Medullary carcinoma of the breast and BRCA1 mutation

Development of a novel PTT assay for mutation detection in PALB2 large exons and PALB2 screening in medullary breast cancer

Beyond BRCA1 and BRCA2 genes, PALB2 (Partner and localizer of BRCA2) emerges as the third breast cancer susceptibility gene due to its role in the same DNA repair pathway: homologous recombination. In most populations studied so far, PALB2 mutations are detected in 1-2% of BRCA negative female patients. PALB2 gene contains 13 exons; exons 4 and 5 consist 65% of the coding area. We developed a protein truncation test (PTT) for quick screening of truncating pathogenic mutations of these two large exons. Specific primers were de novo, in silico designed and the PTT-PCR products were translated in the presence of biotinylated lysine and detected colorimetrically. The assay was initially tested in 30 patients with hereditary breast cancer, negative for BRCA mutations and then, in 17 patients with the rare medullary breast cancer subtype. Small PALB2 exons were screened with high-resolution melting curve analysis (HRMA) and the large DNA rearrangements with multiplex ligation-dependent probe amplification (MLPA). Any alterations detected were verified by Sanger DNA Sequencing. The developed PTT methodology is highly specific for clinical significant mutations; positive control samples that produce truncated PALB2 peptides were correctly identified and the method was accurate when compared to DNA sequencing. We did not detect any deleterious PALB2 mutation in both groups of patients. HRMA and MLPA were also negative for all tested samples. However, our novel, fast and cost-effective PTT method for pathogenic mutation detection of the two large PALB2 exons can be applied in screening of a large number of breast cancer patients.

What is the difference between triple-negative and basal breast cancers?

Triple-negative breast cancer (TNBC) represents a phenotype defined by the lack of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 expression. Because TNBCs have more aggressive features and lack a therapeutic target, they have become a key topic of clinical and research interest within the oncology community. With advancements in the field of molecular biology, gene expression profiling has resulted in the identification of intrinsic subtypes including basal-like breast cancers (BLBCs). Although often thought to be synonymous, TNBC and BLBC represent different biologic phenomena. Furthermore, even within the basal-like subtype, diversity exists. The purpose of this review is to outline the most current evidence in an attempt to answer the question: what is BLBC?

Rare (new) entities of the breast and medullary carcinoma

Rare tumours are a heterogeneous group of conditions that encompass benign to malignant lesions both of stromal and epithelial origin. Here some of these tumours are described, in which the authors have most familiarity. An outline of medullary carcinoma is also presented.

Why microscopy will remain a cornerstone of surgical pathology

Recent years have seen increasing predictions of the demise of conventional microscopy in patient care and investigative medicine. However, these predictions fail to recognize the power of morphologic analysis by a skilled observer. The amount of information that can be obtained from a simple H&E slide represents a windfall in terms of data quality, quantity and cost when compared to any other available technique. Moreover, the value of such interpretation is irreplaceable as we develop newer and more sophisticated technologies. Overall, it appears that reports of the death of microscopy have been greatly exaggerated.

Sporadic Invasive Breast Carcinomas With Medullary Features Display a Basal-like Phenotype

It is not clear whether invasive breast carcinomas with medullary features (IBCMFs, atypical medullary carcinomas) constitute a specific phenotype of breast cancer that is of biologic significance. Because medullary features are common in BRCA1-associated carcinomas and these tumors frequently show a basal-like phenotype, we examined whether IBCMFs expressed basal/myoepithelial markers and had a basal-like phenotype. We studied the immunohistochemical expression of 15 markers in tissue microarrays containing samples from 35 IBCMFs and 39 grade 3 invasive ductal carcinomas (IDCG3s) of no special type. In addition, we analyzed EGFR, C-MYC, and CCNE gene amplification by fluorescence in situ hybridization, because the expression of these genes is known to be associated with the basal-like phenotype. We defined the basal-like phenotype according to the criteria of Nielsen et al as being those tumors that were ER/HER2-negative and cytokeratin (CK) 5/6- and/or epidermal growth factor receptor-positive. IBCMFs were more frequently hormone receptor- and HER2-negative, but had greater expression of proliferation markers and p53. In addition, IBCMFs more frequently expressed basal/myoepithelial markers, such as CK5/6 and P-cadherin. A basal-like phenotype was found in 62.9% of IBCMFs but in only 18.9% of IDCG3s. No differences in gene amplification were found between IBCMFs and IDCG3s, although C-MYC amplification was more common in tumors without a basal-like phenotype. The identification of IBCMF as an independent group of tumors could be of clinical significance, given the high incidence of cases with a basal-like phenotype, which is a group of tumors with different prognosis and chemotherapy response from those of IDCG3s of no special type.

Clinicopathologic significance of the basal-like subtype of breast cancer: a comparison with hormone receptor and Her2/neu-overexpressing phenotypes

DNA microarray profiling studies have led to the classification of invasive breast carcinoma into luminal/estrogen receptor-positive, normal breast-like, Her2/neu-overexpressing, and basal-like types. Among these groups, the basal-like subtype is associated with the poorest clinical outcome in Western countries. To date, the clinicopathologic characteristics of the basal-like carcinomas, compared with other subtypes, have not been described in the Korean population. In this study, we used tissue microarray to examine the expression of basal cytokeratins (CK) (CK5 and CK14) and luminal CK (CK8/18), epidermal growth factor receptor, c-kit, hormone receptors (HRs), p53, and Her2/neu in 776 consecutive patients diagnosed with invasive breast carcinoma from January 1993 to December 1998 and categorized these cases into 5 subgroups (basal-like, HR-expressing, Her2/neu-overexpressing, HR and Her2/neu-expressing, and null subtypes negative for all markers), based on the immunohistochemical data. We identified cases of 114 (14.7%) basal-like, 345 (44.5%) HR-expressing, 133 (17.1%) Her2/neu-overexpressing, 61 (7.8%) HR and Her2/neu-expressing, and 123 (15.9%) null subtypes. Histologically, most basal-like breast cancers were invasive ductal carcinoma, not otherwise specified (98 cases, 86.0%), with high nuclear and/or histologic grades, and most metaplastic carcinomas (6 [75.0%] of 8 cases) were the basal-like subtype. Both basal-like and Her2/neu-overexpressing subtypes were associated with larger tumor sizes (mean, 3.6 and 3.3 cm, respectively) than the HR-expressing group (mean, 2.8 cm) (P = .001 and P = .036, respectively). Nodal stage of Her2/neu-overexpressing subtype was higher than that of basal-like subtype; however, overall stage was not different between the 2 groups (P = .010 and .123, respectively). Distant metastasis was most frequently observed in the Her2/neu-overexpressing subtype (33.8%), which was prognostically the worst subgroup of breast cancers. In contrast to previous findings from Western countries, our analyses reveal that the Her2/neu status is the most important prognostic factor of breast cancers.

Clinicopathologic features and long-term outcome of patients with medullary breast carcinoma managed with breast-conserving therapy (BCT)

PURPOSE

The purpose of this study is to compare the clinical characteristics and outcome of medullary carcinoma to infiltrating ductal carcinoma of the breast in a large cohort of conservatively managed patients with long-term follow-up.

METHODS AND MATERIALS

Chart records of patients with invasive breast cancer managed with breast-conserving therapy (BCT) at the therapeutic radiology facilities of Yale University School of Medicine before 2001 were reviewed. Forty-six cases (1971-2001) were identified with medullary histology; 1,444 patients with infiltrating ductal carcinoma served as a control group.

RESULTS

The medullary cohort presented at a younger age with a higher percentage of patients in the 35 years or younger age group (26.1% vs. 6.6%, p < 0.00001). Twelve patients with medullary histology underwent genetic screening, and 6 patients were identified with deleterious mutations. This group showed greater association with BRCA1/2 mutations compared with screened patients in the control group (50.0% vs. 15.8%, p = 0.0035). The medullary cohort was also significantly associated with greater T stage and tumor size (37.0% vs. 17.2% T2, mean size 3.2 vs. 2.5 cm, p = 0.00097) as well as negative ER (84.9% vs. 37.6%, p < 0.00001) and PR (87.5% vs. 48.1%, p = 0.00001) status. As of February 2003, median follow-up times for the medullary and control groups were 13.9 and 14.0 years, respectively. Although breast relapse-free rates were not significantly different (76.7% vs. 85.2%), 10-year distant relapse-free survival in the medullary cohort was significantly better than in the control group (94.9% vs. 77.5%, p = 0.028).

CONCLUSIONS

Despite poor clinicopathologic features, patients with medullary histology demonstrate favorable long-term distant relapse-free survival. Local control rates of patients with medullary and infiltrating ductal carcinoma are comparable. These findings suggest that patients diagnosed with medullary carcinoma are appropriate candidates for BCT and are associated with favorable long-term prognosis.

High proportion of recurrent germline mutations in the BRCA1 gene in breast and ovarian cancer patients from the Prague area

Background

Germline mutations in the BRCA1 and BRCA2 genes have been shown to account for the majority of hereditary breast and ovarian cancers. The purpose of our study was to estimate the incidence and spectrum of pathogenic mutations in BRCA1/2 genes in high-risk Czech families.

Methods

A total of 96 Czech families with recurrent breast and/or ovarian cancer and 55 patients considered to be at high-risk but with no reported family history of cancer were screened for mutations in the BRCA1/2 genes. The entire coding sequence of each gene was analyzed using a combination of the protein truncation test and direct DNA sequencing.

Results

A total of 35 mutations in the BRCA1/2 genes were identified in high-risk families (36.5%). Pathogenic mutations were found in 23.3% of breast cancer families and in 59.4% of families with the occurrence of both breast and ovarian cancer. In addition, four mutations were detected in 31 (12.9%) women with early onset breast cancer. One mutation was detected in seven (14.3%) patients affected with both a primary breast and ovarian cancer and another in three (33.3%) patients with a bilateral breast cancer. A total of 3 mutations in BRCA1 were identified among 14 (21.4%) women with a medullary breast carcinoma. Of 151 analyzed individuals, 35 (23.2%) carried a BRCA1 mutation and 9 (6.0%) a BRCA2 mutation. One novel truncating mutation was found in BRCA1 (c.1747A>T) and two in BRCA2 (c.3939delC and c.5763dupT). The 35 identified BRCA1 mutations comprised 13 different alterations. Three recurrent mutations accounted for 71.4% of unrelated individuals with detected gene alterations. The BRCA1 c.5266dupC (5382insC) was detected in 51.4% of mutation positive women. The mutations c.3700_3704del5 and c.181T>G (300T>G) contributed to 11.4% and 8.6% of pathogenic mutations, respectively. A total of eight different mutations were identified in BRCA2. The novel c.5763dupT mutation, which appeared in two unrelated families, was the only recurrent alteration of the BRCA2 gene identified in this study.

Conclusion

Mutational analysis of BRCA1/2 genes in 151 high-risk patients characterized the spectrum of gene alterations and demonstrated the dominant role of the BRCA1 c.5266dupC allele in hereditary breast and ovarian cancer.

Prognostic relevance of gene amplifications and coamplifications in breast cancer

Multiple different oncogenes have been described previously to be amplified in breast cancer including HER2, EGFR, MYC, CCND1, and MDM2. Gene amplification results in oncogene overexpression but may also serve as an indicator of genomic instability. As such, presence of one or several gene amplifications may have prognostic significance. To assess the prognostic importance of amplifications and coamplifications of HER2, EGFR, MYC, CCND1, and MDM2 in breast cancer, we analyzed a breast cancer tissue microarray containing samples from 2197 cancers with follow-up information. Fluorescence in situ hybridizations revealed amplifications of CCND1 in 20.1%, HER2 in 17.3%, MDM2 in 5.7%, MYC in 5.3%, and EGFR in 0.8% of the tumors. All gene amplifications were significantly associated with high grade. HER2 (P < 0.001) and MYC amplification (P < 0.001) were also linked to shortened survival. In case of HER2, this was independent of grade, pT, and pN categories. MYC amplification was almost 3 times more frequent in medullary cancer (15.9%), than in the histologic subtype with the second highest frequency (ductal; 5.6%; P = 0.0046). HER2 and MYC amplification were associated with estrogen receptor/progesterone receptor negativity (P < 0.001) whereas CCND1 amplification was linked to estrogen receptor/progesterone receptor positivity (P < 0.001). Coamplifications were more prevalent than expected based on the individual frequencies. Coamplifications of one or several other oncogenes occurred in 29.6% of CCND1, 43% of HER2, 55.7% of MDM2, 65% of MYC, and 72.8% of EGFR-amplified cancers. HER2/MYC-coamplified cancers had a worse prognosis than tumors with only one of these amplifications. Furthermore, a gradual decrease of survival was observed with increasing number of amplifications. In conclusion, these data support a major prognostic impact of genomic instability as determined by a broad gene amplification survey in breast cancer.

Medullary carcinoma, provocative now as then

The recent observation that studies of BRCA1-associated tumors contain a high proportion of medullary carcinomas and ductal carcinomas with medullary features has re-introduced pathologists to an old diagnostic problem. The term "medullary carcinoma" dates to the 19th century, but the modern entity was introduced in 1949 by Moore and Foote, who described a carcinoma with a lymphoid infiltrate, a favorable prognosis, and low frequency of metastasis. Almost three decades later, Ridolfi et al proposed specific criteria for diagnosis, resulting in an entity with an even more favorable prognosis and a lower incidence. The reproducibility and clinical relevance of the diagnosis have been questioned recently, and new criteria have been proposed and compared. The tumors typically express cytokeratin 7, often vimentin and S100-protein, but not cytokeratin 20. The usual ones are positive for p53 and negative for estrogen receptor, Her2/neu, and bcl-2. Medullary carcinomas express e-cadherin and beta-catenin more often than ordinary high-grade ductal carcinomas, and the former have genetic differences from the latter. The lymphoid infiltrate of medullary carcinomas is related to beta-actin fragments exposed by apoptotic cells. The present review discusses historical and recent developments and emphasizes diagnostic criteria.

Morphologic spectrum of estrogen receptor-negative breast carcinoma

CONTEXT

Estrogen receptor (ER)-negative breast carcinomas are a heterogeneous group of breast cancers that are generally thought to be aggressive.

OBJECTIVE

To determine the morphologic and immunohistochemical spectrum of a consecutive series of ER-negative breast carcinomas, in an attempt to understand the pathogenesis and behavior of these lesions.

DESIGN

Seventy-four consecutive cases of ER-negative invasive carcinomas were studied. Hematoxylin-eosin-stained sections were reviewed, and new sections were stained for c-erbB-2, p53, vimentin, and androgen and prolactin receptors. The findings were correlated with the axillary lymph node status as a measure of tumor aggressiveness.

SETTING

The histopathology department of a tertiary referral teaching hospital.

RESULTS

The tumors included 50 (68%) invasive ductal carcinomas, 21 (28%) medullary/atypical medullary carcinomas, and 1 each of invasive lobular, apocrine, and papillary carcinoma. Some of the invasive ductal cases had distinctive features that are described in this report. Maximum tumor diameter varied between 5 and 100 mm. Sixty tumors (81%) were grade 3, 13 (18%) were grade 2, and 1 (1%) was grade 1. Of the 60 cases in which the axillary node status was known, 34 (57%) had metastases, and 26 did not. Tumors associated with positive nodes were significantly larger than those associated with negative nodes (37.2 vs 17.8 mm, P <.001). A higher percentage of node-negative tumors were c-erbB-2 positive (42% vs 21%, P <.05). There were no differences between the 2 groups with regard to histologic type, tumor grade, or the expression of p53, vimentin, or androgen or prolactin receptors.

CONCLUSIONS

Many ER-negative breast carcinomas have distinctive microscopic features. Not all ER-negative tumors are aggressive, as judged by the absence of lymph node metastases in 43% of cases in this series. Tumor size is the most important indicator for the likelihood of the presence of lymph node metastases. The wide range of tumor sizes encountered in this series suggests that the ER status of a tumor is determined early in its natural history and supports the existence of 2 separate pathways for the development of ER-negative and ER-positive breast carcinomas.