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Purpose We aimed to analyze the treatment outcomes of ipsilateral cervical lymph node (CLN)-positive breast cancer without other distant metastasis and compare the outcomes with those of supraclavicular lymph node (SCL)-positive breast cancer. Methods Seventy-eight patients with breast cancer and ipsilateral CLN metastasis above the supraclavicular fossa (CLN[+] group) were treated at 7 institutions (2000-2014). Seventy-four patients received systemic chemotherapy and breast surgery followed by locoregional radiotherapy. Outcomes of the CLN(+) group were compared with those of the SCL(+) group, which included 183 patients with SCL involvement. Results The median follow-up duration was 55.9 months. Twenty-two regional failures were found in 15 patients-axillary lymph node (LN) in 8, SCL in 6, internal mammary LN in 3, previously involved CLN in 4, and previously uninvolved ipsilateral CLN in one patient. The 5-year overall survival (OS), disease-free survival (DFS), locoregional relapse-free survival (LRRFS), and distant metastasis-free survival (DMFS) rates were 68.6%, 46.7%, 68.4%, and 57.0%, respectively. Neck dissection did not improve LRRFS and DFS (p = 0.86 and p = 0.26, respectively). Multivariate analysis showed that hormone receptor negativity and the presence of extracapsular extension were prognostic factors for poor DFS. On comparison with stage IIIC using propensity score matching, survival outcomes of the CLN(+) and SCL(+) groups were not different (5-year OS, p = 0.75; DFS, p = 0.88; LRRFS, p = 0.86; and DMFS, p = 0.45). Conclusion The comparable clinical outcomes indicate that patients with breast cancer who have ipsilateral CLN metastasis without other distant metastasis may benefit from locoregional treatment of the ipsilateral breast and systemic therapies, as do those with N3c disease.

Purpose In some patients who receive adjuvant radiotherapy (RT) for the left breast, the stomach is located inside the RT field. This study investigates the incidence of gastric complications following adjuvant RT for breast cancer using data of the Health Insurance Review and Assessment Service in South Korea. Methods We identified 37,966 women who underwent surgery and received adjuvant RT for breast cancer. The cumulative incidence rate of gastric hemorrhage and gastric cancer was calculated and compared for left and right breast cancers. Results Among 37,966 patients, 19,531 (51.4%) and 18,435 (48.6%) had right and left breast cancers, respectively. After a median follow-up duration of 6.3 years, the cumulative incidence of gastric cancer and gastric hemorrhage did not differ between right and left breast cancers (p = 0.414 and p = 0.166, respectively). The multivariable analysis revealed that old age was the only factor associated with the development of gastric cancer (p < 0.001) and gastric hemorrhage (p < 0.001). The incidence of gastric cancer and hemorrhage did not differ between patients who received adjuvant RT for right and left breast cancers. Conclusion Irradiation-related chronic complications of the stomach in patients with breast cancer are minimal. A study with a longer follow-up duration might be needed to assess the risk of gastric cancer.

Purpose The purpose of this study was to evaluate the risk of central nervous system (CNS) failure in Korean patients with human epidermal growth factor receptor 2 (HER2)-enriched breast cancer treated with surgery followed by postoperative radiotherapy (RT). Methods A total of 749 patients from eight institutions were enrolled in this study. All of them underwent surgery followed by postoperative RT from 2003 to 2011; 246 (32.8%) received neoadjuvant chemotherapy and 649 (81.7%) received adjuvant chemotherapy. Adjuvant trastuzumab was administered to 386 patients (48.6%). Results The median follow-up duration was 84 (range, 8-171) months. The 7-year disease-free and overall survival rates were 79.0% and 84.2%, respectively. On multivariate analysis, mastectomy, nodal involvement, and presence of lymphatic invasion were correlated with poor overall survival (p = 0.004, 0.022, and 0.011, respectively), whereas T stage and lymphatic invasion were associated with disease-free survival (p = 0.018 and 0.005, respectively). Regarding CNS failures, 30 brain metastases, 2 leptomeningeal metastases, and 8 brain and leptomeningeal metastases were noted. The 7-year CNS relapse-free survival rates in patients receiving and not receiving trastuzumab were 91.2% and 96.9%, respectively (p = 0.005). On multivariate analysis, the administration of adjuvant trastuzumab was the only prognostic factor in predicting a higher CNS failure rate (hazard ratio, 2.260; 95% confidence interval, 1.076-4.746; p = 0.031). Conclusion Adjuvant trastuzumab was associated with higher CNS failure rate in Korean patients with HER2-enriched breast cancer. Close monitoring and reasonable approaches such as CNS penetrating HER2 blockades combined with the current standard therapy could contribute to improving intracranial tumor control and quality of life in patients with CNS metastasis from HER2-enriched breast cancer.

Purpose In this study, we examined the impact of reconstruction using tissue expander insertion (TEI) on the risk of radiation dermatitis in patients undergoing postmastectomy radiotherapy (PMRT). Methods Between August 2015 and March 2019, patients with breast cancer who had received systemic chemotherapy and PMRT were prospectively included. Skin parameters, including melanin, erythema, hydration, sebum, and elasticity, were measured using a multi-probe instrument at 6 time points: before the initiation of radiotherapy (pre-RT), at weeks 1, 3, and 5 during radiotherapy (weeks 1-5), and 1 and 3-month after radiotherapy (post-RT-1m and post-RT-3m). Patient-reported outcomes (PROs) were assessed at each time point. Changes in biophysical parameters and PRO were compared between patients with and without TEI (TEI+ vs. TEI-). Results Thirty-eight patients, including 18 with TEI+ and 20 with TEI-, were analyzed. The pattern of time-course changes in biophysical parameters and PRO did not differ between TEI+ and TEI- patients. The melanin index was highest at post-RT-1m, while the erythema index was highest at week 5. At post-RT-3m, TEI+ patients presented higher melanin values than TEI- patients, with no statistical significance (coefficient, 47.9 vs. 14.2%; p = 0.07). In all patients, water content decreased throughout the measurement period. At post-RT-3m, TEI+ patients demonstrated a further decrease in water content, while the TEI- group nearly recovered the water content to pre-RT status (coefficient, -17.1, -2.5; p = 0.11). The sebum and elasticity levels were not altered by TEI. Conclusion In patients undergoing PMRT, TEI did not significantly affect the changing patterns of skin biophysical parameters and PRO during radiotherapy.

Purpose This study aimed to identify risk factors that have significant interaction with radiation exposure to the heart, and thus to determine candidates for heart-sparing radiotherapy (RT) among women with left breast cancer. Methods We identified 4,333 patients who received adjuvant RT following breast-conserving surgery for ductal carcinoma in situ or invasive breast cancer from 1996 to 2010. Incidence rates of cardiovascular disease were compared between left-sided and right-sided RT, and stratified by age and risk factors such as body mass index (BMI), smoking, hyperlipidemia, hypertension, diabetes, administration of anthracycline, and trastuzumab. Results In all patients, the cumulative incidence of cardiovascular disease was greater in patients treated with left-sided RT than in those treated with right-sided RT, but the difference was not significant (p=0.428). Smoking (hazard ratio [HR], 5.991; 95% confidence interval [CI], 2.109-17.022; p=0.002) and hyperlipidemia (HR, 5.567; 95% CI, 3.235-9.580; p

Purpose The benefit of post-mastectomy radiation therapy (PMRT) in patients with breast cancer who achieve ypN0 following neoadjuvant chemotherapy (NAC) has not yet been established. This study aimed to identify the role of PMRT in patients who achieve ypN0 according to molecular subtype. Methods We identified patients initially suspected with axillary disease who achieved ypN0 following NAC. From 13 institutions of the Korean Radiation Oncology Group between 2005 and 2011, a total of 189 patients were included in the analysis. Effects of PMRT on loco-regional control (LRC), disease-free survival (DFS), and overall survival (OS) were evaluated for different molecular subtypes. Results In all patients, the prognostic effect of PMRT on LRC, DFS, or OS was not significant. Subgroups analysis showed that the effect of PMRT on LRC was different according to molecular subtype (p for interaction = 0.019). PMRT was associated with greater LRC in the luminal subtype (p = 0.046), but not in other subtypes. Conclusion In patients who achieve ypN0 following NAC and mastectomy, PMRT shows no additional survival benefits for any molecular subtype.

Adjuvant radiotherapy (RT) is a well-established treatment for breast cancer. However, there is a large degree of variation and controversy in practice patterns. A nationwide survey on the patterns of practice in breast RT was designed by the Division for Breast Cancer of the Korean Radiation Oncology Group. All board-certified members of the Korean Society for Radiation Oncology were sent a questionnaire comprising 39 questions on six domains: hypofractionated whole breast RT, accelerated partial breast RT, postmastectomy RT (PMRT), regional nodal RT, RT for ductal carcinoma in situ, and RT toxicity. Sixty-four radiation oncologists from 54 of 86 (62.8%) hospitals responded. Twenty-three respondents (35.9%) used hypofractionated whole breast RT, and the most common schedule was 43.2 Gy in 16 fractions. Only three (4.7%) used accelerated partial breast RT. Five (7.8%) used hypofractionated PMRT, and 40 (62.5%) had never used boost RT after chest wall irradiation. Indications for regional nodal RT varied; ≥pN2 (n=7) versus ≥pN1 (n=17) versus ≥pN1 with pathologic risk factors (n=40). Selection criteria for internal mammary lymph node (IMN) irradiation also varied; only four (6.3%) always treated IMN when regional nodal RT was administered and 30 (46.9%) treated IMN only if IMN involvement was identified through imaging. Thirty-one (48.4%) considered omission of whole breast RT after breast-conserving surgery for ductal carcinoma in situ based on clinical and pathologic risk factors. Fifty-two (81.3%) used heart-sparing techniques. Overall, there were wide variations in the patterns of practice in breast RT in Korea. Standard guidelines are needed, especially for regional nodal RT and omission of RT for ductal carcinoma in situ.

We describe two cases of post-radiation sarcoma after breast cancer treatment. The first patient was a 61-year-old woman who underwent partial mastectomy of the right breast and adjuvant whole breast irradiation 7 years previously. Subsequently, a rapidly growing mass from the anterior arc of the right fifth rib was incidentally detected on an abdomino-pelvic computed tomography scan. The second patient was a 70-year-old woman who received neoadjuvant chemotherapy and a partial mastectomy of the left breast 9 years ago. Adjuvant irradiation was delivered to the whole breast and supraclavicular region. Subsequently, an approximate 8 cm mass developed in the left axillary area. Both patients received wide excision of the tumor with negative resection margins. The pathological diagnoses were osteosarcoma and undifferentiated pleomorphic sarcoma, respectively. Although post-radiation sarcomas are rare complications with a poor prognosis, enhanced awareness and early detection by clinicians are essential to improve outcomes via curative surgical resection.

Purpose: To study clinical features and patterns of recurrence after breast-conserving treatment (BCT) for three molecular subtypes of early stage breast cancer. Methods: The sample studied included 596 patients with T1-2N0-1 breast cancer who received BCT. Three groups were defined by receptor status. Luminal: es trogen receptor (ER) or progesterone receptor (PR) positive; triple negative (TN): ER, PR, and epidermal growth factor receptor-2 (HER2) receptor negative; and HER2 overexpressing: ER and PR negative but HER2 receptor positive. Results: The number of patients in each group was 408 (68.5%), 105 (17.6%), and 83 (13.9%), respectively. The median follow-up period was 79 months. The TN and HER2 subtypes occurred in younger patients (p= 0.0007) and had higher nuclear grade and poorer histologic grade (p< 0.0001 and 0.0071, respectively). During the follow-up period, locoregional recurrence was detected as the first site of recurrence in 26 (6.4%), 11 (10.5%), and 9 (10.8%) patients in the luminal, TN, and HER2 subtypes, respectively (p= 0.1924). Thirty-one (7.6%), 7 (6.7%), and 7 (8.4%) patients in each group had distant metastases as the first sign of recurrence ( p= 0.8996). Median time to locoregional and distant recurrence was shorter in the HER2 subtype (p= 0.0889 and 0.0780, respectively), and the HER2 subtype was significantly associated with poor overall survival (p=0.0009). Conclusion: After BCT in Korean women with early stage breast cancer, the patterns of recurrence were not different among the molecular subtypes, although the TN and HER2 subtypes were associated with younger age, higher nuclear grade, and poorer histologic grade.

Purpose The optimal indications for omitting adjuvant radiation therapy (RT) after breast-conserving surgery are still controversial in ductal carcinoma in situ (DCIS) of the breast. The purpose of this study was to validate the role of postoperative RT in DCIS patients aged ≤50 years and with tumor margin widths of

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

Purpose: We investigated the relationship between BRCA mutations and the distribution of familial cancers other than breast or ovary in high-risk breast cancer patients. Methods: Patients with breast cancer who had at least one of the following risk factors were enrolled: reported family history of breast or ovarian cancer; 40 years of age or younger age at diagnosis; bilateral breast cancer; or male gender. Genetic testing for BRCA mutation and questionnaires about personal and family histories of malignancies were performed. Results: Among the 238 eligible patients, 49 (20.6%) patients had BRCA1/2 mutations, which were more frequent in patients with multiple risk factors (p< 0.0001). There were 271 members of 156 (65.5%) families who had histories of other primary cancer. The distribution of the families was 119 (63.0%) and 37 (75.5%) in the BRCA-negative and positive group, respectively (p= 0.0996). Multiple familial cancers occurred in 70 families, which were significantly more frequent in BRCApositive families (p= 0.0034). By ordinal logistic regression, the occurrence of multiple familial cancers was associated with BRCA mutations (p= 0.0045), not with other risk factors. The most common site of disease was the stomach, which is the most common in nationwide. And the proportional incidence of pancreatic cancer (6.8%) was significantly higher than that of nationwide cancer statistics (2.4%, p= 0.0137). Conclusion: BRCA mutations in high-risk breast cancer patients were associated with multiple risk factors and multiple family members with other primary cancers. Genetic counseling based on accurate information should be provided to families with BRCA mutation carriers.

Purpose The purpose of this study was to assess the incidence of invasive lobular carcinoma (ILC) and to compare the clinicopathological features and treatment results after breast conserving surgery (BCS) followed by radiotherapy between ILC and invasive ductal carcinoma (IDC). Methods A total of 1,071 patients who underwent BCS followed by radiotherapy were included in the study. Medical records and pathological reports were retrospectively reviewed. Results The incidence of ILC was 5.2% (n=56). Bilateral breast cancer, lower nuclear grade, and hormone receptor-positive breast cancer were more frequent in patients with ILC than in those with IDC. There were no cases of lymphovascular invasion or the basal-like subtype in patients with ILC. There were no statistically significant differences in patterns of failure or treatment outcomes between patients with ILC and those with IDC. The development of metachronous contralateral breast cancer was more frequent in patients with IDC (n=27). Only one patient with ILC developed contralateral breast cancer, with a case of ductal carcinoma in situ. Conclusion The incidence of ILC was slightly higher in our study than in previous Korean studies, but was lower than the incidences reported in Western studies. The differences we observed in clinico pathological features between ILC and IDC were similar to those described elsewhere in the literature. Although there were no statistically significant differences, there was a trend toward better disease-specific survival and disease-free survival rates in patients with ILC than in those with IDC.

Purpose: We investigated the relationship between BRCA mutations, pathological findings, and magnetic resonance imaging (MRI) features in patients with breast cancer at risk for the mutation. Methods: Genetic testing for BRCA mutations was performed in 275 breast cancer patients with at least one risk factor for the mutation. Using the breast imaging reporting and data system MR lexicon, morphological and kinetic features were reviewed on MRI scans of 230 tumors in 209 patients. The relationship between BRCA mutations, pathologic findings, and MRI data was examined, and disease recurrence was estimated. Results: BRCA mutations were detected in 48 patients (23.0%), of which 21 (10.0%) were in BRCA1, and 25 (12.0%) in BRCA2. Additionally, two patients (1.0%) had mutations in both genes. Cancers in patients with BRCA1 mutations more frequently showed a higher nuclear grade (p= 0.0041), and triple-negative (TN) phenotype (p< 0.0001). On MRI scans, the cancers were seen as mass-type in 182 out of 230 lesions (79.1%), and nonmass type in 48 cases (20.9%). Among the features indentified by MRI, rim enhancement was significantly associated with mo lecular subtypes based on immunohistochemistry (p< 0.0001), and nuclear grade (p= 0.0387) in multiple logistic regression analysis. Rim enhancement on MRI, along with advanced pathologic N stage, was associated with increased disease recurrence (p= 0.0023) based on multivariate analysis. However, the proportion of mass and nonmass tumors, and the distribution of morphological shape, margin, internal enhancement, and kinetic features assessed by MRI were not different according to BRCA mutation status. Conclusion: BRCA1 mutations were associated with aggressive pathological characteristics, and the TN phenotype. Rim enhancement was frequently seen on MRI scans of high-grade cancers and in the TN phenotype. And it was a significant predictor of disease recurrence. However, a direct asso ciation with BRCA mutations was not observed.

Purpose This study evaluated the treatment results and the necessity to irradiate the supraclavicular lymph node (SCN) region in pathological N0-N1 (pN0-N1) patients with locally advanced breast cancer treated with neoadjuvant chemotherapy (NAC) followed by surgery and radiotherapy (RT). Methods Between 1996 and 2008, 184 patients with initial tumor size >5 cm or clinically positive lymph nodes were treated with NAC followed by surgery and RT. Among these patients, we retrospectively reviewed 98 patients with pN0-N1. Mastectomy was performed in 55%. The pathological lymph node stage was N0 in 49% and N1 in 51%. All patients received adjuvant RT to chest wall or breast and 56 patients (57%) also received RT to the SCN region (SCNRT). Results At 5 years, locoregional recurrence (LRR)-free survival, distant metastasis-free survival, disease-free survival (DFS), and overall survival rates were 93%, 83%, 81%, and 91%, respectively. In pN0 patients, LRR was 7% in SCNRT- group and 5% in SCNRT+ group. In pN1 patients, LRR was 7% in SCNRT- group and 6% in SCNRT+ group. There was no significant difference of LRR, regardless of SCNRT. However, in pN1 patients, there were more patients with poor prognostic factors in the SCNRT+ group compared to SCNRT- group. These factors might be associated with worse DFS in the SCNRT+ group, even though RT was administered to the SCN region. Conclusion Our study showed the similar LRR, regardless of SCNRT in pN0-pN1 breast cancer patients after NAC followed by surgery. Prospective randomized trial is called for to validate the role of SCNRT.

Purpose: To assess the incidence of brain metastasis in patients with breast cancer receiving surgery and adjuvant radiotherapy (RT) and to evaluate subtypes associated with brain metastasis. Methods: We retrospectively reviewed the medical records of 1,000 patients with breast cancer who were treated with surgery and adjuvant RT for a cure between January 2001 and July 2005 at Samsung Medical Center. Seventy-one patients received neoadjuvant chemotherapy before surgery. The pathological stage was I in 430 patients, II in 327, and III in 243. We divided the patients into three subtypes according to immunohistochemistry: triple negative (TN, 245 patients), human epidermal growth factor 2 (HER2) enriched (HE, 166 patients) and positive estrogen receptor or progesterone receptor without HER2 overexpression (EP, 589 patients). The median follow up time was 72 months after surgery. Results: Locoregional failure-free survival rate and distant metastasis-free survival rate at 5 years were 92.8% and 86.1%, respectively. The disease free survival rate and overall survival rate at 5 years were 84.6% and 94.7%, respectively. Thirty-nine patients had brain metastasis, and the brain metastasis-free survival rate at 5 years was 97.2%. A univariate analysis showed that younger age, neoadjuvant chemotherapy, modified radical mastectomy, advanced pathological stage and the TN and HE subtypes were significant risk factors for brain metastasis. A multivariate analysis revealed that age, neoadjuvant chemotherapy, pathological stage and the TN and HE subtypes were statistically significant factors for brain metastasis. Conclusion: The cumulative incidence of brain metastasis was 3.9% after curative treatment. If patients have a clinically suspicious symptoms suggesting brain metastasis, clinicians should be aware that an early brain imaging work up and management are necessary. Because patients with the TN or HE subtypes accompanied by younger age and advanced pathological stage have increased brain metastasis (>10%), annual regular imaging follow-up may be recommended for these high risk patients.

change in the practice patterns for managing hereditary breast and ovarian cancer (HBOC) among Korean physicians after the Korean Hereditary Breast Cancer (KOHBRA) study. Methods: The first survey was performed from July to August 2007, at the initiation of the KOHBRA study, and the followup survey was conducted from July to December 2009. Members of the Korean Breast Cancer Society were invited to participate in the study by e-mail. The 2009 survey was conducted with a self-administered questionnaire concerning HBOC management and was identical to the previous questionnaire. Results: According to the 2009 survey, most physicians (60.0%) tended to draw a pedigree (48.0% in 2007 survey). The rate of genetic test recommendations for patients at risk for HBOC was higher in the 2009 survey (84.0%) than that in the 2007 survey (64.0%). Physicians tended to select a BRCA genetic testing candidate more appropriately than in the previous survey (42.4% answered right in 2007 survey; 74.4% in 2009 survey). Fifteen of 25 participants (60.0%) provided genetic counseling before their patients underwent a genetic test, which was higher than that (40.0%) in the 2007 survey. According to the 2009 survey, half of the genetic counseling was being conducted by KOHBRA study research nurses; whereas most of the genetic counseling was conducted by physicians in 2007. Conclusion: The KOHBRA study The Change of Practice Patterns of the Hereditary Breast Cancer Management in Korea after the Korean Hereditary Breast Cancer Study

trance) of breast and ovarian cancers among female family members with BRCA1 and BRCA2 mutation. Methods: Among the 61 BRCA1 mutation carriers in the 42 families and 47 BRCA2 mutation carriers in 31 families identified at 5 academic breast clinics, the probands were excluded to estimate the cumulative risk till each age of breast cancer in the Korean BRCA1 and BRCA2 carriers. Using Kaplan-Meier analyses, cumulative cancer risk estimates were determined. Results: By the age 70, the female breast cancer risk for the BRCA1 and BRCA2 mutation carriers was 72.1% (95% confidence interval [CI]=59.5% to 84.8%) and 66.3% (95% CI=41.2% to 91.5%), respectively, and the ovarian cancer risk was 24.6% (95% CI=0% to 50.3%) and 11.1% (95% CI= The Breast and Ovarian Cancer Risks in Korea Due to Inherited Mutations in BRCA1 and BRCA2: A Preliminary Report

2 (CHEK2 1100delC) are associated with an increased risk for breast cancer in women carrying this mutation. It is a lowpenetrance breast cancer susceptibility allele, frequently observed in patients with a family history of breast cancer and/or young age, with the frequency varying according to race or ethnicity. In this study, we evaluated the significance of CHEK2 1100delC in predisposition to breast cancer by assessing its frequency in material from 101 Korean women patients with early-onset breast cancer. Methods: One hundred and one Korean patients with earlyonset breast cancer (40 yr old or younger) were selected for this study. All the patients had been screened for BRCA1 and BRCA2 mutations and 14 patients had deleterious mutations. Of the 101 patients entered for this study, 14 had family history of breast cancer and 7 had bilateral breast cancers. Mutation detection of CHEK2 1100delC was based on analysis of primer extension products generated from previously-amplified genomic DNA using a chip based MALDI-TOP mass spectrometry platform (Sequenom, Inc., San Diego, CA, USA). Results: None of the 101 Korean patients with a family history of breast cancer and early-onset breast cancer who were candidates for the BRCA1 and BRCA2 test carried the 1100 delC mutation, which is observed in Caucasians with limited frequency. Conclusion: We previously observed higher or comparable prevalence of BRCA1 and BRCA2 mutations in Korean patients with breast cancer compared to Caucasians. However, the CHEK2 1100delC mutation is absent or infrequent in Korean patients with breast cancer who have a high risk of BRCA1 and BRCA2 mutations, making its screening irrelevant.