Only 32.3% of Breast Cancer Families with Pathogenic Variants in Cancer Genes Utilized Cascade Genetic Testing

BACKGROUND

Hereditary cancer predisposition syndromes are responsible for approximately 5-10% of all diagnosed cancer cases. In order to identify individuals at risk in a cost-efficient manner, family members of individuals carrying pathogenic alterations are tested only for the specific variant that was identified in their carrier relative. The purpose of this study was to investigate the clinical use and implementation of cascade family testing (CFT) in families of breast cancer patients with pathogenic/likely pathogenic variants (PVs/LPVs) in cancer-related predisposition genes.

METHODS

Germline sequencing was carried out with NGS technology using a 52-gene panel, and cascade testing was performed by Sanger sequencing or MLPA.

RESULTS

In a cohort of 1785 breast cancer patients (families), 20.3% were found to have PVs/LPVs. Specifically, 52.2%, 25.1%, and 22.7% of patients had positive findings in high-, intermediate-, and low-penetrance breast cancer susceptibility genes, respectively. Although CFT was recommended to all families, only 117 families (32.3%) agreed to proceed with genetic testing. Among the first-degree relatives who underwent CFT, 70.3% were female, and 108 of 121 (89.3%) were cancer free. Additionally, 42.7%, 36.7%, and 20.6% were offspring, siblings, and parents of the subject, respectively. Our data suggest that CFT was mostly undertaken (104/117, 88.8%) in families with positive findings in high-risk genes.

CONCLUSIONS

Cascade family testing can be a powerful tool for primary cancer prevention by identifying at-risk family members. It is of utmost importance to implement genetic counseling approaches leading to increased awareness and communication of genetic testing results.

Copy Number Variations (CNVs) Account for 10.8% of Pathogenic Variants in Patients Referred for Hereditary Cancer Testing

BACKGROUND/AIM

Germline copy number variation (CNV) is a type of genetic variant that predisposes significantly to inherited cancers. Today, next-generation sequencing (NGS) technologies have contributed to multi gene panel analysis in clinical practice.

MATERIALS AND METHODS

A total of 2,163 patients were screened for cancer susceptibility, using a solution-based capture method. A panel of 52 genes was used for targeted NGS. The capture-based approach enables computational analysis of CNVs from NGS data. We studied the performance of the CNV module of the commercial software suite SeqPilot (JSI Medical Systems) and of the non-commercial tool panelcn.MOPS. Additionally, we tested the performance of digital multiplex ligation-dependent probe amplification (digitalMLPA).

RESULTS

Pathogenic/likely pathogenic variants (P/LP) were identified in 464 samples (21.5%). CNV accounts for 10.8% (50/464) of pathogenic variants, referring to deletion/duplication of one or more exons of a gene. In patients with breast and ovarian cancer, CNVs accounted for 10.2% and 6.8% of pathogenic variants, respectively. In colorectal cancer patients, CNV accounted for 28.6% of pathogenic/likely pathogenic variants.

CONCLUSION

In silico CNV detection tools provide a viable and cost-effective method to identify CNVs from NGS experiments. CNVs constitute a substantial percentage of P/LP variants, since they represent up to one of every ten P/LP findings identified by NGS multigene analysis; therefore, their evaluation is highly recommended to improve the diagnostic yield of hereditary cancer analysis.

Prognostic Significance of Low HER2 Expression in Patients With Early Hormone Receptor Positive Breast Cancer

BACKGROUND/AIM

A possible role of antibody-drug conjugates against tumors with low HER2-expression, leads to the emergence of a new "low-HER2" classification in breast cancer, encompassing tumors from the hormonal-receptor-positive and the triple-negative subgroups. There is a need for data (clinical trial data and real-world evidence) that will accurately describe this population, the risk of recurrence and the possible benefit of HER2 targeted therapies.

PATIENTS AND METHODS

We retrospectively analyzed 949 patients from our Department databases, with hormonal receptor-positive and HER2-negative early breast cancer, for whom detailed data for immunohistochemical HER2-staining could be retrieved.

RESULTS

HER2-low expression was detected in 66.6% of patients (472 IHC +1 and 160 IHC +2 and ISH-negative). Lobular, or mixed lobular and ductal cancers had a statistically significantly lower chance of being HER2-low when compared to pure infiltrative ductal carcinomas (53.1% vs. 69.3% respectively). HER2-low status was not prognostic for recurrence-free survival or response to neoadjuvant chemotherapy. There was a non-significant trend for increased risk of recurrence for HER2-low, compared to HER2-0, in patients with lobular or mixed lobular and ductal carcinomas (HR=2.192, 95% CI=0.819-5.912).

CONCLUSION

Low expression of HER2 in hormonal receptor-positive early breast cancer does not affect prognosis but may lead to a shorter progression-free-survival in lobular and mixed ductal and lobular cancers. Despite optimal management, a large proportion of hormonal receptor-positive patients will relapse. Targeting HER2 in HER2-low cancers may offer a potential additional treatment strategy to improve survival of this group.

Abstract P2-09-10: Different CNVs account for 10.4% of pathogenic variants in 1418 patients referred for hereditary breast cancer testing

Background: Breast cancer is the most frequently diagnosed cancer in women and about 10% of breast cancer cases are hereditary. BRCA1 and BRCA2 are the genes most frequently associated with Hereditary Breast Cancer, although there are numerous other genes, such as PALB2, CHEK2 and ATM, that require to be considered as well. Germline Copy Number Variation (CNV) is one mutation type that is an important contributor to hereditary breast cancer. Nowadays, next-generation sequencing (NGS) technologies has contributed to multi-gene panel analysis used in clinical practice. Methods: In total, 1418 individuals were tested for breast cancer predisposition, using a solution-based capture approach. Targeted NGS was performed with a panel of 36 genes. The capture-based approach allowed for computational analysis of CNVs from NGS data. Results: We investigate the performance of the CNV module of the commercial software suite SeqPilot (JSI Medical Systems) and the non-commercial tool panelcn.MOPS. Both algorithms are specifically developed for CNV analysis of sequencing data reporting 99-100% sensitivity and up to 100% specificity for the prediction of CNVs up to the level of a single gene exon. All CNVs detected with these algorithms were then verified experimentally using the MLPA technique as an orthogonal assay. At least one pathogenic/likely pathogenic variant was identified in 289 samples (20.4%). CNVs accounted for 10.4% (30/289), referring to the deletion of one or more exons of a gene. Interestingly, 50% of deletions were single exon and approximately 36% of CNVs were detected in genes other than BRCA1/2. In specific, of the 30 CNVs detected, 60% occurred in BRCA1, 3.3% in BRCA2, 20% in CHEK2, 6.7% in FANCA, 6.7% in PMS2, and 3.3% in ATM. The majority of CNVs in BRCA1 were deletions of exons 19, 22, and 22-23 whereas deletions of exons 9-10 were the most common deletions in CHEK2. Detailed information of all CNVs detected is provided in Table 1.

Conclusions: Our results suggest that CNV analysis should not be restricted to BRCA1/2 due to the significant proportion of CNVs (36%) in additional breast cancer predisposition genes. Furthermore, in silico CNV detection tools provide a cost-effective and feasible methodology for the identification of CNVs from NGS experiments. This outlines the clinical utility of comprehensive genetic testing that includes full sequencing and CNV analysis in hereditary breast cancer facilitating personalized management decisions for patients.

Table 1.Pathogenic Copy Number Variations (CNVs) identified in this studyGeneHGVS nomenclatureOther nomenclature# detectedATMNM_000051:c.(-30+1_-29-1)_(331+1_332-1)deldeletion of exons 2-41BRCA1NM_007294:c.(5467+1_5468-1)-(*1_?)deldeletion of exon 237BRCA1NM_007294:c.(5406+1_5407-1)_(*1_?)deldeletion of exons 23-245BRCA1NM_007294:c.(5193+1_5194-1)-(5277+1_5278-1)deldeletion of exon 196BRCA2NM_000059:c.(6841+1_6842-1)_(7007+1_7008-1)deldeletion of exons 12-131CHEK2NM_007194:c.(908+1_909-1)_(1095+1_1096-1)deldeletion of exons 9-104CHEK2NM_007194:c.(792+1_793-1)_(846+1_847-1)deletion of exon 72FANCANM_000135:c.(1626+1_1627-1)_ (2852+1_2853-1)deldeletion of exons 18-291FANCANM_000135:c.(893+1_894-1)_(1359+1_1360-1)deldeletion of exons 11-141PMS2NM_000535: c.(903+1_904-1)_(988+1_989-1)deldeletion of exon 91PMS2NM_000535:c.(705+1_706-1)_(2006+1_2007-1)deldeletion of exons 7-111

Citation Format: Nikolaos Tsoulos, Konstantinos Agiannitopoulos, Georgia Pepe, Eirini Papadopoulou, Georgios N Tsaousis, Despina Apostolopoulou, Angeliki Meintani, Vassileios Venizelos, Christos Markopoulos, Rodoniki Iosifidou, Sofia Karageorgopoulou, Christos Christodoulou, Ioannis Natsiopoulos, Konstantinos Papazisis, Maria Vasilaki-Antonatou, Eleftherios Kabletsas, Amanta Psyrri, Stylianos Giassas, Dimitrios Ziogas, Efthalia Lalla, Anna Koumarianou, Christos Papadimitriou, Vahit Ozmen, Sualp Tansan, Kerim Kaban, Tahsin Ozatlı, Dan Tudor Eniu, Angelica Chiorean, Alexandru Blidaru, George Nasioulas. Different CNVs account for 10.4% of pathogenic variants in 1418 patients referred for hereditary breast cancer testing [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-09-10.

Follow-up of tissue genomics in BRCA1/2 carriers who underwent prophylactic surgeries

PURPOSE

The genomic status of non-malignant tissues from carriers of pathogenic germline BRCA1/2 (gBRCA1/2) variants may reveal information towards individualized prophylaxis. We performed spatiotemporal tissue genotype comparisons in a real-life cohort of gBRCA1/2 carriers of Greek origin, who underwent multiple risk-reducing/prophylactic surgeries at various time points.

METHODS

Fifty-three women (median age 36 years) within cancer families were observed for up to 37.5 years; 43 were cancer carriers and 10 were healthy carriers. Histology review and genotyping were performed for 187 paraffin tissues (average: 3.5 per carrier) including 46 carcinomas (40 breast) and 141 non-malignant breast and gynecological samples.

RESULTS

High allelic imbalance (AI) and somatic pathogenic TP53 variants were present in cancer carriers only (p values < 0.0001). High AI was associated with gBRCA1/2 indels (p < 0.0001) and gBRCA2 alterations (p = 0.0109). Somatic (pathogenic) variants were infrequently shared between non-malignant tissues and matched carcinomas. Aberrations of gBRCA1 variant heterozygosity were noticed in tissues from cancer carriers only (13/43, 30.2%). These pertained to classic LOH (neoplastic lesions in 9/43 carriers, 20.9%) and under-representation of the germline variants (5 samples, 4 non-malignant, all in the breast). Both aberrations coexisted in matched samples in one case. Over time, germline variant heterozygosity prevailed in non-malignant tissues; intra-carrier genomic alterations were aggravated (21.1%), ameliorated (26.3%) or remained stable.

CONCLUSION

This real-life case study supports the need to address tissue genotypes from prophylactic surgeries in combination with polygenic scores towards personalized prophylaxis. To this end, knowing the traditionally classified pathogenic potential of a gBRCA1/2 variant may not be enough.

Clinical Utility of Functional RNA Analysis for the Reclassification of Splicing Gene Variants in Hereditary Cancer

BACKGROUND

Classification of splicing variants (SVs) in genes associated with hereditary cancer is often challenging. The aim of this study was to investigate the occurrence of SVs in hereditary cancer genes and the clinical utility of RNA analysis.

MATERIAL AND METHODS

1518 individuals were tested for cancer predisposition, using a Next Generation Sequencing (NGS) panel of 36 genes. Splicing variant analysis was performed using RT-PCR and Sanger Sequencing.

RESULTS

In total, 34 different SVs were identified, 53% of which were classified as pathogenic or likely pathogenic. The remaining 16 variants were initially classified as Variant of Uncertain Significance (VUS). RNA analysis was performed for 3 novel variants.

CONCLUSION

The RNA analysis assisted in the reclassification of 20% of splicing variants from VUS to pathogenic. RNA analysis is essential in the case of uncharacterized splicing variants, for proper classification and personalized management of these patients.

Real-world experience of neoadjuvant chemotherapy for early breast cancer patients: an observational non-interventional study in Thessaloniki, Greece

PURPOSE

Neoadjuvant chemotherapy has been increasingly used in early-stage breast cancer. The results of large randomized clinical trials suggest the need for the wider use of preoperative therapy as it can result in a more conservative surgery, and can guide physicians to a more individualized approach in the adjuvant setting.

METHODS

We aimed to analyze the outcomes of 203 patients with early-stage breast cancer who had received neoadjuvant chemotherapy at our institutions.

RESULTS AND CONCLUSION

Pathological complete responses (pCR) were obtained in 42.4% of all patients, with the highest percentage in hormonal receptor (HR)-negative and human epidermal growth factor receptor-2 (HER2)-positive cancers. Conversion of a clinically and/or cytologically node-positive to node-negative disease was achieved in 55.8% of patients. Patients who achieved a pCR had a significantly better outcome in terms of disease-free and distant disease-free survival. Patients with residual disease experienced a worse prognosis if they had HR-negative cancer compared to HR-positive patients for whom the use of adjuvant endocrine treatment likely led to better outcomes. These results are encouraging as they show that outcomes from large randomized clinical trials can be reproduced in the everyday clinical setting. Neoadjuvant chemotherapy may be the treatment of choice for HR-negative and/or HER2-positive early breast cancer patients. This may also be the case for the majority of HR-positive and HER2-negative patients with either locally advanced disease or disease extending to the axillary lymph nodes, as it may result in more conservative surgical interventions with fewer post-operative complications.

Axillary Lymph Node Tattooing and Targeted Axillary Dissection in Breast Cancer Patients Who Presented as cN+ Before Neoadjuvant Chemotherapy and Became cN0 After Treatment

INTRODUCTION

Targeted axillary dissection (TAD) is an alternative to axillary dissection for breast cancer patients who presented as cN+ before neoadjuvant chemotherapy (NAC) and became cN0 after treatment. TAD is defined as the removal of sentinel lymph nodes (SLNs) along with the pre-NAC marked positive nodes. Tattooing is an option to mark positive nodes. In this study we aimed to investigate the identification rate of tattooed nodes during surgery, correspondence between tattooed nodes and SLNs, and difficulties and pitfalls of the method.

PATIENTS AND METHODS

In 75 patients who were cN+, with axillary lymph nodes known to have or suspected to have disease were tattooed pre-NAC with a sterile carbon suspension (Spot). After NAC completion all patients became cN0 and underwent TAD as an axillary staging procedure.

RESULTS

SLNs were identified successfully in 70 of 75 patients (93.3%). All tattooed nodes were identified successfully intraoperatively in 71 of 75 patients (94.6%). Retrieval of all tattooed nodes in surgical specimens was achieved in 74 patients (98.6%). Correspondence between tattooed nodes and SLNs was observed in 53 of 70 patients (75.3%). In 34 patients (45.3%) the number of pigmented nodes in pathological examination was greater than the number of initially tattooed nodes, indicating the possibility of tattoo ink migration.

CONCLUSION

Tattoo of axillary lymph nodes is a feasible, accurate, and low-cost method of positive node marking pre-NAC. Pathological confirmation of black pigment in the lymph nodes excised is not by itself warranty of retrieval of all marked node because of tattoo ink migration from one node to another. Intraoperative identification using visual inspection is essential.

Abstract 1359: Somatic involution of pathogenic BRCA1 germline mutations

There is currently a wealth of data on the tumor genomic contexture from BRCA1/2 carriers, particularly breast and ovarian carcinomas. By contrast, little attention has as yet been paid to the genomic status of cancer-related normal tissues from these individuals. Here, we investigated the status of pathogenic BRCA1 germline mutations (GM) in breast (B) and gynecologic (GYN) tissues.

Methods: We examined 121 DNA samples (48 B; 36 GYN; 37 tumors) from an equal number of paraffin blocks obtained upon prophylactic or debulking surgery from 44 BRCA1/2 carriers (mean age 38 yrs, range 24-62; 43 BRCA1 carriers). Six women had never had cancer manifestation (CM). At the time of surgery, 32 were cancer-free but had received neo- or adjuvant chemotherapy, and 6 had concurrent cancer without prior treatment. Following multimethod DNA quality control, mutation validation and sample identity match to exclude false negatives, we interrogated GM presence in tissues in comparison to clinicopathologic data and tumor genotypes (60-gene panel; mean read depth over 800).

Results: In 19 samples from 13 BRCA1 carriers, including 13 normal B/GYN and 6 tumors, the germline mutation was present at frequencies lower than 5% (observed with the integrated genome viewer) up to 12%, or it was undetectable with Sanger sequencing and multiplex PCR. This condition, termed GM-loss, was present in 13 GYN, 12 of which in the histologically normal tube, and in only 3 B with fibrocystic disease (p=0.0210). It was also present in one ovarian thecoma but it was absent in usual or atypical hyperplasia in B. GM-loss was observed in 9/55 normal tissues from breast cancer and in 4/6 normal tissues from ovarian cancer patients, while it was absent in the normal tissues from women without CM (p=0.0002). GM-loss mostly affected the BRCA1 BRCT functional domain (p&lt;0.0001) and concerned large deletions (10/17 samples), small indels (5/32; 15.6%) and less so single-nucleotide substitutions (4/66; 6.0%; p&lt;0.0001). Normal tissue GM-loss was rather localized, e.g., in 10 patients with multiple samples it was present in only one B or fallopian tube. It was, however, related to the status of concurrent ovarian tumors in 3/6 cases. In the normal tube of these patients, next to the low-frequency GM a somatic pathogenic BRCA1 mutation was present at 25-41% allelic frequency; the same was observed in one breast tumor after neoadjuvant chemotherapy. Three of the replaced GMs were indels, two corresponded to the well-known BRCA1 p.Q1777fs, and all novel mutations were missense.

Conclusions: We observed BRCA1 GM-loss in normal tissues, breast and mostly fallopian tube, in about 30% of the carriers in the present cohort, all with previous or concurrent cancer. The phenomenon seems analogous to the GM reversion described in tumors but, as shown, it may also occur in the absence of prior treatment. Its origin and impact on cancer dynamics and therapeutic approaches seem worth further pursuing with functional studies.

Citation Format: Vassiliki Kotoula, Efterpi Demiri, Florentia Fostira, Eleni Vrettou, Kyriaki Papadopoulou, Ioannis Tikas, Konstantinos Papazisis, Thomas Zaramboukas, Asimina Asimaki-Vlachopoulou, Spyridon Miliaras, Elena Fountzilas, Ananias Ananiadis, Sofia Chrisafi, Christos Poulios, Ioannis Natsiopoulos, Aris Tsiftsoglou, George Fountzilas. Somatic involution of pathogenic BRCA1 germline mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1359.

Abstract P3-04-04: Germline and somatic mutation status in tissues from BRCA1/2 carriers

Background – aim: In carriers of BRCA1/2 pathogenic mutations (mut), it is expected that the germline mut is present in all tissues, particularly in normal; the somatic mut status in normal tissues from these patients is usually not addressed. We investigated the mut status in normal and tumor tissues in a real-life cohort of BRCA1/2 carriers who underwent prophylactic surgery.

Methods: All 53 women had known BRCA1/2 germline mut that had been assessed independently; 42 had previous cancer manifestation (PCM); all had prophylactic mastectomy; 22 had prophylactic hystero-salpingo-oophorectomy. By using a 60-gene NGS panel, we examined the mut status of 231 samples, 39 peripheral blood and 192 paraffin tissues (FFPE: 46 tumors, out of which 43 breast; 97 normal breast [NB]; 49 normal ovary and salpinx [NGYN]). Germline mut status was interrogated in tissues with the above panel, Sanger sequencing and a multiplex PCR protocol for large exonic deletions, along with extensive FFPE DNA quality control (QC) to exclude false negatives.

Results: Eight patients carried germline BRCA2 and 45 BRCA1 mut (29 in the BRCT-domain; 31 substitutions/indels). We identified somatic mut in 85% of the tumors and in 64% of the normal samples; mut were found significantly more often (p=0.003) and in higher numbers (p&lt;0.001) in NGYN than in NB. In NB and NGYN, top 3 genes with somatic mut were BRCA2 (28%), BRCA1 (17%), TP53 (7%). In tumors, somatic mut were most frequent in TP53 (49%; p&lt;0.001) and BRCA1 (38%; p=0.039). Among all tissue types, the 5 tumors post-neoadjuvant treatment had the highest and NB the lowest mut load (p=0.001). In NB and NGYN, mut load was not affected by PCM or BRCA1 mut domain but it was higher in BRCA1 vs. BRCA2 carriers (p=0.027) and in those with BRCA1 substitutions/indels vs. exon deleting and skipping mut (p&lt;0.001). In tumors, germline BRCA1 substitutions/indels were associated with higher mut load (p=0.014). We validated germline mut status in all blood samples and in 111 tissue samples that passed FFPE DNA QC from 40 patients. The germline mut was not found in 14 samples (4 breast tumors; 3 NB; 7 NGYN) from 10 (25%) patients, all BRCA1 carriers, 9 with germline mut in the BRCT-domain. The only non-BRCT domain germline mut that was lost in one breast tumor, p.V1234fs, was replaced by the R1751* (validated), again in the BRCT domain. In normal tissues, those with lost germline mut had significantly less somatic mut compared to those with preserved germline mut (p&lt;0.001).

Conclusions: In BRCA1/2 carriers, somatic mut in BRCA genes and TP53 are present in normal breast and GYN tissues, more frequently in the latter, and seem associated with the mutated gene and with the type of mut in the germline. The mut status of normal breast tissue does not seem to be affected by neoadjuvant chemotherapy for breast cancer. The observed BRCA1 germline mut loss, particularly in normal tissues, may be approached as a negative selection for the inherited mut; similarly to the described germline mut reversion after chemotherapy, tissues may react to deleterious effects of haploinsufficiency, which needs functional validation.

Citation Format: Kotoula V, Demiri E, Fostira F, Vrettou E, Papadopoulou K, Tikas I, Papazisis K, Zaramboukas T, Asimaki-Vlachopoulou A, Miliaras S, Fountzilas E, Ananiadis A, Chrisafi S, Poulios C, Natsiopoulos I, Tsiftsoglou A, Fountzilas G. Germline and somatic mutation status in tissues from BRCA1/2 carriers [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-04-04.

Genomic features of normal tissues from prophylactic surgery in BRCA1/2 mutation carriers

e13055

Background: Genomic alterations in normal tissues from pathogenic germline BRCA1/2 mutation (mut) carriers are as yet poorly described. We investigated the genomic status of normal breast (NB) and hystero-salpingo-oophorectomy (GYN) tissues removed upon prophylactic surgery in a real-life cohort of BRCA1/2 carriers. Methods: By using targeted NGS we examined the mut status of 220 samples (39 peripheral blood and 181 paraffin tissue) from 53 BRCA1/2 carriers who underwent prophylactic surgery, 42 with and 11 without prior cancer manifestation (PCM). We compared germline BRCA1/2 mut status with tumor, NB and GYN mut status. Results: Eight patients carried germline BRCA2 and 45 BRCA1 mut. Somatic mut were most frequent in BRCA2 (28%), BRCA1 (17%), TP53 (7%) among 136 NB and GYN samples; and, in TP53 (49%; p < 0.001) and BRCA1 (38%; p = 0.039) among 45 tumor samples. Among all tissue types, the 85 NB had the lowest mut load (p = 0.001). In NB and GYN, mut load was higher in BRCA1 vs. BRCA2 carriers (p = 0.027) and in those with BRCA1 substitutions/indels vs. exon deleting and skipping mut (p < 0.001). In tumors, only germline BRCA1 substitutions/indels were associated with higher mut load (p = 0.014). Preservation of germline mut in tissues was assessable in 84 samples from 26 patients. The germline mut was lost in 8 tumor and NB samples from 6 patients (23%) with PCM. Somatic deleterious mut in the BRCA1 BRCT-domain emerged in two such cases; the rest had combinations of TP53, MRE11A and NF1 mut. GYN samples from these patients retained the germline mut and presented the highest mut load among all examined samples (p < 0.001). Conclusions: Somatic mut in normal tissues from BRCA1/2 carriers are affected by the inherited mutated gene and by the type of the germline mut concerning BRCA1. Germline BRCA1 mut may be substituted by somatic mut in tumor and normal tissues, in an organ specific manner. Mutagenesis in tumors and normal tissues appear to be driven by different pathways. Our findings shed new light on the biological impact of BRCA1/2 mut in tissues.

Abstract P1-03-08: Different genomic rearrangements account for 17% of BRCA1/2 mutations in Greece

AIM: The aim of this study was to further delineate the extent and nature of mutations in the BRCA1 and BRCA2 genes, responsible for hereditary breast and ovarian cancer in Greek families.

MATERAILS & METHODS: Genomic DNA was isolated from whole peripheral blood of patients referred to our center for mutation analysis of the BRCA1 and BRCA2 genes. Patients were included on the basis of affected family members, types of cancer present in the family and age at diagnosis of breast cancer in the proband. Families were subdivided into high, medium and low risk depending on the number of affected family members, types of cancer diagnosed in the family and age at diagnosis of affected family members. In total, 675 families have been analyzed by our group in the past 4 years. Mutation analysis in all cases included sequencing of the coding region and the splice sites of the two genes. In addition, MLPA analysis was carried in 585 of the patients.

RESULTS: In total, a pathogenic mutation has been identified in 12% of the 675 patients analyzed. Of the 78 mutations identified in total, 13 (17%) were large genomic rearrangements. These were deletions of exons 8, 20, 23, 23-24 and the entire BRCA1 gene, in addition to a duplication of exons 3-8 of the BRCA1 gene. As far as BRCA2 is involved deletions of exons 3, 15 and the entire BRCA2 gene were detected. All deletions were confirmed by use of other MLPA probe sets and/or relative quantitation by Real Time PCR. Of the rearrangements identified, two, namely deletions of exon 20 and exons 23-24 of the BRCA1 gene were identified in more than one unrelated families. In addition, the recurrent mutations 5382insC and G1738R, which have been previously identified as founder mutations in the Greek population, were identified in multiple unrelated analyzed families.

CONCLUSIONS: Our results indicate that different large genomic rearrangements account for an important proportion (17%) of the mutations in the BRCA1 and BRCA2 genes, in Greek families at risk of carrying a germline mutation as judged by family / personal history. The use of the available technologies for the identification of such mutational events is therefore necessary when carrying out complete analysis of the genes in high risk families of Greek background.

Citation Format: Angela Apessos, Eirini Papadopoulou, Vassiliki Metaxa-Mariatou, Konstantinos Agiannitopoulos, Christos Markopoulos, Vasileios Venizelos, Grigorios Xepapadakis, Maria Vasilaki-Antonatou, Antonios Keramopoulos, Nikolaos Bredakis, Aristeidis Tsiftsoglou, Georgios Kesisis, Stylianos Kakolyris, Nikolaos Touroutoglou, Ioannis Natsiopoulos, Konstantinos Papazisis, Georgios Nasioulas. Different genomic rearrangements account for 17% of BRCA1/2 mutations in Greece [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-03-08.

Metaplastic breast carcinoma in a patient with Von Recklinghausen's disease

Metaplastic carcinomas of the breast are uncommon lesions and account for < 5% of all breast malignancies. A type of metaplastic carcinoma is carcinosarcoma, an even more rare lesion. We present a case of carcinosarcoma in association with Von Recklinghausen's disease in a 60-year-old woman. Von Recklinghausen's disease is an autosomal dominant disorder that is localized at the long arm of chromosome 17 and affects 1 in 4000 individuals. There are few reports on breast tumor development and incidence in patients with Von Recklinghausen's disease. To our knowledge, there has been no report of breast carcinosarcoma associated with Von Recklinghausen's disease. We comment on the difficulties of diagnosis and treatment and the possibility of breast tumors occurring more frequently in patients with Von Recklinghausen's disease.