3150566
Molecular characterization of breast cancer in young Brazilian women.
OBJECTIVE
To evaluate the distribution of molecular subtypes of breast tumors diagnosed in young Brazilian women and to analyze the frequency of loss of heterozygocity (LOH) in BRCA1 among different molecular subtypes of early-onset breast cancer.


METHODS
Samples from 72 cases of invasive breast carcinoma diagnosed in women aged between 19 and 40 years were evaluated using an immunohistochemical panel of biomarkers. Three intragenic BRCA1 locus microsatellites, D17S1322, D17S1323, and D17S855, were PCR amplified from matched normal (lymphocyte) and tumor DNAs for (LOH) analysis.


RESULTS
We found 13 cases (18%) that had an immunohistochemical profile consistent with being basal-like. Forty cases (55%) were luminal A type; 11% (8 cases) were luminal B type, 13% (9 cases) were HER2-overexpressing tumors and two cases were ER-/HER2- carcinomas lacking basal marker expression. Four of the 16 informative cases at D17S1322, one of the four informative cases at D17S855, and none of the five informative cases at D17S1323 displayed LOH (four basal-like and one Luminal A). Microsatellite instability (MSI) at D17S855 and D17S1322 was found in two cases (one a basal-like and one Luminal A).


CONCLUSION
In our study, basal-like tumor was the second most frequent molecular type among young Brazilian women and was only observed in women diagnosed under the age of 35 years. There was no significant difference of LOH at BRCA1 locus rates between basal-like breast tumors and not-basal-like breast tumors (p=0.62). LOH in BRCA1 and MSI in these breast cancers were not frequent but may indicate a small group of breast cancers with a specific molecular makeup.
1280204
Molecular portraits of human breast tumours
Human breast tumours are diverse in their natural history and in their responsiveness to treatments. Variation in transcriptional programs accounts for much of the biological diversity of human cells and tumours. In each cell, signal transduction and regulatory systems transduce information from the cell's identity to its environmental status, thereby controlling the level of expression of every gene in the genome. Here we have characterized variation in gene expression patterns in a set of 65 surgical specimens of human breast tumours from 42 different individuals, using complementary DNA microarrays representing 8,102 human genes. These patterns provided a distinctive molecular portrait of each tumour. Twenty of the tumours were sampled twice, before and after a 16-week course of doxorubicin chemotherapy, and two tumours were paired with a lymph node metastasis from the same patient. Gene expression patterns in two tumour samples from the same individual were almost always more similar to each other than either was to any other sample. Sets of co-expressed genes were identified for which variation in messenger RNA levels could be related to specific features of physiological variation. The tumours could be classified into subtypes distinguished by pervasive differences in their gene expression patterns.
15549055
Gene expression patterns of breast carcinomas distinguish tumor subclasses with clinical implications
The purpose of this study was to classify breast carcinomas based on variations in gene expression patterns derived from cDNA microarrays and to correlate tumor characteristics to clinical outcome. A total of 85 cDNA microarray experiments representing 78 cancers, three fibroadenomas, and four normal breast tissues were analyzed by hierarchical clustering. As reported previously, the cancers could be classified into a basal epithelial-like group, an ERBB2-overexpressing group and a normal breast-like group based on variations in gene expression. A novel finding was that the previously characterized luminal epithelial/estrogen receptor-positive group could be divided into at least two subgroups, each with a distinctive expression profile. These subtypes proved to be reasonably robust by clustering using two different gene sets: first, a set of 456 cDNA clones previously selected to reflect intrinsic properties of the tumors and, second, a gene set that highly correlated with patient outcome. Survival analyses on a subcohort of patients with locally advanced breast cancer uniformly treated in a prospective study showed significantly different outcomes for the patients belonging to the various groups, including a poor prognosis for the basal-like subtype and a significant difference in outcome for the two estrogen receptor-positive groups.
6840112
Repeated observation of breast tumor subtypes in independent gene expression data sets
Characteristic patterns of gene expression measured by DNA microarrays have been used to classify tumors into clinically relevant subgroups. In this study, we have refined the previously defined subtypes of breast tumors that could be distinguished by their distinct patterns of gene expression. A total of 115 malignant breast tumors were analyzed by hierarchical clustering based on patterns of expression of 534 “intrinsic” genes and shown to subdivide into one basal-like, one ERBB2-overexpressing, two luminal-like, and one normal breast tissue-like subgroup. The genes used for classification were selected based on their similar expression levels between pairs of consecutive samples taken from the same tumor separated by 15 weeks of neoadjuvant treatment. Similar cluster analyses of two published, independent data sets representing different patient cohorts from different laboratories, uncovered some of the same breast cancer subtypes. In the one data set that included information on time to development of distant metastasis, subtypes were associated with significant differences in this clinical feature. By including a group of tumors from BRCA1 carriers in the analysis, we found that this genotype predisposes to the basal tumor subtype. Our results strongly support the idea that many of these breast tumor subtypes represent biologically distinct disease entities.
2279518
Breast cancer classification and prognosis based on gene expression profiles from a population-based study
Comprehensive gene expression patterns generated from cDNA microarrays were correlated with detailed clinico-pathological characteristics and clinical outcome in an unselected group of 99 node-negative and node-positive breast cancer patients. Gene expression patterns were found to be strongly associated with estrogen receptor (ER) status and moderately associated with grade, but not associated with menopausal status, nodal status, or tumor size. Hierarchical cluster analysis segregated the tumors into two main groups based on their ER status, which correlated well with basal and luminal characteristics. Cox proportional hazards regression analysis identified 16 genes that were significantly associated with relapse-free survival at a stringent significance level of 0.001 to account for multiple comparisons. Of 231 genes previously reported by others [van't Veer, L. J., et al. (2002) Nature 415, 530-536] as being associated with survival, 93 probe elements overlapped with the set of 7,650 probe elements represented on the arrays used in this study. Hierarchical cluster analysis based on the set of 93 probe elements segregated our population into two distinct subgroups with different relapse-free survival (P < 0.03). The number of these 93 probe elements showing significant univariate association with relapse-free survival (P < 0.05) in the present study was 14, representing 11 unique genes. Genes involved in cell cycle, DNA replication, and chromosomal stability were consistently elevated in the various poor prognostic groups. In addition, glutathione S-transferase M3 emerged as an important survival marker in both studies. When taken together with other array studies, our results highlight the consistent biological and clinical associations with gene expression profiles.
1220508
Immunohistochemical and Clinical Characterization of the Basal-Like Subtype of Invasive Breast Carcinoma
Purpose: Expression profiling studies classified breast carcinomas into estrogen receptor (ER)+/luminal, normal breast-like, HER2 overexpressing, and basal-like groups, with the latter two associated with poor outcomes. Currently, there exist clinical assays that identify ER+/luminal and HER2-overexpressing tumors, and we sought to develop a clinical assay for breast basal-like tumors. Experimental Design: To identify an immunohistochemical profile for breast basal-like tumors, we collected a series of known basal-like tumors and tested them for protein patterns that are characteristic of this subtype. Next, we examined the significance of these protein patterns using tissue microarrays and evaluated the prognostic significance of these findings. Results: Using a panel of 21 basal-like tumors, which was determined using gene expression profiles, we saw that this subtype was typically immunohistochemically negative for estrogen receptor and HER2 but positive for basal cytokeratins, HER1, and/or c-KIT. Using breast carcinoma tissue microarrays representing 930 patients with 17.4-year mean follow-up, basal cytokeratin expression was associated with low disease-specific survival. HER1 expression was observed in 54% of cases positive for basal cytokeratins (versus 11% of negative cases) and was associated with poor survival independent of nodal status and size. c-KIT expression was more common in basal-like tumors than in other breast cancers but did not influence prognosis. Conclusions: A panel of four antibodies (ER, HER1, HER2, and cytokeratin 5/6) can accurately identify basal-like tumors using standard available clinical tools and shows high specificity. These studies show that many basal-like tumors express HER1, which suggests candidate drugs for evaluation in these patients.
16766927
p63, cytokeratin 5, and P-cadherin: three molecular markers to distinguish basal phenotype in breast carcinomas
Human breast carcinomas represent a heterogeneous group of tumors diverse in behavior, outcome, and response to therapy. However, the current system of pathological classification does not take into account biologic determinants of prognosis. The purpose of this study was to classify and characterize breast carcinomas based on variations in protein expression patterns derived from immunohistochemical analyses on tissue microarrays (TMAs). Therefore, 11 TMAs representing 168 invasive breast carcinomas were constructed. Breast tumors were classified into four different subtypes depending on estrogen receptor (ER) and HER2 expression. Basal-type tumors expressed neither of these proteins and represented 7.6% of our series; basal-like HER2-overexpressing tumors did not express ER and represented 17.7%; luminal-type tumors expressed ER and represented 72.8% of this series (luminal A 56.3%, luminal B 16.5%). Moreover, we characterized each subtype based on P-cadherin (P-CD), p63, cytokeratin (CK)5, BCL2, and Ki67 expression. Basal-type tumors were mostly grade III, more frequently P-CD-, p63-, and CK5-positive, and had a high proliferation rate. Conversely, luminal-type tumors rarely expressed basal markers and had a low grade and proliferation rate. Basal-like HER2-overexpressing tumors showed a basal-type profile similar with a high grade and up-regulation of P-CD and CK5. With this study, we show that P-CD, p63, and CK5 are important molecular markers that can be used to distinguish a basal phenotype. In addition, we also demonstrate the usefulness of TMAs in breast carcinoma immunoprofiling.
34903395
High‐throughput protein expression analysis using tissue microarray technology of a large well‐characterised series identifies biologically distinct classes of breast cancer confirming recent cDNA expression analyses
Recent studies on gene molecular profiling using cDNA microarray in a relatively small series of breast cancer have identified biologically distinct groups with apparent clinical and prognostic relevance. The validation of such new taxonomies should be confirmed on larger series of cases prior to acceptance in clinical practice. The development of tissue microarray (TMA) technology provides methodology for high‐throughput concomitant analyses of multiple proteins on large numbers of archival tumour samples. In our study, we have used immunohistochemistry techniques applied to TMA preparations of 1,076 cases of invasive breast cancer to study the combined protein expression profiles of a large panel of well‐characterized commercially available biomarkers related to epithelial cell lineage, differentiation, hormone and growth factor receptors and gene products known to be altered in some forms of breast cancer. Using hierarchical clustering methodology, 5 groups with distinct patterns of protein expression were identified. A sixth group of only 4 cases was also identified but deemed too small for further detailed assessment. Further analysis of these clusters was performed using multiple layer perceptron (MLP)‐artificial neural network (ANN) with a back propagation algorithm to identify key biomarkers driving the membership of each group. We have identified 2 large groups by their expression of luminal epithelial cell phenotypic characteristics, hormone receptors positivity, absence of basal epithelial phenotype characteristics and lack of c‐erbB‐2 protein overexpression. Two additional groups were characterized by high c‐erbB‐2 positivity and negative or weak hormone receptors expression but showed differences in MUC1 and E‐cadherin expression. The final group was characterized by strong basal epithelial characteristics, p53 positivity, absent hormone receptors and weak to low luminal epithelial cytokeratin expression. In addition, we have identified significant differences between clusters identified in this series with respect to established prognostic factors including tumour grade, size and histologic tumour type as well as differences in patient outcomes. The different protein expression profiles identified in our study confirm the biologic heterogeneity of breast cancer and demonstrate the clinical relevance of classification in this manner. These observations could form the basis of revision of existing traditional classification systems for breast cancer. © 2005 Wiley‐Liss, Inc.
9548639
Basal-like breast cancer: a critical review.
Recent gene expression profiling of breast cancer has identified specific subtypes with clinical, biologic, and therapeutic implications. The basal-like group of tumors is characterized by an expression signature similar to that of the basal/myoepithelial cells of the breast and is reported to have transcriptomic characteristics similar to those of tumors arising in BRCA1 germline mutation carriers. They are associated with aggressive behavior and poor prognosis, and typically do not express hormone receptors or HER-2 ("triple-negative" phenotype). Therefore, patients with basal-like cancers are unlikely to benefit from currently available targeted systemic therapy. Although basal-like tumors are characterized by distinctive morphologic, genetic, immunophenotypic, and clinical features, neither an accepted consensus on routine clinical identification and definition of this aggressive subtype of breast cancer nor a way of systematically classifying this complex group of tumors has been described. Different definitions are, therefore, likely to produce variable and contradictory results that may hamper consistent identification and development of treatment strategies for these tumors. In this review, we discuss definition, heterogeneity, morphologic spectrum, relation to BRCA1, and clinical significance of this important class of breast cancer.
42976929
Triple Negative Breast Carcinoma and the Basal Phenotype: From Expression Profiling to Clinical Practice
Triple negative breast carcinomas (TNBCs) are a group of primary breast tumors with aggressive clinical behavior. Most TNBCs possess a basal phenotype (BP) and show varying degrees of basal cytokeratin and myoepithelial marker expression. The importance of recognizing these tumors came to light largely as the result of gene expression profiling studies that categorized breast cancer into 3 major groups. Two of these groups are defined by their respective expression of estrogen receptor and HER2. TNBCs represent a third group and are defined by negativity for hormone receptors and HER2. TNBCs currently lack effective targeted therapies and are frequently resistant to standard chemotherapeutic regimens. These tumors tend to occur in premenopausal women and members of specific ethnic groups and a subset are associated with heritable BRCA1 mutations. For patients with sporadic TNBCs and BP tumors, BRCA1 dysfunction seems to play a major role in the development and progression of disease. The pathologist's role in the diagnosis and characterization of TNBCs and BP tumors is currently being defined as we are acquiring knowledge of the biologic and genetic underpinnings that drive this heterogeneous group of diseases. This review will provide a historical prospective on TNBCs and tumors that express basal cytokeratins and myoepithelial makers. Additionally, we will discuss the molecular biologic, genetic and pathologic aspects of these tumors. Guidelines will be provided on how to best approach the diagnosis of these cases and on what input pathologists should provide clinicians to help develop optimal therapeutic and preventative strategies against this aggressive group of breast cancers.
9492029
Basal cytokeratins and their relationship to the cellular origin and functional classification of breast cancer
Recent publications have classified breast cancers on the basis of expression of cytokeratin-5 and -17 at the RNA and protein levels, and demonstrated the importance of these markers in defining sporadic tumours with bad prognosis and an association with BRCA1-related breast cancers. These important observations using different technology platforms produce a new functional classification of breast carcinoma. However, it is important in developing hypotheses about the pathogenesis of this tumour type to review the nomenclature that is being used to emphasize potential confusion between terminology that defines clinical subgroups and markers of cell lineage. This article reviews the lineages in the normal breast in relation to what have become known as the 'basal-like' carcinomas.
10253460
Germline BRCA1 mutations and a basal epithelial phenotype in breast cancer.
A basal epithelial phenotype is found in not more than 15% of all invasive breast cancers. Microarray studies have shown that this phenotype is associated with breast cancers that express neither estrogen receptor (ER) nor erbB-2 (HER2/neu) (i.e., ER/erbB-2-negative tumors). The ER/erbB-2- negative phenotype is also found in breast cancers occurring in BRCA1 mutation carriers (i.e., BRCA1-related breast cancers). We tested the hypothesis that BRCA1-related breast cancers are more likely than non-BRCA1/ 2-related breast cancer to express a basal epithelial phenotype. Among 292 breast cancer specimens previously analyzed for ER, erbB-2, p53, and germline mutations in BRCA1 and BRCA2, we identified 76 that did not overexpress ER or erbB-2. Of the 72 specimens with sufficient material for testing, 40 expressed stratified epithelial cytokeratin 5 and/or 6 (5/6). In univariate analysis, the expression of cytokeratin 5/6 was statistically significantly associated with BRCA1-related breast cancers (odds ratio = 9.0, 95% confidence interval = 1.9 to 43; P =.002, two-sided Fisher's exact test). Thus, germline BRCA1 mutations appear to be associated with a distinctive breast cancer phenotype.
13996527
Prediction of BRCA1 Status in Patients with Breast Cancer Using Estrogen Receptor and Basal Phenotype
Purpose: To investigate the proportion of breast cancers arising in patients with germ line BRCA1 and BRCA2 mutations expressing basal markers and developing predictive tests for identification of high-risk patients. Experimental Design: Histopathologic material from 182 tumors in BRCA1 mutation carriers, 63 BRCA2 carriers, and 109 controls, collected as part of the international Breast Cancer Linkage Consortium were immunohistochemically stained for CK14, CK5/6, CK17, epidermal growth factor receptor (EGFR), and osteonectin. Results: All five basal markers were commoner in BRCA1 tumors than in control tumors (CK14: 61% versus 12%; CK5/6: 58% versus 7%; CK17: 53% versus 10%; osteonectin: 43% versus 19%; EGFR: 67% versus 21%; P < 0.0001 in each case). In a multivariate analysis, CK14, CK5/6, and estrogen receptor (ER) remained significant predictors of BRCA1 carrier status. In contrast, the frequency of basal markers in BRCA2 tumors did not differ significant from controls. Conclusion: The use of cytokeratin staining in combination with ER and morphology provides a more accurate predictor of BRCA1 mutation status than previously available, that may be useful in selecting patients for BRCA1 mutation testing. The high percentage of BRCA1 cases positive for EGFR suggests that specific anti-tyrosine kinase therapy may be of potential benefit in these patients.
8648022
Loss of Heterozygosity in Bilateral Breast Cancer
Women who develop bilateral breast cancer at an early age are likely to harbour germline mutations in breast cancer susceptibility genes. The aim of this study was to test for concordant genetic changes in left and right breast cancer of young women (age <50) with bilateral breast cancer that may suggest an inherited breast cancer predisposition. Microsatellite markers were used to test for loss of heterozygosity (LOH) in left and right tumours for 31 women with premenopausal bilateral breast cancer. Markers adjacent to or within candidate genes on 17p (p53), 17q (BRCA1), 13q (BRCA2), 11q (Ataxia Telangiectasia-ATM) and 3p (FHIT) were chosen. Mutational testing for BRCA1 and BRCA2 was performed for cases where blood was available. Concordant LOH in both left and right tumours was demonstrated for at least one of the markers tested in 16/31(54%) cases. Where allelic loss was demonstrated for both left and right breast cancer, the same allele was lost on each occasion. This may suggest a common mutational event. Four cases showed concordant loss of alleles in both left and right breast cancer at D17S791 (BRCA1). BRCA1 mutations were identified in two of these cases where blood was available. Four cases showed concordant LOH at D13S155 (BRCA2). Concordant LOH was further demonstrated in seven cases for D11S1778 (ATM) and four cases for D3S1300 (which maps to the FHIT gene), suggesting a possible role for these tumour suppressor genes in this subgroup of breast cancer patients. No concordant allelic loss was demonstrated for D17S786 suggesting that germline mutations in p53 are unlikely in such cases of bilateral breast cancer.
20899015
Biophenotypes and survival of BRCA1 and TP53 deleted breast cancer in young women
The aim of this study was to examine the loss of heterozygosity (LOH) of BRCA1 (17q21) and TP53 (17p13.1) in early-onset breast cancer patients; to correlate biopathological characteristics with molecular alterations; and to investigate the survival of LOH-related cancers.BRCA1 and TP53 LOH were evaluated in 78 early-onset breast cancers (≤40 years, Group 1) and 80 patients with age <55 years (Group 2). Cases were characterized for multiple biological markers (ER, PR, proliferation index (PI), NEU and p53). LOH was carried out on microdissected paraffin embedded tissues; microsatellites D17S855 (BRCA1) and D17S786 (TP53) were amplified by fluorescent PCR and analyzed by an automated DNA sequencer. Early-onset breast cancers showed a higher frequency of ductal histotype (89,7% vs. 56,3% p<0.001), node-positive (53,8% vs. 38,7%), larger size (p=0.017), higher mitotic rate (p=0.025), higher nuclear and final grade (p=0.01 and p=0.001, respectively). D17S855 LOH was 32,8% in group 1 vs. 21% in group 2; D17S786 LOH was 50,7% vs. 31.3% (p=0.03), respectively. BRCA1 LOH was correlated with higher PI (p=0.032) and higher p53 expression (p<0.001) in group 1 and with higher NEU expression (p=0.028) in group 2. TP53 LOH was correlated with p53 overexpression (p=0.03) in group 1. A worse clinical outcome in early-onset LOH related cancers emerged from follow-up data: TP53 and BRCA1 LOH were associated with a shorter relapse free interval (RFI) (p=0.03) and a poorer overall survival (OS) (p=0.04), respectively. This study underlines different biological profiles in the two age groups investigated, probably reflecting different mechanisms of carcinogenesis. In accordance with adverse histopathological features in early-onset patients, LOH-related cancers have an unfavorable prognosis.
23610563
[Clinical and economic issues in adjuvant chemotherapy for HER-2 positive breast cancer].
PURPOSE
To examine efficacy figures and drug expenditure for adjuvant chemotherapy in human epidermal growth factor receptor 2 (HER-2) positive breast cancer, in the Brazilian supplemental health insurance market.


METHODS
We obtained efficacy data (disease free survival at 3-years) and drug cost estimate for current adjuvant strategies in HER-2 positive breast cancer: Finland Herceptin (FinHER), National Surgical Adjuvant Breast and Bowel Project (NSAPB-31), North Central Cancer Treatment Group (N9831), Herceptin Adjuvant (HERA) and Breast Cancer International Research Group (BCIRG-006). We estimated clinical impact measures--number needed to treat (NNT) and absolute risk reduction (ARR)--and total drug cost by protocol to avoid one single cancer recurrence.


RESULTS
The largest ARR was 11.7% (95% CI: 2.2% to 21.2%) in the FinHER study, and the smallest in the nonanthracycline arm of the BCIRG trial, 4.9% (95% CI: 1.8% to 8.1%). The NNT was 8 (95% CI: 3 to 28) in the FinHER, 8 (95% CI: 7 to 11) in the NSABP-31/N9831, 12 (95% CI: 9 to 18) in the HERA, 14 (95% CI: 11 to 24) in the BCIRG/Anthracycline, and 17 (CI 95% CI: 12 to 34) in the BCIRG/Nonanthracycline. Drug cost to avoid one single cancer recurrence would be R$ 418,285.44 with the FinHER regimen, R$ 1,716,789.44 with the NSABP-31/N9831, R$ 2,481,891.58 with the HERA, R$ 2,963,634.62 with the BCIRG/Anthracycline, and R$ 3,930,520.43 with the BCIRG/Nonanthracycline (exchange rate: R$ 1.00=USD 0.56).


CONCLUSION
From an economic viewpoint, four to seven times more patients could benefit by using a short-course of trastuzumab at the initial adjuvant chemotherapy cycles (FinHER regimen) than by the prolonged trastuzumab administration as used in other adjuvant schedules.
25916135
Rabbit antibodies for hormone receptors and HER2 evaluation in breast cancer.
BACKGROUND
Novel rabbit monoclonal antibodies (RabMab) for estrogen (ER), progesterone (PR) receptors and HER2 evaluation by immunohistochemistry have recently been commercially released. We compared the RabMab anti-ER, anti-PR and anti-HER2 to mouse monoclonal antibodies (Mab) using tissue microarrays (TMA) of breast carcinomas.


METHODS
Two TMA containing breast carcinomas were built. Sections were immunostained using anti-ER and anti-PR, Mab and RabMab. The sections stained for ER and PR were evaluated considering positive those tumors in which more than 1% of the tumor cell nuclei stained moderate or strong. For HER2, the immunostained sections were evaluated using the ASCO/CAP guidelines for HER2. Chromogenic in situ hybridization (CISH) was used as the gold standard for HER2 evaluation. CISH was evaluated using the Zymed HER2 CISH interpretation guidelines.


RESULTS
RabMab against ER have similar staining patterns compared to the 6F11 (Mab), but stronger than 1D5 (Mab) from three different suppliers. The RabMab against PR provide stronger and sharper immunohistochemical signals compared to Mab. The detection of HER2 protein overexpression was more prevalent with the polyclonal antibodies and RabMab than with the Mab. These were more specific than the RabMab, which were more sensitive when compared to CISH.


CONCLUSION
The novel RabMab against ER and PR showed higher intensity of staining than the Mab. The RabMab against HER2 is more sensitive than Mab, however, Mab presented more specificity than RabMab when compared to CISH for HER2 evaluation of breast carcinomas.
16379567
Distinct molecular pathogeneses of early-onset breast cancers in BRCA1 and BRCA2 mutation carriers: a population-based study.
Breast cancers arising in women with and without a germline mutation in the BRCA1 or BRCA2 gene display different histological features, which suggests unique mechanisms of molecular pathogenesis: We used a molecular pathological analysis to define the genetic abnormalities relevant to these specific pathogeneses. Tumor material was studied from 40 women with breast cancer diagnosed before 40 years of age, sampled from a population-based study and stratified by BRCA1 and BRCA2 germline mutation status. Cases were not selected for family history or ethnic origin, and none were known to be genetically related. Thus, germline mutation itself is likely to impact on the molecular pathogenesis of these tumors, with no substantial influence due to modifying genetic or environmental factors. Breast cancers occurring in BRCA1 mutation carriers had significantly higher levels of p53 expression, including the preinvasive (carcinoma in situ) stage of disease, compared with cancers occurring in BRCA2 mutation carriers or women with no detectable germline mutation. These cancers also had a higher proliferation rate as measured by Ki-67 antibody. Expression of the prognostic factors c-erbB-2, cyclin D1, and estrogen receptor was significantly less common in BRCA1 mutation carriers. Lower levels of cyclin D1 were also found in cancers from BRCA2 mutation carriers compared with non-mutation carriers. Direct p53 mutation analysis revealed mutations in 18% of all of the early-onset breast cancers within the study and included rare insertion and deletional mutations in cancers from BRCA1 mutation carriers. Our data indicate that a BRCA1 breast cancer phenotype may be recognized by an exceptionally high proliferation rate and early and frequent p53 overexpression but infrequent selection for overexpression of several other prognostic factor proteins known to be involved in breast oncogenesis. In contrast, breast cancers arising in BRCA2 mutation carriers have a more heterogeneous phenotypic profile.
12573498
Relationship of patients' age to histopathological features of breast tumours in BRCA1 and BRCA2 and mutation-negative breast cancer families
IntroductionOur aim was to evaluate the relationship of patients' age to histopathological features of hereditary breast tumours in a series of breast cancer families not selected for age at diagnosis. In sporadic breast cancer, tumours from premenopausal patients have been shown to differ from those of postmenopausal patients, but this phenomenon has been little studied among familial patients.MethodsRepresentative areas of all available breast cancer tissue specimens (n = 262) from 25 BRCA1, 20 BRCA2, and 74 non-BRCA1/2 breast cancer families were punched into a tissue microarray. Immunohistochemical staining of oestrogen receptor, progesterone receptor, ERBB2, and p53 as well as the histology and grade of tumours in these three groups of families were studied in different age groups and compared with each other.ResultsWe found that only breast cancers from young (<50 years) BRCA1+ patients represent features documented as being typical of BRCA1-associated cancers, such as high tumour grade, negativity for oestrogen and progesterone receptors, and overexpression of p53. Among the BRCA2 families, the opposite was found, with a significantly higher frequency of tumours negative for oestrogen and progesterone receptors among the older patients than among the other groups, but no distinctive tumour characteristics among the younger BRCA2 patients.ConclusionTumours of BRCA1 and BRCA2 carriers aged 50 years or more differed significantly from those of younger carriers. This difference may reflect different biological behaviour and pathways of tumour development among the older and the younger BRCA1 and BRCA2 patients, with impact also on prognosis and survival.
8082129
Population-based estimate of the average age-specific cumulative risk of breast cancer for a defined set of protein-truncating mutations in BRCA1 and BRCA2. Australian Breast Cancer Family Study.
The average breast cancer risk for carriers of a germ-line mutation in BRCA1 or BRCA2 (penetrance) has been estimated from the multiple-case families collected by the Breast Cancer Linkage Consortium (BCLC) to be approximately 80% to age 70. However, women now being tested for these mutations do not necessarily have the intense family history of the BCLC families. Testing for protein-truncating mutations in exons 2, 11, and 20 of BRCA1 and exons 10 and 11 of BRCA2 was conducted in a population-based sample of 388 Australian women with breast cancer diagnosed before age 40. Onset of breast cancer was analyzed in the known and potential mutation-carrying first- and second-degree female relatives of cases found to carry a mutation. Of the 18 mutation-carrying cases (9 BRCA1 and 9 BRCA2), only 5 (1 BRCA1 and 4 BRCA2) had at least one affected relative, so family history of breast cancer was not a strong predictor of mutation status in this setting. The risk in mutation carriers was, on average, 9 times the population risk [95% confidence interval (CI), 4-23; P < 0.001]. Penetrance to age 70 was 40% (95% CI, 15-65%), about half that estimated from BCLC families. By extrapolation, approximately 6% (95% CI, 2-20%) of breast cancer before age 40 may be caused by protein-truncating mutations in BRCA1 or BRCA2. Breast cancer risk in BRCA1 or BRCA2 mutation carriers may be modified by other genetic or environmental factors. Genetic counselors may need to take into account the family history of the consultand.
16162590
Placental Cadherin and the Basal Epithelial Phenotype of BRCA1-Related Breast Cancer
Purpose:BRCA1-related breast cancer frequently has a basal epithelial phenotype, and P-cadherin is a basal marker. We undertook a detailed evaluation of the relationship among P-cadherin, prognostic markers in breast cancer, and outcome. Experimental Design: This study was restricted to 292 cases of first primary invasive breast cancer diagnosed in Ashkenazi Jewish women between 1980 and 1995. All available blocks were stained for P-cadherin, and 261 were included in the final statistical analyses, including 27 germ line BRCA1 mutation carriers and 8 BRCA2 mutation carriers. Descriptive analyses were done followed by survival analyses and a Poisson regression analysis. Results: P-cadherin was present in 80 of the 261 breast cancers (31%) and was more frequently present in tumors that have a basal epithelial phenotype [i.e., high-grade, estrogen receptor– and KIP1 (p27Kip1)–negative tumors, with expression of cytokeratin 5/6, cyclin E, TP53, and presence of BRCA1 mutations and vascular nests (all P < 0.001)]. In a univariate survival model, expression of P-cadherin was associated with a relative risk (RR) of death from breast cancer at a 10-year follow-up of 2.9 (95% confidence interval, 1.8-4.7; P < 0.0001) and was a predictor of poor univariate survival in both lymph node–negative and –positive breast cancers. In a multivariate analysis, the effect of P-cadherin levels was not independent of other basal-related markers. Multivariable interaction modeling showed that P-cadherin positivity was highly predictive of a poor prognosis in small, node-negative breast cancers (RR, 7.1; P = 0.006). Conclusions: P-cadherin is a marker for basal-like breast cancers and is strongly associated with the presence of a BRCA1 mutation. It is an adverse prognostic factor, particularly in small, node-negative breast cancers.
19005778
BRCA1 mutations and other sequence variants in a population-based sample of Australian women with breast cancer
SummaryThe frequency, in women with breast cancer, of mutations and other variants in the susceptibility gene, BRCA1, was investigated using a population-based case–control-family study. Cases were women living in Melbourne or Sydney, Australia, with histologically confirmed, first primary, invasive breast cancer, diagnosed before the age of 40 years, recorded on the state Cancer Registries. Controls were women without breast cancer, frequency-matched for age, randomly selected from electoral rolls. Full manual sequencing of the coding region of BRCA1 was conducted in a randomly stratified sample of 91 cases; 47 with, and 44 without, a family history of breast cancer in a first- or second-degree relative. All detected variants were tested in a random sample of 67 controls. Three cases with a (protein-truncating) mutation were detected. Only one case had a family history; her mother had breast cancer, but did not carry the mutation. The proportion of Australian women with breast cancer before age 40 who carry a germline mutation in BRCA1 was estimated to be 3.8% (95% Cl 0.3–12.6%). Seven rare variants were also detected, but for none was there evidence of a strong effect on breast cancer susceptibility. Therefore, on a population basis, rare variants are likely to contribute little to breast cancer incidence.
19278299
Extracolonic cancer in hereditary nonpolyposis colorectal cancer.
BACKGROUND
It has been hypothesized that in some but not all families with hereditary nonpolyposis colorectal cancer (HNPCC) there is a high risk of certain cancers other than colon cancer.


METHODS
The authors compared the observed frequency of cancer at specific sites in more than 1300 high-risk members of 23 kindreds with HNPCC with expectations based on general population incidence and evaluated the hypothesis that there was heterogeneity in cancer frequency among families.


RESULTS
The authors observed significantly increased numbers of cancers of the stomach, small intestine, upper urologic tract (renal pelvis and ureter), and ovary. No excess was seen in other cancer types that have been associated previously with HNPCC, including cancer of the breast, pancreas, and urinary bladder. Significant heterogeneity among families was observed in the frequencies of endometrial, ovarian, and upper urologic system cancer.


CONCLUSION
In addition to early onset cancers of the colorectum, HNPCC family members are at increased risk for cancers of other gastrointestinal tract organs, and, especially in some families, cancers of the upper urologic and female genital tract.
24612963
Molecular Pathologic Analysis Enhances the Diagnosis and Management of Muir-Torre Syndrome and Gives Insight Into Its Underlying Molecular Pathogenesis
The Muir-Torre syndrome (MTS) is an autosomal dominantly inherited disorder, characterized by visceral malignancies and sebaceous skin lesions. In a subset of MTS families the disease is due to an underlying DNA mismatch-repair defect. We have identified a MTS family whose spectrum of reported neoplasia included adenocarcinomas of numerous gastrointestinal sites, carcinomas of the endometrium, ovary and breast, papillary transitional cell carcinoma of the ureter, a range of cutaneous tumors, as well as keratoacanthomas. All tumors were tested for microsatellite instability and immunohistochemically stained for expression of MLH1 and MSH2 proteins. All tumors were found to be microsatellite unstable and lacking in MSH2 protein expression. The subsequent mutation detection focused on hMSH2, and a germline mutation was identified (CAA→TAA, Gln→STOP, codon 337). This mutation was subsequently found in a family member with a single skin lesion only. We propose that the combination of immunohistologic and microsatellite instability analysis can be exploited to screen individuals with characteristic skin lesions even before development of visceral tumors and to direct the subsequent germline mutation search. The profile of microsatellite instability and the genes rendered dysfunctional differed between tumor samples, suggesting that the molecular pathogenesis varied between lesions, despite a common germline mutation.
23463767
Molecular genetic evidence of the occurrence of breast cancer as an integral tumor in patients with the hereditary nonpolyposis colorectal carcinoma syndrome
The hereditary nonpolyposis colorectal carcinoma (HNPCC) syndrome is an autosomal dominant genetic disorder caused by the inheritance of a mutation in one of a family of genes encoding DNA mismatch repair (MMR) proteins. HNPCC manifests as genetic instability in linked tumors. Clinically, the syndrome is characterized by early onset malignancies, primarily of the colon and endometrium, with an increased incidence of tumors at other gastrointestinal sites, upper urologic tract, ovary, and pancreas as well. However, the inclusion of breast cancer as an integral tumor of this syndrome is controversial.
25227331
Microsatellite instability in hereditary and sporadic breast cancers
Sporadic cancers and familial breast cancers are characterized by an increase in genetic instability. Little is known about whether mismatch repair defects accompany this genetic instability. We investigated invasive and/or in situ breast cancers from 30 women with deleterious BRCA1/2 mutations and unclassified variant BRCA1/2 alterations. Forty cases of sporadic breast cancers were also investigated, including 7 medullary carcinomas. Malignant and benign lesions were examined from all cases to better understand tumor progression. Automated immunohistochemistry, with antibodies directed against hMLH1 and hMSH2, was used to screen cases for possible mismatch repair defects. When loss of expression was noted, DNA ploidy was performed by cytomorphometry. DNA, after laser microdissection, was extracted from a majority of familial cases and their corresponding controls, and microsatellite instability analysis was performed. None of the familial or sporadic cases had loss of hMSH2 expression. All but one lesion, a DCIS arising in a deleterious BRCA2 mutation carrier, had loss of hMLH1 expression and a tetraploid profile by image cytomorphometry. There was no MSI in any explored lesions (n = 34), as determined by molecular analysis, including the DCIS with loss of hMLH1 expression. We conclude that DNA mismatch repair defects involving hMLH1 and hMSH2 underexpression are extremely rare events in sporadic and familial breast cancer. Mismatch repair gene mutations may be secondary random events in breast cancer progression. © 2003 Wiley‐Liss, Inc.
9479982
[Loss of heterozygosity and microsatellite instability in the region including BRCA1 of breast cancer in Chinese].
OBJECTIVE
To shed light on the relationship between BRCA1 gene and breast cancer in Chinese Han women.


METHODS
Four microsatellites DNA (D17S855, D17S579, D17S1327 and THRA1) within the BRCA1 gene were used as polymorphic markers. A study of loss of heterozygosity(LOH) and microsatellite instability(MSI) at the above- mentioned 4 microsatellites of 50 breast cancer patients was conducted by using PCR -PAUGE-DNA silver staining (polymerase chain reaction-polyacrylamide urea gel electrophoresis) method.


RESULTS
Twenty-nine or 58% of the informative cases showed LOH; 35.71%, 15. 38%, 18.18%, and 26.19% of the informative cases showed positive LOH at the D17S855, D17S579, D17S1327 and THRA1 loci respectively. The rate of MSI was 46%, and the rates of MSI at the four loci were 16%, 18%, 18% and 12% respectively. Further study on the associations between the phenomena of LOH and MSI and different clinical stages revealed that MSI was an early event in mammary tumorigenesis while LOH occurred at a later stage.


CONCLUSION
All of these suggest that breast cancer in Chinese be somehow linked to BRCA1.
24745859
Genetic instability of BRCA1 gene at locus D17S855 is related to clinicopathological behaviors of gastric cancer from Chinese population.
AIM
To investigate genetic instability of gene BRCA1 at locus D17S855, and their relationship with clinicopathological characteristics of gastric cancer in Chinese population.


METHODS
Microsatellite instability (MSI) and loss of heterozygosity (LOH) of gene BRCA1 at locus D17S855 were compared between 37 samples of gastric cancer and corresponding non-cancerous gastric tissue.


RESULTS
MSI at locus D17S855 was positive in 7 of 37 samples of gastric cancer (18.95%). MSI had a close relationship with TNM staging but no relation with lymph node metastasis, histological type or tumor differentiation. MSI positive frequency in TNM I + II (31.58%, 6/19) was much higher than that in TNM III + IV (5.56%, 1/18), (P < 0.05). LOH positive rate was 18.92% (7/37). LOH had no relationship to histological type, tumor differentiation or lymph node metastasis, but LOH positive rate in TNM III + IV was 33.33% (6/18), much higher than that in TNM I + II ( 5.26%, 1/19), (P < 0.05). BRCA1 protein was expressed in 14 of 37 samples of gastric cancer. The positive rates of BRCA1 protein in TNM I + II and TNM III + IV were 57.89% and 16.67%, respectively, (P < 0.05). The positive rate of BRCA1 protein was 77.78% in high differentiation samples, 30.77% in middle differentiation and 12.50% in lower differentiation samples, (P < 0.05).


CONCLUSION
MSI of BRCA1 gene could be used as a molecular marker in early phases of sporadic gastric cancer in Chinese population. LOH occurs at later period of gastric cancer, therefore, it could be used as prognostic factor.