Breast cancer risk in Chinese women with BRCA1 or BRCA2 mutations

Characteristics of Chinese breast cancer patients with double heterozygosity for BRCA1 and BRCA2 germline pathogenic variants

PURPOSE

Despite of very rare, breast cancer patients with double heterozygosity (DH) variants in BRCA1 and BRCA2 genes have been identified in other ethnic groups and seem to be associated with distinctive phenotypes. However, little is known about the frequency and clinical characteristics of Chinese breast cancer patients with BRCA1/2 DH variants.

METHODS

Four hundred and eleven unrelated patients with BRCA1 or BRCA2 pathogenic variants (PVs) were identified in a large series of unselected breast cancer patients. Another two siblings with metachronous bilateral breast cancer were referred for genetic counseling, after which BRCA1/2 DH variants were detected.

RESULTS

Four unrelated breast cancer patients with BRCA1/2 DH were identified in the cohort of 411 patients with BRCA1 or BRCA2 PVs, the frequency of BRCA1/2 DH was 0.97%. In total, six BRCA1/2 DH patients from five families were found in this study. In two families, the hereditary pattern of DH was speculated to have originated from both sides of the family. BRCA1/2 DH patients were more likely to have a family history of breast cancer than patients with a BRCA1 (100% vs. 29.2%, P = 0.004) or BRCA2 (100% vs. 29.6%, P = 0.004) single PV. BRCA1/2 DH patients were more likely to be triple-negative breast tumors than patients with single BRCA2 PVs (66.7% vs. 14.1%, P = 0.020), which was comparable to the findings in patients with single BRCA1 PVs (66.7% vs. 56.9%, P = 1.00).

CONCLUSION

Chinese patients with BRCA1/2 DH exhibit a high percentage of family history of breast cancer. The tumor pathological features of BRCA1/2 DH carriers are similar to those of BRCA1 PV carriers.

Age-specific breast and ovarian cancer risks associated with germline BRCA1 or BRCA2 pathogenic variants - an Asian study of 572 families

Background

Clinical management of Asian BRCA1 and BRCA2 pathogenic variants (PV) carriers remains challenging due to imprecise age-specific breast (BC) and ovarian cancer (OC) risks estimates. We aimed to refine these estimates using six multi-ethnic studies in Asia.

Methods

Data were collected on 271 BRCA1 and 301 BRCA2 families from Malaysia and Singapore, ascertained through population/hospital-based case-series (88%) and genetic clinics (12%). Age-specific cancer risks were estimated using a modified segregation analysis method, adjusted for ascertainment.

Findings

BC and OC relative risks (RRs) varied across age groups for both BRCA1 and BRCA2. The age-specific RR estimates were similar across ethnicities and country of residence. For BRCA1 carriers of Malay, Indian and Chinese ancestry born between 1950 and 1959 in Malaysia, the cumulative risk (95% CI) of BC by age 80 was 40% (36%-44%), 49% (44%-53%) and 55% (51%-60%), respectively. The corresponding estimates for BRCA2 were 29% (26-32%), 36% (33%-40%) and 42% (38%-45%). The corresponding cumulative BC risks for Singapore residents from the same birth cohort, where the underlying population cancer incidences are higher compared to Malaysia, were higher, varying by ancestry group between 57 and 61% for BRCA1, and between 43 and 47% for BRCA2 carriers. The cumulative risk of OC by age 80 was 31% (27-36%) for BRCA1 and 12% (10%-15%) for BRCA2 carriers in Malaysia born between 1950 and 1959; and 42% (34-50%) for BRCA1 and 20% (14-27%) for BRCA2 carriers of the same birth cohort in Singapore. There was evidence of increased BC and OC risks for women from >1960 birth cohorts (p-value = 3.6 × 10-5 for BRCA1 and 0.018 for BRCA2).

Interpretation

The absolute age-specific cancer risks of Asian carriers vary depending on the underlying population-specific cancer incidences, and hence should be customised to allow for more accurate cancer risk management.

Funding

Wellcome Trust [grant no: v203477/Z/16/Z]; CRUK (PPRPGM-Nov20∖100002).

A nomogram model combining ultrasound-based radiomics features and clinicopathological factors to identify germline BRCA1/2 mutation in invasive breast cancer patients

Objective

BRCA1/2 status is a key to personalized therapy for invasive breast cancer patients. This study aimed to explore the association between ultrasound radiomics features and germline BRCA1/2 mutation in patients with invasive breast cancer.

Materials and methods

In this retrospective study, 100 lesions in 92 BRCA1/2-mutated patients and 390 lesions in 357 non-BRCA1/2-mutated patients were included and randomly assigned as training and validation datasets in a ratio of 7:3. Gray-scale ultrasound images of the largest plane of the lesions were used for feature extraction. Maximum relevance minimum redundancy (mRMR) algorithm and multivariate logistic least absolute shrinkage and selection operator (LASSO) regression were used to select features. The multivariate logistic regression method was used to construct predictive models based on clinicopathological factors, radiomics features, or a combination of them.

Results

In the clinical model, age at first diagnosis, family history of BRCA1/2-related malignancies, HER2 status, and Ki-67 level were found to be independent predictors for BRCA1/2 mutation. In the radiomics model, 10 significant features were selected from the 1032 radiomics features extracted from US images. The AUCs of the radiomics model were not inferior to those of the clinical model in both training dataset [0.712 (95% CI, 0.647-0.776) vs 0.768 (95% CI, 0.704-0.835); p = 0.429] and validation dataset [0.705 (95% CI, 0.597-0.808) vs 0.723 (95% CI, 0.625-0.828); p = 0.820]. The AUCs of the nomogram model combining clinical and radiomics features were 0.804 (95% CI, 0.748-0.861) in the training dataset and 0.811 (95% CI, 0.724-0.894) in the validation dataset, which were proved significantly higher than those of the clinical model alone by DeLong's test (p = 0.041; p = 0.007). To be noted, the negative predictive values (NPVs) of the nomogram model reached a favorable 0.93 in both datasets.

Conclusion

This machine nomogram model combining ultrasound-based radiomics and clinical features exhibited a promising performance in identifying germline BRCA1/2 mutation in patients with invasive breast cancer and may help avoid unnecessary gene tests in clinical practice.

Survival Outcomes and Efficacy of Platinum in Early Breast Cancer Patients with Germline BRCA1 or BRCA2 Mutation: A Multicenter Retrospective Cohort Study

Purpose

The study aimed to compare the survival outcomes and efficacy of platinum in early breast cancer patients with BRCA1 and BRCA2 mutations.

Methods

Patients diagnosed with stage I-III breast cancer and carrying germline pathogenic/likely pathogenic BRCA mutations in three medical institutions in China from April 2016 to January 2021 were retrospectively analyzed. Data on clinical and pathological characteristics, treatment information, pathogenic variants of BRCA, and survival outcomes were collected for all eligible patients.

Outcomes

One hundred and sixty-nine patients with BRCA mutations were enrolled, including BRCA1 mutation (53.3%, n = 90) and BRCA2 mutation (46.7%, n = 79). The median age was 39 years, and most patients (68.1%, n = 115) were stage I-II. Patients with BRCA1 mutations were characterized by histological grade III (55.6%) and higher Ki-67 index (Ki-67 ≥ 30%, 78.9%) compared with patients with BRCA2 mutations (27.8%, 58.2%). BRCA1 mutation patients accounted for a significantly higher proportion of triple negative breast cancer than BRCA2 mutation patients (71.1% vs 19.0%, P < 0.0001). A total of 142 (84.0%) patients received neo/adjuvant chemotherapy, including anthracycline and/or taxane-based regimens (55.6%) or platinum-based regimens (27.2%). Median follow-up was 33.2 months. Three-year DFS (disease-free survival) and DRFS (distant recurrence-free survival) had no significant differences between patients with BRCA1 and BRCA2 mutations (82.0% vs 85.4%, P = 0.35; 94.3% vs 94.6%, P = 0.39). The 3-year DFS rate in BRCA1 mutation cohort of patients received platinum regimen was significantly higher than patients received non-platinum regimen (96.0% vs 75.2%, P = 0.01). No differences between DFS and DRFS were observed in patients with BRCA2 mutation received platinum regimen and non-platinum regimen.

Conclusion

Similar survival outcomes were observed in early breast cancer patients with BRCA1 and BRCA2 mutation, though they had different biological characteristics. Patients with BRCA1 mutations are more benefit from platinum-regimen. The value of platinum-regimen for early breast cancer patients with BRCA1 and BRCA2 needs to be verified further.

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.

Young age is associated with inferior outcomes in early-stage luminal B breast cancer patients who undergo mastectomy

Background: This retrospective study aimed to evaluate the effect of age on cancer relapse and survival in breast cancer patients undergoing different treatments. Methods: The propensity score method was used to correct for disparities between two groups; 2049 young patients were matched to 4053 older patients. Kaplan-Meier curves and Cox proportional hazards models were used to assess disease-free survival. Results: In the original cohort, young patients showed higher lymph node metastasis, hormone-receptor positivity and high Ki-67 levels. After propensity score matching, the disease-free survival of young patients with the luminal B-like subtype who received mastectomy with early stage disease exhibited inferior survival. Conclusion: Decisions about biology-driven systemic treatment strategies for young patients are worthy of discussion with a multidisciplinary tumor board.

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.

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.

Ovarian cancer risk of Chinese women with BRCA1/2 germline pathogenic variants

Estimating the lifetime risk of ovarian cancer in Chinese women with BRCA1/2 germline pathogenic variants (PVs) is of great importance for the clinical management of BRCA1/2 carriers. This cohort study recruited 9903 unselected Chinese breast cancer patients whose BRCA1/2 status was determined. Of these, 3984 probands completed family history questionnaires, which investigated the health status of their relatives, including 11,997 female first-degree relatives. The ovarian cancer risk of BRCA1/2 germline pathogenic carriers was estimated using the ovarian cancer history of proband first-degree female relatives via the Kin-cohort method. Of the 3984 probands, 126 (3.2%) carried BRCA1 PVs, and 183 (4.6%) carried BRCA2 PVs. The estimated cumulative risks of ovarian cancer by age 70 were 15.3% (95% CI 8.4-18.6%) for BRCA1 carriers, 5.5% (95% CI 2.0-10.2%) for BRCA2 carriers, and 0.4% (95% CI 0.3-0.7%) for noncarriers. The cumulative risks of ovarian cancer were very low before the age of 40 for both BRCA1 and BRCA2 carriers and were an increase up to age 45. The cumulative ovarian cancer risk of BRCA1 carriers was approximately three times higher than that of BRCA2 carriers, and BRCA1 and BRCA2 carriers had 38- and 14-fold higher risks than non-BRCA carriers, respectively. The findings indicate that Chinese women with BRCA1/2 PVs have high risks of ovarian cancer in their lifetime, especially BRCA1 carriers. These results are useful for devising optimal strategies to reduce ovarian cancer risk in BRCA1/2 carriers.

Breast cancer screening and early diagnosis in Chinese women

Breast cancer is the most common malignant tumor in Chinese women, and its incidence is increasing. Regular screening is an effective method for early tumor detection and improving patient prognosis. In this review, we analyze the epidemiological changes and risk factors associated with breast cancer in China and describe the establishment of a screening strategy suitable for Chinese women. Chinese patients with breast cancer tend to be younger than Western patients and to have denser breasts. Therefore, the age of initial screening in Chinese women should be earlier, and the importance of screening with a combination of ultrasound and mammography is stressed. Moreover, Chinese patients with breast cancers have several ancestry-specific genetic features, and aiding in the determination of genetic screening strategies for identifying high-risk populations. On the basis of current studies, we summarize the development of risk-stratified breast cancer screening guidelines for Chinese women and describe the significant improvement in the prognosis of patients with breast cancer in China.

Assessing the Variations in Breast/Ovarian Cancer Risk for Chinese BRCA1/2 Carriers

Background. Cancer risks vary in different BRCA1/2 mutations. We are interested in identifying regions associated with elevated/reduced risks of breast/ovarian cancers in the Chinese population and comparing with previously reported Caucasian-based breast/ovarian cancer cluster regions (OCCR/BCCR). We also aim to characterize the distribution and estimate the cancer risks of different Chinese recurrent mutations. Methods. A total of 3,641 cancer-free women and 4,278 female cancer patients were included in the study. Germline BRCA1/2 status was detected with amplicon-based next-generation sequencing. We calculated the odds ratio (OR) of breast cancer and OR of ovarian cancer, and their ratio of the two ORs (ROR) for each region. ROR >1 indicated elevated odds of breast cancer and/or decreasing odds of ovarian cancer, and vice versa. The frequency, distribution, and penetrance of six known Chinese founder mutations were characterized, respectively. Haplotype analysis and age estimation were performed on the most prevalent founder mutation BRCA1: c.5470_5477del. Results. A total of 729 subjects were detected with germline BRCA1/2 deleterious mutations. The putative Chinese OCCR/BCCR partially overlapped with Caucasian-based OCCR/BCCR and shared structural-functional characteristics. The six known Chinese founder mutations greatly vary in both distribution and penetrance. The two widely spread mutations are estimated to convey low penetrance, while the area-restricted founder mutations seemed to confer higher/complete penetrance. BRCA1: c.5470_5477del is estimated to have emerged ∼2,090 years ago (70 B.C.) during the Han dynasty. Conclusions. BRCA1/2 carriers with different genotypes have significantly different cancer risks. An optimal risk assessment should be mutation specific, rather than concerning a single figure.

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.

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.

Frequency of mutations in BRCA genes and other candidate genes in high-risk probands or probands with breast or ovarian cancer in the Czech Republic

Breast cancer is currently the most common form of malignant tumour in womenboth in the Czech Republic and in most countries of the western world, and its incidence is constantly increasing. Many risk factors are known to play a major role in the development of this form of cancer. One of them is genetics, especially the BRCA1/2 genes. A higher risk of ovarian cancer is also associated with these genes. With the development of laboratory diagnostics massive parallel sequencing methods (NGS) are now routinely employed, enabling the detection of other pathogenic sequence variants, or variants of uncertain significance (VUS) not previously detected. Besides the high penetrance BRCA1/2 genes, medium and low penetrant genes also come to the fore. There were 2046 probands examined in the study, men and women, mainly from eastern part of the Czech Republic. These were selected for a genetic examination, after meeting indication criteria (probands from high-risk families or with breast or ovarian cancer). From this group only women, 2033 probands, were selected and were given a genetic examination for the possible presence of patogenic sequence variants in BRCA1/2 genes, or other candidate genes. Analyses were conducted in the laboratory using DHPLC or next generation sequencing. MLPA method is used for large rearrangements in genes. From all examined women 212 mutations were detected. The most mutations (128) were found in the BRCA1 gene (60%). In the BRCA2 gene 71 mutations (34%) were found and 13 more mutations (6%) were detected in another candidate genes (CHEK2, PALB2, ERCC4). The most frequent sequence variant was c.5266dupC in the BRCA1 gene. The results show that 72% of women with a confirmed mutation in the BRCA1 gene and 77.5% of women with the sequence variant BRCA2, already had breast cancer and 16.4% of women with BRCA1 and 7% of women with BRCA2 already had ovarian cancer. Only 21 high risk families used the possibility to be tested and had undergone targeted mutation testing. The study results suggest a reflection of the causes and needs for examination of patients and women predisposed to breast or ovarian cancer.

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.

Interpretation of breast cancer screening guideline for Chinese women

Breast cancer is the most common malignant tumor in Chinese women. Early screening is the best way to improve the rates of early diagnosis and survival of breast cancer patients. The peak onset age for breast cancer in Chinese women is considerably younger than those in European and American women. It is imperative to develop breast cancer screening guideline that is suitable for Chinese women. By summarizing the current evidence on breast cancer screening in Chinese women, and referring to the latest guidelines and consensus on breast cancer screening in Europe, the United States, and East Asia, the China Anti-Cancer Association and National Clinical Research Center for Cancer (Tianjin Medical University Cancer Institute and Hospital) have formulated population-based guideline for breast cancer screening in Chinese women. The guideline provides recommendations on breast cancer screening for Chinese women at average or high risk of breast cancer according to the following three aspects: age of screening, screening methods, and screening interval. This article provides more detailed information to support the recommendations in this guideline and to provide more direction for current breast cancer screening practices in China.

Germline mutations in 40 cancer susceptibility genes among Chinese patients with high hereditary risk breast cancer

Multigene panel testing of breast cancer predisposition genes have been extensively conducted in Europe and America, which is relatively rare in Asia however. In this study, we assessed the frequency of germline mutations in 40 cancer predisposition genes, including BRCA1 and BRCA2, among a large cohort of Chinese patients with high hereditary risk of BC. From 2015 to 2016, consecutive BC patients from 26 centers of China with high hereditary risk were recruited (n = 937). Clinical information was collected and next-generation sequencing (NGS) was performed using blood samples of participants to identify germline mutations. In total, we acquired 223 patients with putative germline mutations, including 159 in BRCA1/2, 61 in 15 other BC susceptibility genes and 3 in both BRCA1/2 and non-BRCA1/2 gene. Major mutant non-BRCA1/2 genes were TP53 (n = 18), PALB2 (n = 11), CHEK2 (n = 6), ATM (n = 6) and BARD1 (n = 5). No factors predicted pathologic mutations in non-BRCA1/2 genes when treated as a whole. TP53 mutations were associated with HER-2 positive BC and younger age at diagnosis; and CHEK2 and PALB2 mutations were enriched in patients with luminal BC. Among high hereditary risk Chinese BC patients, 23.8% contained germline mutations, including 6.8% in non-BRCA1/2 genes. TP53 and PALB2 had a relatively high mutation rate (1.9 and 1.2%). Although no factors predicted for detrimental mutations in non-BRCA1/2 genes, some clinical features were associated with mutations of several particular genes.

Breast and ovarian cancer penetrance of BRCA1/2 mutations among Hong Kong women

Germline mutations in BRCA1 and BRCA2 (BRCA1/2) are associated with increased risk of breast and ovarian cancer. The penetrance of breast and ovarian cancer in BRCA1/2 mutation carriers has been well characterized in Caucasian but not in Asian. Two studies have investigated the breast cancer risk in Asian women with BRCA1/2 mutations, and no published estimates are available for ovarian cancer. Therefore, we estimated the age-specific cumulative risk of BRCA1/2-associated breast and ovarian cancer in Chinese women. From Jan 2007 to Nov 2015, the Hong Kong Hereditary Breast Cancer Family Registry identified 1635 families with hereditary breast-ovarian cancer. Among probands in these families, 66 had BRCA1 mutations, 84 had BRCA2 mutations, and 1,485 tested negative for BRCA1/2 mutations. Using the female first-degree relatives of these probands, we estimated the risk of breast and ovarian cancer using a modified marginal likelihood approach. Estimates of breast cancer penetrance by age 70 were 53.7% (95% CI 34.5-71.6%) for BRCA1 mutation carriers and 48.3% (95% CI 31.8-68.5%) for BRCA2. The estimated risk of ovarian cancer by age 70 was 21.5% and 7.3% for Chinese women carrying BRCA1 or BRCA2 mutation respectively. A meta-analysis of available studies in Asian women revealed pooled estimates of breast cancer risk by age 70 of 44.8% (95% CI 33-57.2%) and 40.7% (95% CI 31.3-50.9%) for BRCA1 and BRCA2 mutation carriers respectively. These data suggest that BRCA1/2-associated breast cancer risk for Chinese women is similar to that for Caucasian women, although BRCA1/2-associated ovarian cancer risks are lower for Chinese women.

Increased centrosome number in BRCA-related breast cancer specimens determined by immunofluorescence analysis

BRCA‐related breast carcinoma can be prevented through prophylactic surgery and an intensive follow‐up regimen. However, BRCA genetic tests cannot be routinely performed, and some BRCA mutations could not be defined as deleterious mutations or normal variants. Therefore, an easy functional assay of BRCA will be useful to evaluate BRCA status. As it has been reported that BRCA functions in the regulation of centrosome number, we focused on centrosome number in cancer tissues. Here, 70 breast cancer specimens with known BRCA status were analyzed using immunofluorescence of γ‐tubulin (a marker of centrosome) foci. The number of foci per cell was higher in cases with BRCA mutation compared to wild‐type cases, that is, 1.9 (95% confidence interval [CI], 1.5‐2.3) vs 0.5 (95% CI, 0.2‐0.8) (P < .001). Specifically, foci numbers per cell in BRCA1 and BRCA2 mutation cases were 1.2 (95% CI, 0.6‐1.8) and 2.2 (95% CI, 1.7‐2.6), respectively, both higher than those in wild‐type cases (P = .042 and P < .0001, respectively). The predictive value of γ‐tubulin foci as determined by area under the curve (AUC = 0.86) for BRCA status was superior to BRCAPRO (AUC = 0.69), Myriad Table (AUC = 0.61), and KOHBRA BRCA risk calculator (AUC = 0.65) pretest values. The use of γ‐tubulin foci to predict BRCA status had sensitivity = 83% (19/23), specificity = 89% (42/47), and positive predictive value = 77% (20/26). Thus, γ‐tubulin immunofluorescence, a functional assessment of BRCA, can be used as a new prospective test of BRCA status.

Inherited mutations in BRCA1 and BRCA2 in an unselected multiethnic cohort of Asian patients with breast cancer and healthy controls from Malaysia

BACKGROUND

Genetic testing for BRCA1 and BRCA2 is offered typically to selected women based on age of onset and family history of cancer. However, current internationally accepted genetic testing referral guidelines are built mostly on data from cancer genetics clinics in women of European descent. To evaluate the appropriateness of such guidelines in Asians, we have determined the prevalence of germ line variants in an unselected cohort of Asian patients with breast cancer and healthy controls.

METHODS

Germ line DNA from a hospital-based study of 2575 unselected patients with breast cancer and 2809 healthy controls were subjected to amplicon-based targeted sequencing of exonic and proximal splice site junction regions of BRCA1 and BRCA2 using the Fluidigm Access Array system, with sequencing conducted on a Illumina HiSeq2500 platform. Variant calling was performed with GATK UnifiedGenotyper and were validated by Sanger sequencing.

RESULTS

Fifty-five (2.1%) BRCA1 and 66 (2.6%) BRCA2 deleterious mutations were identified among patients with breast cancer and five (0.18%) BRCA1 and six (0.21%) BRCA2 mutations among controls. One thousand one hundred and eighty-six (46%) patients and 97 (80%) carriers fulfilled the National Comprehensive Cancer Network guidelines for genetic testing.

CONCLUSION

Five per cent of unselected Asian patients with breast cancer carry deleterious variants in BRCA1 or BRCA2. While current referral guidelines identified the majority of carriers, one in two patients would be referred for genetic services. Given that such services are largely unavailable in majority of low-resource settings in Asia, our study highlights the need for more efficient guidelines to identify at-risk individuals in Asia.

Identification and analysis of CHEK2 germline mutations in Chinese BRCA1/2-negative breast cancer patients

PURPOSE

Cell-cycle-checkpoint kinase 2 (CHEK2) is an important moderate-penetrance breast cancer predisposition gene; however, recurrent CHEK2 mutations found in Caucasian women are very rare in Chinese population. We investigated the mutation spectrum and clinical relevance of CHEK2 germline mutations in Chinese breast cancer patients.

METHODS

The entire coding regions and splicing sites of CHEK2 were screened in 7657 Chinese BRCA1/2-negative breast cancer patients, using 62-gene panel-based sequencing.

RESULTS

Out of 7657 BRCA1/2-negative breast cancer patients, 26 (0.34%) carried CHEK2 pathogenic germline mutations. Most of these mutations (92.3%, 24/26) were nonsense or frameshift mutations; 84.6% (22/26) of them were in forkhead-associated (FHA) or kinase domains. Of the 18 types of CHEK2 mutations we found, 61.1% (11/18) of were novel mutations and two recurrent mutations (Y139X and R137X) were found in this cohort. Patients with CHEK2 mutations were significantly more likely to have family histories of breast and/or ovarian cancer (23.1% vs. 8.6%, p = 0.022) and family histories of any cancer (50.0% vs. 31.6%, p = 0.044); and were significantly more likely to have lymph node-positive (53.8% vs. 27.3%, p = 0.002) and progesterone receptor (PR)-positive (88.5% vs. 64.5%, p = 0.011) breast cancers.

CONCLUSIONS

Among Chinese breast cancer patients, the CHEK2 germline mutation rate is approximately 0.34% and two specific mutations (Y139X and R137X) are recurrent. Patients with CHEK2 mutations are significantly more likely to have family histories of cancer, and to develop lymph node-positive and/or PR-positive breast cancers.

Predictive value of BRCA1/2 mRNA expression for response to neoadjuvant chemotherapy in BRCA-negative breast cancers

It is well known that BRCA1 and BRCA2 play a central role in DNA repair, but the relationship between BRCA1 and BRCA2 mRNA expression and response to neoadjuvant chemotherapy in sporadic breast cancer patients has not been well established. Here, we investigate the association between BRCA1 or BRCA2 mRNA expression levels and pathological response in 674 BRCA1/2 mutation‐negative breast cancer patients who received neoadjuvant chemotherapy. BRCA1 and BRCA2 mRNA expression were assessed using quantitative real‐time polymerase chain reaction in core biopsy breast cancer tissue obtained prior to the initiation of neoadjuvant chemotherapy. A total 129 patients (19.1%) achieved pathological complete response (pCR) after neoadjuvant chemotherapy. Among patients treated with anthracycline‐based chemotherapy (n = 531), BRCA1 mRNA low expression patients had a significantly higher pCR rate than intermediate or high BRCA1 mRNA expression groups (24.6% vs 16.8% or 14.0%, P = .031) and retained borderline significance (OR = 1.54, 95% CI = 0.93‐2.56, P = .094) in multivariate analysis. Among the 129 patients who received a taxane‐based regimen, pCR rate showed no differences in BRCA1 low, intermediate, and high mRNA level subgroups (19.6%, 26.8% and 21.4%, respectively; P = .71). BRCA2 mRNA level was not associated with pCR rate in the anthracyline‐based treated subgroup (P = .60) or the taxane‐based regimen subgroup (P = .82). Taken together, our findings suggested that BRCA1 mRNA expression could be used as a predictive marker in BRCA1/2 mutation‐negative breast cancer patients who received neoadjuvant anthracycline‐based treatment.

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.