The prevalence of BRCA1 and BRCA2 germline mutations in high-risk breast cancer patients of Chinese Han nationality: two recurrent mutations were identified

Breast cancer risk associated with BRCA1 and BRCA2 pathogenic variants in the Eastern Chinese population

Background

Population-based penetrance studies of breast cancer gene 1/2 (BRCA1/2) pathogenic or likely pathogenic (P/LP) variants in the Eastern Chinese population are currently lacking; thus, we aimed to investigate the penetrance of breast cancer and other malignant tumors among BRCA1/2 P/LP variant carriers using a population-based breast cancer cohort from communities in Eastern China.

Methods

Between July 2019 and March 2021, we tested 2216 breast cancer probands from Chinese communities for BRCA1/2 mutations and collected detailed information on the age, survival status, and malignancy history of first-degree relatives. The kin-cohort method was used to calculate the penetrance of breast cancer and other malignant tumors.

Results

Of the 2216 breast cancer probands, 109 (4.90%) carried BRCA1/2 P/LP variants, 49 in the BRCA1 gene and 60 in the BRCA2 gene. The penetrance of female breast cancer by 85 years of age was 22.50% and 18.20% in BRCA1 and BRCA2 P/LP variant carriers, respectively. The penetrance of ovarian cancer by 85 years of age was 26.00% in BRCA1 P/LP variant carriers. The penetrance of other malignancies did not reach statistical significance owing to the small number of events.

Conclusions

Our findings showed that breast cancer penetrance among BRCA1 and BRCA2 P/LP variant carriers was 22.50% and 18.20%, respectively, which suggests that prophylactic mastectomy may not be necessary for such Chinese individuals.

Trial registration

ClinicalTrials.gov; https://clinicaltrials.gov/ct2/show/NCT04265937.

An overview of the research progress of BRCA gene mutations in breast cancer

The breast cancer susceptibility gene (BRCA) is an important tumor suppressor gene, including BRCA1 and BRCA2, a biomarker that assesses the risk of breast cancer and influences a patient's individualized treatment options. BRCA1/2 mutation (BRCAm) increases the risk of breast cancer. However, breast-conserving surgery is still an option for BRCAm, and prophylactic mastectomy and nipple-sparing mastectomy may also reduce the risk of breast cancer. BRCAm is sensitive to Poly (ADP-ribose) polymerase inhibitor (PARPi) therapy due to specific types of DNA repair defects, and its combination with other DNA damage pathway inhibitors and endocrine therapy and immunotherapy are also used for the treatment of BRCAm breast cancer. The current treatment and research progress of BRCA1/2 mutant breast cancer in this review provides a basis for the individualized treatment of patients with this type of breast cancer.

BRCA Mutations-The Achilles Heel of Breast, Ovarian and Other Epithelial Cancers

Two related tumor suppressor genes, BRCA1 and BRCA2, attract a lot of attention from both fundamental and clinical points of view. Oncogenic hereditary mutations in these genes are firmly linked to the early onset of breast and ovarian cancers. However, the molecular mechanisms that drive extensive mutagenesis in these genes are not known. In this review, we hypothesize that one of the potential mechanisms behind this phenomenon can be mediated by Alu mobile genomic elements. Linking mutations in the BRCA1 and BRCA2 genes to the general mechanisms of genome stability and DNA repair is critical to ensure the rationalized choice of anti-cancer therapy. Accordingly, we review the literature available on the mechanisms of DNA damage repair where these proteins are involved, and how the inactivating mutations in these genes (BRCAness) can be exploited in anti-cancer therapy. We also discuss a hypothesis explaining why breast and ovarian epithelial tissues are preferentially susceptible to mutations in BRCA genes. Finally, we discuss prospective novel therapeutic approaches for treating BRCAness cancers.

Germline Variants in 32 Cancer-Related Genes among 700 Chinese Breast Cancer Patients by Next-Generation Sequencing: A Clinic-Based, Observational Study

Breast cancer (BC) is associated with hereditary components, and some deleterious germline variants have been regarded as effective therapeutic targets. We conducted a clinic-based, observational study to better understand the distribution of deleterious germline variants and assess any clinicopathological predictors related to the variants among Chinese BC patients using a 32 cancer-related genes next-generation sequencing panel. Between November 2020 and February 2022, a total of 700 BC patients were recruited, and 13.1% (92/700) of them carried deleterious germline variants in 15 cancer-related genes, including 37 (37/700, 5.3%) in BRCA2, 29 (29/700, 4.1%) in BRCA1, 8 (8/700, 1.1%) in PALB2, 4 (4/700, 0.6%) in NBN, 3 (3/700, 0.4%) in MRE11A, 3 (3/700, 0.4%) in TP53 and 12 (12/700, 1.7%) in other genes. There were 28 novel variants detected: 5 in BRCA1, 14 in BRCA2, and 9 in non-BRCA1/2 genes. The variants in panel genes, HRR (homologous recombination repair)-related genes, and BRCA1/2 were significantly associated with the following clinicopathological factors: age at the initial diagnosis of BC, family history of any cancer, molecular subtype, Ki-67 index, and hereditary risk. In conclusion, we further expanded the spectrum of germline deleterious variants in Chinese BC patients, and the clinicopathological predictors of variants were identified to facilitate clinical genetic testing and counseling for appropriate individuals.

Prevalence and Factors Associated with BRCA1/2 Gene Mutation in Chinese Populations with Breast Cancer

Objective

We aimed to evaluate the prevalence of BRCA1 and BRCA2 mutations in Chinese populations with breast cancer. Factors associated with BRCA1 and BRCA2 mutations are also evaluated.

Methods

This was a cross-sectional study, and patients with breast cancer were included. Data on clinical characteristics, information of breast cancer, and BRCA1 and BRCA2 mutations were extracted. Patients were divided into the carrier and noncarrier groups.

Results

A total of 368 patients were included. Compared to the noncarrier group (n = 240), patients in the carrier group (n = 128) were younger and more likely to have breast cancer at age <40 years. Of the overall 128 patients in the carrier groups, 58 had BRCA1 mutation and 70 had BRCA2 mutation. Among patients with early onset breast cancer, there was no difference in the prevalence of BRCA1 and BRCA2 (20.7% vs 17.1%, P = 0.35). While among patients with a family history of breast/ovarian cancer, BRCA2 mutation was more prevalent than BRCA1 mutation (54.3% vs 44.8%, P = 0.01); and among patients with triple-negative breast cancer, BRCA1 mutation was more prevalent than BRCA2 mutation (34.5% vs 28.6%, P = 0.04). After adjusting for covariates, factors associated with BRCA1 mutation included breast cancer diagnosed <40 years, tumor size >2 cm, and lymph node metastasis; and after adjusting for covariates, factors associated with BRCA2 mutation included age, tumor size >2 cm, and triple-negative breast cancer.

Conclusion

The prevalence of BRCA1 and BRCA2 mutations varied according to three specific subgroups. Factors associated with BRCA1 and BRCA2 mutations were differential.

The Features of BRCA1 and BRCA2 Germline Mutations in Hakka Ovarian Cancer Patients: BRCA1 C.536 A>T Maybe a Founder Mutation in This Population

Objective

To investigate the frequencies of BRCA1 and BRCA2 mutations in Chinese Hakka patients with ovarian cancer.

Methods

The protein coding regions and exon intron boundary regions of the BRCA gene were sequenced using genomic DNA isolated from the lymphocytes of patients with next-generation sequencing. The patients’ family history and clinical records were collected.

Results

A total of 195 patients with ovarian cancer were included in the study, and 52 distinct variants of the BRCA gene were identified. It was found that 64 patients (64/195, 32.8%) had BRCA gene mutations, including 32 patients (50.0%) with BRCA1 mutation, 27 patients (42.2%) with BRCA2 mutation, and 5 patients (7.8%) with both mutations. Furthermore, 22 pathogenic mutations were detected in 26 patients, 2 likely pathogenic variants in 2 patients, 12 variants of uncertain significance in 20 patients, and 16 likely benign variants in 24 patients. The mutations were mainly found to occur in exons 8, 14, and 17 of BRCA1 and exons 10, 11, 14, and 15 of BRCA2. The results showed that the BRCA genes possess different mutation hotspots in different ethnic groups. In addition, recurrent mutations were noted in many patients. BRCA1 c.536 A>T, considered a founder mutation, was identified in 10 patients (15.63%, 10/64), followed by BRCA1 c.2635 G>T (6.25%, 4/64) and BRCA2 c.2566 T>C (6.25%, 4/64).

Conclusion

The BRCA1 c.536 A>T could be considered to be a founder mutation in this ovarian cancer population. This recurrent BRCA1 mutation has rarely been observed in other ethnic groups. Our findings are expected to provide valuable data for clinical consultation and for designing individualized treatment for ovarian cancer.

Characteristics of Germline Non-BRCA Mutation Status of High-Risk Breast Cancer Patients in China and Correlation with High-Risk Factors and Multigene Testing Suggestions

Background:Expert consensus on BRCA1/2 genetic testing and clinical application in Chinese breast cancer patients recommends that BRCA1/2 testing should be performed in those with clinical risk factors, such as an early onset, triple-negative breast cancer (TNBC) or family history of cancer. With the increasing application of multigene panels, testing for genes beyond BRCA1/2 has become more prevalent. However, the non-BRCA mutation status of Chinese high-risk breast cancer patients has not been fully explored.

Methods: A total of 230 high-risk breast cancer patients from Fudan University Shanghai Cancer Center who had undergone peripheral blood germline 72 genes next-generation sequencing (NGS) from June 2018 to June 2020 were enrolled for retrospective analysis. The 72 genes include common hereditary breast cancer genes, such as homologous recombination repair (HRR) genes and other DNA damage repair genes. High-risk factors included: 1) TNBC; 2) male breast cancer; 3) primary bilateral breast cancer; 4) diagnosed with breast cancer at age less than or equal to 40 years; or 5) at least one first- and/or second-degree relative with BRCA-related cancer (breast or ovarian or prostate or pancreatic cancer).

Results: The germline pathogenic or likely pathogenic mutation rate was 29.6% (68/230) in high-risk breast cancer patients. Among them, 44 (19.1%, 44/230) were identified as harboring BRCA1/2 mutation, and 28 (12.2%, 28/230) patients carried non-BRCA germline variants. Variants were detected in 16 non-BRCA genes, including PALB2 (5, 2.2%), ATM (4, 1.7%), RAD51D (3, 1.3%), TP53 (3, 1.3%), CHEK2 (2, 0.9%), FANCA (2, 0.9%) and ATR, BARD1, BRIP1, ERCC3, HOXB13, MLH1, MRE11, PMS2, RAD51C, RAD54L (1, 0.4%). Besides, 22 (9.6%, 22/230) patients were non-BRCA HRR gene mutation (including ATM, ATR, BARD1, BRIP1, CHEK2, FANCA, MRE11, PALB2, RAD51C RAD51D and RAD54L) carriers. Among high-risk factors, family history showed a correlation with both BRCA (p = 0.005) and non-BRCA HRR gene mutation status (p = 0.036). In addition, TNBC showed a correlation with BRCA1 gene mutation status (p = 0.038). However, other high-risk factors have not shown significantly related to BRCA1/2, non-BRCA genes and non-BRCA HRR gene mutations (p > 0.05). In addition, 312 unique variants of uncertain significance (VUS) were identified among 175 (76.1%, 175/230) patients and 65 different genes.

Conclusions: Non-BRCA gene mutations are frequently identified in breast cancer patients with high risk factors. Family history showed a correlation with both BRCA (p = 0.005) and non-BRCA HRR gene mutation status (p = 0.036), so we strongly suggest that breast cancer patients with a BRCA-related family history receive comprehensive gene mutation testing in China, especially HRR genes, which are not only related to high risk of breast cancer, but also potentially related to poly ADP ribose polymerase inhibitor (PARPi) targeted therapy. The exact relationship of rare gene mutations to breast cancer predisposition and the pathogenicity of VUS need to be further investigated.

Clinical and Pathological Characteristics of Patients with High-Risk Breast Cancer Based on BRCA Mutation Profiles: A Retrospective Study

Objective

This study aimed to determine the differences in clinicopathological features of Turkish patients with high-risk breast cancer based on the mutation status of two breast cancer susceptibility genes (BRCA1/2) .

Materials and Methods

This study enrolled patients with invasive breast cancer who have been evaluated for BRCA1/2 mutations due to the presence of high-risk factors admitted to two tertiary referral centers in Turkey. Clinical and histopathological features were analyzed in BRCA1 mutation carriers, BRCA2 mutation carriers, and non-carriers.

Results

A total of 302 patients with a mean age of 44.2±9.9 (22-82) years were included. BRCA1/2 mutation was found in 75 (24%) patients, of whom 41 (13.6%) were BRCA1 mutation carriers and 37 (12.3%) were BRCA2 mutation carriers. Moreover, 104 (34.4%) and 4 (1.3%) patients had family history of breast and ovarian carcinoma, respectively. The rates of triple negativity (56.1%), histologic grade 3 (65.9%), and lymphovascular invasion (78%) were significantly higher in BRCA1 mutation carriers than in non-carriers and BRCA2 mutation carriers. Furthermore, 87% of triple-negative BRCA1 mutation carriers had histologic grade 3 tumors compared with 38.9% in non-triple-negative BRCA1 mutation carriers, and the difference was significant.

Conclusion

Findings of this study showed that BRCA1-related breast cancers represent a distinct group with unique pathological features, which are usually associated with a poor prognosis.

Association Between a Tri-allelic Polymorphism in the Estrogen Metabolism Oxidoreductase NRH:Quinone Oxidoreductase 2 Gene and Risk of Breast Cancer by Molecular Subtype

Background: We hypothesized that NRH:quinone oxidoreductase 2 (NQO2) is a candidate susceptibility gene for breast cancer because of its known enzymatic activity on estrogen-derived quinones. A tri-allelic polymorphism in the NQO2 gene might be associated with the risk of luminal-like breast cancer.

Methods: In this case-control study, 2,865 women were recruited, including 1,164 patients with pathologically confirmed breast cancer and 1,701 cancer-free controls. The tri-allelic genetic polymorphism (I-29, I-16, and D alleles) was genotyped by a polymerase chain reaction and restriction fragment length polymorphism (RFLP)-based assay. Because the I-16 allele frequency is rare (approximately 1.0%), individuals carrying the I-16 allele were excluded from the analysis. Breast cancer subtypes were classified according to ER, PR, HER2, and grade.

Results: In the association analysis of allele, an increased risk of breast cancer is associated with I-29 allele [82.5% in case group and 79.0% in the control group; odds ratio (OR), 1.25; 95% CI, 1.09–1.43, compared with D allele, p = 0.0015]. In the association analysis of genotype, the I-29-containing genotype was significantly correlated with breast cancer under a dominant model (adjusted OR, 1.31, 95% CI, 1.12–1.54, p = 0.001). Moreover, in the subtype analysis, there was a significant association of the I-29/D polymorphism with luminal-like breast cancer (adjusted OR, 1.54, 95% CI, 1.22–1.94, p = 0.001 for luminal-A disease; adjusted OR, 1.37, 95% CI, 1.06–1.76, p = 0.014 for luminal-B disease) but not with HER2-enriched or triple-negative subtypes.

Conclusion: The tri-allelic polymorphism in the NQO2 gene is associated with breast cancer risk, especially for the luminal-like subtype. Our findings provide a new piece of molecular epidemical evidence supporting the hypothesis that estrogen and its metabolites are carcinogens of luminal-like breast cancer. Further external validation studies are needed.

Insights Into the Impacts of BRCA Mutations on Clinicopathology and Management of Early-Onset Triple-Negative Breast Cancer

Background

Little is known regarding the clinicopathologic characteristics, oncologic outcomes, and treatment strategies that could be ascribed to BRCA mutation in early-onset triple-negative breast cancer (eTNBC).

Methods

eTNBC patients who underwent BRCA genetic testing were derived from our clinical database between 2012 and 2018. Differences in clinical features and pathologic characteristics were examined in groups divided by BRCA mutation status, and the contribution of germline mutations in conjunction with treatment modalities to survival outcomes was determined.

Results

Of the 355 qualifying eTNBC patients, 67 (18.87%) were BRCA mutated and 288 (81.13%) were BRCA wild. Overall, median age at diagnosis was 34 years (range, 24-40 years) in the BRCA mutated subgroup and 35 years (range, 21-40 years) in BRCA wild. The majority of clinicopathologic parameters were parallel; however, tumor size (P = 0.07) and nuclear grade (P =0.08) tend to be more aggressive in the BRCA mutated subgroup. Compared with BRCA wild patients, BRCA mutated patients had a higher likelihood of receiving anthracyclines and taxane-based combination chemotherapy (P = 0.04) and tend to be lower tumor burden (P =0.01). After approximately 5-year median follow-up, the overall survival (OS) (P = 0.021) and breast cancer-specific survival (BCSS) (P = 0.004) in BRCA mutated patients were superior to those in their BRCA wild counterparts. Intriguingly, the clinical outcomes were comparable in patients with breast conserving surgery (BCS) regardless of BRCA mutations and in patients with BRCA mutations in spite of surgical schedules.

Conclusions

These results suggest that eTNBC patients with BRCA mutations are prone to better OS and BCSS, which might be largely attributed to more benefit from anthracyclines and taxane-based chemotherapy. The BCS procedure could be a safe alternative surgical option for eTNBC patients with BRCA mutations. Future studies with substantial numbers of participants are urgently needed to validate whether BRCA mutation eTNBC patients are more sensitive to chemotherapy.

Identification of Recurrent Variants in BRCA1 and BRCA2 across Multiple Cancers in the Chinese Population

BRCA1 and BRCA2 as important DNA repair genes have been thoroughly investigated in abundant studies. The potential relationships of BRCA1/2 pathogenic variants between multicancers have been verified in Caucasians but few in Chinese. In this study, we performed a two-stage study to screen BRCA1/2 pathogenic variants or variants of uncertain significance (VUS) with 7580 cancer cases and 4874 cancer-free controls, consisting of a discovery stage with 70 familial breast cancer cases and a subsequent validation stage with 7510 cases (3217 breast cancer, 1133 cervical cancer, 2044 hepatocellular carcinoma, and 1116 colorectal cancer). 48 variants were obtained from 70 familial breast cancer cases after BRCA1/2 exon detection, and finally, 20 pathogenic variants or VUS were selected for subsequent validation. Four recurrent variants in sporadic cases (BRCA1 c.4801A>T, BRCA1 c.3257del, BRCA1 c.440del, and BRCA2 c.7409dup) were identified and three of them were labeled Class 5 by ENIGMA. Two variants (BRCA1 c.3257del and c.440del) were specific in breast cancer cases, while BRCA2 c.7409dup and c.4307T>C were detected in two hepatocellular carcinoma patients and the BRCA1 c.4801A>T variant in one cervical cancer patient, respectively. Moreover, BRCA1 c.3257del was the most frequent variant observed in Chinese sporadic breast cancer and showed increased proliferation of BRCA1 ^c.3257del-overexpressing triple-negative breast cancer cell lines (MDA-MB-231) in vitro. In addition to the known founder deleterious mutations, our findings highlight that the recurrently pathogenic variants in breast cancer cases could be taken as candidate genetic screening loci for a more efficient genetic screening of the Chinese population.

BRCA2 c.8827C>T pathogenic mutation in a consanguineous Chinese family with hereditary breast cancer

Background

Mutations in the BRCA2 DNA repair associated gene (BRCA2) are associated with the development of breast cancer, with different ethnic mutations at different sites. Based on different types of BRCA2 variants, the underlying mechanism remains still elusive.

Methods

Next‐generation sequencing (NGS) was performed to detect germ line mutations in BRCA2. The expressions of BRCA2 mRNA and BRCA2 protein were detected by Real‐time PCR and Western blot, respectively.

Results

In a consanguineous Chinese family with hereditary breast cancer, one woman had unilateral breast cancer, two women had bilateral asynchronous breast cancer, and one man had prostate cancer. We identified a mutation site (NM_000059.4: c.8827C>T, NP_ 000050.3: p.(Gln2943*)) in BRCA2 gene, which was a nonsense mutation that predicted disrupting peptide chain synthesis and limiting BRCA2 protein production, validated by the decreased expressions of both BRCA2 mRNA and BRCA2 protein.

Conclusion

In this study, we identified a BRCA2 c.8827C>T nonsense mutation with a truncated BRCA2 protein in a consanguineous Chinese Han family, suggesting individuals with this mutation should be regularly screened for malignancies such as breast, prostate, and ovarian cancer. Our study verified the function of this BRCA2 mutation site and provided a new target for the precise treatment of such patients.

Clinicopathological characteristics of BRCA-associated breast cancer in Asian patients

BRCA1/2 germline mutations account for the majority of hereditary breast cancers. Since the identification of the BRCA genes, several attempts have been made to define the clinicopathological characteristics of BRCA-associated breast cancer in comparison with sporadic breast cancer. Asians constitute 60% of the world population, and although the incidence of breast cancer in Asia remains low compared to the West, breast cancer is the most prevalent female cancer in the region. The epidemiological aspects of breast cancer are different between Asians and Caucasians. Asian patients present with breast cancer at a younger age than Western patients. The contributions of BRCA1/2 mutations to breast cancer incidence are expected to differ between Asians and Caucasians, and the different genetic backgrounds among races are likely to influence the breast cancer phenotypes. However, most large-scale studies on the clinicopathological characteristics of BRCA-associated breast cancer have been on Western patients, while studies on Asian populations were small and sporadic. In this review, we provide an overview of the clinical and pathological characteristics of BRCA-associated breast cancer, incorporating findings on Asian patients.

Frequency of BRCA1 and BRCA2 Mutations in Individuals with Breast and Ovarian Cancer in a Chinese Hakka Population Using Next-Generation Sequencing

BACKGROUND

It is necessary to investigate the frequency of BRCA1 and BRCA2 mutations in Hakka populations due to the variations in breast cancer epidemiology and genetics.

METHODS

359 breast cancer patients and 66 ovarian cancer patients were included in this retrospective clinical study. Mutations of BRCA1 and BRCA2 were detected in blood samples by semiconductor sequencing.

RESULTS

The sensitivity of tumor markers including CEA, CA15-3, CA12-5, and CA199 for screening breast cancer was 16.44, 15.11, 8.44, and 7.56%, the combination of these 4 tumor markers reached the highest sensitivity index (31.11%). For ovarian cancer, the tumor markers were CA12-5 (54.05%), HE-4 (54.05%), CA72-4 (51.35%), and CEA (2.70%) in order of decreasing sensitivity. Moreover, the combination of these 4 tumor markers has the best sensitivity (75.68%) for screening ovarian cancer. In breast cancer patients, we found 5 (1.39%) patients with mutations in BRCA1, 13 (3.62%) mutations in BRCA2, and the total carrier rate is 5.01% (18/359). For ovarian cancer patients, the corresponding results were 3 (4.54%) mutations, 2 (3.03%) mutations, and 7.58% (5/66), respectively. The proportion of BRCA mutations was 5.41% (23/425) in breast and ovarian cancer patients of a Hakka population. The pathogenic, likely pathogenic, and benign mutations, and mutations of uncertain significance in this study mainly occurred in exon 14 of the BRCA1 gene, and exon 10 and exon 11 of the BRCA2 gene.

CONCLUSIONS

Understanding the spectrum and frequency of BRCA1 and BRCA2 mutations in a Hakka population will assist in the prevention and control of hereditary breast and ovarian cancers in this population.

BRCA1 c.5470_5477del, a founder mutation in Chinese Han breast cancer patients

The spectrum and frequency of BRCA1/2 pathogenic variants may be ethnicity-specific. Whether high-frequency founder mutations are present in Chinese women remains largely unknown. In the current study, germline pathogenic variants in the BRCA1/2 genes were determined in 9,505 unselected Chinese Han breast cancer (BC) patients by next-generation and/ or Sanger sequencing. Four hundred and seventy-one (5.0%) BC patients carried BRCA1/2 pathogenic variants in this cohort. A total of 25 recurrent pathogenic variants (at least found in four unrelated patients) were identified in this cohort (8 BRCA1 and 17 BRCA2 recurrent pathogenic variants), 161 patients carried one of these recurrent pathogenic variants in this cohort of 9,505 patients. All of these 25 recurrent pathogenic variants were further explored whether they had founder effect through haplotype analysis. The most common pathogenic variant, BRCA1 c.5470_5477del, was found in 30 BC patients from 29 unrelated families. Twenty-seven of these 29 unrelated patients who carried this BRCA1 c.5470_5477del mutation shared an identical haplotype, indicating that BRCA1 c.5470_5477del was a founder mutation in the Chinese Han population. Furthermore, BRCA1 c.5470_5477del mutation carriers had a significantly worse survival than noncarriers (disease-free survival, p = 0.049; overall survival, p = 0.029). Taken together, our data suggested that BRCA1 c.5470_5477del is a founder mutation in the Chinese Han population and BRCA1 c.5470_5477del mutation carriers have a poor survival.

The spectrum of BRCA1 and BRCA2 mutations and clinicopathological characteristics in Chinese women with early-onset breast cancer

PURPOSE

BRCA1/2 mutations represent a high risk of breast cancer and are related to early-onset breast cancer. However, few studies have reported the relationship between BRCA1/2 mutations and their clinical characteristics in early-onset breast cancers. This study is the first article that characterizes the risk factor profiles in Chinese patients selected by the age of onset (≤ 40 years old). We found some differences in the prevalence of germline BRCA1/2 mutations between Asian and Western countries.

METHODS

A total of 1371 consecutive unselected Chinese early-onset breast cancer patients were enrolled from the Fujian Medical University Union Hospital, China, and screened for germline BRCA1/2 mutations. Full-exome sequencing in next-generation sequencing technology was performed in all patients to examine BRCA1/2 mutations.

RESULTS

In our study, 25 (1.8%) and 61 (4.4%) patients were identified with BRCA1 and BRCA2 mutations, respectively, among the unselected early-onset breast cancer patients. BRCA1 mutations were associated with pregnancies (p = 0.026), and BRCA1 carriers had a higher likelihood of being HR positive (p < 0.001), HER2 negative (p < 0.001), or high grade (p = 0.002) than noncarriers. Among BRCA2 mutations, the age of onset was younger in carriers than in noncarriers (p = 0.017), and BRCA2 carriers were more likely to have lymph node metastasis (p = 0.004). HR-positive or HER2-negative patients were likely to be positive for BRCA2 mutations (p < 0.001). Overall, 14 BRCA1 mutations and 8 BRCA2 mutations were first reported in our study CONCLUSION: This study provided some information about the spectrum of BRCA1/2 mutations and characterized the risk factors for early-onset breast cancer in China.

Fertility preservation in BRCA mutation carriers-efficacy and safety issues: a review

BRCA mutation carriers face various situations that influence their fertility potential. There is still a lack of guideline or expert consensus on Fertility Preservation (FP) in BRCA mutation carriers and the necessity and safety of FP in BRCA mutation carriers is still in dispute. This review aims to focus on the population of BRCA mutation carriers by analyzing the existing FP strategies, comprehensively comparing the pros and cons of each strategy and its applicability.FP is a suggestion for BRCA mutation carriers with birth planning. Different FP strategies have different characteristics. Considering the particularity of BRCA mutation carriers, multiple factors need to be carefully considered. This review focuses on the applicability of each FP method for carriers under various circumstances. Available FP strategies including oocyte cryopreservation, ovarian tissue cryopreservation, preimplantation genetic diagnosis, and egg/embryo donation are analyzed by comparing existing methods comprehensively. In the attempt to provide an up-to-date decision-making guidance. Conditions taking into consideration were the carrier's age, the risk of breast and ovarian metastasis, plans for oncotherapy, FP outcome, time available for FP intervention and accessibility.Overall, FP is necessary and safe for BRCA mutation carriers. Among all available FP methods, oocyte cryopreservation is the most reliable procedure; ovarian tissue cryopreservation is the only way for preserving both fertility and endocrine function, recommended for pre-pubertal carriers and when time is limited for oocyte stimulation. A clear framework provides frontline clinical practitioners a new thought and eventually benefit thousands of BRCA mutation carriers.

The spectrum of BRCA1 and BRCA2 pathogenic sequence variants in Middle Eastern, North African, and South European countries

BRCA1 BRCA2 mutational spectrum in the Middle East, North Africa, and Southern Europe is not well characterized. The unique history and cultural practices characterizing these regions, often involving consanguinity and inbreeding, plausibly led to the accumulation of population-specific founder pathogenic sequence variants (PSVs). To determine recurring BRCA PSVs in these locales, a search in PUBMED, EMBASE, BIC, and CIMBA was carried out combined with outreach to researchers from the relevant countries for unpublished data. We identified 232 PSVs in BRCA1 and 239 in BRCA2 in 25 of 33 countries surveyed. Common PSVs that were detected in four or more countries were c.5266dup (p.Gln1756Profs), c.181T>G (p.Cys61Gly), c.68_69del (p.Glu23Valfs), c.5030_5033del (p.Thr1677Ilefs), c.4327C>T (p.Arg1443Ter), c.5251C>T (p.Arg1751Ter), c.1016dup (p.Val340Glyfs), c.3700_3704del (p.Val1234Glnfs), c.4065_4068del (p.Asn1355Lysfs), c.1504_1508del (p.Leu502Alafs), c.843_846del (p.Ser282Tyrfs), c.798_799del (p.Ser267Lysfs), and c.3607C>T (p.Arg1203Ter) in BRCA1 and c.2808_2811del (p.Ala938Profs), c.5722_5723del (p.Leu1908Argfs), c.9097dup (p.Thr3033Asnfs), c.1310_1313del (p. p.Lys437Ilefs), and c.5946del (p.Ser1982Argfs) for BRCA2. Notably, some mutations (e.g., p.Asn257Lysfs (c.771_775del)) were observed in unrelated populations. Thus, seemingly genotyping recurring BRCA PSVs in specific populations may provide first pass BRCA genotyping platform.

Novel Germline Mutations of BRCA1 and BRCA2 in Korean Familial Breast Cancer Patients

Breast cancer is the second most common cancer in Korean women. Germline mutations in the BRCA1 and BRCA2 genes cause hereditary breast cancer and are detected in 15–20% of hereditary breast cancer. We investigated the BRCA1 and BRCA2 mutations in 114 familial breast cancer patients using next-generation sequencing. We confirmed 20 different mutations of BRCA1 and BRCA2 in 25 subjects (21.9%). Two such mutations in eight patients were novel (not reported in any variant database or previous study). Six mutations have been reported as disease-causing mutations in public databases. Seven mutations were found only in a single nucleotide polymorphism database and one mutation has been reported in Korea. The BRCA1/2 mutation frequency was similar to that of other studies on familial breast cancer patients in the Korean population. Further studies should examine more cases and mutations of whole exons.

Identifying a BRCA2 c.5722_5723del mutation in a Han-Chinese family with breast cancer

Breast cancer (BC) is the most common female cancer found worldwide. It is responsible for 25% of all cancer patients in females. Hereditary BC accounts for about 5–10% of all BC cases. The breast cancer 1 gene (BRCA1) and the breast cancer 2 gene (BRCA2) are the two most-studied BC susceptibility genes. Genetic testing for disease-causing mutations in BRCA1, BRCA2, and other BC susceptibility genes is strongly recommended for members of families having a BC family history. The present study found a heterozygous c.5722_5723del mutation in the BRCA2 exon 11 of a large Han-Chinese BC family using whole exome sequencing and Sanger sequencing. It may cause DNA double-strand breaks repair dysfunction by disturbing homologous recombination, further resulting in BC. The study findings may help supplement and further improve genetic testing strategies and BC risk estimation methodologies in China.

Toll-like receptor 3 acts as a suppressor gene in breast cancer initiation and progression: a two-stage association study and functional investigation

Toll-like receptor 3 (TLR3) is a receptor recognizing double-stranded RNA (dsRNA) from viruses as well as from lytic mammalian cells. In the present study, we performed a two-stage association study (n = 3,551) and found that the minor alleles of two SNPs (the T-allele of rs5743312 and the T-allele of rs3775296) conferred increased risks of breast cancer incidence. The adjusted odds ratios (ORs) were 2.281 (P = 7.01 × 10-5) and 2.086 (P = 8.69 × 10-5), respectively. Specifically, the susceptibility variants within TLR3 were significantly associated with larger tumor size (adjusted P-values: 0.004 for rs5743312 and 0.004 for rs3775296). Furthermore, we investigated the biological function of the TLR3 protein in breast cancer cell lines. Notably, the stable expression of TLR3 directly inhibited cell proliferation both in vitro and in vivo. We also verified that TLR3 conferred less invasive phenotypes on breast cancer cells by regulating the mRNA expression of a panel of genes. TLR3-mediated inhibition of proliferation was caused by downregulation of the EGFR/PI3K/AKT pathway. In summary, our findings strongly suggest that common genetic changes in the TLR3 gene may influence breast cancer susceptibility and development, and TLR3 plays a negative regulatory role in the initiation and progression of human breast cancer cells, at least in part by downregulating the EGFR/PI3K/AKT pathway.

Mutations in context: implications of BRCA testing in diverse populations

Cancer is a common non-communicable disease worldwide, although it exhibits differential population trends in incidence and mortality rates. The differences relate to population structure, environmental risk factors as well as health system organization. This article discusses the potential impact of genetic testing on population health, focusing in particular on the mutational spectrum of breast cancer susceptibility genes in diverse populations. We identify the need for improved access to, and increased investment in, comprehensive cancer risk assessment and genetic testing as well as cancer control measures that take into account lifestyle, environmental, and social factors in understudied minority groups.

Association Between BRCA Status and Triple-Negative Breast Cancer: A Meta-Analysis

Triple-negative breast cancer (TNBC) is a subtype of aggressive breast cancer and characterized by a lack of the expression of estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2. BRCA genes are tumor-suppressor genes that are involved in DNA damage repair and mutations of BRCA genes may increase the risk of developing breast cancer and/or ovarian cancer due to defective DNA repair mechanisms. However, the relationship between BRCA status and TNBC needs to be further investigated and validated. The aim of this meta-analysis was to evaluate the association between BRCA status and TNBC. We systematically searched the electronic databases of MEDLINE (PubMed), Embase, and Cochrane Library to identify relevant publications from April, 1959 to November, 2017. The data from the studies were examined by a meta-analysis using STATA software to calculate the odds ratio (OR) with 95% confidence interval (CI) by fixed-effect and random-effect models. We identified 16 qualified studies from 527 publications with 46,870 breast cancer patients including 868 BRCA1 mutations (BRCA1^Mut) carriers, 739 BRCA2 mutations (BRCA2^Mut) carriers, and 45,263 non-carriers. The results showed that breast cancer patients with BRCA1^Mut carriers were more likely to have TNBC than those of BRCA2^Mut carriers (OR: 3.292; 95% CI: 2.773–3.909) or non-carriers (OR: 8.889; 95% CI: 6.925–11.410). Furthermore, high expression of nuclear grade and large tumor burden (>2 cm) were significantly more common in breast cancer patients with BRCA1^Mut carriers than those of BRCA2^Mut carriers (OR: 2.663; 95% CI: 1.731–4.097; P = 0.211) or non-carriers (OR: 1.577; 95% CI: 1.067–2.331; P = 0.157). The data suggest that breast cancer patients with BRCA1^Mut are more likely to have TNBC, high nuclear grade, and larger tumor burden.

Prevalence and Spectrum of BRCA1/2 Germline Mutations in Women with Breast Cancer in China Based on Next-Generation Sequencing

Background

BRCA1 and BRCA2 (BRCA1/2) play important roles in the development of breast cancer, but information regarding BRCA1/2 mutations in Chinese females remains limited. The aim of this study was to investigate the prevalence and spectrum of BRCA1/2 mutations in China.

Material/Methods

In total, 595 breast cancer patients in China were screened with an amplicon-based panel for the detection of BRCA1/2 mutations in coding regions using next-generation sequencing (NGS) with a Personal Genome Machine. Every pathogenic mutation detected was confirmed by Sanger sequencing. The disease-causing potential of variants of uncertain significance (VUS) was predicted using PolyPhen-2, SIFT, PhyloP, and Grantham.

Results

The prevalence of BRCA1/2 mutations was 8.07% in the Chinese population. Forty-two pathogenic mutations were identified in 48 cases (17 BRCA1 cases and 31 BRCA2 cases), including 19 novel mutations. Nine VUS were predicted to be deleterious by PolyPhen-2 and SIFT and subsequently predicted by PhyloP and Grantham for the evolutionary conservation.

Conclusions

These results suggest that NGS is useful as a rapid, high-throughput, and cost-effective screening tool for the analysis of BRCA1/2 mutations. Based on this panel, we found that BRCA1/2 germline mutations in China exhibit distinct characteristics compared to those in Western populations.

Rapid detection of BRCA1/2 recurrent mutations in Chinese breast and ovarian cancer patients with multiplex SNaPshot genotyping panels

BRCA1/2 mutations are significant risk factors for hereditary breast and ovarian cancer (HBOC), its mutation frequency in HBOC of Chinese ethnicity is around 9%, in which nearly half are recurrent mutations. In Hong Kong and China, genetic testing and counseling are not as common as in the West. To reduce the barrier of testing, a multiplex SNaPshot genotyping panel that targeted 25 Chinese BRCA1/2 mutation hotspots was developed, and its feasibility was evaluated in a local cohort of 441 breast and 155 ovarian cancer patients. For those who tested negative, they were then subjected to full-gene testing with next-generation sequencing (NGS). BRCA mutation prevalence in this cohort was 8.05% and the yield of the recurrent panel was 3.52%, identifying over 40% of the mutation carriers. Moreover, from 79 Chinese breast cancer cases recruited overseas, 2 recurrent mutations and one novel BRCA2 mutation were detected by the panel and NGS respectively. The developed genotyping panel showed to be an easy-to-perform and more affordable testing tool that can provide important contributions to improve the healthcare of Chinese women with cancer as well as family members that harbor high risk mutations for HBOC.

Characterization of a novel germline BRCA1 splice variant, c.5332+4delA

PURPOSE

Germline mutations in BRCA1 and BRCA2 confer a significant increase in risk for cancer, and determining pathogenicity of a BRCA variant can guide the clinical management of the disease. About 1/3 of BRCA1 variants reported in the public databases have uncertain clinical significance due to lack of conclusive evidence. This study aims to characterize a novel BRCA1 deletion affecting the + 4 splice donor site identified in an individual with early-onset breast cancer.

METHODS

The effect of BRCA1 c.5332+4delA variant on RNA splicing was evaluated by amplifying regions of BRCA1 from cDNA derived from the patient. The proportion of abnormal transcript in the total transcripts was quantified. Loss of heterozygosity (LOH) in tumor tissue was investigated using Sanger sequencing and fragment analysis.

RESULTS

BRCA1 c.5332+4delA caused skipping of exon 21 in patient-derived samples. Semi-quantitative analysis indicated that this aberrant RT-PCR product accounts for about 40% of the total transcript levels. Loss of heterozygosity (LOH) was observed in patient's tumor tissue.

CONCLUSIONS

Our results indicate that the BRCA1 c.5332+4delA variant contributes to cancer predisposition through disruption of normal mRNA splicing. We classify this variant as likely pathogenic.

Clinical and genetic characterization of hereditary breast cancer in a Chinese population

BACKGROUND

Breast cancer develops as a result of multiple gene mutations in combination with environmental risk factors. Causative variants in genes such as BRCA1 and/or BRCA2 have been shown to account for hereditary nature of certain breast cancers. However,other genes, such as ATM, PALB2, BRIP1, CHEK, BARD1, while lower in frequency, may also increase breast cancer risk. There are few studies examining the role of these causative variants. Our study aimed to examine the clinical and genetic characterization of hereditary breast cancer in a Chinese population.

METHODS

We tested a panel of 27 genes implicated in breast cancer risk in 240 participants using Next-Generation Sequencing. The prevalence of genetic causative variants was determined and the association between causative variants and clinico-pathological characteristics was analyzed.

RESULTS

Causative variant rate was 19.2% in the breast cancer (case) group and 12.5% in the high-risk group. In the case group 2.5% of patients carried BRCA1 causative variant, 7.5% BRCA2 variants, 1.7% patients had MUTYH, CHEK or PALB2 variants, and 0.8% patients carried ATM, BARD1, NBN, RAD51C or TP53 variants. In the high-risk group 5.8% women carried MUTYH causative variants, 2.5% had causative variants in ATM, 1.7% patients had variants in BRCA2 and 0.8% in BARD1, BRIP1 or CDH1. There was no significant difference in the presence of causative variants among clinical stages of breast cancer, tumor size and lymph nodes status. However, eight of the 12 BRCA1/2 causative variants were found in the TNBC group.

CONCLUSIONS

We found increased genetic causative variants in the familial breast cancer group and in high-risk women with a family history of breast cancer. However, the variant MUTYH c.892-2A > G may not be directly associated with hereditary breast carcinoma.

The spectrum of BRCA mutations and characteristics of BRCA-associated breast cancers in China: Screening of 2,991 patients and 1,043 controls by next-generation sequencing

To characterize the prevalence of BRCA mutations and characteristics of BRCA carriers in China and to update the clinical recommendations for BRCA testing, we conducted a wide screen for BRCA mutations using next-generation sequencing (NGS). A total of 4,034 Chinese subjects were screened for germline BRCA1/2 mutations, including 2,991 breast cancer patients and 1,043 healthy individuals from the community enrolled as controls. We developed an NGS-based approach to perform BRCA1/2 screening. BRCA mutations were identified in 9.1% (232/2,560) of cases with at least one risk factor, in 3.5% (15/431) of sporadic patients and in 0.38% (4/1,043) of healthy controls. The mutation frequency ranged from 8.9 to 15.2% in cohorts with a single risk factor to 16.6-100% in groups with multiple risk factors. We identified 70 novel BRCA mutations. A high frequency of BRCA1 c.5470_5477del was detected, accounting for 13.9% (16/115) of the BRCA1 mutations detected in our study. Clinical characteristics such as family history, invasive carcinoma, negative human epidermal growth factor receptor 2 (HER2), high Ki67 index, lymph node status, and high tumour grade were closely related to BRCA mutations. BRCA2 carriers had poorer disease-free survival among HER2- or hormone receptor-positive patients (hazard ratio = 1.892; 95% confidence interval: 1.132-3.161; p = 0.013). This study shows that BRCA mutation carriers could be frequently identified among breast cancer patients with multiple risk factors. Importantly, we established an NGS-based pipeline for BRCA1/2 testing in clinical practice and strongly suggest that breast cancer patients of premier- and moderate-grade risks receive BRCA1/2 mutations testing in China.

Identification of recurrent BRCA1 mutation and its clinical relevance in Chinese Triple-negative breast cancer cohort

Triple‐negative breast cancer (TNBC) accounts for 15–20% of all newly diagnosed breast cancers, and is enriched for germline mutation of BRCA. In Asian patients diagnosed with breast cancer, 268 deleterious mutations of BRCA1 and 242 of BRCA2 have been identified so far, including a reported BRCA1 frameshift mutation (rs80350973), apparently found only in Asian people, with a low prevalence of 0.3–1.7% in different breast cancer cohorts. Here, we reported the high prevalence (7.2%) of rs80350973 among 125 Chinese patients with TNBC, which implies its mutational predilection for certain breast cancer subtypes. Although its low prevalence had not indicated any particular clinical significance in previous studies, our results associated rs80350973 mutation with cell checkpoint malfunction, and was found to be more common in TNBC patients with high Ki‐67 indices (P = 0.004). As Ki‐67 overexpression is a predictor of poor prognosis in TNBC, inclusion of this mutation into genetic assessments may improve the clinical management of Chinese patients with TNBC.

Prevalence and spectrum of BRCA germline variants in mainland Chinese familial breast and ovarian cancer patients

Germline mutations in BRCA1 and BRCA2 are the most penetrating genetic predispositions for breast and ovarian cancer, and their presence is largely ethnic-specific. Comprehensive information about the prevalence and spectrum of BRCA mutations has been collected in European and North American populations. However, similar information is lacking in other populations, including the mainland Chinese population despite its large size of 1.4 billion accounting for one fifth of the world's population. Herein, we performed an extensive literature analysis to collect BRCA variants identified from mainland Chinese familial breast and ovarian cancer patients. We observed 137 distinct BRCA1 variants in 409 of 3,844 and 80 distinct BRCA2 variants in 157 of 3,024 mainland Chinese patients, with an estimated prevalence of 10.6% for BRCA1 and 5.2% for BRCA2. Of these variants, only 40.3% in BRCA1 and 42.5% in BRCA2 are listed in current Breast Cancer Information Core database. We observed higher frequent variation in BRCA1 exons 11A, 11C, 11D, and 24 and BRCA2 exon 10 in Chinese patients than in the patients of other populations. The most common pathogenic variant in BRCA1 wasc.981_982delAT in exon 11A, and in BRCA2 c.3195_3198delTAAT in exon 11B and c.5576_5579delTTAA in exon 11E; the most common novel variant in BRCA1 was c.919A>G in exon 10A, and in BRCA2 c.7142delC in exon 14. None of the variants overlap with the founder mutations in other populations. Our analysis indicates that the prevalence of BRCA variation in mainland Chinese familial breast and ovarian cancer patients is at a level similar to but the spectrum is substantially different from the ones of other populations.

Genetic evaluation of BRCA1 associated a complex genes with triple-negative breast cancer susceptibility in Chinese women

BACKGROUND

The tumor suppressor BRCA1 plays a pivotal role in maintaining genomic stability and tumor suppression. The BRCA1-A complex is required for recruitment of BRCA1 to DNA damage sites, DNA repair and cell cycle checkpoint control. Since germline mutations of BRCA1 often lead to breast tumors that are triple-negative breast cancer (TNBC) type, we aimed to investigate whether genetic deficiency in genes of the BRCA1-A complex is associated with risk to TNBC development.

RESULTS

We found that rs7250266 in the promoter region of NBA1 confers a decreased risk to TNBC development, but not to non-TNBC susceptibility. In addition, the haplotypes containing two polymorphisms rs7250266 and rs2278256 are associated with a lower chance of TNBC development specifically. Our studies also showed that the protective alleles of rs7250266 (C > G) and rs2278256 (T > C) down-regulate promoter activity of NBA1 in mammary epithelial cells.

METHODS

We investigated associations between the BRCA1-A complex genes and TNBC developing risk in first case-control study of Chinese Han Women population including 414 patients with TNBC and 354 cancer-free controls. We detected 37 common variants in ABRAXAS, RAP80, BRE, BRCC36 and NBA1/MERIT40 genes encoding the BRCA1-A complex and evaluated their genetic susceptibility to the risk of TNBC. An additional cohort with 652 other types of breast cancer (non-TNBC) cases and 890 controls was used to investigate the associations between TNBC-specific SNPs genotype and non-TNBCs susceptibility.

CONCLUSIONS

Genetic variants in NBA1 may be an important genetic determinant of TNBC susceptibility. Further investigation and validation of these SNPs in larger cohorts may facilitate in predication and prevention of TNBC and in counseling individuals for risk of TNBC development.

Prevalence and Prognostic Role of BRCA1/2 Variants in Unselected Chinese Breast Cancer Patients

Background

The prevalence of BRCA1/2 variants in Chinese breast cancer patients varies among studies. Germline or somatic BRCA1/2 mutations are associated with sensitivity to poly(ADP-ribose) polymerase-1 inhibitors and DNA-damaging agents. We aimed to investigate the distribution of both somatic and germline BRCA1/2 variants in unselected Chinese breast cancer patients, and explore their roles in tumor phenotype and disease prognosis.

Methods

507 breast cancer patients, unselected for family history of breast cancer or age at diagnosis, were prospectively enrolled from West China Hospital between Feb. 2008 and Feb. 2014. BRCA1/2 variants in the exons/flanking regions were detected in fresh-frozen tumors using next-generation sequencing and confirmed by independent methods. Germline/somatic status was validated by Sanger sequencing in paired blood/normal tissue.

Results

BRCA1/2 pathogenic or likely pathogenic (P/LP) variants were detected in 50 patients (9.9%), including 40 germline carriers (18 in BRCA1, 22 in BRCA2), 9 patients with somatic variants (3 in BRCA1, 6 in BRCA2), and 1 patient with concurrent germline/somatic variants in BRCA2. The triple-negative (21.4%) and Luminal B (9.7%) subtypes had higher rates of BRCA1/2 variants. In patients with disease stage 0~II, presence of a germline or somatic BRCA1 P/LP variant increased the risk of relapse as compared to non-carriers [univariate hazard ratio (HR): 3.70, P = 0.04]. Germline BRCA1 P/LP variants, which were associated with aggressive tumor phenotypes, predicted worse disease-free survival in the subgroup of stage 0~II (HR: 4.52, P = 0.02) and N0 (HR: 5.4, P = 0.04) compared to non-carriers.

Conclusion

A high frequency of germline and somatic BRCA1/2 P/LP variants was detected in unselected Chinese breast cancer patients. Luminal B subtype should be considered as a high-risk population of BRCA1/2 mutation, in addition to triple-negative breast cancer. BRCA1 status was associated with aggressive tumor phenotype and worse disease progression in early stage breast cancer patients.

Clinical and pathological features of BRCA1/2 tumors in a sample of high-risk Moroccan breast cancer patients

BACKGROUND

BRCA1 and BRCA2 genes explain a large part of hereditary breast cancer. Several studies have shown that BRCA1 and BRCA2 tumors exhibit some specific morphological and immunohistochemical characteristics. The aim of our study is to compare the clinicopathological characteristics between Moroccan breast cancers associated or not with BRCA1 and BRCA2 mutations. Previously, we had identified 11 BRCA carriers in a series of 40 selected breast cancer patients at increased risk for carrying a mutation in the BRCA1 and BRCA2 genes. The clinical and pathological features of patients carrying BRCA1 or BRCA2 mutation (n = 11) were evaluated and compared to those of non-mutated patients (n = 29).

RESULTS

In comparison with non carriers, women with BRCA1/2 mutation present younger mean age at diagnosis (37.90 vs. 44.48 years, p = 0.05), younger mean age of 1st menarche (13.08 vs. 14.24 years, p = 0.05) and shorter duration of breastfeeding (8.71 vs. 19.35 months, p = 0.05). Moreover, 63.6 and 62.5% of BRCA1/2 carriers present SBR grade III and triple negative tumors respectively (p = 0.02).

CONCLUSIONS

In this first Moroccan study comparing clinical and pathological characteristics of women carrying or not BRCA1/2 mutation, patients with BRCA mutation tend to develop early breast cancer with high-grade and triple negative tumors. However, further large scale research including more data is needed to better characterize BRCA1/2 cases and to evaluate the survival rate associated with these mutations in our population tumors. Moreover, it would be more interesting to study women with BRCA1 and BRCA2 mutations separately in order to determine if they exhibit distinct characteristics.

Novel germline mutations and unclassified variants of BRCA1 and BRCA2 genes in Chinese women with familial breast/ovarian cancer

BACKGROUND

Germline mutations in the BRCA1 and BRCA2 genes greatly increase a woman's risk of developing breast and/or ovarian cancer. The prevalence and distribution of such mutations differ across races/ethnicities. Several studies have investigated Chinese women with high-risk breast cancer, but the full spectrum of the mutations in these two genes remains unclear.

METHODS

In this study, 133 unrelated Chinese women with familial breast/ovarian cancer living in Zhejiang, eastern China, were enrolled between the years 2008 and 2014. The complete coding regions and exon-intron boundaries of BRCA1 and BRCA2 were screened by PCR-sequencing assay. Haplotype analysis was performed to confirm BRCA1 and BRCA2 founder mutations. In silico predictions were performed to identify the non-synonymous amino acid changes that were likely to disrupt the functions of BRCA1 and BRCA2.

RESULTS

A total of 23 deleterious mutations were detected in the two genes in 31 familial breast/ovarian cancer patients with a total mutation frequency of 23.3% (31/133). The highest frequency of 50.0% (8/16) was found in breast cancer patients with a history of ovarian cancer. The frequencies of BRCA1 and BRCA2 mutations were 13.5 % (18/133) and 9.8% (13/133), respectively. We identified five novel deleterious mutations (c.3295delC, c.3780_3781delAG, c.4063_4066delAATC, c.5161 > T and c.5173insA) in BRCA1 and seven (c.1-40delGA, c.4487delC, c.469_473delAAGTC, c.5495delC, c.6141T > A, c.6359C > G and c.7588C > T) in BRCA2, which accounted for 52.2% (12/23) of the total mutations. Six recurrent mutations were found, including four (c.3780_3781delAG, c.5154G > A, c.5468-1del8 and c.5470_5477del8) in BRCA1 and two (c.3109C > T and c.5682C > G) in BRCA2. Two recurrent BRCA1 mutations (c.5154G > A and c.5468-1del8) were identified as putative founder mutations. We also found 11 unclassified variants, and nine of these are novel. The possibility was that each of the non-synonymous amino acid changes would disrupt the function of BRCA1 and BRCA2 varied according to the different algorithms used.

CONCLUSIONS

BRCA1 and BRCA2 mutations accounted for a considerable proportion of hereditary breast/ovarian cancer patients from eastern China and the spectrum of the mutations of these two genes exhibited some unique features. The two BRCA1 putative founder mutations may provide a cost-effective option to screen Chinese population, while founder effects of the two mutations should be investigated in a lager sample size of patients.

Familial Gastric Cancers

Although the majority of gastric carcinomas are sporadic, approximately 10% show familial aggregation, and a hereditary cause is determined in 1%-3% cases. Of these, hereditary diffuse gastric cancer is the most recognized predisposition syndrome. Although rare, the less commonly known syndromes also confer a markedly increased risk for development of gastric cancer. Identification and characterization of these syndromes require a multidisciplinary effort involving oncologists, surgeons, genetic counselors, biologists, and pathologists. This article reviews the molecular genetics, clinical and pathologic features, surveillance guidelines, and preventive measures of common and less common hereditary gastric cancer predisposition syndromes.

Addressing health disparities in Hispanic breast cancer: accurate and inexpensive sequencing of BRCA1 and BRCA2

BACKGROUND

Germline mutations in the BRCA1 and BRCA2 genes account for 20-25 % of inherited breast cancers and about 10 % of all breast cancer cases. Detection of BRCA mutation carriers can lead to therapeutic interventions such as mastectomy, oophorectomy, hormonal prevention therapy, improved screening, and targeted therapies such as PARP-inhibition. We estimate that African Americans and Hispanics are 4-5 times less likely to receive BRCA screening, despite having similar mutation frequencies as non-Jewish Caucasians, who have higher breast cancer mortality. To begin addressing this health disparity, we initiated a nationwide trial of BRCA testing of Latin American women with breast cancer. Patients were recruited through community organizations, clinics, public events, and by mail and Internet. Subjects completed the consent process and questionnaire, and provided a saliva sample by mail or in person. DNA from 120 subjects was used to sequence the entirety of BRCA1 and BRCA2 coding regions and splice sites, and validate pathogenic mutations, with a total material cost of $85/subject. Subjects ranged in age from 23 to 81 years (mean age, 51 years), 6 % had bilateral disease, 57 % were ER/PR+, 23 % HER2+, and 17 % had triple-negative disease.

RESULTS

A total of seven different predicted deleterious mutations were identified, one newly described and the rest rare. In addition, four variants of unknown effect were found.

CONCLUSIONS

Application of this strategy on a larger scale could lead to improved cancer care of minority and underserved populations.

A recessive variant of XRCC4 predisposes to non- BRCA1/2 breast cancer in chinese women and impairs the DNA damage response via dysregulated nuclear localization

XRCC4 plays a crucial role in the non-homologous end joining pathway that maintains genome stability. In this two-stage case-control study with 1,764 non-BRCA1/2 breast cancer patients and 1,623 cancer-free controls, we investigated the contribution of genetic variants of XRCC4 to breast cancer susceptibility in Chinese women. We identified a recessive missense variant, rs3734091 (c.739G>T, p.Ala247Ser), of XRCC4 that was significantly associated with an increased risk of breast cancer (odds ratio [OR] = 3.92, P = 0.007), particularly with the risk of developing triple-negative breast cancer (OR = 18.65, P < 0.0001). This p.Ala247Ser variant disturbed the nuclear localization of XRCC4 in cells homozygous for the rs3734091-T allele but not in heterozygous cells at both the cellular and tissue levels. In heterozygous cells, wild-type XRCC4 facilitated the nuclear localization of the XRCC4^A247S mutant, thus compensating for the impaired localization of XRCC4^A247S. This provided a biological mechanism by which rs3734091 conferred an increased susceptibility to non-BRCA1/2 breast cancer exclusively under a recessive model. Further functional analyses revealed that p.Ala247Ser impaired the DNA damage repair capacity and ultimately perturbed genomic stability. Taken together, our findings document the role of XRCC4 in non-BRCA1/2 breast cancer predisposition and reveal its underlying biological mechanism of action.

Comprehensive spectrum of BRCA1 and BRCA2 deleterious mutations in breast cancer in Asian countries

Approximately 5%-10% of breast cancers are due to genetic predisposition caused by germline mutations; the most commonly tested genes are BRCA1 and BRCA2 mutations. Some mutations are unique to one family and others are recurrent; the spectrum of BRCA1/BRCA2 mutations varies depending on the geographical origins, populations or ethnic groups. In this review, we compiled data from 11 participating Asian countries (Bangladesh, Mainland China, Hong Kong SAR, Indonesia, Japan, Korea, Malaysia, Philippines, Singapore, Thailand and Vietnam), and from ethnic Asians residing in Canada and the USA. We have additionally conducted a literature review to include other Asian countries mainly in Central and Western Asia. We present the current pathogenic mutation spectrum of BRCA1/BRCA2 genes in patients with breast cancer in various Asian populations. Understanding BRCA1/BRCA2 mutations in Asians will help provide better risk assessment and clinical management of breast cancer.

Identification of a comprehensive spectrum of genetic factors for hereditary breast cancer in a Chinese population by next-generation sequencing

The genetic etiology of hereditary breast cancer has not been fully elucidated. Although germline mutations of high-penetrance genes such as BRCA1/2 are implicated in development of hereditary breast cancers, at least half of all breast cancer families are not linked to these genes. To identify a comprehensive spectrum of genetic factors for hereditary breast cancer in a Chinese population, we performed an analysis of germline mutations in 2,165 coding exons of 152 genes associated with hereditary cancer using next-generation sequencing (NGS) in 99 breast cancer patients from families of cancer patients regardless of cancer types. Forty-two deleterious germline mutations were identified in 21 genes of 34 patients, including 18 (18.2%) BRCA1 or BRCA2 mutations, 3 (3%) TP53 mutations, 5 (5.1%) DNA mismatch repair gene mutations, 1 (1%) CDH1 mutation, 6 (6.1%) Fanconi anemia pathway gene mutations, and 9 (9.1%) mutations in other genes. Of seven patients who carried mutations in more than one gene, 4 were BRCA1/2 mutation carriers, and their average onset age was much younger than patients with only BRCA1/2 mutations. Almost all identified high-penetrance gene mutations in those families fulfill the typical phenotypes of hereditary cancer syndromes listed in the National Comprehensive Cancer Network (NCCN) guidelines, except two TP53 and three mismatch repair gene mutations. Furthermore, functional studies of MSH3 germline mutations confirmed the association between MSH3 mutation and tumorigenesis, and segregation analysis suggested antagonism between BRCA1 and MSH3. We also identified a lot of low-penetrance gene mutations. Although the clinical significance of those newly identified low-penetrance gene mutations has not been fully appreciated yet, these new findings do provide valuable epidemiological information for the future studies. Together, these findings highlight the importance of genetic testing based on NCCN guidelines and a multi-gene analysis using NGS may be a supplement to traditional genetic counseling.

Androgen receptor, EGFR, and BRCA1 as biomarkers in triple-negative breast cancer: a meta-analysis

OBJECTIVE

More and more evidences demonstrate that androgen receptor (AR), epidermal growth factor receptor (EGFR), and breast cancer susceptibility gene 1 (BRCA1) have unique clinical implications for targeted therapy or prognosis in triple-negative breast cancer (TNBC). Therefore, we conducted a meta-analysis to summarize the possible associations.

METHODS

We retrieved published articles about AR, EGFR, and BRCA1 in TNBC from PubMed and EMBASE. The analysis was performed with Rev-Man 5.2 software.

RESULTS

A total of 38 articles were eligible for the meta-analysis. Our study showed that the expression level of EGFR (OR = 6.88, P < 0.00001) and the prevalence of BRCA1 mutation (RR = 5.26, P < 0.00001) were higher in TNBC than non-TNBC. In contrast, the expression level of AR was lower in TNBC than non-TNBC (OR = 0.07, P < 0.00001). In the subgroup related to EGFR expression, the level of EGFR expression was significantly increased in Asians (OR = 9.60) compared with Caucasians (OR = 5.53) for TNBC patients. Additionally, the prevalence of BRCA1 mutation in Asians (RR = 5.43, P < 0.00001) was higher than that in Caucasians (RR = 5.16, P < 0.00001).

CONCLUSIONS

The distinct expression of AR and EGFR and the prevalence of BRCA1 mutation indicated that AR, EGFR, and BRCA1 might be unique biomarkers for targeted therapy and prognosis in TNBC.

Novel and recurrent BRCA1/BRCA2 mutations in early onset and familial breast and ovarian cancer detected in the Program of Genetic Counseling in Cancer of Valencian Community (eastern Spain). Relationship of family phenotypes with mutation prevalence

During the first 6 years of the Program of Genetic Counselling in Cancer of Valencia (eastern Spain), 310 mutations (155 in BRCA1 and 155 in BRCA2) in 1,763 hereditary breast (BC) and ovarian cancer (OC) families were identified. Of the mutations found 105 were distinct (53 in BRCA1 and 52 in BRCA2), eight new and 37 recurrent. Two of the novel mutations were frame-shift placed in exons 2 and 11 of BRCA1 and the remaining six were placed in BRCA2; four frame-shift (three in exon 11 and one in exon 23), one deletion of the entire exon 19 and one in the intervening sequence of exon 22. The BRCA1 mutations with higher recurrence were c.66_68delAG, c.5123C > A, c.1961delA, c.3770_3771delAG and c.5152+5G > A that covered 45.2% of mutations of this gene. The age of onset of BCs of c.68_69delAG mutation carriers occurs later than for the other recurrent mutations of this gene (45 vs. 37 years; p = 0.008). The BRCA2 mutations with higher recurrence were c.9026_9030delATCAT, c.3264insT and c.8978_8991del14 which represented 43.2% of all mutations in this gene, being the most recurrent mutation by far c.9026_9030delATCAT that represents 21.3% of BRCA2 mutations and 10.6% of all mutations. Probands with family histories of BC and OC, or OC and/or BC in at least two first degree relatives, were the more likely to have BRCA1/BRCA2 mutations (35.2% of the total mutations). And that most BRCA1mutations (73.19% mutations) occurred in probands with early-onset BC or with family history of OC.

BRCA1 gene exon 11 mutations in Uighur and Han women with early-onset sporadic breast cancer in the northwest region of China

The prevalence of BRCA1 gene mutations in breast cancer differs between diverse ethnic groups. Relatively little information is known about patterns of BRCA1 mutations in early-onset breast cancer in women of Uighur or Han descent, the major ethnic populations of the Xinjiang region in China. The aim of this study was to identify BRCA1 mutations in Uighur and Han patients with early-onset (age <35 years), and sporadic breast cancer for genetic predisposition to breast cancer. For detection of BRCA1 mutations, we used a polymerase chain reaction single-stranded conformation polymorphism approach, followed by direct DNA sequencing in 22 Uighur and 13 Han women with early-onset sporadic breast cancer, and 32 women with benign breast diseases. The prevalence of BRCA1 mutations in this population was 22.9% (8/35) among early-onset sporadic breast cancer cases. Of these, 31.8% (7/22) of Uighur patients and 7.69% (1/13) of Han patients were found to have BRCA1 mutations. In 7 Uighur patients with BRCA1 mutations, there were 11 unique sequence alterations in the BRCA1 gene, including 4 clearly disease-associated mutations on exon 11 and 3 variants of uncertain clinical significance on exon 11, meanwhile 4 neutral variants on intron 20 or 2. None of the 11 BRCA1 mutations identified have been previously reported in the Breast Cancer Information Core database. These findings reflect the prevalence of BRCA1 mutations in Uighur women with early-onset and sporadic breast cancer, which will allow for provision of appropriate genetic counseling and treatment for Uighur patients in the Xinjiang region.

Characteristics of BRCA1/2 Mutation-Positive Breast Cancers in Korea: A Comparison Study Based on Multicenter Data and the Korean Breast Cancer Registry

Purpose

Mutations in BRCA genes are the main cause of hereditary breast cancer in Korea. The aim of this study was to investigate the characteristics of breast cancers involving BRCA1 (BRCA1 group) and BRCA2 (BRCA2 group) mutations.

Methods

We retrospectively reviewed the medical records of patients with BRCA1 (BRCA1 group) or BRCA2 (BRCA2 group) mutation positive breast cancer from multiple centers and compared the data to that of the Korean Breast Cancer Society registry (registry group).

Results

The patients of the BRCA1 group were diagnosed at a younger age (median age, 37 years) and had tumors of higher histological (61.3% with histological grade 3) and nuclear (37.5% with nuclear grade 3) grade than those of the registry group. In addition, the frequency of ductal carcinoma in situ in the BRCA1 group was lower (3.7%) than in the registry group, and the BRCA1 group were more likely to be triple-negative breast cancer (61.3%). Patients in the BRCA2 group were also younger at diagnosis (mean age, 41 years) and were more likely to have involvement of the axillary node than the registry group (45.5% vs. 33.5%, p=0.002). The BRCA1 and BRCA2 groups did not show a correlation between tumor size and axillary node involvement.

Conclusion

We report the characteristics of BRCA mutation positive breast cancer patients in the Korean population through multicenter data and nation-wide breast cancer registry study. However, BRCA-mutated breast cancers appear highly complex, and further research on their molecular basis is needed in Korea.

Recurrent mutation testing of BRCA1 and BRCA2 in Asian breast cancer patients identify carriers in those with presumed low risk by family history

Although the breast cancer predisposition genes BRCA1 and BRCA2 were discovered more than 20 years ago, there remains a gap in the availability of genetic counselling and genetic testing in Asian countries because of cost, access and inaccurate reporting of family history of cancer. In order to improve access to testing, we developed a rapid test for recurrent mutations in our Asian populations. In this study, we designed a genotyping assay with 55 BRCA1 and 44 BRCA2 mutations previously identified in Asian studies, and validated this assay in 267 individuals who had previously been tested by full sequencing. We tested the prevalence of these mutations in additional breast cancer cases. Using this genotyping approach, we analysed recurrent mutations in 533 Malaysian breast cancer cases with <10 % a priori risk, and found 1 BRCA1 (0.2 %) and 5 BRCA2 (0.9 %) carriers. Testing in a hospital-based unselected cohort of 532 Singaporean breast cancer cases revealed 6 BRCA1 (1.1 %) and 3 BRCA2 (0.6 %) carriers. Overall, 2 recurrent BRCA1 and 1 BRCA2 mutations in Malays, 3 BRCA1 and 2 BRCA2 mutations in Chinese and 1 BRCA1 mutation in Indians account for 60, 24 and 20 % of carrier families, respectively. By contrast, haplotype analyses suggest that a recurrent BRCA2 mutation (c.262_263delCT) found in 5 unrelated Malay families has at least 3 distinct haplotypes. Taken together, our data suggests that panel testing may help to identify carriers, particularly Asian BRCA2 carriers, who do not present with a priori strong family history characteristics.

Distribution of BRCA1 and BRCA2 Mutations in Asian Patients with Breast Cancer

Breast cancer is the most prevalent cancer in Asian females, and the incidence of breast cancer has been increasing in Asia. Because Asian patients develop breast cancer at a younger age than their Caucasian counterparts, the contributions of BRCA1 and BRCA2 (BRCA1/2) mutations in Asians are expected to be different than in Caucasians. The prevalence of BRCA1/2 mutations in the Asian population varies among countries and studies. Most Asian studies have reported more frequent mutations in BRCA2 than in BRCA1, with the exception of studies from India and Pakistan. In addition, the contribution of large genomic rearrangements of BRCA1/2 genes is relatively small in Asian populations in comparison to other ethnic populations. Various statistical models for the prediction of BRCA1/2 mutations have underestimated the risk of having these genetic mutations in Asians, especially in predicting BRCA2 gene mutation. Until recently, BRCA1/2 mutation analyses in Asia were mostly conducted by independent single institutions with different patient selection criteria and using various genotyping methods. However, a couple of Asian groups have initiated nationwide studies collecting BRCA1/2 mutational data. These national collaborative studies will help a comprehensive understanding of the prevalence of BRCA1/2 mutations in the Asian population.

A comprehensive focus on global spectrum of BRCA1 and BRCA2 mutations in breast cancer

Breast cancer (BC) is the most common cancer of women all over the world. BRCA1 and BRCA2 gene mutations comprise the most important genetic susceptibility of BC. Except for few common mutations, the spectrum of BRCA1 and BRCA2 mutations is heterogeneous in diverse populations. 185AGdel and 5382insC are the most important BRCA1 and BRCA2 alterations which have been encountered in most of the populations. After those Ashkenazi founder mutations, 300T>G also demonstrated sparse frequency in African American and European populations. This review affords quick access to the most frequent alterations among various populations which could be helpful in BRCA screening programs.

Hereditary breast cancer in the Han Chinese population

Breast cancer is the most common malignancy among women and has a strong genetic background. So far, 13 breast cancer susceptibility genes of high or moderate penetrance have been identified. This review summarizes findings on these genes in Han Chinese. BRCA1 and BRCA2 are the 2 most important susceptibility genes. They have a relatively low mutation rate, and the most frequent sites of mutation are in exon 11. Frameshift mutations are the main type of mutation. Founder mutations may also exist, and BRCA-associated breast cancer has specific clinicopathologic characteristics. TP53 and PALB2 are relatively rare susceptibility genes. The relationship between the other 9 genes and breast cancer has not been fully elucidated. At present, the mutation spectrum for these susceptibility genes is not well understood in the Chinese population, and there are few reports on prognosis and clinical intervention in high-risk populations. Therefore, the true value of genetic counseling for breast cancer has yet to be realized. This article reviews studies of hereditary breast cancer in the Han Chinese population, highlights potential inadequacies, and provides a foundation for genetic counseling for breast cancer in China.