Comparison of Survival After Breast-Conserving Therapy vs Mastectomy Among Patients With or Without the BRCA1/2 Variant in a Large Series of Unselected Chinese Patients With Breast Cancer.

Importance: Whether patients with breast cancer who carry a BRCA1/2 variant can safely undergo breast-conserving therapy (BCT) remains controversial. Objective: To compare survival rates after BCT vs mastectomy in BRCA1/2 variant carriers and noncarriers in a large series of unselected patients with breast cancer. Design, Setting, and Participants: In this cohort study, a large consecutive series of 8396 unselected patients with primary breast cancer underwent either BCT, mastectomy with radiotherapy, or mastectomy alone from October 1, 2003, to May 31, 2015, at the Breast Center of Peking University Cancer Hospital in China. All patients were assessed for BRCA1/2 germline variant status. Statistical analysis was performed from May 1 to September 30, 2020. Main Outcomes and Measures: The primary outcomes were breast cancer-specific survival (BCSS) and overall survival (OS); secondary outcomes included recurrence-free survival, distant recurrence-free survival, and ipsilateral breast tumor recurrence. Results: Of these 8396 Chinese patients (8378 women [99.8% women]; mean [SD] age, 50.8 [11.4] years; 187 BRCA1 carriers, 304 BRCA2 carriers, and 7905 noncarriers), 3135 (37.3%) received BCT, 1511 (18.0%) received mastectomy with radiotherapy, and 3750 (44.7%) received mastectomy alone. After a median follow-up of 7.5 years (range, 0.3-16.6 years), both BRCA1 and BRCA2 variant carriers treated with BCT had similar rates of survival compared with those treated with mastectomy with radiotherapy (BCSS: hazard ratio [HR] for BRCA1, 0.58 [95% CI, 0.16-2.10]; P = .41; HR for BRCA2, 0.46 [95% CI, 0.15-1.41]; P = .17; OS: HR for BRCA1, 0.61 [95% CI, 0.18-2.12]; P = .44; HR for BRCA2, 0.72 [95% CI, 0.26-1.96]; P = .52) or mastectomy alone (BCSS: HR for BRCA1, 0.70 [95% CI, 0.22-2.20]; P = .54; HR for BRCA2, 0.59 [95% CI, 0.18-1.93]; P = .39; OS: HR for BRCA1, 0.77 [95% CI, 0.27-2.21]; P = .63; HR for BRCA2, 0.62 [95% CI, 0.22-1.73]; P = .37) after adjusting for clinicopathologic factors and adjuvant therapy. For noncarriers, patients receiving BCT had significantly better survival than those receiving mastectomy with radiotherapy (BCSS: HR, 0.45 [95% CI, 0.36-0.57]; P < .001; OS: HR, 0.46 [95% CI, 0.37-0.58]; P < .001) or mastectomy alone (BCSS: HR, 0.71 [95% CI, 0.57-0.89]; P = .003; OS: HR, 0.71 [95% CI, 0.58-0.87]; P < .001) in multivariable analyses. Conclusions and Relevance: This study suggests that BRCA1/2 variant carriers treated with BCT have survival rates at least comparable to those treated with mastectomy with radiotherapy or mastectomy alone and that BCT could be an option for BRCA1/2 variant carriers when the tumor is clinically appropriate for BCT.

Single-Cell RNA Sequencing Reveals the Cellular Origin and Evolution of Breast Cancer in BRCA1 Mutation Carriers.

The cell of origin and the development of breast cancer are not fully elucidated in BRCA1 mutation carriers, especially for estrogen receptor (ER)-positive breast cancers. Here, we performed single-cell RNA sequencing (RNA-seq) on 82,122 cells isolated from the breast cancer tissues and adjacent or prophylactic normal breast tissues from four BRCA1 mutation carriers and three noncarriers. Whole-exome sequencing was performed on breast tumors from the four BRCA1 mutation carriers; for validation, bulk RNA-seq was performed on adjacent normal breast tissues from eight additional BRCA1 mutation carriers and 14 noncarriers. Correlation analyses suggested that breast cancers in BRCA1 mutation carriers might originate from luminal cells. The aberrant luminal progenitor cells with impaired differentiation were significantly increased in normal breast tissues in BRCA1 mutation carriers compared with noncarriers. These observations were further validated by the bulk RNA-seq data from additional BRCA1 mutation carriers. These data suggest that the cell of origin of basal-like breast tumors (ERneg) in BRCA1 mutation carriers might be luminal progenitor cells. The expression of TP53 and BRCA1 was decreased in luminal progenitor cells from normal breast tissue in BRCA1 mutation carriers, which might trigger the basal/mesenchymal transition of luminal progenitors and might result in basal-like tumor development. Furthermore, ERhigh luminal tumors might originate from mature luminal cells. Our study provides in-depth evidence regarding the cells of origin of different breast cancer subtypes in BRCA1 mutation carriers. SIGNIFICANCE: Single-cell RNA-seq data indicate that basal-like breast cancer (ERneg) might originate from luminal progenitors, and ERhigh luminal breast cancer might originate from mature luminal cells in BRCA1 mutation carriers.

Clinical phenotypes combined with saturation genome editing identifying the pathogenicity of BRCA1 variants of uncertain significance in breast cancer.

Characterizing the pathogenicity of BRCA1 variants of uncertain significance (VUSs) is a major bottleneck in clinical management of BRCA1-associated breast cancer. Saturation genome editing (SGE) was recently reported as an innovative laboratory-based approach to assess the pathogenicity of BRCA1 variants. We combined clinical phenotypes and SGE score to identify the pathogenicity of BRCA1 VUSs detected in a cohort of 8,085 breast cancer patients. According to SGE function score, 33 out of 144 BRCA1 VUSs detected were classified into "loss of function" (n = 13), "intermediate" (n = 2), and "functional" (n = 18) groups. Compared with non-carriers, "loss of function" VUS carriers (n = 19) presented significantly worse clinicopathological characteristics. These included younger age at breast cancer diagnosis (44.4 years vs. 51.2 years, P = 0.01), stronger family history of any cancer (57.9% vs. 32.3%, P = 0.017) especially breast or ovarian cancer (47.4% vs. 9.3%, P < 0.001), more bilateral breast cancer (31.6% vs. 3.4%, P < 0.001), and triple-negative breast cancer (47.4% vs. 12.8%, P < 0.001), which were comparable to those of pathogenic variant carriers. In contrast, the clinical phenotypes of "functional" VUS carriers were similar to those of non-carriers. These results indicated that SGE was a reliable method in BRCA1 variant classification. Combining SGE function score and the available evidence, twelve out of 33 BRCA1 VUSs were reclassified as pathogenic or likely pathogenic variants and one was benign.

Impact of the addition of carboplatin to anthracycline-taxane-based neoadjuvant chemotherapy on survival in BRCA1/2-mutated triple-negative breast cancer.

Whether adding carboplatin to standard neoadjuvant chemotherapy improves survival in BRCA1/2-mutated triple-negative breast cancer (TNBC) is unknown. In this retrospective study, we aimed to explore the efficacy of anthracycline-taxane (A-T)-based or anthracycline-taxane/carboplatin (A-TP)-based neoadjuvant chemotherapy in BRCA1/2-mutated TNBC. A total of 1585 operable primary breast cancer patients were treated with either neoadjuvant A-T (n = 886) or A-TP regimen (n = 699). BRCA1 and BRCA2 germline mutations were determined in all subjects. Pathological complete response (pCR), recurrence-free survival (RFS), distant recurrence-free survival (DRFS) and overall survival (OS) were estimated. Of the entire cohort, 102 patients (6.4%) carried a pathogenic BRCA1/2 germline mutation. After a median follow-up of 81 months, no significant differences in survival between the A-T and A-TP arms were found in the entire cohort. However, among 288 TNBC patients, BRCA1/2 mutation carriers had significantly better survival when treated with the A-TP regimen than with the A-T regimen (5-year RFS: 82.6% vs 47.9%; P = .024; 5-year DRFS: 88.5% vs 46.9%; P = .010; 5-year OS: 88.2% vs 49.9%; P = .036). Multivariate analyses revealed that the A-TP regimen was a significantly favourable factor for RFS and DRFS and showed a trend towards better OS when compared with the A-T regimen in BRCA1/2-mutated TNBC (RFS: adjusted hazard ratio [HR], 0.24; 95% confidence interval [CI], 0.06-0.91, P = .035; DRFS: HR, 0.17; 95% CI, 0.03-0.80; P = .025; OS: HR, 0.29; 95% CI, 0.06-1.49; P = .14). Our study suggested that BRCA1/2-mutated TNBC patients gain a survival benefit when carboplatin is added to standard A-T-based neoadjuvant chemotherapy.

Contralateral breast cancer risk in BRCA1 and BRCA2 mutation carriers in a large cohort of unselected Chinese breast cancer patients.

To estimate the cumulative risk of contralateral breast cancer (CBC) in BRCA1/2 carriers in a large cohort of unselected Chinese breast cancer patients. Our study comprised 9,401 unselected Chinese breast cancer patients and BRCA1/2 germline mutations were determined in all patients. After a median follow-up of 5.7 years, 181 patients developed CBC in this cohort. Compared to noncarriers, BRCA1 and BRCA2 carriers had a 4.52-fold (95% CI, 2.63-7.76) and 5.54-fold (95% CI, 3.51-8.74) increased risk of CBC, respectively. The 10-year cumulative risk of CBC was 15.5% (95% CI, 9.9-24.2) for BRCA1 carriers, 17.5% (95% CI, 10.9-28.0) for BRCA2 carriers and 3.2% (95% CI, 2.5-4.1) for noncarriers. Younger age at first breast cancer diagnosis was significantly associated with an increased 10-year risk of CBC for BRCA1 carriers (≤40 years vs. >40 years: 21.5% vs. 11.9%, unadjusted hazard ratio [HR] = 2.51, 95% CI, 1.03-6.15, p = 0.044), but not for BRCA2 carriers and noncarriers. The 10-year cumulative CBC risk was significantly higher in both BRCA1 and BRCA2 carriers who had a family history of breast cancer than in those who did not (BRCA1: 27.5% vs. 9.4%, adjusted HR = 2.64, 95% CI, 1.01-6.97, p = 0.049; BRCA2: 27.1% vs. 12.8%, adjusted HR = 2.29, 95% CI, 1.04-5.06, p = 0.040). In conclusion, the risk of CBC was a substantial high in BRCA1/2 carriers in unselected Chinese breast cancer patients, and CBC risk is much more remarkable in both BRCA1 and BRCA2 carriers who had a family history of breast cancer. Younger age at first breast cancer diagnosis also enhanced CBC risk in BRCA1 carriers.

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

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

Spectrum and clinical relevance of PALB2 germline mutations in 7657 Chinese BRCA1/2-negative breast cancer patients.

PURPOSE: To investigate the prevalence and clinical relevance of PALB2 germline mutations in BRCA1/2-negative breast cancer patients. METHODS: The exons and intron-exon boundaries of the PALB2 gene were sequenced by multigene panel testing in a cohort of 7657 Chinese BRCA1/2-negative breast cancer patients. RESULTS: Of the 7657 patients, 54 (0.71%) carried pathogenic PALB2 germline mutations, all of which were nonsense or frameshift mutations leading to a truncated protein. The 54 patients carried 42 distinct pathogenic mutations, of which 17 (40.5%) were novel and 8 were recurrent mutations. Compared with non-carriers, PALB2 pathogenic mutation carriers developed breast cancer at a younger age (47.52 years vs. 51.35 years, p = 0.016) and were more likely to have triple-negative (24.1% vs. 13.4%, p = 0.022) or HER2 negative (87.0% vs. 74.2%, p = 0.031) breast cancer and large breast tumors (> 2 cm) at diagnosis (72.2% vs. 57.0%, p = 0.024). PALB2 mutation carriers were also more likely to have family histories of breast and/or ovarian cancer (27.8% vs. 8.4%, p < 0.001) and any types of cancer (57.4% vs. 31.6%, p < 0.001) when compared with non-carriers. CONCLUSIONS: PALB2 germline mutations are present at 0.71% in Chinese BRCA1/2-negative breast cancer patients and are more frequent in patients with triple-negative breast cancer and family histories of breast and/or ovarian cancer.

Prevalence and clinical impact of TP53 germline mutations in Chinese women with breast cancer.

The prevalence and clinical relevance of TP53 germline mutations in a large unselected breast cancer series are largely unknown. Here, we determined TP53 germline mutations in a large cohort of 10,053 unselected breast cancer patients through multigene panel-based next-generation and/or Sanger sequencing assays. We found that 0.5% of patients (50 cases) carried a pathogenic TP53 germline mutation in this large series of 10,053 unselected breast cancer patients, and the prevalence of TP53 germline mutation was 3.8% in very early onset breast cancer (age ≤30 years) in this large cohort. TP53 mutation carriers were significantly more likely to have early onset cancer (p < 0.001) and bilateral breast cancer (p = 0.03), they and were significantly more likely to respond to carboplatin-based neoadjuvant chemotherapy compared to anthracycline- or taxane-based regimen in terms of pathologic complete response (50% vs. 0%, p = 0.006). At the median follow-up of 54 months, TP53 mutation was an independent unfavorable factor for recurrence-free survival (RFS), distant recurrence-free survival (DRFS), and overall survival (OS) (RFS, adjusted hazard ratio [HR]: 2.24, 95% confidence interval [CI]: 1.15-4.33, p = 0.02; DRFS, adjusted HR: 2.73, 95% CI: 1.41-5.30, p = 0.003; OS, adjusted HR: 4.60, 95% CI: 2.26-9.41, p < 0.001) in multivariate analyses. Our study suggested that TP53 germline mutations occur more frequently in very early onset unselected breast cancer patients; and TP53 germline mutation carriers have a very poor survival and may benefit from carboplatin-based neoadjuvant chemotherapy in unselected breast cancer patients.

Germline mutation in DNA-repair genes is associated with poor survival in BRCA1/2-negative breast cancer patients.

BRCA1/2 genes are the most frequently germline mutated DNA-repair genes, and the survival of BRCA1/2 carriers has been extensively explored in breast cancer. However, the prevalence of germline mutations in non-BRCA1/2 DNA-repair genes and the survival of carriers are largely unknown in a large cohort of unselected breast cancer patients. Germline mutations in 16 DNA-repair genes were determined using a multigene panel in 7657 BRCA1/2-negative breast cancer patients who were unselected for family history of cancer or age at diagnosis. Among the 7657 BRCA1/2-negative breast cancer patients, 257 (3.4%) carried at least 1 pathogenic germline mutation in the 16 DNA-repair genes. The prevalence of DNA-repair gene mutations was significantly higher in familial breast cancers (5.2%, P = 0.002) and early-onset breast cancers (diagnosed at and before the age of 40) (4.5%, P = 0.003) than that of sporadic breast cancers (2.9%) (diagnosed above age of 40), respectively. The DNA-repair gene mutation carriers were significantly more likely to have a larger tumor (P = 0.04) and axillary lymph node metastasis (P = 0.03). Moreover, DNA-repair gene mutation was an independent unfavorable factor for recurrence-free survival (adjusted hazard ratio [HR] = 1.38, 95% CI: 1.00-1.91, P = 0.05) and disease-specific survival (adjusted HR=1.63, 95% CI: 1.04-2.57, P = 0.03) in this cohort. Overall, 3.4% of BRCA1/2-negative breast cancer patients carried germline mutations in the 16 DNA-repair genes, and the DNA-repair gene mutation carriers exhibited an aggressive phenotype and had poor survival compared with noncarriers.

Co-mutation of TP53 and PIK3CA in residual disease after neoadjuvant chemotherapy is associated with poor survival in breast cancer.

PURPOSE: The prevalence and clinical relevance of TP53 and PIK3CA mutations in pretreatment breast cancer have been previously reported. However, little is known regarding these mutations in residual tumor tissues after neoadjuvant chemotherapy. Here, we investigated the association between TP53 and PIK3CA mutations in residual disease and survival of breast cancers. METHODS: TP53 and PIK3CA somatic mutations were examined in 353 post-neoadjuvant chemotherapy residual tumor tissues by Sanger sequencing. Survival curves of patients with TP53 and PIK3CA mutations were compared using the Kaplan-Meier method. RESULTS: Fifty-six (15.9%) of the 353 patients carried a TP53 somatic mutation and 79 patients (22.4%) carried a PIK3CA somatic mutation. A total of 18 patients carried co-mutation of TP53 and PIK3CA. Patients with somatic co-mutation were more likely to have high-grade tumors (35.3% vs. 10.6%, P = 0.010), estrogen receptor-negative tumors (55.6% vs. 26.7%, P = 0.009), progesterone receptor-negative tumors (61.1% vs. 30.5%, P = 0.008) and triple-negative tumors (35.3% vs. 13.3%, P = 0.025) compared with non-carriers. More importantly, co-mutation of TP53 and PIK3CA carriers had a significantly worse disease-free survival (DFS) and distant disease-free survival (DDFS) than non-carriers (5-year DFS: 58.0% vs. 83.2%, P < 0.001; 5-year DDFS: 70.3% vs. 86.4%, P = 0.024). Furthermore, in multivariate regression analysis, TP53 and PIK3CA co-mutation carriers showed a significantly worse DFS (adjusted hazard ratio = 3.70; 95% confidence interval, 1.79-7.63; P < 0.001). CONCLUSIONS: Patients with somatic co-mutation of TP53 and PIK3CA were associated with unfavorable survival compared with non-carriers. Co-mutation of TP53 and PIK3CA could be used as a potential prognosis marker in post-neoadjuvant chemotherapy breast cancer patients.

Prevalence and characterization of ATM germline mutations in Chinese BRCA1/2-negative breast cancer patients.

PURPOSE: The ataxia telangiectasia-mutated (ATM) gene is a moderate susceptibility gene for breast cancer. However, little is known about the breast cancer phenotypes associated with ATM mutation. We therefore investigated the spectrum and clinical characteristics of ATM germline mutations in Chinese breast cancer patients. METHODS: A multi-gene panel was performed to screen for ATM germline mutations in 7657 BRCA1/2-negative breast cancer patients. All deleterious mutations were validated by independent polymerase chain reaction (PCR)-Sanger sequencing. RESULTS: A total of 31 pathogenic mutations in the ATM gene across 30 carriers were identified, and the ATM mutation rate was 0.4% (30/7,657) in this cohort. The majority of the mutations (90.3%, 28/31) were nonsense or frameshift mutations. Of the total ATM mutations, 61.3% (19/31) were novel mutations and 13 recurrent mutations were found. ATM mutations carriers were significantly more likely to have a family history of breast and/or ovarian cancer (26.7% in carriers vs. 8.6% in non-carriers, p < 0.001), as well as a family history of any cancer (60.0% in carriers vs. 31.5% in non-carriers, p = 0.001). In addition, ATM mutations carriers were significantly more likely to have oestrogen receptor (ER)-positive (p = 0.011), progesterone receptor (PR)-positive (p = 0.040), and lymph node-positive breast cancer (p = 0.034). CONCLUSIONS: The prevalence of the ATM mutation is approximately 0.4% in Chinese BRCA1/2-negative breast cancer. ATM mutation carriers are significantly more likely to have a family history of cancer and to develop ER- and/or PR-positive breast cancer or lymph node-positive breast cancer.

Association between HER2 germline mutation A270S and prognosis in patients with primary breast cancer.

PURPOSE: To investigate the association between the HER2 germline mutation Ala270Ser (A270S), located in HER2 extracellular domain, and survival in breast cancer patients. METHODS: HER2 germline mutation A270S was identified in 5395 consecutive patients with operable primary breast cancer using direct Sanger sequencing analysis. Survival curves for patients with HER2 A270S mutation were compared using the Kaplan-Meier method with log-rank test. RESULTS: We identified that 31 cases carried HER2 germline mutation A270S in 5395 patients (0.6%, 31/5395). The HER2 A270S mutation was significantly associated with recurrence-free survival (RFS) and distant recurrence-free survival (DRFS) in the entire cohort of 5395 patients (RFS, unadjusted hazard ratio [HR] = 2.23; 95% confidence interval [CI] = 1.00-5.00; P= 0.045; DRFS, unadjusted HR = 2.80; 95% CI = 1.25-6.28; P= 0.009). Among the HER2-negative patients (n= 3825), those with the HER2 A270S mutation had a significantly worse RFS (unadjusted HR = 3.19; 95% CI = 1.42-7.16; P= 0.003) and DRFS (unadjusted HR = 3.98; 95% CI = 1.77-8.96; P< 0.001) than did those with wild type. Moreover, the A270S mutation remained an independent unfavorable factor for RFS and DRFS in the HER2-negative patients (RFS, HR = 3.30; 95% CI = 1.34-8.10; P= 0.009; DRFS, HR = 4.26; 95% CI = 1.73-10.47; P= 0.002). CONCLUSIONS: Breast cancer patients with the HER2 germline mutation A270S had a worse survival, especially in HER2-negative patients. Therefore, HER2-negative patients with a HER2 germline mutation A270S might be potential candidates for HER2-targeted therapy.

Low expression of RECQL is associated with poor prognosis in Chinese breast cancer patients.

BACKGROUND: RECQL is a number of the RecQ DNA helicase family and plays an important role in maintaining genome stability. Although several studies have reported that RECQL mutations were correlated with the susceptibility to breast cancer, the effect on prognosis in breast cancer was not yet clarified. Here, we explored the association between RECQL expression level and survival in patients with breast cancer. METHODS: In the first cohort, the RECQL mRNA expression level was evaluated in 774 primary breast cancer patients using a quantitative real-time PCR assay. Then, in the second independent cohort, the level of RECQL protein expression was detected in 322 patients with breast cancer using immunohistochemistry assay. Survival curves of patients with RECQL expression were compared using the Kaplan-Meier method with log-rank test. RESULTS: In the first cohort of 774 breast cancer patients, the low expression level of RECQL mRNA was significantly correlated with aggressive clinicopathological characteristics, including the positive lymph node status (P = 0.026), HER2 overexpression (P < 0.001), ER negative status (P = 0.047) and high tumor grade (P = 0.041). Moreover, the low expression level of RECQL mRNA was significantly associated with poor distant recurrence-free survival (DRFS, unadjusted hazard ratio (HR): 2.77, 95% confidence interval (CI): 1.88-4.09, P < 0.001) and disease-specific survival (DSS, unadjusted HR: 3.10, 95% CI: 1.84-5.20,P < 0.001), and it remained an independent unfavorable factor for DRFS and DSS (DRFS: adjusted HR: 3.04, 95% CI: 1.89-4.87, P < 0.001; DSS: adjusted HR: 4.25, 95% CI: 2.12-8.46, P < 0.001). In the second cohort of 322 breast cancer patients, low expression of RECQL protein was also subject to poor survival in breast cancer, and it was an independent prognosis factor of poor DRFS by multivariate analysis (DRFS: adjusted HR: 2.12, 95% CI: 1.16-3.88, P = 0.015). CONCLUSIONS: Breast cancer patients with low RECQL expression had a worse survival. The expression level of RECQL may be a potential prognosis factor for breast cancer.

RAD50 germline mutations are associated with poor survival in BRCA1/2-negative breast cancer patients.

RAD50 is a highly conserved DNA double-strand break (DSB) repair gene. However, the associations between RAD50 germline mutations and the survival and risk of breast cancer have not been fully elucidated. Here, we aimed to investigate the clinical impact of RAD50 germline mutations in a large cohort of unselected breast cancer patients. In our study, RAD50 germline mutations were determined using next-generation sequencing in 7657 consecutive unselected breast cancer patients without BRCA1/2 mutations. We also screened for RAD50 recurrent mutations (L719fs, K994fs, and H1269fs) in 5000 healthy controls using Sanger sequencing. We found that 26 out of 7,657 (0.34%) patients had RAD50 pathogenic mutations, and 16 patients carried one of the three recurrent mutations (L719fs, n = 6 cases; K994fs, n = 5 cases; and H1269fs, n = 5 cases); the recurrent mutation rate was 0.21%. The frequency of the three recurrent mutations in the 5,000 healthy controls was 0.18% (9/5,000). These mutations did not confer an increased risk of breast cancer in the studied patients [odds ratios (OR), 1.16; 95% confidence interval (CI), 0.51-2.63; p = 0.72]. Nevertheless, multivariate analysis revealed that RAD50 pathogenic mutations were an independent unfavourable predictor of recurrence-free survival (RFS) [adjusted hazard ratio (HR) 2.66; 95% CI, 1.18-5.98; p = 0.018] and disease-specific survival (DSS; adjusted HR 4.36; 95% CI, 1.58-12.03; p = 0.004) in the entire study cohort. Our study suggested that RAD50 germline mutations are not associated with an increased risk of breast cancer, but patients with RAD50 germline mutations have unfavourable survival compared to patients without these mutations.

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.

Germline Mutations in Cancer Susceptibility Genes in a Large Series of Unselected Breast Cancer Patients.

Purpose: The prevalence of mutations in cancer susceptibility genes such as BRCA1 and BRCA2 and other cancer susceptibility genes and their clinical relevance are largely unknown among a large series of unselected breast cancer patients in the Chinese population.Experimental Design: A total of 8,085 consecutive unselected Chinese breast cancer patients were enrolled. Germline mutations in 46 cancer susceptibility genes were detected using a 62-gene panel.Results: Pathogenic mutations were identified in 9.2% of patients among the 8,085 unselected breast cancer patients. Of these, 5.3% of patients carried a BRCA1 or BRCA2 mutation (1.8% in BRCA1 and 3.5% in BRCA2), 2.9% carried other breast cancer susceptibility genes (BOCG) and 1.0% carried another cancer susceptibility genes. Triple-negative breast cancers had the highest prevalence of BRCA1/2 mutations (11.2%) and other BOCG mutations (3.8%) among the four molecular subgroups, whereas ER-/PR-HER2+ breast cancers had the lowest mutations in BRCA1/2 (1.8%) and BOCG (1.6%). In addition, BRCA1 mutation carriers had a significant worse disease-free survival [unadjusted hazard ratio (HR) 1.60; 95% confidence interval (CI) 1.10-2.34; P = 0.014] and disease-specific survival (unadjusted HR 1.96; 95% CI, 1.03-3.65; P = 0.040) than did non-carriers, whereas no significant difference in survival was found between BRCA2 mutation carriers and non-carriers.Conclusions: 9.2% of breast cancer patients carry a pathogenic mutation in cancer susceptibility genes in this large unselected series. Triple-negative breast cancers have the highest prevalence of mutations in BRCA1 /2 and other breast cancer susceptibility genes among the four molecular subgroups, whereas ER-/PR-HER2+ breast cancers had the lowest mutations in these genes. Clin Cancer Res; 23(20); 6113-9. ©2017 AACR.

HER2 Pro1170Ala polymorphism is associated with decreased survival rate in HER2-negative breast cancer.

The Pro1170Ala polymorphism is one of the most common polymorphisms of human epidermal growth factor receptor 2 (HER2) and may affect the clinical outcome in breast cancer. Therefore, in the present study, the incidence of the HER2 Pro1170Ala polymorphism was determined in 3,305 female patients with operable primary breast cancer using a DNA-sequencing assay, and the potential association with survival was investigated. Of these 3,305 patients, 29% (955/3,305) were homozygous for the Pro/Pro genotype, 51% (1,679/3,305) were heterozygous for the Pro/Ala genotype and 20% (671/3,305) were homozygous for the Ala/Ala genotype. The frequency of this polymorphism conformed to the Hardy-Weinberg equilibrium (P=0.175). No significant association between the HER2 Pro1170Ala polymorphism and recurrence-free survival (RFS) or distant recurrence-free survival (DRFS) was identified in the entire cohort of 3,305 patients. HER2 status was available for 3,170/3,305 patients; no significant association between the HER2 Pro1170Ala polymorphism and survival was identified in HER2-positive patients (n=728). However, among the HER2-negative patients (n=2,442), those with the Pro/Ala or Ala/Ala genotype had a significantly decreased RFS [unadjusted hazard ratio (HR), 1.45; 95% confidence interval (CI), 1.03-2.04; P=0.033] and DRFS (unadjusted HR, 1.65; 95% CI, 1.11-2.44; P=0.012) compared with those with the Pro/Pro genotype. Multivariate analysis revealed that the Pro/Ala or Ala/Ala genotype was an independent unfavorable factor for DRFS (adjusted HR, 1.63; 95% CI, 1.05-2.53; P=0.029) in the subgroup of HER2-negative patients. The results of the present study suggest that patients with HER2-negative breast cancer with the HER2 Pro1170Ala polymorphism variant exhibit a decreased survival outcome.

HER2 somatic mutations are associated with poor survival in HER2-negative breast cancers.

It is well documented that human epidermal growth factor receptor 2 (HER2) overexpression/amplification is associated with poor survival in breast cancer patients. However, it is largely unknown whether HER2 somatic mutations are associated with survival in HER2-negative breast cancer patients. Here, we identified HER2 somatic mutations in tumors from 1348 unselected breast cancer patients by sequencing the entire HER2 coding region. All of these mutations were tested for in corresponding blood samples to determine whether they were somatic or germline mutations. We further investigated the associations between HER2 somatic mutations and recurrence-free survival and distant recurrence-free survival in this cohort of patients. We found that 27 of 1348 (2.0%) of these patients carried a HER2 somatic mutation. In vitro experiments indicated that some of the novel mutations and those with unknown functions increased HER2 activity. HER2 status was available for 1306 patients, and the HER2 somatic mutation rates in HER2-positive (n = 353) and HER2-negative breast cancers (n = 953) were 1.4% and 2.3%, respectively. Among the HER2-negative patients, those with a HER2 somatic mutation had a significantly worse recurrence-free survival (unadjusted hazard ratio = 2.67; 95% confidence interval, 1.25-5.72, P = 0.002) and distant recurrence-free survival (unadjusted hazard ratio = 2.50; 95% confidence interval, 1.10-5.68, P = 0.004) than those with wild-type HER2. Taken together, our findings suggested that HER2 somatic mutations occur at a higher frequency in HER2-negative breast cancer, and HER2-negative breast cancer patients with these mutations have poor survival. Therefore, HER2-negative patients with a HER2 somatic mutation are potentially good candidates for HER2-targeted therapy.

Comprehensive analysis of BRCA1 and BRCA2 germline mutations in a large cohort of 5931 Chinese women with breast cancer.

We determined the prevalence and characteristics of BRCA1/2 germline mutations in a large cohort of Chinese women with breast cancer. A total of 5931 unselected Chinese women with breast cancer were enrolled in this study and underwent testing for BRCA1/2 mutations. Of these, 543 patients were familial breast cancer, 1033 were early-onset disease (≤40 years) without family history of breast cancer, and 4355 were sporadic breast cancer. In total, 232 patients (3.9 %) carried a BRCA1 or BRCA2 mutation (110 in BRCA1and 122 in BRCA2) in this cohort of 5931 patients. BRCA1/2 mutation rate was 16.9 % (92/543) in familial breast cancers, 5.2 % (54/1033) in early-onset breast cancers (≤40 years), and 2.0 % in sporadic breast cancers (>40 years), respectively. The BRCA1/2 mutation rate was 27.0 % in 111 familial breast cancers diagnosed at and before the age of 40. 41.4 % of mutations in this cohort were specific for Chinese population. Recurrent mutations accounted for 44.8 % of the entire mutations in 2382 cases that BRCA1 and BRCA2 genes were fully sequenced in this study. Both BRCA1 and BRCA2 mutation carriers were significantly more likely to be early-onset and bilateral breast cancers, high-grade cancer, and to have a family history of breast cancer compared with non-carriers. BRCA1 mutation carriers were more likely to be triple-negative cancer than BRCA2 mutation carriers and non-carriers. Our data provide guidelines for Chinese women with breast cancer who should undergo BRCA1/2 genetic testing; additionally, recurrent mutations account for nearly half of the mutations and some of them are specific for Chinese women.