The prevalence and spectrum of BRCA1 and BRCA2 mutations in Korean population: recent update of the Korean Hereditary Breast Cancer (KOHBRA) study

Long-term oncologic outcomes of unselected triple-negative breast cancer patients according to BRCA1/2 mutations

Triple-negative breast cancer (TNBC) patients are more likely to have BRCA1/2 mutations, with a prevalence rate of about 10-20%. Although several studies have analyzed the oncologic outcomes between BRCA1/2 carriers and non-carriers, the impact on breast cancer patients is still unclear. A retrospective review was performed to determine the long-term outcomes of TNBC patients, focusing on the impact of BRCA1/2 mutations. A total of 953 TNBC patients who underwent primary breast cancer surgery from June 2008 to January 2016 were included. We examined long-term outcomes, including contralateral breast cancer (CBC) incidence, recurrence patterns, and survival rates over a median follow-up of 80.9 months (range 3-152 months). 122 patients (12.8%) had BRCA1/2 mutations. BRCA1/2 mutation carriers were significantly younger at diagnosis and more likely to have a family history of breast/ovarian cancer. CBC incidence at 60, 120, and 150 months was significantly higher in BRCA1/2 mutation carriers compared to non-carriers (P = 0.0250, 0.0063, and 0.0184, respectively). However, there were no significant differences in disease-free survival, overall survival, breast cancer-specific survival, or distant-metastasis-free survival between the two groups. BRCA1/2 mutation status was a significant risk factor for CBC (HR = 6.242, P < 0.0001). Interestingly, among 29 patients with CBC recurrence, 24 patients (82.8%) had recurring TNBC subtype and among the CBC recurrence patients, 19 patients (65.5%) resumed chemotherapy. In the TNBC subtype, appropriate genetic testing and counseling are pivotal for surgical decisions like risk-reducing mastectomy (RRM). Furthermore, long-term surveillance is warranted, especially in BRCA1/2 carriers who did not receive RRM.

Increased risk of contralateral breast cancer for BRCA1/2 wild-type, high-risk Korean breast cancer patients: a retrospective cohort study

BACKGROUND

This study aimed to investigate the contralateral breast cancer (CBC) recurrence rate in Korean breast cancer patients according to their BRCA1/2 germline mutation status, focusing particularly on the CBC recurrence risk in BRCA1/2 negative (BRCAx) patients.

METHODS

We conducted a retrospective study on 13,107 primary breast cancer patients. The patients were divided into high-risk and low-risk groups for hereditary breast cancer based on the Korean National Health Insurance Service's eligibility criteria for BRCA1/2 germline mutation testing. The high-risk group was further categorized into the BRCA mutation group, the BRCAx group, and the not tested group. We evaluated the overall survival and cumulative risk of developing CBC in these patients.

RESULTS

Among 4494 high-risk patients, 973 (21.7%) underwent genetic testing for BRCA1/2 germline mutation, revealing mutations in 158 patients (16.2%). We observed significant overall survival differences across all four groups, with the high-risk, not-tested group demonstrating notably worse overall survival (p < 0.001). However, when adjusted for other prognostic factors, there was no significant differences in hazard ratio of death between the four groups. The cumulative risk of CBC also varied among the groups. Patients with BRCA1/2 mutations showed a 7.3-fold increased risk of CBC compared to the low-risk group (95% CI 4.11-13.0, p < 0.001). Interestingly, BRCAx patients also demonstrated a significantly higher risk of CBC (HR 2.77, 95% CI 1.76-4.35, p < 0.001). The prognostic importance of the BRCAx for CBC recurrence persisted after adjusting for the age and subtype, but became insignificant when the family history of breast cancer was adjusted.

CONCLUSION

Breast cancer patients who are at high risk of hereditary breast cancer but with wild-type BRCA 1/2 genes (BRCAx) have increased risk of developing contralateral breast cancer when compared to the low-risk patients. More careful surveillance and follow-up can be offered to these patients especially when they have family history of breast cancer.

BRCA mutation status and pathological characterization of breast cancer in Zhoushan Islands, China

OBJECTIVE

To investigate BRCA1/2 gene mutations and their relationship with clinicopathological features in patients with breast cancer in Zhoushan Islands.

METHODS

High-throughput whole-exome gene sequencing was used to detect BRCA1/2 mutations in 776 breast cancer patients in Zhoushan Islands.

RESULTS

The BRCA1/2 mutation rate of breast cancer patients in Zhoushan Islands was 4.38% (34/776). BRCA1 mutations were significantly correlated with age, molecular type, and family history of breast and ovarian cancers. BRCA2 mutations were most commonly found in invasive lobular carcinoma. Moreover, the BRCA2 mutation rate of cancers with molecular type luminal B (receptor protein-tyrosine kinase [HER2]-negative) was also relatively high.

CONCLUSION

The rate of BRCA1/2 mutations in breast cancer patients from Zhoushan Islands is approximately 4.38%, and BRCA1 mutation is related to age, molecular type, and family history of breast and ovarian cancers.

Frequency of germline pathogenic variants in breast cancer predisposition genes among young Turkish breast cancer patients

PURPOSE

One of the most important risk factors for hereditary breast and ovarian cancer is young age. We aim to report the frequency of pathogenic/likely pathogenic variants in breast cancer predisposing genes in young (≤ 40 years old) breast cancer patients who undergone 26-gene inherited cancer panel at our Breast Health Center.

METHODS

Medical records of breast cancer patients who were referred to genetic counseling based on NCCN criteria and were ≤ 40 years of age are reviewed. The frequency of germline pathogenic/likely pathogenic variants who undergone 26-gene inherited cancer panel was analyzed.

RESULTS

Among 414 breast cancer patients who were ≤ 40 years of age, 308 undergone 26-gene inherited cancer panel and 108 had next generation sequencing (NGS)-based BRCA 1 and 2 genetic testing. Median age was 35 (22-40), Family history in first degree relatives was present in 14% of patients. Forty-five percent of patients met one of the NCCN criteria for genetic testing, 41% of them met two criteria, and 14% of patients fulfilled ≥ 3 criteria. Seventy pathogenic/likely pathogenic variants (PV/LPV) were found in 65 (21%) patients. PV/LPs in BRCA genes and non-BRCA genes represented 53% and 44% of all PV/LPVs, accounting for 12% and 10% of patients in the study cohort respectively. Two PVs were present in 5 patients and eleven PVs were novel. The most common PVs were in BRCA 1 (n:18), BRCA 2 (n:19), ATM (n:7), CHEK2 (n:7) and TP53 (n:5) genes. Thirty-one percent of the patients with triple-negative tumors and 25% of the patients with hormone receptor-positive tumors had PV/LPVs with panel testing. Family history in first degree relatives (p = 0.029), the number of met NCCN criteria (p = 0.036) and axillary nodal involvement (p = 0.000) were more common in patients with PVs. When combined with patient group (n:106) who had only BRCA1 and 2 gene testing, 16% of Turkish breast cancer patients ≤ 40 years of age had PVs in BRCA genes.

CONCLUSION

One fifth of Turkish breast cancer patients ≤ 40 years of age had at least one PV/LPV in breast cancer predisposing genes with 26-gene inherited cancer panel. The frequency of PV/LPVs was higher in triple-negative young-onset patients compared to hormone receptor and Her-2 positive subtypes. Our findings regarding to frequency PV/LPVs in BRCA 1/2 and non-BRCA genes in young-onset breast cancer patients are in line with the literature.

Determination of genetic predisposition to early breast cancer in women of Kazakh ethnicity

Breast cancer (BC) is the most common type of cancer among women in Kazakhstan. To date, little data are available on the spectrum of genetic variation in Kazakh women with BC. We aimed to identify population-specific genetic markers associated with the risk of developing early-onset BC and test their association with clinical and prognostic factors. The study included 224 Kazakh women diagnosed with BC (≤40 age). Entire coding regions (>1700 exons) and the flanking noncoding regions of 94 cancer-associated genes were sequenced from blood DNA using MiSeq platform. We identified 38 unique pathogenic variants (PVs) in 13 different cancer-predisposing genes among 57 patients (25.4%), of which 6 variants were novel. In total, 12 of the 38 distinct PVs were detected recurrently, including BRCA1 c.5266dup, c.5278-2del, and c.2T>C, and BRCA2 c.9409dup and c.9253del that may be founder in this population. BRCA1 carriers were significantly more likely to develop triple-negative BC (OR = 6.61, 95% CI 2.44-17.91, p = 0.0002) and have family history of BC (OR = 3.17, 95% CI 1.14-8.76, p = 0.03) compared to non-carriers. This study allowed the identification of PVs specific to early-onset BC, which may be used as a foundation to develop regional expertise and diagnostic tools for early detection of BC in young Kazakh women.

Ethnic-specificity, evolution origin and deleteriousness of Asian BRCA variation revealed by over 7500 BRCA variants derived from Asian population

Pathogenic variation in BRCA1 and BRCA2 (BRCA) causes high risk of breast and ovarian cancer, and BRCA variation data are important markers for BRCA-related clinical cancer applications. However, comprehensive BRCA variation data are lacking from the Asian population despite its large population size, heterogenous genetic background and diversified living environment across the Asia continent. We performed a systematic study on BRCA variation in Asian population including extensive data mining, standardization, annotation and characterization. We identified 7587 BRCA variants from 685 592 Asian individuals in 40 Asia countries and regions, including 1762 clinically actionable pathogenic variants and 4915 functionally unknown variants (https://genemutation.fhs.um.edu.mo/Asian-BRCA/). We observed the highly ethnic-specific nature of Asian BRCA variants between Asian and non-Asian populations and within Asian populations, highlighting that the current European descendant population-based BRCA data is inadequate to reflect BRCA variation in the Asian population. We also provided archeological evidence for the evolutionary origin and arising time of Asian BRCA variation. We further provided structural-based evidence for the deleterious variants enriched within the functionally unknown Asian BRCA variants. The data from our study provide a current view of BRCA variation in the Asian population and a rich resource to guide clinical applications of BRCA-related cancer for the Asian population.

Racial and ethnic variation in BRCA1 and BRCA2 genetic test results among individuals referred for genetic counseling at a large urban comprehensive cancer center

PURPOSE

The prevalence of pathogenic variants in BRCA1 and BRCA2 in populations other than Ashkenazi Jewish (AJ) is not well defined. We describe the racial and ethnic-specific prevalence of BRCA1/2 pathogenic variants and variants of uncertain significance (VUS) among individuals referred for genetic testing in a large urban comprehensive cancer center over a 20-year period.

METHODS

The population included 3,537 unrelated individuals who underwent genetic testing from January 1999 to October 2019 at the Karmanos Cancer Institute. We estimated the prevalence of pathogenic variants and VUS and evaluated associations with race and ethnicity for African American (AA), Arab, AJ and Hispanic individuals compared to Non-Hispanic Whites (NHW). We used multivariable models to adjust for other predictors of pathogenic variants. We also reported the most common pathogenic variants by racial and ethnic group.

RESULTS

The racial and ethnic breakdown of our population was: NHW (68.9%), AA (20.3%), AJ (2.5%), Arab (2.2%), Hispanic (1.0%), Asian Pacific Islander, Native American/Alaskan Native (4.7%), and < 1% unknown. The overall prevalence of pathogenic variants in BRCA1/2 was 8.9% and the prevalence of VUS was 5.6%. Compared to NHW, there were no racial or ethnic differences in the rate of pathogenic variants. However, AA individuals were more likely to have VUS in BRCA1 (adjusted OR 2.43, 95% CI 1.38-4.28) and AJ were more likely to have VUS in BRCA2 (adjusted OR 3.50, 95% CI 1.61-6.58).

CONCLUSION

These results suggest the continued need for genetic testing and variant reclassification for individuals of all racial and ethnic groups.

Mutations of TP53 and genes related to homologous recombination repair in breast cancer with germline BRCA1/2 mutations

BACKGROUND

Germline mutations of breast cancer susceptibility gene BRCA1 and BRCA2 (gBRCA1/2) are associated with elevated risk of breast cancer in young women in Asia. BRCA1 and BRCA2 proteins contribute to genomic stability through homologous recombination (HR)-mediated double-strand DNA break repair in cooperation with other HR-related proteins. In this study, we analyzed the targeted sequencing data of Korean breast cancer patients with gBRCA1/2 mutations to investigate the alterations in HR-related genes and their clinical implications.

MATERIALS AND METHODS

Data of the breast cancer patients with pathogenic gBRCA1/2 mutations and qualified targeted next-generation sequencing, SNUH FiRST cancer panel, were analyzed. Single nucleotide polymorphisms, small insertions, and deletions were analyzed with functional annotations using ANNOVAR. HR-related genes were defined as ABL1, ATM, ATR, BARD1, BRCA1, BRCA2, CDKN1A, CDKN2A, CHEK1, CHEK2, FANCA, FANCD2, FANCG, FANCI, FANCL, KDR, MUTYH, PALB2, POLE, POLQ, RAD50, RAD51, RAD51D, RAD54L, and TP53. Mismatch-repair genes were MLH1, MSH2, and MSH6. Clinical data were analyzed with cox proportional hazard models and survival analyses.

RESULTS

Fifty-five Korean breast cancer patients with known gBRCA1/2 mutations and qualified targeted NGS data were analyzed. Ethnically distinct mutations in gBRCA1/2 genes were noted, with higher frequencies of Val1833Ser (14.8%), Glu1210Arg (11.1%), and Tyr130Ter (11.1%) in gBRCA1 and Arg2494Ter (25.0%) and Lys467Ter (14.3%) in gBRCA2. Considering subtypes, gBRCA1 mutations were associated with triple-negative breast cancers (TNBC), while gBRCA2 mutations were more likely hormone receptor-positive breast cancers. At least one missense mutation of HR-related genes was observed in 44 cases (80.0%). The most frequently co-mutated gene was TP53 (38.1%). In patients with gBRCA1/2 mutations, however, genetic variations of TP53 occurred in locations different from the known hotspots of those with sporadic breast cancers. The patients with both gBRCA1/2 and TP53 mutations were more likely to have TNBC, high Ki-67 values, and increased genetic mutations, especially of HR-related genes. Survival benefit was observed in the TP53 mutants of patients with gBRCA2 mutations, compared to those with TP53 wild types.

CONCLUSION

Our study showed genetic heterogeneity of breast cancer patients with gBRCA1 and gBRCA2 mutations in the Korean populations. Further studies on precision medicine are needed for tailored treatments of patients with genetic diversity among different ethnic groups.

BRCA2 gene mutation in cancer

Breast cancer susceptibility gene 2 (BRCA2) is the main gene associated with hereditary breast cancers. However, a mutation in BRCA2 has also been found in other tumors, such as ovarian, pancreatic, thyroid, gastric, laryngeal, and prostate cancers. In this review, we discuss the biological functions of BRCA2 and the role of BRCA2 mutations in tumor progression and therapy.

Clinical application of artificial neural network (ANN) modeling to predict BRCA1/2 germline deleterious variants in Chinese bilateral primary breast cancer patients

BACKGROUND

Bilateral breast cancer (BBC), as well as ovarian cancer, are significantly associated with germline deleterious variants in BRCA1/2, while BRCA1/2 germline deleterious variants carriers can exquisitely benefit from poly (ADP-ribose) polymerase (PARP) inhibitors. However, formal genetic testing could not be carried out for all patients due to extensive use of healthcare resources, which in turn results in high medical costs. To date, existing BRCA1/2 deleterious variants prediction models have been developed in women of European or other descent who are quite genetically different from Asian population. Therefore, there is an urgent clinical need for tools to predict the frequency of BRCA1/2 deleterious variants in Asian BBC patients balancing the increased demand for and cost of cancer genetics services.

METHODS

The entire coding region of BRCA1/2 was screened for the presence of germline deleterious variants by the next generation sequencing in 123 Chinese BBC patients. Chi-square test, univariate and multivariate logistic regression were used to assess the relationship between BRCA1/2 germline deleterious variants and clinicopathological characteristics. The R software was utilized to develop artificial neural network (ANN) and nomogram modeling for BRCA1/2 germline deleterious variants prediction.

RESULTS

Among 123 BBC patients, we identified a total of 20 deleterious variants in BRCA1 (8; 6.5%) and BRCA2 (12; 9.8%). c.5485del in BRCA1 is novel frameshift deleterious variant. Deleterious variants carriers were younger at first diagnosis (P = 0.0003), with longer interval between two tumors (P = 0.015), at least one medullary carcinoma (P = 0.001), and more likely to be hormone receptor negative (P = 0.006) and HER2 negative (P = 0.001). Area under the receiver operating characteristic curve was 0.903 in ANN and 0.828 in nomogram modeling individually (P = 0.02).

CONCLUSION

This study shows the spectrum of the BRCA1/2 germline deleterious variants in Chinese BBC patients and indicates that the ANN can accurately predict BRCA deleterious variants than conventional statistical linear approach, which confirms the BRCA1/2 deleterious variants carriers at the lowest costs without adding any additional examinations.

Prevalence of BRCA1 and BRCA2 pathogenic variants in 8627 unselected patients with breast cancer: stratification of age at diagnosis, family history and molecular subtype

PURPOSE

Comprehensively analyzing the prevalence of BRCA1/2 germline pathogenic variants (PVs) in a large cohort of unselected Chinese patients with breast cancer has great clinical importance.

METHODS

Germline pathogenic variants in full-length BRCA1/2 genes were determined through next-generation sequencing and/or Sanger sequencing assays in 8627 unselected Chinese patients with breast cancer who were treated at the Breast Center of Peking University Cancer Hospital. The prevalence of BRCA1/2 PVs was further stratified by age at diagnosis, family history of cancer and molecular subtype.

RESULTS

We found that the overall prevalence of BRCA1/2 PVs was 6.0% in the entire cohort, 2.4% in BRCA1 and 3.7% in BRCA2. The prevalence of BRCA1/2 PVs in patients with early-onset breast cancer (age at diagnosis ≤ 40 years) was significantly higher than that in patients over the age of 40 (9.7% vs. 5.1%). The prevalence rates of BRCA1/2 PVs in patients with a family history of breast, ovarian, pancreatic, and prostate cancer were 19.5%, 39.0%, 11.1%, and 12.8%, respectively. Moreover, the number of relatives affected by breast cancer was associated with a higher prevalence of BRCA1/2 PVs. Molecular subtypes were associated with the prevalence of BRCA1/2 PVs. Patients with the triple-negative phenotype had the highest prevalence of BRCA1/2 PVs (13.3%) among the three molecular groups, followed by the HR + and HER2- group (5.9%), and the lowest was in the HER2 + group (2.5%).

CONCLUSION

Our study provides the most comprehensive information to date on the prevalence of BRCA1/2 PVs in unselected Chinese patients with breast cancer.

Characteristics of breast cancer patients tested for germline BRCA1/2 mutations by next-generation sequencing in Ramathibodi Hospital, Mahidol University

INTRODUCTION

Germline mutations in BRCA1/2 are the most common cause of hereditary breast and ovarian cancer (HBOC) syndrome. Few studies published during the past decade reported the prevalence of germline BRCA mutations in Asian patients with breast cancer. We aimed to assess the prevalence and characteristics of Thai patients with breast cancer with germline BRCA1/2 mutations.

METHODS

We retrospectively reviewed all breast cancer patients who were tested for germline BRCA1/2 mutations during 2014-2018. BRCA mutations were detected using next-generation sequencing and confirmed using Sanger sequencing. We analyzed the characteristics of patients with or without BRCA mutations. Disease-free survival (DFS) and the associated factors were determined.

RESULTS

Among 67 patients, 12 (18%) were BRCA1/2 carriers (6 each), 4 (6%) harbored variants of uncertain significance, and 51 (76%) were non-carriers. We discovered two novel BRCA2 frameshift mutations (c.2380delA and c.8855dupT). Mean ages at breast cancer diagnosis of BRCA1, BRCA2, and non-carriers were 39.8, 46.2, and 42.0 years, respectively. The 12 tumors of BRCA carriers were mainly the luminal-B subtype. Two of these tumors were HER2-positive luminal-B, and the triple-negative subtype was not detected. After adjusting for stages and luminal subtypes, BRCA carriers experienced worse 3-year DFS than non-carriers (81.5% vs. 90.3%, HR 2.04 [0.64-6.49], p = .229). The stage at diagnosis was the sole factor significantly associated with 3-year DFS (100%, 84.8%, and 72.7%; stages I, II, and III, respectively).

CONCLUSION

Thai patients with breast cancer with BRCA1/2 mutations were mainly the luminal-B subtypes with worse prognosis than those without mutations.

Spectrum of germline pathogenic variants using a targeted next generation sequencing panel and genotype-phenotype correlations in patients with suspected hereditary breast cancer at an academic medical centre in Pakistan

BACKGROUND

Breast cancer is the most common malignancy in women, affecting over 1.5 million women every year, which accounts for the highest number of cancer-related deaths in women globally. Hereditary breast cancer (HBC), an important subset of breast cancer, accounts for 5-10% of total cases. However, in Low Middle-Income Countries (LMICs), the population-specific risk of HBC in different ethnicities and the correlation with certain clinical characteristics remain unexplored.

METHODS

Retrospective chart review of patients who visited the HBC clinic and proceeded with multi-gene panel testing from May 2017 to April 2020. Descriptive and inferential statistics were used to analyze clinical characteristics of patients. Fisher's exact, Pearson's chi-squared tests and Logistic regression analysis were used for categorical variables and Wilcoxon rank-sum test were used for quantitative variables. For comparison between two independent groups, Mann-Whitney test was performed. Results were considered significant at a p value of < 0.05.

RESULTS

Out of 273 patients, 22% tested positive, 37% had a VUS and 41% had a negative genetic test result. Fifty-five percent of the positive patients had pathogenic variants in either BRCA1 or BRCA2, while the remaining positive results were attributed to other genes. Patients with a positive result had a younger age at diagnosis compared to those having a VUS and a negative result; median age 37.5 years, IQR (Interquartile range) (31.5-48). Additionally, patients with triple negative breast cancer (TNBC) were almost 3 times more likely to have a positive result (OR = 2.79, CI = 1.42-5.48 p = 0.003). Of all patients with positive results, 25% of patients had a negative family history of breast and/or related cancers.

CONCLUSIONS

In our HBC clinic, we observed that our rate of positive results is comparable, yet at the higher end of the range which is reported in other populations. The importance of expanded, multi-gene panel testing is highlighted by the fact that almost half of the patients had pathogenic or likely pathogenic variants in genes other than BRCA1/2, and that our test positivity rate would have only been 12.8% if only BRCA1/2 testing was done. As the database expands and protocol-driven referrals are made across the country, our insight about the genetic architecture of HBC in our population will continue to increase.

Differences in Willingness to Undergo BRCA1/2 Testing and Risk Reducing Surgery among the General Public, Cancer Patients, and Healthcare Professionals: A Large Population-Based Survey

We aimed to understand the decision-making process related to the willingness to undergo BRCA1/2 genetic testing, risk-reducing salpingo-oophorectomy (RRSO), or risk-reducing mastectomy (RRM) among the general public, cancer patients, and healthcare professionals in South Korea. In total, 3444 individuals (1496 from the general public, 1500 cancer patients, 108 clinicians, and 340 researchers) completed a survey addressing genetic testing and related risk management options in a hypothetical scenario. Differences in intent and associated factors for undergoing the above procedures or sharing test results were analyzed. Overall, 67% of participants were willing to undergo BRCA1/2 testing, with proportions of the general public (58%), cancer patients (70%), clinicians (88%), and researchers (90%). The willingness to undergo RRSO was highest among clinicians (58%), followed by among patients (38%), the general public (33%), and researchers (32%) (p < 0.001). Gender, age, education level, and household income were associated with willingness to undergo genetic testing, RRM, and RRSO (p < 0.05). The intent for undergo genetic testing, RRM, and RRSO were affected by many factors. Finally, 69% of the general public intended to share information with family, while this percentage was 92%, 91%, and 94% for patients, clinicians, and researchers, respectively (p < 0.05). These results highlight the requirement for developing targeted educational materials and counseling strategies for facilitating informed decision making.

Identification of the most common BRCA alterations through analysis of germline mutation databases: Is droplet digital PCR an additional strategy for the assessment of such alterations in breast and ovarian cancer families?

Breast and ovarian cancer represent two of the most common tumor types in females worldwide. Over the years, several non‑modifiable and modifiable risk factors have been associated with the onset and progression of these tumors, including age, reproductive factors, ethnicity, socioeconomic status and lifestyle factors, as well as family history and genetic factors. Of note, BRCA1 and BRCA2 are two tumor suppressor genes with a key role in DNA repair processes, whose mutations may induce genomic instability and increase the risk of cancer development. Specifically, females with a family history of breast or ovarian cancer harboring BRCA1/2 germline mutations have a 60‑70% increased risk of developing breast cancer and a 15‑40% increased risk for ovarian cancer. Different databases have collected the most frequent germline mutations affecting BRCA1/2. Through the analysis of such databases, it is possible to identify frequent hotspot mutations that may be analyzed with next‑generation sequencing (NGS) and novel innovative strategies. In this context, NGS remains the gold standard method for the assessment of BRCA1/2 mutations, while novel techniques, including droplet digital PCR (ddPCR), may improve the sensitivity to identify such mutations in the hereditary forms of breast and ovarian cancer. On these bases, the present study aimed to provide an update of the current knowledge on the frequency of BRCA1/2 mutations and cancer susceptibility, focusing on the diagnostic potential of the most recent methods, such as ddPCR.

Chasing the origin of 23 recurrent BRCA1 mutations in Pakistani breast and ovarian cancer patients

Knowledge of population specific BRCA1/2 founder mutations provides a valuable and cost-effective genetic testing strategy. Twenty-three recurrent BRCA1 mutations have been identified previously in 100 Pakistani breast and/or ovarian cancer families. These accounted for 72.5% of all BRCA1 mutations identified. In this study, we investigated whether these mutations (identified in ≥2 unrelated patients) have a common ancestral origin and estimated the ages of these mutations. Haplotype analyses were performed in 188 individuals (100 index patients, 88 relatives) from Pakistani breast/ovarian cancer families, all harboring one of the 23 recurrent BRCA1 mutations, and 90 healthy controls. Six microsatellite markers (D17S800, D17S1801, D17S855, D17S1322, D17S1323, and D17S951) were analyzed. Mutation ages were estimated using DMLE+2.3 software. An identical haplotype of different length was found in families harboring the same BRCA1 mutation and suggested founder effects for all 23 mutations. Sixteen founder mutations were ethnicity-specific: 15 occurred in families of Punjabi background and one in a family of Pathan background. The remaining seven mutations occurred in families with two ethnic backgrounds. All BRCA1 founder mutations were estimated to have arisen approximately 147 to 159 generations ago. Our findings suggest founder effects for all 23 recurrent BRCA1 mutations. This knowledge allows the design and development of a cost effective local genetic testing strategy in Pakistan.

Spectrum of BRCA1/2 Mutations in Romanian Breast and Ovarian Cancer Patients

Background: About 10,000 women are diagnosed with breast cancer and about 2000 women are diagnosed with ovarian cancer each year in Romania. There is an insufficient number of genetic studies in the Romanian population to identify patients at high risk of inherited breast and ovarian cancer. Methods: We evaluated 250 women of Romanian ethnicity with BC and 240 women of Romanian ethnicity with ovarian cancer for the presence of damaging germline mutations in breast cancer genes 1 and 2 (BRCA1 and BRCA2, respectively) using Next-Generation Sequencing (NGS) technology. Results: Of the 250 breast cancer patients, 47 carried a disease-predisposing BRCA mutation (30 patients (63.83%) with a BRCA1 mutation and 17 patients (36.17%) with a BRCA2 mutation). Of the 240 ovarian cancer patients, 60 carried a BRCA mutation (43 patients (72%) with a BRCA1 mutation and 17 patients (28%) with a BRCA2 mutation). In the BRCA1 gene, we identified 18 variants (4 in both patient groups (ovarian and breast cancer patients), 1 mutation variant in the BC patient group, and 13 mutation variants in the ovarian cancer patient group). In the BRCA2 gene, we identified 17 variants (1 variant in both ovarian and breast cancer patients, 6 distinct variants in BC patients, and 10 distinct variants in ovarian cancer patients). The prevailing mutation variants identified were c.3607C>T (BRCA1) (18 cases) followed by c.5266dupC (BRCA1) (17 cases) and c.9371A>T (BRCA2) (12 cases). The most prevalent mutation, BRCA1 c.3607C>T, which is less common in the Romanian population, was mainly associated with triple-negative BC and ovarian serous adenocarcinoma. Conclusion: The results of our analysis may help to establish specific variants of BRCA mutations in the Romanian population and identify individuals at high risk of hereditary breast and ovarian cancer syndrome by genetic testing.

Awareness and Availability of Routine Germline BRCA1/2 Mutation Testing in Patients with Advanced Breast Cancer in Germany

Introduction

Diagnostic testing of germline mutations in breast cancer susceptibility genes 1 or 2 (gBRCA1/2) in patients with human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer (ABC; locally advanced or metastatic breast cancer) is necessary to assess eligibility for poly(ADP-ribose) polymerase inhibitors (PARPi). We investigated awareness, clinical practice, and the availability of gBRCA1/2 mutation testing in the German outpatient oncology setting.

Methods

Office-based oncologists completed a 23-item online survey. Responses were evaluated collectively and by center type.

Results

Of 50 oncologists, 33 and 17 were medical and gynecological oncologists, respectively. Oncologists treated a median of 65 (range 14-350) patients with ABC per year. The strongest decision factors to initiate gBRCA1/2 mutation testing were: patient's known family history of gBRCA1/2 mutation-related cancer(s), guideline recommendations, and triple-negative breast cancer (TNBC). In routine practice, 86% of oncologists tested for gBRCA1/2 mutations. Most oncologists (76-98%) reported testing patients with a known family history of gBRCA1/2 mutation-related cancer(s) irrespective of receptor status. For unknown family history, 92% of oncologists reported testing patients with advanced TNBC versus 30% for HR+/HER2- ABC. Oncologists (66%) rated the awareness of therapeutic relevance of gBRCA1/2 mutation testing for targeted treatment selection as good to satisfactory; 22% rated awareness as poor to in-sufficient.

Conclusion

Diagnostic gBRCA1/2 mutation testing in patients with HER2- ABC is available and routinely performed in Germany's outpatient oncology setting. However, specific patient subgroups were not routinely tested despite therapeutic indications. Given PARPi availability, opportunities exist to improve testing rates especially for patients with HR+/HER2- ABC without a known family history of gBRCA1/2 mutation-related cancer(s).

Germline sequence variants contributing to cancer susceptibility in South African breast cancer patients of African ancestry

Since the discovery of the breast cancer susceptibility genes, BRCA1 and BRCA2, various other genes conferring an increased risk for breast cancer have been identified. Studies to evaluate sequence variants in cancer predisposition genes among women of African ancestry are limited and mostly focused on BRCA1 and BRCA2. To characterize germline sequence variants in cancer susceptibility genes, we analysed a cohort of 165 South African women of self-identified African ancestry diagnosed with breast cancer, who were unselected for family history of cancer. With the exception of four cases, all others were previously investigated for BRCA1 and BRCA2 deleterious variants, and were negative for pathogenic variants. We utilized the Illumina TruSight cancer panel for targeted sequencing of 94 cancer susceptibility genes. A total of 3.6% of patients carried a pathogenic/likely pathogenic variant in a known breast cancer susceptibility gene: 1.2% in BRCA1, 0.6% in each of BRCA2, ATM, CHEK2 and PALB, none of whom had any family history of breast cancer. The mean age of patients who carried deleterious variant in BRCA1/BRCA2 was 39 years and 8 months compared to 47 years and 3 months among women who carried a deleterious variant in other breast cancer susceptibility genes.

Hereditary breast and ovarian cancer (HBOC): review of its molecular characteristics, screening, treatment, and prognosis

Breast cancer is a common cancer affecting a large number of patients. Notably, 5-10% of all breast cancer patients are genetically predisposed to cancers. Although the most common breast cancer susceptibility genes are BRCA1 and BRCA2, which are also associated with the risk of developing ovarian and pancreatic cancer, advances in next-generation sequencing (NGS) analysis technology enabled the discovery of several non-BRCA genes responsible for breast and ovarian cancers. Studies on hereditary breast and ovarian cancer (HBOC) involve not only determining the predisposition to developing cancer, but also considering the current treatment for breast cancer, prevention of next cancer, risk diagnosis, and adoption of protective measures for relatives. We present a comprehensive review of HBOC, which will be a useful resource in the clinical setting. Many hereditary tumors, including HBOC, are syndromes characterized by the development of different types of cancer in succession. Taking advantage of knowing predisposition of susceptibility to cancer, it is important to continue and update cancer management protocols, which includes the adoption of preventive measures, countermeasures, and treatments, to accurately assess and prevent the impact of cancer on the quality of life of the next generation of patients.

Clinicopathological Characterization of Double Heterozygosity for BRCA1 and BRCA2 Variants in Korean Breast Cancer Patients

Purpose

Double heterozygosity (DH) for BRCA1 and BRCA2 variant is very rare with only a few cases reported, and most those in Caucasians. In this article, we present seven unrelated cases of DH for BRCA1/2 identified from a single institution in Korea, and describe the characteristics and phenotype of DH individuals compared to those with a single BRCA variant.

Materials and Methods

This study included 27,678 patients diagnosed with breast cancer and surgically treated at Samsung Medical Center (SMC) between January 2008 and June 2020. In total, 4,215 high-risk breast cancer patients were tested for the BRCA1/2 genes, and electronic medical records from 456 cases with pathogenic/likely pathogenic variants were reviewed.

Results

A younger mean age at diagnosis was associated with DH than a single variant of BRCA1/2. More triple-negative breast cancer and higher nuclear and histologic grade cancer occurred with DH than BRCA2 variant. All seven cases of DH were unrelated, and their mutation combinations were different. There were no Ashkenazi founder variants detected.

Conclusion

We suggest that patients with DH for BRCA1/2 variants develop breast cancer at a younger age, but the histopathologic features are similar to those of BRCA1.

Retrospective Analysis of Clinicopathological Features and Familial Cancer History of Synchronous Bilateral Breast Cancer

Bilateral breast cancer is a strong predictor of BRCA 1/2 mutation and hence one criterion indicated for hereditary genetic testing. The purpose of this study is to assess the characteristics of synchronous bilateral breast cancer (SBBC) and its association with personal and familial cancer traits. Patients diagnosed with SBBC in our institute between 1992 and 2018 were retrospectively reviewed, and the information of clinicopathological features, personal and family cancer history were analyzed. Of the 307 SBBCs enrolled, the growing case number generally aligned with the regional breast cancer incidence after the era of population-based mammography screening. SBBC patients had similar cancer stages but worse survival outcomes than those in the standard scenario. A total of 42.0% had mixed pathological diagnoses, and 22.8% had discordant immunohistochemistry (IHC) subtypes from both sides, which contributed to treatment challenges. The correlation of SBBC with hereditary breast and ovarian cancer (HBOC) syndrome was strongly implied, as 20.7% of our SBBC patients with known familial cancer histories had HOBC-related familial cancers (breast, ovarian, or prostate cancers). These findings highlight the need for genetic counseling and germline mutation testing in patients with SBBC. Early PARP inhibitor treatment should also be considered in high-risk cases for outcome improvement.

A report on the 73th Annual Congress of the Japan Society of Obstetrics and Gynecology International Workshop for Junior Fellows: Risk-reducing surgery for hereditary breast and ovarian cancer

At the 73rd Annual Congress of the Japan Society of Obstetrics and Gynecology, young doctors from Japan and South Korea made presentations on the present condition of risk-reducing surgery for hereditary breast and ovarian cancer (RRSO) in their respective country. RRSO was insured in Japan in April 2020, whereas in South Korea, it was insured 7 years earlier in 2013. In Japan, certification criteria have been set for facilities that perform RRSO, and the number of facilities is increasing, but regional disparities still exist in its distribution. The number of gBRCA1/2 testing facilities is larger, and the cost is more affordable in South Korea than in Japan. Additionally, South Korea provides genetic counseling to a wider range of relatives compared to Japan. In the future, as the indications for the gBRCA1/2 test have expanded as a companion diagnostic for the use of PARP inhibitors, it is expected that the number of candidates for the gBRCA1/2 mutation test and RRSO will increase in Japan. It is important to increase the number of BRCA tests while maintaining the quality of genetic counseling in order to provide adequate information on BRCA mutations and RRSO for patients to support their decision. For the development of hereditary breast and ovarian cancer (HBOC) medical care, it is necessary to publish a nationwide database in Japan and continue to analyze and discuss the data based on the results.

Association of Family History with the Development of Breast Cancer: A Cohort Study of 129,374 Women in KoGES Data

Background: Breast cancer is the most common cancer among women. The Korean Genome and Epidemiology Study (KoGES) is a large cohort study that is available to the public. Using this large cohort study, we aimed to unravel the relationship between breast cancer development and a family history of breast cancer in Korea. Methods: This cohort study relied on data from the KoGES from 2001 through 2013. A total of 211,725 participants were screened. Of these, 129,374 women were evaluated. They were divided into two groups, including participants with and without breast cancer. A logistic regression model was used to retrospectively analyze the odds ratio of breast cancer history in families of women with and without breast cancer. Results: Of 129,374 women, 981 had breast cancer. The breast cancer group had more mothers and siblings with histories of breast cancer (p < 0.001). A history of breast cancer in the participant’s mother resulted in an odds ratio of 3.12 (1.75–5.59), and a history of breast cancer in the participant’s sibling resulted in an odds ratio of 2.63 (1.85–3.74). There was no interaction between the history of maternal breast cancer and the history of sibling breast cancer. Based on the subgroup analysis, family history was a stronger factor in premenopausal women than in menopausal and postmenopausal women. Conclusions: A family history of breast cancer is a significant risk factor for breast cancer in Korea. Premenopausal women with a maternal history of breast cancer are of particular concern. Intensive screening and risk-reducing strategies should be considered for this vulnerable subpopulation.

Using a Tailored Digital Health Intervention for Family Communication and Cascade Genetic Testing in Swiss and Korean Families With Hereditary Breast and Ovarian Cancer: Protocol for the DIALOGUE Study

Background

In hereditary breast and ovarian cancer (HBOC), family communication of genetic test results is essential for cascade genetic screening, that is, identifying and testing blood relatives of known mutation carriers to determine whether they also carry the pathogenic variant, and to propose preventive and clinical management options. However, up to 50% of blood relatives are unaware of relevant genetic information, suggesting that potential benefits of genetic testing are not communicated effectively within family networks. Technology can facilitate communication and genetic education within HBOC families.

Objective

The aims of this study are to develop the K-CASCADE (Korean–Cancer Predisposition Cascade Genetic Testing) cohort in Korea by expanding an infrastructure developed by the CASCADE (Cancer Predisposition Cascade Genetic Testing) Consortium in Switzerland; develop a digital health intervention to support the communication of cancer predisposition for Swiss and Korean HBOC families, based on linguistic and cultural adaptation of the Family Gene Toolkit; evaluate its efficacy on primary (family communication of genetic results and cascade testing) and secondary (psychological distress, genetic literacy, active coping, and decision making) outcomes; and explore its translatability using the reach, effectiveness, adoption, implementation, and maintenance framework.

Methods

The digital health intervention will be available in French, German, Italian, Korean, and English and can be accessed via the web, mobile phone, or tablet (ie, device-agnostic). K-CASCADE cohort of Korean HBOC mutation carriers and relatives will be based on the CASCADE infrastructure. Narrative data collected through individual interviews or mini focus groups from 20 to 24 HBOC family members per linguistic region and 6-10 health care providers involved in genetic services will identify the local cultures and context, and inform the content of the tailored messages. The efficacy of the digital health intervention against a comparison website will be assessed in a randomized trial with 104 HBOC mutation carriers (52 in each study arm). The translatability of the digital health intervention will be assessed using survey data collected from HBOC families and health care providers.

Results

Funding was received in October 2019. It is projected that data collection will be completed by January 2023 and results will be published in fall 2023.

Conclusions

This study addresses the continuum of translational research, from developing an international research infrastructure and adapting an existing digital health intervention to testing its efficacy in a randomized controlled trial and exploring its translatability using an established framework. Adapting existing interventions, rather than developing new ones, takes advantage of previous valid experiences without duplicating efforts. Culturally sensitive web-based interventions that enhance family communication and understanding of genetic cancer risk are timely. This collaboration creates a research infrastructure between Switzerland and Korea that can be scaled up to cover other hereditary cancer syndromes.

Trial Registration

ClinicalTrials.gov NCT04214210; https://clinicaltrials.gov/ct2/show/NCT04214210 and CRiS KCT0005643; https://cris.nih.go.kr/cris/

International Registered Report Identifier (IRRID)

PRR1-10.2196/26264

Clinicopathological Features of BRCA1/2 Mutation-Positive Breast Cancer

PURPOSE

The BRCA1/2 gene is the most well-known and studied gene associated with hereditary breast cancer. BRCA1/2 genetic testing is widely performed in high-risk patients of hereditary breast cancer in Korea. This study aimed to investigate the clinicopathological characteristics of BRCA1/2 mutation-positive breast cancer patients.

METHODS

The clinical data of 188 Korean breast cancer patients who underwent genetic testing of BRCA1/2 mutation between March 2015 and February 2020 at Pusan National University Yangsan Hospital were retrospectively reviewed. The characteristics of breast cancer according to the expression of BRCA1 and BRCA2 mutations were analyzed using the Health Insurance Review and Assessment Service guideline criteria and other clinicopathological factors.

RESULTS

The factor associated with BRCA1/2 gene expression was cancer stage, and mutation expression was significantly decreased in stage I compared to stage 0 (p = 0.033; odds ratio [OR], 0.169; 95% confidence interval [CI], 0.033-0.867), and there was a tendency to increase in stage II (p = 0.780; OR, 1.150; 95% CI, 0.432-3.064). BRCA1 was significantly associated with triple-negative breast cancer (TNBC) (p = 0.004; OR, 5.887; 95% CI, 1.778-19.498). Gene expression of BRCA2 was significantly reduced under 40 years of age (p = 0.040; OR, 0.198; 95% CI, 0.042-0.930). There was no difference in disease-free survival (p = 0.900) and overall survival (p = 0.733) between the BRCA1/2 mutation-positive and -negative groups.

CONCLUSION

In this study, the clinicopathological characteristics of breast cancer patients with BRCA1/2 gene mutations were identified. BRCA1 gene expression was highly correlated with TNBC. BRCA1/2 mutation did not have a poor prognosis regarding recurrence and death.

A Population-Based Analysis of BRCA1/2 Genes and Associated Breast and Ovarian Cancer Risk in Korean Patients: A Multicenter Cohort Study

Simple Summary

Although it has been suggested that cancer risk and genetic variation vary by population, there is still a lack of research on non-European populations. In this study, we applied Korean patients as a model to find out the way to conduct BRCA1/2-related clinical studies in non-European populations who do not have as much clinical data as Europeans. The BRCA1/2 variants were classified following the 2015 ACMG standards/guidelines and using a multifactorial probability-based approach. To estimate the additional sample numbers needed to resolve BRCA1/2 unclassified status, we applied a simulation analysis considering population-specific clinical characteristics. In addition, we estimated the risks of breast or ovarian cancer for BRCA1/2 carriers by mutation regions. Data from this study reveal that BRCA1/2 variants in the non-European population are highly specific; therefore, population-specific study is essential for clinical application of treatment or prevention for breast or ovarian cancer.

Abstract

In this study, we performed a comprehensive analysis of BRCA1/2 variants and associated cancer risk in Korean patients considering two aspects: variants of uncertain significance (VUS) and pathogenic or likely pathogenic variants (PLPVs) in BRCA1 and BRCA2. This study included 5433 Korean participants who were tested for BRCA1/2 genes. The BRCA1/2 variants were classified following the standards/guidelines for interpretation of genetic variants and using a multifactorial probability-based approach. In Korea, 15.8% of participants had BRCA1 or BRCA2 PLPVs. To estimate the additional sample numbers needed to resolve unclassified status, we applied a simulation analysis. The simulation study for VUS showed that the smaller the number of samples, the more the posterior probability was affected by the prior probability; in addition, more samples for BRCA2 VUS than those of BRCA1 VUS were required to resolve the unclassified status, and the presence of clinical information associated with their VUS was an important factor. The cumulative lifetime breast cancer risk was 59.1% (95% CI: 44.1–73.6%) for BRCA1 and 58.3% (95% CI: 43.2–73.0%) for BRCA2 carriers. The cumulative lifetime ovarian cancer risk was estimated to be 36.9% (95% CI: 23.4–53.9%) for BRCA1 and 14.9% (95% CI: 7.4–28.5%) for BRCA2 carriers.

Analysis of BRCA1/2 variants of unknown significance in the prospective Korean Hereditary Breast Cancer study

Genetic testing for BRCA1 and BRCA2 is crucial in diagnosing hereditary breast and ovarian cancer syndromes and has increased with the development of multigene panel tests. However, results classified as variants of uncertain significance (VUS) present challenges to clinicians in attempting to choose an appropriate management plans. We reviewed a total of 676 breast cancer patients included in the Korean Hereditary Breast Cancer (KOHBRA) study with a VUS on BRCA mutation tests between November 2007 and April 2013. These results were compared to the ClinVar database. We calculated the incidence and odds ratios for these variants using the Korean Reference Genome Database. A total of 58 and 91 distinct VUS in BRCA1 and BRCA2 were identified in the KOHBRA study (comprising 278 and 453 patients, respectively). A total of 27 variants in the KOHBRA study were not registered in the Single Nucleotide Polymorphism database. Among BRCA1 VUSs, 20 were reclassified as benign or likely benign, four were reclassified as pathogenic or likely pathogenic, and eight remained as VUSs according to the ClinVar database. Of the BRCA2 VUSs, 25 were reclassified as benign or likely benign, two were reclassified as pathogenic or likely pathogenic, and 33 remained as VUS according to the ClinVar database. There were 12 variants with conflicting interpretations of pathogenicity for BRCA1 and 18 for BRCA2. Among them, p.Leu1780Pro showed a particularly high odds ratio. Six pathogenic variants and one conflicting variant identified using ClinVar could be reclassified as pathogenic variants in this study. Using updated ClinVar information and calculating odds ratios can be helpful when reclassifying VUSs in BRCA1/2.

A comprehensive reference for BRCA1/2 genes pathogenic variants in Iran: published, unpublished and novel

BRCA1 and BRCA2 are two prominent genes that account for about 20-40% of inherited breast cancer. Mutations in these genes are often associated with clustering of especially early-onset cancers in the family. The spectrum of BRCA variants showed a significant difference between geographic regions and ethnicities. The frequency and spectrum of BRCA mutations in Iran, a country in southwest Asia, have not yet been thoroughly studied. Here, for the first time, all published and not published BRCA pathogenic variants are presented. Among 1040 high risk families (1258 cases) which were detected, 116 families were found to carry pathogenic variants in either BRCA1 or BRCA2. Altogether 89 distinct types of pathogenic variants have been detected in Iran, including 41 in BRCA1 and 48 in BRCA2. 16 out of 89 mutations had not been previously reported in Iran and are presented for the first time in this article, among which 4 mutations are novel worldwide. 20% of families had one of the seven most commonly observed mutations, including c.81-1G > C, c.66_67delAG, c.4609C>T, c.1568delT, c.1961delA, in BRCA1 and: c.3751_3752insA, c.8585dupT in BRCA2. Combining the data from published articles and our study which has not been published before, a comprehensive table is created as a reference for entire BRCA pathogenic variants and their frequencies in Iran.

Prevalence and reclassification of BRCA1 and BRCA2 variants in a large, unselected Chinese Han breast cancer cohort

Accurate interpretation of BRCA1/2 variants is critical for risk assessment and precise treatment of breast cancer (BC). Hence, the establishment of an ethnicity-based BRCA1/2 variant database of the Chinese population is of paramount importance. In this study, panel-based sequencing served to detect BRCA1/2 variants in a Chinese multicenter cohort of 21,216 BC patients and 6434 healthy controls. Overall, the percentage of subjects carrying pathogenic variants was 5.5% (1174/21,216) in BC patients and 1.1% (71/6434) in healthy controls. We identified 13 pathogenic variants as high-frequency variants that had a frequency of > 0.45‰ in BC patients (≥ 10 in 21,216 patients), none of which has been reported in Caucasians. Pathogenic BRCA1/2 variants correlated with younger onset age, higher frequencies of bilateral and triple-negative BC (TNBC), invasive carcinomas, high histological grades, and family history of BC and other cancers. Furthermore, the percentage of the subjects carrying VUS was 9.8% (2071/21,216) in BC patients and 6.9% (446/6434) in healthy controls. Based on our cohort study, we unambiguously reclassified 7 out of the 858 VUS resulting in lower VUS ratio in patients (from 9.8 to 7.9%) as well as in healthy control (from 6.9 to 5.3%). We also re-analyzed the 100 variants in 13 exons (2–5 and 15–23) of the BRCA1 genes using a functional assay (saturation genome editing; SGE). 55 of the 59 VUS had distinct status in the SGE study: 24 (43.6%) were pathogenic, and 31 (56.4%) were benign. Strong ethnicity-specific occurrences of pathogenic BRCA1/2 variants were identified in the Chinese population. Hence, the findings provide rationale and sequencing information for the implementation of BRCA1/2 variants tailored to the Chinese population into clinical risk assessment.

BRCA and Breast Cancer-Related High-Penetrance Genes

Genetic susceptibility explains 5-10% of all breast cancer cases. High-penetrance breast cancer susceptibility genes deliberate a greater than tenfold relative risk of breast cancer. BRCA1 and BRCA2 genes are the most common cause of hereditary breast cancer, and TP53, PTEN, and SKT11 (LKB1) are rarely present. The prevalence of BRCA1 and BRCA2 genetic alterations differ in various ethnic groups. The Korean Hereditary Breast Cancer (KOHBRA) Study, nationwide-scale study, was established to acquire evidence for the accurate risk assessment and management of hereditary breast and ovarian cancer (HBOC) in Korea prospectively since 2007. In this chapter, we review previous research related to hereditary breast cancer and summarize the present concepts and research results centered on the Korean Hereditary Breast Cancer Research at this time.

Factors associated with the decision to undergo risk-reducing salpingo-oophorectomy among women at high risk for hereditary breast and ovarian cancer: a systematic review

Purpose

This systematic review aims to identify factors associated with risk-reducing salpingo-oophorectomy (RRSO), including the uptake rate and decision timing, among women at high risk for hereditary breast and ovarian cancer (HBOC).

Methods

We found 4,935 relevant studies using MEDLINE, Embase, CINAHL, and PsycINFO on July 6, 2020. Two authors screened the articles and extracted data. Twenty-four studies met the inclusion criteria. Quality assessment of articles was conducted using the Risk of Bias for Nonrandomized Studies tool.

Results

Five types of factors were identified (demographic factors, clinical factors, family history of cancer, psychological factors, and objective cancer risk). The specific significant factors were older age, having child(ren), being a BRCA1/2 carrier, mastectomy history, perceived risk for ovarian cancer, and perceived advantages of RRSO, whereas objective cancer risk was not significant. The uptake rate of RRSO was 23.4% to 87.2% (mean, 45.2%) among high-risk women for HBOC. The mean time to decide whether to undergo RRSO after BRCA testing was 4 to 34 months.

Conclusion

RRSO decisions are affected by demographic, clinical, and psychological factors, rather than objective cancer risk. Nonetheless, women seeking RRSO should be offered information about objective cancer risk. Even though decision-making for RRSO is a complex and multifaceted process, the psychosocial factors that may influence decisions have not been comprehensively examined, including family attitudes toward RRSO, cultural norms, social values, and health care providers’ attitudes.

Trends in Risk-Reducing Mastectomy and Risk-Reducing Salpingo-Oophorectomy in Korean Carriers of the BRCA1/2 Mutation

Purpose

BRCA1/2 mutations are associated with risks of breast and ovarian cancer. In Korea, incidences of BRCA1/2 genetic testing and risk-reducing surgery (RRS) have increased with insurance coverage and the Angelina Jolie effect. The aim of this study was to identify trends in RRS performed in Korean women with the BRCA1/2 mutation.

Methods

We retrospectively reviewed the medical records of BRCA1/2 mutation carriers with (affected carriers) and without (unaffected carriers) breast cancer until August 2018 from 25 Korean Hereditary Breast Cancer (KOHBRA)-affiliated hospitals.

Results

The numbers of contralateral risk-reducing mastectomy (RRM) and risk-reducing bilateral salpingo-oophorectomy (RRBSO) in affected carriers have increased 5.8- and 3.6-fold, respectively, since 2013. The numbers of RRBSO in unaffected carriers has increased 8-fold since 2013. The number of institutions that perform RRS has increased gradually. The number of hospitals that perform contralateral RRM on affected carriers increased from 3 in 2012 to 11 in 2018, and that of those that perform RRBSO increased from 7 to 17. The number of hospitals that perform bilateral RRM on unaffected carriers increased from 1 in 2012 to 2 in 2018, and that of those that perform RRBSO increased from 1 to 8. However, the hospitals showed differences in the rates of RRM or RRBSO performed.

Conclusion

The incidence of RRS increased each year throughout the study period. However, in Korea, the rate of RRS procedures depended on the hospital.

The relationship between BRCA-associated breast cancer and age factors: an analysis of the Japanese HBOC consortium database

BRCA1/2 pathogenic variant prevalence in Japanese breast cancer is unclear. Here, we analyzed BRCA1/2 pathogenic variant prevalence with a particular focus on age factors, using the Japanese HBOC consortium database. All registered subjects were Japanese individuals who underwent BRCA1/2 genetic testing from January 1996 to July 2017 according to the Japanese HBOC consortium database. Cases were extracted and analyzed for each evaluation item. Overall BRCA1 and BRCA2 pathogenic variant prevalence was 11.2% and 9.0% in the cohort of 2366 proband patients, respectively. The age at onset of breast cancer for patients with BRCA1/2 pathogenic variants was significantly lower than that for patients without a BRCA1/2 pathogenic variant. In both BRCA1/2 patients, ages at onset were not statistically significantly different between two subtype groups (ER-positive vs. TNBC). We analyzed the BRCA1/2 pathogenic variant prevalence among age groups in patients with no family history of breast or ovarian cancer. In the TNBC group, the rate of genetic variants was more frequent among younger patients. Our results demonstrated that early breast cancer onset is associated with a BRCA1/2 pathogenic variant in the Japanese population. Younger TNBC patients were more likely to have a BRCA1/2 pathogenic variant irrespective of a family history of breast or ovarian cancer.

Contribution of BRCA1 and BRCA2 germline mutations to early onset breast cancer: a series from north of Morocco

BACKGROUND

To date, the contribution of BRCA1/2 mutations in Moroccan early onset breast cancer patients remains unknown. Here we assess these genetic alterations for the first time in a cohort from North of Morocco.

METHODS

Thirty-three patients diagnosed with breast cancer at the age of ≤40 years were recruited irrespective of breast and/or ovarian cancer family history. Coding regions and intron-exon boundaries of BRCA1 and BRCA2 genes were sequenced from peripheral blood DNA using Ion Proton (Thermo Fisher Scientific) next generation sequencing platform.

RESULTS

Overall, five BRCA germline mutations were identified (15.1%). The frequency of mutations among patients with family history of breast cancer was 16.7%. Three mutations were found in BRCA1 (9%) and two within the BRCA2 gene (6%). These are three frameshift mutations (c.798_799del, c.2125_2126insA, c.5116_5119delAATA), one missense (c.116G > A) and one nonsense mutation (c.289G > T). The mutation c.5116_5119delAATA has a founder effect in North Africa. Moreover, one variant of unknown significance was identified in BRCA2 (c.4090A > G). Most BRCA mutations carriers (80%) had no family history of breast cancer.

CONCLUSION

Our data do not support the hypothesis that BRCA mutations alone explain the higher frequency of breast cancer in Moroccan young women. The young age (≤40 years) for breast cancer diagnosis seems to be strongly predictive of BRCA mutation status in Moroccan patients. These results will help in decision making with regard to genetic counseling and testing in the national scale.

Performance evaluation of an amplicon-based next-generation sequencing panel for BRCA1 and BRCA2 variant detection

BACKGROUND

As next-generation sequencing (NGS) technology matures, various amplicon-based NGS tests for BRCA1/2 genotyping have been introduced. This study was designed to evaluate an NGS test using a newly released amplicon-based panel, AmpliSeq for Illumina BRCA Panel (AmpliSeq panel), for detection of clinically significant BRCA variants, and to compare it to another amplicon-based NGS test confirmed by Sanger sequencing.

METHODS

We reviewed BRCA test results done by NGS using the TruSeq Custom Amplicon kit from patients suspected of hereditary breast/ovarian cancer syndrome (HBOC) in 2018. Of those, 96 residual samples with 100 clinically significant variants were included in this study using predefined criteria: 100 variants were distributed throughout the BRCA1 and BRCA2 genes. All target variants were confirmed by Sanger sequencing. Duplicate NGS testing of these samples was performed using the AmpliSeq panel, and the concordance of results from the two amplicon-based NGS tests was assessed.

RESULTS

Ninety-nine of 100 variants were detected in duplicate BRCA1/2 genotyping using the AmpliSeq panel (sensitivity, 99%; specificity, 100%). In the discordant case, one variant (BRCA1 c.3627dupA) was found only in repeat 1, but not in repeat 2. Automated nomenclature of all variants, except for two indel variants, was in consensus with Human Genome Variation Society nomenclature.

CONCLUSION

Our findings confirm that the analytic performance of the AmpliSeq panel is satisfactory, with high sensitivity and specificity.

Clinical Validity of Next-Generation Sequencing Multi-Gene Panel Testing for Detecting Pathogenic Variants in Patients With Hereditary Breast-Ovarian Cancer Syndrome

Background

Hereditary breast and ovarian cancer syndrome (HBOC) is caused by pathogenic variants in BRCA and other cancer-related genes. We analyzed variants in BRCA gene and other cancer-related genes in HBOC patients to evaluate the clinical validity of next-generation sequencing (NGS) multi-gene panel testing.

Methods

The BRCA1/2 NGS testing was conducted for 262 HBOC patients. Multiplex ligation-dependent probe amplification and direct Sanger sequencing were performed for confirmation. Multi-gene panel testing was conducted for 120 patients who did not possess BRCA1/2 pathogenic variants but met the National Comprehensive Cancer Network criteria.

Results

Pathogenic variants in BRCA1/2 were detected in 30 HBOC patients (11.5%). Additionally, four out of the 120 patients possessed pathogenic variants by multi-gene panel testing (3.3%): MSH2 (c.256G>T, p.Glu86*), PMS2 (c.1687C>T, p.Arg563*), CHEK2 (c.546C>A, p.Tyr182*), and PALB2 (c.3351-1G>C). All the four patients had a family history of cancer.

Conclusions

Multi-gene panel testing could be a significant screening tool for HBOC patients, especially for those with a family history of cancer.

Familial Pancreatic Cancer and Surveillance of High-Risk Individuals

Family history of pancreatic cancer (PC) is a risk factor for PC development, and the risk level correlates with the number of affected families. A case of PC with ≥1 PC cases in the first-degree relative is broadly defined as familial pancreatic cancer (FPC) and accounts for 5% to 10% of total PC cases. FPC possesses several epidemiological, genetic and clinicopathological aspects that are distinct from those of conventional PCs. In Western countries, FPC registries have been established since the 1990s, and high-risk individuals are screened to detect early PCs. For the pharmacotherapy of FPC, especially in cases with germline pathogenic BRCA mutations, regimens using platinum and poly (ADP-ribose) polymerase inhibitor have recently been studied for their effectiveness. To date, the concept of FPC has prevailed in Western countries, and it has begun to infiltrate into Eastern countries. As the genetic background and environmental conditions vary in association with ethnicity and living area, we need to establish our own FPC registries and accumulate data in Asian countries.

Prognosis of BRCA1/2-negative breast cancer patients with HBOC risk factors compared with sporadic breast cancer patients without HBOC risk factors

OBJECTIVE

Demands for genetic counseling with BRCA1/2 examination have markedly increased. Accordingly, the incidence of uninformative results on BRCA1/2 mutation status has also increased. Because most patients examined for BRCA1/2 mutation have a high risk of hereditary breast and/or ovarian cancer, many patients suffer psychological distress even when the BRCA1/2 result is negative. We compared oncological outcomes between BRCA1/2-negative breast cancer with high risk of hereditary breast and/or ovarian cancer and sporadic breast cancer without risk of hereditary breast and/or ovarian cancer.

METHODS

The criteria for high risk for hereditary breast and/or ovarian cancer were defined as family history of breast and/or ovarian cancer in first- or second-degree relative, early onset breast cancer at <35 years old and bilateral breast cancer. Patients were matched maximally 1:3 into those who identified as negative for BRCA1/2 mutation with risk of hereditary breast and/or ovarian cancer (study group) and those who were not examined for BRCA1/2 mutation without risk for hereditary breast and/or ovarian cancer (control group). Matched variables were pathologic stage, estrogen receptor, progesterone receptor and human epidermal growth factor receptor-2 status.

RESULTS

All matching variables were successfully matched. Median follow-up duration was 57.8 months. There was no significant difference between the groups in disease-free survival (log-rank P = 0.197); however, the study group showed significantly better overall survival and breast cancer-specific survival (both P < 0.0001). We conducted subgroup analysis in the middle-aged group (36-54) and showed no significant difference for disease-free survival (P = 0.072) but significantly better overall survival and breast cancer-specific survival in the study group (P = 0.002 and P < 0.0001).

CONCLUSIONS

BRCA1/2-negative breast cancer patients who had hereditary breast and/or ovarian cancer risk factors showed similar disease-free survival and better overall survival and breast cancer-specific survival compared with those with sporadic breast cancer without hereditary breast and/or ovarian cancer risk factors.

Concordance of Hormone Receptor Status and BRCA1/2 Mutation Among Women With Synchronous Bilateral Breast Cancer

Goals: BRCA1/2 mutations are associated with bilateral breast cancer. The extent of concordance between synchronous bilateral breast cancer (SBBC) tumors with respect to hormone receptor expression and BRCA1/2 mutations is unknown. We investigated the distribution of BRCA1/2 mutations and bilateral estrogen receptor (ER) status in SBBC. Methods: A retrospective analysis was performed on 15,337 patients with primary breast cancer who underwent surgical treatment at the Fudan University Shanghai Cancer Center between 2007 and 2014. We included 163 patients with synchronous bilateral breast cancer who had germline BRCA1/2 mutations testing. BRCA1/2 pathogenic/likely pathogenic mutations and other clinicopathological characteristics were studied in further analyses. Results: Patients with SBBC developed breast cancer at an older age and had a higher rate of ER positivity than patients with UBC (p < 0.001, separately). In contrast, 14.1% of SBBC patients had carcinomas with a lobular component in either breast based on pathological reports (p < 0.001). Twelve patients had BRCA1 mutations, and 14 patients had BRCA2 mutations, while no patients had mutations in both genes. The BRCA1/2 mutation rate was higher in younger patients (23.4 vs. 11.1%, p = 0.036). SBBC patients with a family history of breast cancer or bilateral ER-negative disease had a higher frequency of BRCA1/2 mutations than the cohort without a history of these conditions. SBBC with a bilateral ER-discordant status had a very low frequency of BRCA1/2 mutations (5.6%). Patients with an ER-positive (concordant or discordant) status had better 3-year disease-free survival than patients with a concordant ER-negative status (HR = 0.324, 95% CI: 0.126-0.837, P = 0.020). However, the outcomes were similar during long-term follow-up. Pathological lymph node stage was the only prognostic factor for SBBC in both univariate and multivariate Cox analyses. Conclusions: Our study shows that Chinese women with SBBC have different characteristics from their UBC counterparts. SBBC patients with a younger age, family history of breast cancer, or bilateral ER-negative disease are more likely to have BRCA1/2 mutations. SBBC patients with a concordant ER-negative status had worse early outcomes. Our results suggest that there may be additional factors underlying the tumor biology and genetics of SBBC.

Impact of proactive high-throughput functional assay data on BRCA1 variant interpretation in 3684 patients with breast or ovarian cancer

The clinical utility of BRCA1/2 genotyping was recently extended from the selection of subjects at high risk for hereditary breast and ovary cancer to the identification of candidates for poly (ADP-ribose) polymerase (PARP) inhibitor treatment. This underscores the importance of accurate interpretation of BRCA1/2 genetic variants and of reducing the number of variants of uncertain significance (VUSs). Two recent studies by Findlay et al. and Starita et al. introduced high-throughput functional assays, and proactively analyzed variants in specific regions regardless of whether they had been previously observed. We retrospectively reviewed all BRCA1 and BRCA2 germline genetic test reports from patients with breast or ovarian cancer examined at Asan Medical Center (Seoul, Korea) between September 2011 and December 2018. Variants were assigned pathogenic or benign strong evidence codes according to the functional classification and were reclassified according to the ACMG/AMP 2015 guidelines. Among 3684 patients with available BRCA1 and BRCA2 germline genetic test reports, 429 unique variants (181 from BRCA1) were identified. Of 34 BRCA1 variants intersecting with the data reported by Findlay et al., three missense single-nucleotide variants from four patients (0.11%, 4/3684) were reclassified from VUSs to likely pathogenic variants. Four variants scored as functional were reclassified into benign or likely benign variants. Three variants that overlapped with the data reported by Starita et al. could not be reclassified. In conclusion, proactive high-throughput functional study data are useful for the reclassification of clinically observed VUSs. Integrating additional evidence, including functional assay results, may help reduce the number of VUSs.

Germline mutations in cancer-predisposition genes in patients with biliary tract cancer

The prevalence of germline mutations in patients with biliary tract carcinoma (BTC) remains unclear. Here, we investigated the prevalence and types of germline mutations in patients with BTC. We reviewed 269 patients with pathologically proven BTC and collected clinical characteristics, including medical and family histories. Additionally, we evaluated germline variants in 21 genes associated with hereditary predisposition for cancer by targeted sequencing in patients meeting ≥1 of the following criteria: 1) hereditary breast and/or ovarian cancer (HBOC) testing criteria modified for BTC, 2) Revised Bethesda Guidelines (RBGs) modified for BTC (modified RBG), 3) familial BTC criteria, or 4) young BTC criteria. Among the 269 patients, 80 met at least one criterion. Three pathogenic mutations in three patients were identified: two in BRCA2 and one in BRCA1. Among the 16 patients meeting modified HBOC testing criteria, 2 harbored germline BRCA2 mutations, and 1 harbored a germline BRCA1 mutation. However, no mutation in mismatch-repair genes were detected, despite 63 patients meeting modified RBG screening criteria and 18 qualifying as young BTC patients. We detected high prevalence of pathogenic germline mutations in BRCA1/2 and none in mismatch-repair genes in BTC patients following enrichment according to family or medical history in this study.

Insights Into Breast Cancer in the East vs the West: A Review

Importance

During the past few decades, the incidence of breast cancer (BC) has been increasing rapidly in East Asia, and BC is currently the most common cancer in several countries. The rising incidence is likely related to changing lifestyle and environmental factors in addition to the increase in early diagnosis with BC awareness and screening. The understanding and management of BC are generally based on research and data from the West. However, emerging differences in BC epidemiology and tumor and host biology in Asian populations may be clinically relevant.

Observations

A higher proportion of premenopausal BCs occur in Asia, although this factor is possibly an age-cohort effect. Although the relative frequencies of different immunohistochemical subtypes of BC may be similar between the East and West, the higher prevalence of luminal B subtypes with more frequent mutations in TP53 may be confounded by disparities in early detection. In addition, Asian BCs appear to harbor a more immune-active microenvironment than BCs in the West. The spectra of germline mutations in BC predisposition genes and single-nucleotide polymorphisms contributing to BC risk vary with ethnicity as well. Differences in tolerability of certain cytotoxic and targeted agents used in BC treatment may be associated with pharmacogenomic factors, whereas the lower body mass of the average woman in East Asia may contribute to higher toxicities from drugs administered at fixed doses. Phenotypic characteristics, such as lower breast volume, may influence the type of surgery performed in East Asian women. On the other hand, increased breast density may affect the sensitivity of mammography in detecting BCs, limiting the benefits of screening mammography.

Conclusions and Relevance

Breast cancer has become a major health problem in Asia. The inclusion of more women from Asia in clinical trials and epidemiologic and translational studies may help unravel the interethnic heterogeneity of BCs and elucidate the complex interplay between environmental and intrinsic factors in its pathogenesis. These insights may help to refine prevention, diagnosis, and management strategies for BC in the setting of ethnic diversity.

Spectrum and prevalence of BRCA1/2 germline mutations in Pakistani breast cancer patients: results from a large comprehensive study

Background

Pathogenic germline mutations in BRCA1 and BRCA2 (BRCA1/2) account for the majority of hereditary breast and/or ovarian cancers worldwide. To refine the spectrum of BRCA1/2 mutations and to accurately estimate the prevalence of mutation in the Pakistani population, we studied 539 breast cancer patients selected for family history and age of diagnosis.

Methods

Comprehensive screening for BRCA1/2 germline mutations was performed using state-of-the-art technologies.

Results

A total of 133 deleterious mutations were identified in 539 families (24.7%), comprising 110 in BRCA1 and 23 in BRCA2. The prevalence of BRCA1/2 small-range mutations and large genomic rearrangements was 55.4% (36/65) for families with breast and ovarian cancer, 27.4% (67/244) for families with two or more cases of breast cancer, 18.5% (5/27) for families with male breast cancer, and 12.3% (25/203) for families with a single case of early-onset breast cancer. Nine mutations were specific to the Pakistani population. Eighteen mutations in BRCA1 and three in BRCA2 were recurrent and accounted for 68.2% (75/110) and 34.8% (8/23) of all identified mutations in BRCA1 and BRCA2, respectively. Most of these mutations were exclusive to a specific ethnic group and may result from founder effects.

Conclusions

Our findings show that BRCA1/2 mutations account for one in four cases of hereditary breast/ovarian cancer, one in five cases of male breast cancer, and one in eight cases of early-onset breast cancer in Pakistan. Our study suggests genetic testing of an extended panel of 21 recurrent BRCA1/2 mutations for appropriately selected patients and their families in Pakistan.

A systematic review of the international prevalence of BRCA mutation in breast cancer

A systematic review was conducted, summarizing international BRCA 1 or 2 (BRCA1/2) mutation prevalence in breast cancer. Databases (eg, Medline and Embase; N=7) and conferences were searched (January 2012 to December 2017). From 17,872 records, 70 studies were included. In 58 large (N>100) studies, BRCA1/2 mutation prevalence varied widely from 1.8% (Spain) in sporadic breast cancer to 36.9% (United States) in estrogen receptor/progesterone receptor low+ (1-9% on immunohistochemistry/human epidermal growth factor receptor 2-negative [HER2-]) breast cancer. In 2 large studies unselected for family history, ethnicity, sex, or age and no/unclear selection by breast cancer stage or hormone receptor (HR) status, germline BRCA (gBRCA) mutation prevalence was 2.9% (Italy) to 3.0% (South Korea). In the 4 large unselected triple-negative breast cancer studies, gBRCA mutation prevalence varied from 9.3% (Australia) to 15.4% (United States). gBRCA mutation prevalence in 1 large unselected HR positive/HER2- early breast cancer study was 5% (United States). In 2 large unselected metastatic breast cancer studies, gBRCA mutation prevalence was 2.7% (France) and 4.3% (Germany). Locally advanced breast cancer studies were small and not in unselected populations. Poor reporting of gBRCA status and basis of selection implies a need for further large well-reported BRCA mutation prevalence studies in breast cancer.