple tumour suppressor genes rather than major events in a single 16q gene contributing to low-grade breast carcinogenesis.

Predictors for Survival and Distribution of 21-Gene Recurrence Score in Patients With Pure Mucinous Breast Cancer: A SEER Population-Based Retrospective Analysis

BACKGROUND

Pure mucinous breast cancer (PMBC) is a rare pathologic type of breast cancer, the prognostic factors of which have not been clearly defined. This study aimed to analyze the prognostic markers and distribution of 21-gene recurrence score (RS) in patients with PMBC.

PATIENTS AND METHODS

Utilizing the Surveillance, Epidemiology, and End Results (SEER) database, a retrospective analysis of PMBC cases was conducted. Multivariate analyses were used to evaluate the indicators for prognosis and the correlations between RS and traditional clinicopathologic characteristics. Disease was subdivided into 4 molecular phenotypes using estrogen receptor (ER) status and tumor grade.

RESULTS

Of the 8048 patients, most had ER-positive and node-negative tumors. Multivariate analysis revealed that molecular phenotype as well as age, race, tumor size, and lymph node status was an independent prognostic factor for patients with PMBC (P < .05). The 5-year breast cancer-specific survival of patients among different phenotypes was significantly different (97.9% for ER-positive and grade I tumor, 96.9% for ER-positive and grade II-III tumor, 96% for ER-negative and grade I tumor, 90.1% for ER-negative and grade II-III tumors, P < .001). The proportions of patients categorized into low, intermediate, and high RS risk group were 64.9%, 31.9%, and 3.2%, respectively. Grade, progesterone receptor status, and age were identified as independent variables associated with RS.

CONCLUSION

PMBC had favorable biological features and relatively good prognosis. Molecular phenotype as well as age, race, tumor size, and lymph node status were independent prognostic markers. Furthermore, age, progesterone receptor status, and grade could independently predict RS.