Mixed epithelial/mesenchymal metaplastic carcinoma (carcinosarcoma) of the breast in BRCA1 carrier

Carcinosarcoma of the breast: Facing the challenge of a rare nosologic entity

Carcinosarcoma (CS), also known as metaplastic breast carcinoma with mesenchymal differentiation, is one of the five distinct subtypes of metaplastic breast cancer. It is considered as a mixed, biphasic neoplasm consisting of a carcinomatous component combined with a malignant nonepithelial element of mesenchymal origin without an intermediate transition zone. Although cellular origin of this neoplasm remains controversial, most researchers declare that neoplastic cells derive from a cellular structure with potential biphasic differentiation. Despite recent research on the therapeutic strategies against CS neoplastic disorders, surgical resection appears the only potentially curative approach. Since CS metastasize by the lymphatic route, axillary assessment with sentinel lymph node biopsy and/or axillary lymph node dissection is always implemented. Nevertheless, the tumor also presents a hematogenous metastatic pattern including pleural, pulmonary, liver, brain and less commonly bone metastases. Thus, surgical removal of breast CS does not necessarily ensure patient’s long-term recovery. Moreover, alternative therapies, such as radio- and chemotherapy proved insufficient and 5-year survival rate is limited. Nevertheless, there is evidence that following surgery, the combination of radio and chemotherapy is associated with a better prognosis than either treatment alone. The aim of this review is to evaluate the results of surgical treatment for breast CS with special reference to the extent of its histological spread. Clinical features, histogenesis, morphological and immunochemical findings are discussed, while the role of current diagnostic and therapeutic management of this aggressive neoplasm is emphasized.

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

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

Metaplastic breast cancer: an all-round multidisciplinary consensus

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

Metaplastic carcinoma of the breast and BRCA1 germline mutation: a case report and review

BACKGROUND

Metaplastic carcinoma of the breast consists of both invasive ductal carcinoma and metaplastic carcinoma. This rare subtype of cancer has a poor prognosis. The development of metaplastic breast cancer and relationship with BRCA1 are not well known. Here, we report a rare case of germline BRCA1 mutation-positive breast cancer with chondroid metaplasia.

CASE PRESENTATION

A 39-year-old Japanese woman with a family history of breast cancer in her mother and ovarian cancer in her maternal grandmother consulted at our hospital with a left breast mass. Needle biopsy for the mass was performed, leading to a diagnosis of invasive breast cancer with chondroid metaplasia. We performed left mastectomy + sentinel lymph node biopsy + tissue expander insertion and replaced with a silicone implant later. Pathological examination revealed that the patient had triple-negative breast cancer. Four courses of doxorubicin+ cyclophosphamide therapy were performed as adjuvant therapy after surgery. We performed genetic counseling and genetic testing, and the results suggested the germline BRCA1 mutation 307 T> A (L63*). She has currently lived without a relapse for 2 years post-surgery.

CONCLUSIONS

There have been only 6 cases of metaplastic breast carcinoma with germline BRCA1 mutations including our case. Patients with BRCA1 mutations may develop basal-like subtypes or M type of triple-negative breast cancer besides metaplastic breast cancers.

Rapid selection of BRCA1-proficient tumor cells during neoadjuvant therapy for ovarian cancer in BRCA1 mutation carriers

Ovarian carcinomas (OC) often demonstrate rapid tumor shrinkage upon neoadjuvant chemotherapy (NACT). However, complete pathologic responses are very rare and the mechanisms underlying the emergence of residual tumor disease remain elusive. We hypothesized that the change of somatic BRCA1 status may contribute to this process. The loss-of-heterozygosity (LOH) at the BRCA1 locus was determined for 23 paired tumor samples obtained from BRCA1 germ-line mutation carriers before and after NACT. We observed a somatic loss of the wild-type BRCA1 allele in 74% (17/23) of OCs before NACT. However, a retention of the wild-type BRCA1 copy resulting in a reversion of LOH status was detected in 65% (11/17) of those patients after NACT. Furthermore, we tested 3 of these reversion samples for LOH at intragenic BRCA1 single nucleotide polymorphisms (SNPs) and confirmed a complete restoration of the SNP heterozygosity in all instances. The neoadjuvant chemotherapy for BRCA1-associated OC is accompanied by a rapid expansion of pre-existing BRCA1-proficient tumor clones suggesting that continuation of the same therapy after NACT and surgery may not be justified even in patients initially experiencing a rapid tumor regression.

Intraductal carcinoma and carcinosarcoma with bone metastases presenting in one breast: A case report

Carcinosarcoma of the breast is an extremely rare and clinically aggressive tumor possessing carcinomatous components and malignant mesenchymal elements, with few cases reported in the literature. The prognosis of breast carcinosarcoma is poor when compared with more common types of breast cancer, such as ductal or lobular carcinoma. Furthermore, carcinosarcoma presents a diagnostic and therapeutic challenge due to the diversity in histology pattern and the lack of consensus regarding diagnostic criteria and effective systemic management. A 51-year-old female presented to the Department of Medical Oncology of the Second Affiliated Hospital of Zhejiang University (Hangzhou, China) with the complaint of lumbago and physical examination revealed a small mass in the right breast near the areola. Mammography and magnetic resonance imaging revealed two small masses, which were <1 cm in diameter. Positron emission tomography/computed tomography showed a maximum standardized uptake volume of 3.46 for one soft tissue nodule and multiple bones that were exhibiting radioactive enhancement. The patient was diagnosed with a breast carcinosarcoma with bone metastases and breast intraductal carcinoma. The response to chemotherapy was poor and the patient succumbed to the disease within one month of diagnosis.

High prevalence of GPRC5A germline mutations in BRCA1-mutant breast cancer patients

In a search for new breast cancer (BC) predisposing genes, we performed a whole exome sequencing analysis using six patient samples of familial BC and identified a germline inactivating mutation c.183delG [p. Arg61fs] in an orphan G protein-coupled receptor GPRC5A. An extended case-control study revealed a tenfold enrichment for this mutation in BC patients carrying the 5382insC allele of BRCA1, the major founder mutation in the Russian population, compared to wild-type BRCA1 BC cases [6/117 (5.1%) vs. 8/1578 (0.5%), p = 0.0002]. In mammary tumors (n = 60), the mRNA expression of GPRC5A significantly correlated with that of BRCA1 (p = 0.00018). In addition, the amount of GPRC5A transcript was significantly lower in BC obtained from BRCA1 mutation carriers (n = 17) compared to noncarriers (n = 93) (p = 0.026). Accordingly, a siRNA-mediated knockdown of either BRCA1 or GPRC5A in the MDA-MB-231 human BC cell line reduced expression of GPRC5A or BRCA1, respectively. Knockdown of GPRC5A also attenuated radiation-induced BRCA1- and RAD51-containing nuclear DNA repair foci. Taken together, these data suggest that GPRC5A is a modifier of BC risk in BRCA1 mutation carriers and reveals a functional interaction of these genes.

Development of breast tumors in CHEK2, NBN/NBS1 and BLM mutation carriers does not commonly involve somatic inactivation of the wild-type allele

Somatic inactivation of the remaining allele is a characteristic feature of cancers arising in BRCA1 and BRCA2 mutation carriers, which determines their unprecedented sensitivity to some DNA-damaging agents. Data on tumor-specific status of the involved gene in novel varieties of hereditary breast cancer (BC) remain incomplete. We analyzed 32 tumors obtained from 30 patients with non-BRCA1/2 BC-associated germ-line mutations: 25 women were single mutation carriers (7 BLM, 15 CHEK2 and 3 NBN/NBS1) and 5 were double mutation carriers (2 BLM/BRCA1, 1 CHEK2/BLM, 1 CHEK2/BRCA1 and 1 NBN/BLM). Losses of heterozygosity affecting the wild-type allele were detected in none of the tumors from BLM mutation carriers, 3/18 (17 %) CHEK2-associated BC and 1/4 (25 %) NBN/NBS1-driven tumors. The remaining 28 BC were subjected to the sequence analysis of entire coding region of the involved gene; no somatic mutations were identified. We conclude that the tumor-specific loss of the wild-type allele is not characteristic for BC arising in CHEK2, NBN/NBS1 and BLM mutation carriers. Rarity of "second-hit" inactivation of the involved gene in CHEK2-, NBN/NBS1- and BLM-associated BC demonstrates their substantial biological difference from BRCA1/2-driven cancers and makes them poorly suitable for the clinical trials with cisplatin and PARP inhibitors.

First description of an acinic cell carcinoma of the breast in a BRCA1 mutation carrier: a case report

Background

Acinic cell carcinoma (ACC) is a rare malignant epithelial neoplasm characterized by the presence of malignant tubular acinar exocrine gland structures. Diagnosis is generally made in salivary glands and in the pancreas. ACC of the breast has been reported in few cases only. Carriers of inherited mutations in the BRCA1 gene are prone to the development of breast cancer, mainly invasive ductal or medullary type carcinomas. We describe for the first time a BRCA1 mutation carrier with a diagnosis of ACC of the breast.

Case presentation

The patient developed an invasive ductal carcinoma (IDC) at the age of 40 years and an ACC in the contralateral breast at 44 years. Immunohistochemical examination of the ACC revealed a triple negative status (i.e., negativity for estrogen receptor, progesterone receptor and HER2 protein) and positivity for p53. Using a combination of loss of heterozygosity (LOH) and sequencing analyses, the loss of the wild-type BRCA1 allele was detected in both the ACC and the IDC. In addition, two different somatic TP53 mutations, one in the ACC only and another one in the IDC only, were observed.

Conclusion

Both the immunohistochemical and molecular features observed in the ACC are typical of BRCA1-associated breast cancers and suggest an involvement of the patient’s germline mutation in the disease. The occurrence of rare histological types of breast cancers, including malignant phyllodes tumor, atypical medullary carcinoma and metaplastic carcinoma, in BRCA1 mutation carriers has been already reported. Our findings further broaden the spectrum of BRCA1-associated breast malignancies.

Germline mutation of Brca1 alters the fate of mammary luminal cells and causes luminal-to-basal mammary tumor transformation

Breast cancer developed in familial BRCA1 mutation carriers bears striking similarities to sporadic basal-like breast tumors. The mechanism underlying the function of BRCA1 in suppressing basal-like breast cancer remains unclear. We previously reported that the deletion of p18(Ink4c) (p18), an inhibitor of G1 cyclin Ds-dependent CDK4 and CDK6, stimulates mammary luminal progenitor cell proliferation and leads to spontaneous luminal tumor development. We report here that germline mutation of Brca1 in p18-deficient mice blocks the increase of luminal progenitor cells, impairs luminal gene expression and promotes malignant transformation of mammary tumors. Instead of the luminal mammary tumors developed in p18 single-mutant mice, mammary tumors developed in the p18;Brca1 mice, similar to breast cancer developed in familial BRCA1 carriers, exhibited extensive basal-like features and lost the remaining wild-type allele of Brca1. These results reveal distinct functions of the RB and BRCA1 pathways in suppressing luminal and basal-like mammary tumors, respectively. These results also suggest a novel mechanism--causing luminal-to-basal transformation--for the development of basal-like breast cancer in familial BRCA1 carriers and establish a unique mouse model for developing therapeutic strategies to target both luminal and basal-like breast cancers.

Diagnosis and Management of Multiple Carcinosarcoma of the Breast in a Young Chinese Patient

BACKGROUND: Carcinosarcoma is an exceptionally rare and poorly differentiated kind of breast neoplasm with only few published reports in the literature. CASE REPORT: We report a case of breast carcinosarcoma in a 26-year-old Chinese female patient, presenting as multiple lumps in a single breast. A nipple-sparing modified radical mastectomy was performed. The patient is now in her 7th postoperative month and disease-free. CONCLUSION: Carcinosarcoma is challenging to diagnose preoperatively, even with core needle biopsy histopathology. Modified radical mastectomy is an efficient and practical operative treatment. Application of adjuvant therapy should be based on the proportion of carcinomatous component of the lesion in pathological test. Careful periodic follow-up after the initial treatment is strongly recommended.

Deconstructing the molecular portraits of breast cancer

Breast cancer is a heterogeneous disease in terms of histology, therapeutic response, dissemination patterns to distant sites, and patient outcomes. Global gene expression analyses using high‐throughput technologies have helped to explain much of this heterogeneity and provided important new classifications of cancer patients. In the last decade, genomic studies have established five breast cancer intrinsic subtypes (Luminal A, Luminal B, HER2‐enriched, Claudin‐low, Basal‐like) and a Normal Breast‐like group. In this review, we dissect the most recent data on this genomic classification of breast cancer with a special focus on the Claudin‐low subtype, which appears enriched for mesenchymal and stem cell features. In addition, we discuss how the combination of standard clinical‐pathological markers with the information provided by these genomic entities might help further understand the biological complexity of this disease, increase the efficacy of current and novel therapies, and ultimately improve outcomes for breast cancer patients.

Low-grade adenosquamous carcinoma of the breast--A case report with a BRCA1 germline mutation

Breast cancers occurring in women with germline BRCA1 mutations tend to fall into the category of triple-negative or basal-like phenotypes, such as metaplastic carcinoma. Low-grade adenosquamous carcinoma of the breast is a rare variant of metaplastic carcinoma. We present the case of a 49-year-old woman with a past medical history of invasive ductal breast carcinoma 13 years ago, and who was recently diagnosed as having a low-grade adenosquamous carcinoma in the same breast. Genetic analysis of blood DNA revealed a BRCA1 mutation. To our knowledge, BRCA1 mutation in association with a low-grade adenosquamous carcinoma of the breast has not yet been reported. Thus, it may be important to consider the possibility of an association, but supplemental studies are needed.