Korean Hereditary Breast Cancer Research Articles

Pattern Anlysis of Risk-Reducing Strategies in Unaffected Korean BRCA1/2 Mutation Carriers.

The lifetime risk of breast and ovarian cancer increases substantially for individuals with mutations in BRCA1/2. The evidence indicates that BRCA1/2 mutation carriers benefit from early cancer detection and prevention strategies. However, data on the patterns of risk-reducing interventions are lacking. This study investigated the patterns of surveillance and risk-reducing interventions among unaffected BRCA1/2 mutation carriers. A cohort of unaffected BRCA1/2 mutation carriers was identified from the Korean Hereditary Breast cAncer (KOHBRA) study database, and a telephone survey was conducted. The survey included questions on the incidence of new cancers, patterns of cancer (breast, ovarian, prostate, other) surveillance, chemoprevention, risk-reducing surgery, and reasons for participating in risk-reducing strategies. Between November 2016 and November 2020, 192 BRCA1/2 mutation carriers were contacted, of which 83 responded. After excluding 37 responders who refused to participate, 46 participants (15 males, 31 females) were included in the analysis. The mean ± SD follow-up time was 103 ± 17 months (median 107, range 68~154), and the mean ± SD age was 31 ± 8 years. Ten BRCA1/2 mutation carriers developed breast cancer, one developed ovarian cancer, and three developed other cancers. Six BRCA1/2 mutation carriers (19.4%) underwent annual breast cancer surveillance as recommended by guidelines, while none underwent ovarian or prostate cancer surveillance. Three carriers (9.7%) used chemoprevention for breast cancer. Risk-reducing salpingo-oophorectomy was performed on only one BRCA1/2 mutation carrier. The rates of breast/ovarian cancer surveillance, chemoprevention, and risk-reducing surgery were low among unaffected Korean BRCA1/2 mutation carriers. Given this cohort's relatively high risk of developing breast cancer, strategies to encourage active participation in risk reduction are needed.

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.

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 theKorean Hereditary Breast Cancer Research at this time.

Isoflavone intake on the risk of overall breast cancer and molecular subtypes in women at high risk for hereditary breast cancer.

We investigated the association between isoflavone (ISF) intake and hereditary breast cancer (BC) risk, particularly by molecular subtype, in East-Asian BRCA1/2 mutation carriers and non-carriers at a high risk of hereditary breast cancer (i.e., family historyof BC (FHBC) and early-onset BC [EOBC, age < 40years]). The association between ISF intake and BC risk by molecular subtypes was assessed in 1709 participants (407 BRCA1/2 carriers, 585 FHBC non-carriers, 586 EOBC non-carriers, and 131 unaffected non-carriers) from the Korean Hereditary Breast Cancer Study using hazard ratios (HRs) and 95% confidence intervals (CIs) in weighted Cox regression models. Daily ISF intake was assessed using a validated food frequency questionnaire. We evaluated gene-environment interactions between BRCA1/2 mutation and ISF intake in 1604 BC cases by calculating the case-only odds ratios (CORs) and 95% CIs in logistic regression models. ISF intake was inversely associated with luminal A BC risk in BRCA2 mutation carriers and FHBC non-carriers (HR = 0.14, 95% CI = 0.04-0.50 for high intake [ISF intake ≥ 15.50mg/day]; HR = 0.27, 95% CI = 0.11-0.69 for high intake, respectively). We observed a reduced risk of triple negative BC (TNBC) in BRCA1 carriers and FHBC non-carriers (HR = 0.09, 95% CI = 0.02-0.40 for high intake; HR = 0.19, 95% CI = 0.05-0.69 for high intake, respectively). In the case-only design, an interaction between BRCA1 mutation carrier status and ISF intake emerged in TNBC patients (COR = 0.39, 95% CI = 0.16-0.95). This study suggests that ISF intake is inversely associated with BC risk in women at high risk of hereditary BC and that the effect could differ by molecular subtypes.

Clinicopathological Features of Patients with the BRCA1 c.5339T>C (p.Leu1780Pro) Variant.

PurposeRecent studies revealed the BRCA1 c.5339T>C, p.Leu1780Pro variant (L1780P) is highly suggested as a likely pathogenic. The aim of this study was to evaluate clinicopathologic features of L1780P with breast cancer (BC) using multicenter data from Korea to reinforce the evidence as a pathogenic mutation and to compare L1780P and other BRCA1/2 mutations using Korean Hereditary Breast Cancer (KOHBRA) study data.Materials and MethodsThe data of 54 BC patients with L1780P variant from 10 institutions were collected and the clinicopathologic characteristics of the patients were reviewed. The hereditary breast and/or ovarian cancer–related characteristics of the L1780P variant were compared to those of BC patients in the KOHBRA study.ResultsThe median age of all patients was 38 years, and 75.9% of cases showed triple-negative breast cancer. Comparison of cases with L1780P to carriers from the KOHBRA study revealed that the L1780P patients group was more likely to have family history (FHx) of ovarian cancer (OC) (24.1% vs. 19.6% vs. 11.2%, p < 0.001 and p=0.001) and a personal history of OC (16.7% vs. 2.9% vs. 1.3%, p=0.003 and p=0.001) without significant difference in FHx of BC and bilateral BC. The cumulative risk of contralateral BC at 10 years after diagnosis was 31.9%, while the cumulative risk of OC at 50 years of age was 20.0%. Patients with L1780P showed similar features with BRCA1 carriers and showed higher penetrance of OC than patients with other BRCA1 mutations.ConclusionL1780P should be considered as a pathogenic mutation. Risk-reducing salpingo-oophorectomy is highly recommended for women with L1780P.

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

PurposeBRCA1/2 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.MethodsWe 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.ResultsThe 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.ConclusionThe incidence of RRS increased each year throughout the study period. However, in Korea, the rate of RRS procedures depended on the hospital.

Reclassification of BRCA1 and BRCA2 variants of uncertain significance: a multifactorial analysis of multicentre prospective cohort

BackgroundBRCA1 and BRCA2 (BRCA1/2) variants classified ambiguously as variants of uncertain significance (VUS) are a major challenge for clinical genetic testing in breast cancer; their relevance to the cancer risk...

BRCA1/2-negative, high-risk breast cancers (BRCAX) for Asian women: genetic susceptibility loci and their potential impacts

“BRCAX” refers breast cancers occurring in women with a family history predictive of being a BRCA1/2 mutation carrier, but BRCA1/2 genetic screening has failed to find causal mutations. In this study, we report the findings of the genetic architecture of BRCAX with novel and redefined candidate loci and their potential impacts on preventive strategy. We performed a genome-wide association study involving 1,469 BRCAX cases from the Korean Hereditary Breast Cancer study, and high-risk breast cancer cases (1,482 Asians and 9,902 Europeans) from the Breast Cancer Association Consortium. We also evaluated the previously reported susceptibility loci for their roles in the high-risk breast cancers. We have identified three novel loci (PDE7B, UBL3, and a new independent marker in CDKN2B-AS1) associated with BRCAX, and replicated previously reported SNPs (24 of 92) and moderate/high-penetrance (seven of 23) genes for Korean BRCAX. For the novel candidate loci, evidence supported their roles in regulatory function. We estimated that the common low-penetrance loci might explain a substantial part of high-risk breast cancer (39.4% for Koreans and 24.0% for Europeans). Our study findings suggest that common genetic markers with lower penetrance constitute a part of susceptibility to high-risk breast cancers, with potential implications for a more comprehensive genetic screening test.

The Effect of Reproductive Factors on Breast Cancer Presentation in Women Who Are BRCA Mutation Carrier.

PurposeGermline mutations in the BRCA1 and BRCA2 genes confer increased risks for breast cancers. However, the clinical presentation of breast cancer among women who are carriers of the BRCA1 or BRCA2 (BRCA1/2 carriers) mutations is heterogenous. We aimed to identify the effects of the reproductive histories of women with the BRCA1/2 mutations on the clinical presentation of breast cancer.MethodsWe retrospectively analyzed clinical data on women with proven BRCA1 and BRCA2 mutations who were recruited to the Korean Hereditary Breast Cancer study, from 2007 to 2014.ResultsAmong the 736 women who were BRCA1/2 mutation carriers, a total of 483 women had breast cancers. Breast cancer diagnosis occurred at significantly younger ages in women who experienced menarche at ≤14 years of age, compared to those who experienced menarche at >14 years of age (37.38±7.60 and 43.30±10.11, respectively, p<0.001). Additionally, the number of full-term pregnancies was significantly associated with the age of diagnosis, especially in women with the BRCA2 mutation. The prevalence of advanced stages (stage II or III vs. stage I) of disease in parous women was higher than in nulliparous women (68.5% vs. 55.2%, p=0.043). This association was more pronounced in women with the BRCA2 mutation (hazard ratio, 2.67; p=0.014).ConclusionOur results suggest that reproductive factors, such as the age of onset of menarche and the presence of parity, are associated with the clinical presentation patterns of breast cancer in BRCA1/2 mutation carriers.

KOHBRA BRCA risk calculator (KOHCal): a model for predicting BRCA1 and BRCA2 mutations in Korean breast cancer patients.

The widely used Western BRCA mutation prediction models underestimated the risk of having a BRCA mutation in Korean breast cancer patients. This study aimed to identify predictive factors for BRCA1/2 mutations and to develop a Korean BRCA risk calculator. The model was constructed by logistic regression model, and it was based on the Korean Hereditary Breast Cancer study, in which 1669 female patients were enrolled between May 2007 and December 2010. A separate data set of 402 patients, who were enrolled from Jan 2011 to August 2012, was used to test the performance of our model. In total, 264 (15.8%) and 67 (16.7%) BRCA mutation carriers were identified in the model and validation set, respectively. Multivariate analysis showed that age at breast cancer diagnosis, bilateral breast cancer, triple-negative breast cancer (TNBC) and the number of relatives with breast or ovarian cancer within third-degree relatives were independent predictors of the BRCA mutation among familial breast cancer patients. An age <35 years at diagnosis, bilateral breast cancer, both breast and ovarian cancer and TNBC remained significant predictors in non-familial breast cancer cases. Our model was developed based on logistic regression models. The validation results showed no differences between the observed and expected carrier probabilities. This model will be a useful tool for providing genetic risk assessments in Korean populations.

Breast cancer risk for Korean women with germline mutations in BRCA1 and BRCA2.

The average age-specific cumulative risk (penetrance) of breast cancer has been studied for BRCA1 and BRCA2 mutation carriers living in Western countries, but not for those living in East Asian countries where the population breast cancer incidence is lower. From 2007 to 2011, the Korean Hereditary Breast Cancer study identified 151 BRCA1 and 225 BRCA2 mutation-carrying families from family cancer clinics. We estimated the hazard ratio (HR) for female carriers relative to the population, and hence the penetrance, using a modified segregation analysis of cancer family histories conditioned on ascertainment. The breast cancer HR estimates [95 % confidence interval (CI)] for BRCA1 and BRCA2 mutation carriers were 18 (3-103) and 11 (5-27), respectively. The breast cancer penetrance estimates (95 % CI) to age 70 years were 49 % (11-98) and 35 % (16-65) for BRCA1 and BRCA2 mutation carriers, respectively. The breast cancer HR and penetrance estimates were similar for Korean and Western women (all P > 0.4). The point estimates of breast cancer penetrance were similar to age 50 years, though less for Korean carriers at older ages. Breast cancer risk for Korean and Western mutation carriers might reflect underlying population risks which in turn likely reflect differences in environmental and lifestyle factors. This raises the possibility of identifying modifiers of cancer risk for carriers with implications for prevention.

Abstract P3-08-05: Association of mammographic density in high risk BRCA mutated tumors compared to average risk tumors and healthy controls: Analysis of Korean Hereditary Breast and Cancer Study (KOHBRA)

Abstract Introduction: Mammographic density is a well-known risk factor of breast cancer as a whole. Nonetheless only few studies have examined the association of density among high risk breast cancer regarding BRCA mutation. We examined mammographic density of 2019 breast cancer patients and 2029 healthy controls, regarding risk factors and BRCA mutation status. Method: Total 2019 breast cancer patients diagnosed between 1980 to 2011 were divided into two groups- high versus average risk group. Women with 1)family history of breast/ovarian cancer or 2)younger than age 40 or 3)bilateral cases were considered high risk group and were participants of ‘Korean Hereditary Breast Cancer study’ (KOHBRA) whom undergone BRCA testing. Density of 2029 healthy women who took screening mammogram during the same period were analyzed for comparison. Density was measured of the unaffected contralateral CC view using computer-assisted method Cumulus by single observer (10% randomly selected, intra-class correlation coefficient=0.96). Percent density (PD, dense area/breast area, %) among three groups, association with BRCA mutation status and breast cancer subtypes were examined. Results and Discussion: Percent density (PD) was significantly higher in high risk group compared to average risk and controls in a consecutive manner. This finding was consistent after adjusting age and BMI (p*&amp;lt;0.001). Mammographic percent density(PD) among three group (high risk cancer vs average risk cancer vs control)High risk cancers (N=1066)Average risk cancers (N=953)Control (N=2029)High vs AverageHigh vs controlAverage vs controlAge(yr)mean±SD41.12±9.8651.03±7.9850.52±9.090.001&amp;lt;0.0010.141PD (%)mean±SD52.90±12.9345.52±16.0441.52±15.80&amp;lt;0.001 (&amp;lt;0.001*)&amp;lt;0.001 (&amp;lt;0.001*)&amp;lt;0.001 (&amp;lt;0.001*)PD_median (%)&amp;lt;50442 (41.5%)567 (59.4%)1414 (69.7%)&amp;lt;0.001&amp;lt;0.001&amp;lt;0.00150≤624 (58.5%)387 (40.6%)615 (30.3%)PD_quartile (%)&amp;lt;2526 (2.4%)106 (11.1%)329 (16.2%)&amp;lt;0.001&amp;lt;0.001&amp;lt;0.00125≤ &amp;lt;50416 (39.0%)461 (48.3%)1085 (53.5%)50≤ &amp;lt;75564 (52.9%)360 (37.7%)570 (28.1%)75≤60 (5.6%)27 (2.8%)45 (2.2%)* adjusted p value by age and BMI High mammographic density showed to be a significant risk factor throughout different subtypes. Magnitude of mammographic density as a risk factor according to receptor statusTNBC (control(ref))Non-TNBCLuminalNon-Luminal25%≤PD&amp;lt;50% (&amp;lt;25%(ref))HR 4.21, 95%CI 2.12-8.38HR 1.91, 95%CI 1.50-2.43HR 1.77, 95%CI 1.38-2.26HR 3.04, 95%CI 2.00-4.6450%≤PD&amp;lt;75%HR 8.85, 95%CI 4.45-17.61HR 3.81, 95%CI 2.98-4.89HR 3.89, 95%C I3.03-5.00HR 5.08, 95%CI 3.32-7.8075%≤PDHR 16.25, 95%CI 6.97-37.87HR 4.09, 95%CI 2.61-6.41HR 4.09, 95%CI 2.61-6.43HR 8.16, 95%CI 4.41-15.07 Among the 1066 high risk group, 81.5% (869) undergone BRCA testing and 70(6.6%) had BRCA1, 78(7.3%) had BRCA2 mutations without significant difference in density. Similar strong magnitude association of mammographic density was observed in both BRCA mutated/non-mutated tumors and among subtypes. The ongoing GWAS and whole exome analysis of this population-subset will give insight into the tumor etiology and how density could stratify breast cancer risk for personalized screening especially in high risk population. Citation Format: Jisun Kim, Jong Won Lee, Sung Won Park, Hee Jung Shin, Hak Hee Kim, Sae-Byul Lee, Jong Han Yu, Hee Jeong Kim, Beom Seok Koh, Byung Ho Son, Sei-Hyun Ahn. Association of mammographic density in high risk BRCA mutated tumors compared to average risk tumors and healthy controls: Analysis of Korean Hereditary Breast and Cancer Study (KOHBRA) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-08-05.

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

The Korean Hereditary Breast Cancer (KOHBRA) study was established to evaluate the prevalence and spectrum of BRCA1/2 mutations in Korean breast cancer patients at risk for hereditary breast and ovarian cancer. A total of 2953 subjects (2403 index patients and 550 family members of affected carriers) from 36 centers participated in this study between May 2007 and December 2013. All participants received genetic counseling and BRCA genetic testing. In total, 378 mutation carriers among 2403 index patients were identified. The prevalence of BRCA mutations in specific subgroups was as follows: 22.3% (274/1228) for breast cancer patients with a family history of breast/ovarian cancers, 8.8% (39/441) for patients with early-onset (<35years) breast cancer without a family history, 16.3% (34/209) for patients with bilateral breast cancer, 4.8% (1/21) for male patients with breast cancer, and 37.5% (3/8) for patients with both breast and ovarian cancer. From an analysis of the mutation spectrum, 63 BRCA1 and 90 BRCA2 different mutations, including 44 novel mutations, were identified. The c.7480 (p.Arg2494Ter) mutation in BRCA2 (10.1%) was the most commonly identified in this cohort. The KOHBRA study is the largest cohort to identify BRCA mutation carriers in Asia. The results suggest that the prevalence of BRCA mutations in familial breast cancer patients is similar to that among Western cohorts. However, some single risk factors without family histories (early-onset breast cancer, male breast cancer, or multiple organ cancers) may limit the utility of BRCA gene testing in the Korean population.

Dietary intake and breast cancer among carriers and noncarriers of BRCA mutations in the Korean Hereditary Breast Cancer Study

Soy intake is associated with a lower risk of breast cancer. However, it is unclear whether the same reduction in risk associated with high soy intake is also applicable to familial or genetic breast cancer. The aim of this study was to assess the dietary factors among carriers and noncarriers of BRCA mutations in the Korean Hereditary Breast Cancer Study (KOHBRA). The KOHBRA Study is an ongoing project composed of affected breast cancer patients and familial members of breast cancer cases with BRCA mutations. To assess the association between dietary diversity and breast cancer risk, an HR was estimated by comparing affected subjects with their familial nonaffected members. To assess the interaction between the combination of BRCA mutation and diet diversity, the case-only OR (COR) was estimated by comparing BRCA mutation carriers and noncarriers only in affected subjects. Soy product intake was associated with a lower risk of breast cancer in carriers (HR: 0.39; 95% CI: 0.19, 0.79 for the highest quartile). The highest quartile of meat intake was associated with a higher risk of breast cancer regardless of BRCA mutation in carriers (HR: 1.97; 95% CI: 1.13, 3.44) and noncarriers (95% CI: 1.41; 1.12, 1.78). The associations of meat intake and soybean intake for breast cancer were more prominent in BRCA2 mutation carriers. In the analysis with only cases, the highest quartile of soy intake, but not meat intake, was associated with BRCA-related breast cancer (COR: 0.57; 95% CI: 0.36, 0.91). Our study suggests that soy product consumption is associated with lower breast cancer risk and it had an interaction with BRCA mutation.

The Korean Hereditary Breast Cancer Study: Review and Future Perspectives

Most studies related to BRCA mutations have been performed in Western populations, and only a few small studies have been conducted in Korean populations. In 2007, the Korean Hereditary Breast Cancer (KOHBRA) Study was established to obtain evidence for the accurate risk assessment and management of hereditary breast and ovarian cancer (HBOC) in Korea. Between May 2007 and May 2010, the first phase of the KOHBRA Study was performed to estimate the prevalence of BRCA1/2 mutations among patients and their families at risk for HBOC. Between June 2010 and May 2013, the second phase of the KOHBRA Study was performed to identify the clinical characteristics and prognostic indicators of BRCA-related breast cancer and environmental and genetic modifiers of BRCA mutations and to develop a Korean BRCA risk calculator and nationwide genetic counseling network for HBOC. Herein, we review the results of the KOHBRA Study and describe the future perspectives of the study.

The prevalence of BRCA mutations among familial breast cancer patients in Korea: results of the Korean Hereditary Breast Cancer study

The primary aim of this study was to estimate the prevalence of BRCA1/2 mutations among familial breast cancer (BC) patients in Korea. We analyzed 775 familial BC patients who were enrolled in the Korean Hereditary Breast Cancer (KOHBRA) study and treated at 36 institutions between May 2007 and May 2010. Patients with familial BC were defined as BC patients with family histories of BC or ovarian cancer (OC) in any relatives. All probands received genetic counseling and BRCA genetic testing was performed after obtaining informed consent. The mean age of BC diagnosis was 43.6 years. The numbers of probands with family histories of BC only and OC only were 682 and 93, respectively. The overall prevalence of the BRCA mutation among familial BC patients was 21.7 % (BRCA1 9.3 % and BRCA2 12.4 %). Subgroup analyses observed prevalences of the BRCA mutation as follows: 19.6 % among patients with BC family history only (BRCA1 7.6 % and BRCA2 12.0 %) and 36.6 % among patients with OC family history only (BRCA1 21.5 % and BRCA2 15.1 %). Most of the subgroups satisfied the 10 % probability criteria to undergo BRCA testing. However, the prevalence of the BRCA mutations among subgroups that had 2 BC patients in a family with both age at diagnosis of more than 50 years old did not reach the 10 % criteria (4.1 %). Korean familial BC patients are good candidates for BRCA testing even when they have family histories of single breast cancers. However, proband age at diagnosis should be carefully considered when selecting patients for testing.

Characteristics and spectrum of BRCA1 and BRCA2 mutations in 3,922 Korean patients with breast and ovarian cancer

This investigation is aimed at evaluating the epidemiologic characteristics of BRCA1/2 germline mutations in Korean patients with breast and ovarian cancer (BOC). We analyzed the entire mutational data of BRCA1/2 genes in BOC patients who were tested in Korea since the first Korean report of BRCA1 mutation in 1995 with the exception of the data covered in the Korean Hereditary Breast Cancer (KOHBRA) study, the project launched in 2007 for establishing BRCA1/2 carrier cohorts in Korea. In total, BRCA1/2 gene mutations of 3,922 Korean BOC patients were evaluated, including the unpublished data of 2,139 breast cancer patients examined by four Korean institutions and the data of 1,783 BOC patients covered in ten previous reports. Overall, 420 (150 distinct) pathogenic mutations were identified, 211 (73 distinct) in BRCA1 and 209 (77 distinct) in BRCA2. The majority (134 of 150) of the distinct mutations resulted in premature termination codon of the BRCA1/2 translation. BRCA1 c.4186-1593_4676-1465del was the only large genomic rearrangements mutation. Out of 150 distinct BRCA1/2 mutations, 84 (56 %) mutations were considered specific to Korean BOC. Eighty-five BRCA1/2 mutations were detected in at least two unrelated patients. These recurrent mutations account for 84.5 % (355 of 420) of mutations detected in the Korean population. In the pooled mutational data of BRCA1/2 genes, this study discovered the prevalence of BRCA1/2 mutations in the Korean BOC patients is similar to those found in other ethnic groups. Large genomic rearrangements in BRCA1/2 genes were infrequently detected among the Korean patients with BOC. There were several BRCA1/2 mutation candidates for founder mutations. To further establish a Korean cohort for BRCA1/2 mutations, the nationwide KOHBRA study is in progress.

Prevalence of BRCA1 and BRCA2 mutations in non-familial breast cancer patients with high risks in Korea: The Korean Hereditary Breast Cancer (KOHBRA) Study

Prevalence and phenotype of BRCA mutation can vary by race. The purpose of this study is to evaluate the prevalence of BRCA1/2 mutations in non-familial breast cancer patients with high risks in Korea. A subset of 758 patients was selected for this study from the KOHBRA nationwide multicenter prospective cohort study. Mutations in BRCA1/2 genes were tested using fluorescent-conformation sensitive gel electrophoresis, denaturing high performance liquid chromatography or direct sequencing. Mutation of BRCA1/2 genes were identified in 65 (8.6%) patients among total 758 patients [BRCA1 mutation: 25 (3.3%), BRCA2 mutation: 40 (5.3%)]. According to risk groups, mutation of BRCA1/2 genes were identified in 53 (8.5%) of 625 early onset patients (age ≤40), in 22 (17.7%) of 124 bilateral breast cancer patients, in 3 (50.0%) of 6 breast and ovarian cancer patients, in one (5.9%) of 17 male breast cancer patients, in 5 cases (7.6%) of 66 multiple organ cancer patients. The most common mutation was 509C>A for BRCA1 and 7708C>T for BRCA2. The prevalence of BRCA1/2 mutations by age in early onset patients was significantly different (age <35 vs age ≥35; 10.0 vs 2.9%, p = 0.0007). BRCA1/2 mutations for non-familial Korean breast cancer patients were detected at a high rate, particularly, in patients with early onset of less than 35 years of age, bilateral breast cancer, and breast and ovarian cancer. Individualized genetic counseling should be offered for non-familial breast cancer patients with these risk factors.

Communication with Family Members about Positive BRCA1/2 Genetic Test Results in Korean Hereditary Breast Cancer Families

’Materials and Methods: A total of 106 probands who had positive BRCA genetic test results from the Korean Hereditary Breast Cancer Study participated in our study. Subjects were asked whether they had disclosed their genetic test results to first-, second-, and third-degree relatives. Univariate and multivariate analyses were used to identify factors associated with positive result sharing with close and distant relatives. Results: In total, 99 respondents (93.4%) informed at least one at-risk relative of the test result, and they all reported that they had disclosed their genetic test result to a first-degree relative. Communication of test results to other relatives occurred significantly less often, with only 31 of 99 subjects (31.3%) sharing their results with second- or third-degree relatives. In the results of univariate analyses, disclosure of genetic test results to more distant relatives was associated with marital status and months since post-test counseling. The reasons for communication were to provide information about the BRCArelated cancer risk and to recommend the genetic test. Conclusion: Most individuals with the BRCA mutation share their test results with first-degree family members; however, these results reach more distant relatives significantly less often. Therefore, it is necessary to encourage patients communication with extended family members through systematic genetic

The Korean Hereditary Breast Cancer (KOHBRA) Study: Protocols and Interim Report

Aims The primary aims of the Korean Hereditary Breast Cancer (KOHBRA) study are to estimate the prevalence of BRCA1/2 mutations and ovarian cancer among a high-risk group of patients with hereditary breast cancer and their families. Materials and methods The KOHBRA study is a prospective multicentre cohort identifying cases and their families. Between May 2007 and May 2010, the KOHBRA study enrolled up to 2000 subjects. All participants received genetic counselling and BRCA genetic testing; the clinical information and blood samples for blood banking were collected. An interim analysis of the prevalence of BRCA1/2 mutations and ovarian cancer in Korean subjects was determined from the initial 975 patients who presented to 33 centres. Results By April 2009, a total of 167 mutation carriers among 853 probands were identified. The prevalence of the BRCA mutation was as follows: 24.8% (106/428) for breast cancer patients with a family history of breast/ovarian cancers; 11.3% (24/212) for patients with early-onset (<35 years) breast cancer without a family history; 22.1% (15/68) for patients with bilateral breast cancer; male breast cancer in 8.3% (1/12); and 33.4% (1/3) for patients with breast and ovarian cancer. Conclusions The results of this study suggest that the prevalence of BRCA mutations in Korean subjects is similar to the prevalence reported among Western cohorts. However, weak family history and non-familial early-onset of breast cancer were significant factors associated with carrying the BRCA mutation in Korean breast cancer patients. Completion of the KOHBRA study is needed to confirm these findings.