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Background: There is a clinical need to omit axillary lymph node dissection (ALND) when residual disease in sentinel lymph nodes (SLNs) is low after neoadjuvant chemotherapy (NAC). This study aimed to clarify the relationship between micrometastasis in SLNs after NAC and additional non-SLN metastases by analyzing SLN biopsy results followed by ALND., Methods: This retrospective study reviewed clinical records of patients who underwent breast cancer surgery between January 2010 and June 2022 after NAC at Samsung Medical Center. Of 3944 patients, 806 underwent SLN biopsy followed by ALND. Intraoperative frozen SLN biopsy results were examined, including the number and size of metastases in SLNs, and further investigated the number of additional non-SLN metastases., Results: Among the 806 patients, 95 (11.8%) had micrometastasis on SLNs in frozen sections, of which 89 (93.7%) had clinically node-positive (cN1-3) breast cancer before NAC. Twenty-three patients (24.2%) exhibited positive additional non-SLNs after ALND. The presence of lymphovascular invasion (vs. absence; odds ratio [OR] = 4.02, p = .0151) and having two or more SLNs with micrometastasis (vs. a positive SLN; OR = 3.65, p = .0301) were significantly associated with additional non-SLN metastases. Tumor subtypes and breast pathological complete response after NAC showed no correlation with the additional non-SLN metastases., Conclusion: The study identified a 24.2% possibility of additional non-SLN metastasis if micrometastases was detected in the SLN after NAC. This rate is significant, indicating that ALND cannot be omitted if low volume residual disease, such as micrometastasis, is identified in the SLN after NAC., (© 2024 American Cancer Society.)

Purpose: This study aimed to evaluate the clinical outcomes and prognostic implications of regional nodal irradiation (RNI) after neoadjuvant chemotherapy (NAC) in patients with residual triple-negative breast cancer (TNBC)., Materials and Methods: We analyzed 152 patients with residual TNBC who underwent breast-conserving surgery after NAC between December 2008 and December 2017. Most patients (n = 133; 87.5%) received taxane-based chemotherapy. Adjuvant radiotherapy (RT) was administered at a total dose of 45-65 Gy in 15-30 fractions to the whole breast, with some patients also receiving RT to regional nodes. Survival was calculated using the Kaplan-Meier method, and prognostic factors influencing survival were analyzed using the Cox proportional-hazards model., Results: During a median follow-up of 66 months (range, 9 to 179 months), the 5-year disease-free survival (DFS) rate was 68.0%. The 5-year locoregional recurrence-free survival, distant metastasis-free survival, and overall survival rates were 83.6%, 72.6%, and 78.7%, respectively. In the univariate analysis, the cN stage, ypT stage, ypN stage, axillary operation type, and RT field were associated with DFS. Multivariate analysis revealed that higher ypT stage (hazard ratio [HR] = 2.0; 95% confidence interval [CI] 1.00-3.82; p = 0.049) and ypN stage (HR = 4.7; 95% CI 1.57-14.24; p = 0.006) were associated with inferior DFS. Among clinically node-positive patients, those who received RT to the breast only had a 5-year DFS of 73.7%, whereas those who received RNI achieved a DFS of 59.6% (p = 0.164). There were no differences between the DFS and RNI., Conclusion: In patients with residual TNBC, higher ypT and ypN stages were associated with poorer outcomes after NAC. RNI did not appear to improve DFS. More intensive treatments incorporating systemic therapy and RT should be considered for these patients.

Introduction: Ipsilateral breast tumor recurrence (IBTR) remains a concern despite standard treatments. Advances in early detection have shifted surgical paradigms towards less invasive approaches. While repeat sentinel lymph node biopsy (rSLNB) emerges as a viable option according to the 2023 National Comprehensive Cancer Network (NCCN) guidelines, its efficacy remains uncertain. This study aimed to assess lymphatic drainage patterns in IBTR and evaluate the feasibility of rSLNB, along with analyzing oncologic outcomes., Methods: A retrospective analysis involving 78 patients with IBTR who had prior breast-conserving surgery (BCS) with sentinel lymph node biopsy (SLNB) and adjuvant whole breast irradiation (WBI) at Samsung Medical Center was conducted. Data on patient characteristics, lymphatic mapping techniques, and oncologic outcomes were collected and analyzed., Results: Among 78 patients with IBTR, 82.1 % underwent successful rSLNB, predominantly detecting lymphatic drainage to the ipsilateral axilla (80.8 %). The initial tumor location correlated significantly with failed lymphatic mapping (p = 0.019). A third event occurred in 28.8 % of invasive IBTR cases, notably associated with postmenopausal status, higher T stages, and HR(-)/HER2(-) subtype (p < 0.001). The risk of a third event increased by over 50 % within a 2-year interval post-IBTR., Conclusion: rSLNB in patients with IBTR, particularly for tumors initially located outside the upper-outer quadrant, demonstrated technical feasibility. The combined use of blue dye with lymphoscintigraphy may enhance rSLNB success rates. Active surveillance, especially for triple negative IBTR cases, may be important due to their aggressive nature and rapid progression potential within a short interval post-IBTR., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: This study evaluated the effectiveness of different surveillance intensities on morbidity and mortality in women with breast cancer., Methods: This retrospective study included patients who had undergone breast cancer surgery in the Republic of Korea between 2009 and 2011. The patients were divided into two groups based on the intensity of their postsurgical surveillance: intensive surveillance group (ISG) and less-intensive surveillance group. Surveillance intensity was measured based on the frequency and type of follow-up diagnostic tests conducted, including mammography, ultrasonography, computed tomography, magnetic resonance imaging, bone scans, and positron emission tomography scans., Results: We included 1,356 patients with a median follow-up period of 121.2 months (range, 12.8-168.0 months). The analysis revealed no significant difference in the overall survival (OS) between the two groups within five years of surgery. However, patients with ISG exhibited significantly better breast cancer-specific survival (BCSS) and distant metastasis-free survival (DMFS) within the same period. Five years after surgery, the differences in survival outcomes between the groups were not statistically significant., Conclusion: Intensive surveillance did not demonstrate a significant improvement in OS for patients with breast cancer beyond five years postoperatively. However, within the first five years, intensive surveillance was associated with better BCSS and DMFS. These findings suggest that personalized surveillance strategies may benefit specific patient subsets, particularly in the early years after treatment. Further nationwide randomized studies are warranted to refine surveillance guidelines and optimize outcomes in patients with breast cancer., Competing Interests: The authors declare that they have no competing interests., (© 2024 Korean Breast Cancer Society.)

TNBC is noted for its aggressive behavior and poor prognosis. Recently developed HER2 target agents have shown potential benefit even in HER2-low expressing breast cancers. This study retrospectively analyzed 2542 non-metastatic TNBC patients from 2008 to 2020, revealing that 26.0% were HER2-low. Data on demographics, tumor characteristics, pathologic complete response (pCR) rates and disease-free survival (DFS), distant metastasis-free survival (DMFS), overall survival (OS), and breast cancer-specific survival (BCSS) were analyzed. The HER2-low group, compared to the HER2-0 group, showed significantly better DFS, DMFS, OS, BCSS ( p = 0.0072, p = 0.0096, p = 0.0180, and p = 0.0001, respectively) with older age and higher rates of postmenopausal status ( p < 0.0001). No significant differences in pCR rates were observed. Multivariate analyses identified HER2 status as a significant prognostic factor for DFS ( p = 0.048), DMFS ( p = 0.018), OS ( p = 0.049), and BCSS ( p = 0.008). Subgroup analysis revealed that these effects varied with menopausal status, showing more pronounced benefits in postmenopausal women. Our findings suggest that HER2-low TNBC patients exhibit a distinct clinical profile and improved survival compared to HER2-0 TNBC patients, especially in postmenopausal patients. Further research on estrogen and HER2 interaction is needed.

Purpose: The metabolism of tamoxifen is influenced by various cytochrome p450 enzymes, including CYP2D6 and CYP2C19, leading to variations in the levels of endoxifen, even with the same tamoxifen dosage. However, the clinical significance of endoxifen on the prognosis of breast cancer patients remains controversial. This study aimed to elucidate the relevance of endoxifen level to recurrence-free survival censored with tamoxifen discontinuation (RFSt), representing the RFS for tamoxifen itself, of breast cancer patients and determine a suitable cutoff for prognostication., Materials and Methods: The study included 478 breast cancer patients, and tamoxifen and its metabolites, including endoxifen, were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). An optimal cutoff was determined with maximally selected rank statistics. Survival analysis and Cox regression were conducted based on this cutoff., Results: An endoxifen level of 21.00 ng/mL was the optimal cutoff for prognostication. Survival analysis revealed a statistically significant difference in RFSt between the low endoxifen group (≤ 21.00 ng/mL) and high endoxifen group (> 21.00 ng/mL) (log-rank test, p=0.032). The 10-year probability of RFSt was 83.2% (95% CI, 77.0-89.9%) and 88.3% (95% CI, 83.3-93.5%) in the low and high endoxifen groups, respectively. Multivariable Cox proportional hazards regression indicated endoxifen concentration as a significant factor affecting prognosis, which was adjusted with other clinical characteristics., Conclusion: Endoxifen could serve as a marker for appropriate tamoxifen treatment, and an endoxifen cutoff of 21.00 ng/mL could be advantageous in prognostication. Based on this cutoff, therapeutic drug monitoring would benefit patients displaying a suboptimal concentration.

In our previous study, we developed a triple-negative breast cancer (TNBC) subtype classification that correlated with the TNBC molecular subclassification. In this study, we aimed to evaluate the predictor variables of this subtype classification on the whole slide and to validate the model's performance by using an external test set. We explored the characteristics of this subtype classification and investigated genomic alterations, including genomic scar signature scores. First, TNBC was classified into the luminal androgen receptor (LAR) and non-luminal androgen receptor (non-LAR) subtypes based on the AR Allred score (≥ 6 and < 6, respectively). Then, the non-LAR subtype was further classified into the lymphocyte-predominant (LP), lymphocyte-intermediate (LI), and lymphocyte-depleted (LD) groups based on stromal tumor-infiltrating lymphocytes (TILs) (< 20%, > 20% but < 60%, and ≥ 60%, respectively). This classification showed fair agreement with the molecular classification in the test set. The LAR subtype was characterized by a high rate of PIK3CA mutation, CD274 (encodes PD-L1) and PDCD1LG2 (encodes PD-L2) deletion, and a low homologous recombination deficiency (HRD) score. The non-LAR LD TIL group was characterized by a high frequency of NOTCH2 and MYC amplification and a high HRD score., (© 2024. The Author(s).)

Purpose: This study aims to evaluate the impact of South Korea's national insurance coverage (NIC) expansion and the addition of genetic counselors on BRCA1/2 mutation testing rates in breast cancer patients., Materials and Methods: A retrospective review was conducted at the Samsung Medical Center (SMC), dividing patients into three groups: pre-NIC expansion, post-NIC expansion, and post-extra genetic counselor involvement. The number of BRCA1/2 tests performed and the detection rates among newly diagnosed and follow-up patients, particularly focusing on triple-negative breast cancer (TNBC) cases, were analyzed., Results: Post-NIC expansion, there was a significant increase in BRCA1/2 testing rates, with a gradual rise in detection rates while maintaining statistical significance. TNBC patients under 60 experienced substantial increases in testing rates. The number of follow-up patients recalled for testing also rose significantly after the extra genetic counselor involvement. Additionally, NIC expansion increased insurance coverage for TNBC patients, enhancing accessibility to testing., Conclusion: The study highlights the positive impact of NIC expansion and genetic counselor involvement on BRCA1/2 mutation testing rates and subsequent patient management. Addressing financial barriers to testing and incorporating genetic counseling significantly improve patient outcomes. This model provides a potential strategy for enhancing early detection and personalized treatment for breast cancer patients with BRCA1/2 mutations, contributing to global cancer management efforts.

Background: As breast augmentation has become more popular, an increasing number of women with augmented breasts require treatment for breast cancer. This study aimed to assess the outcomes of postoperative whole breast radiation therapy (WB-RT) in Asian patients with breast cancer who underwent prior cosmetic breast implantation., Methods: We retrospectively reviewed the medical records of 61 patients with breast cancer who had prior cosmetic breast implants (prior-CBI) and underwent breast-conserving surgery (BCS) and WB-RT between 2015 and 2020. The median implant volume was 238.8 cc, with a median interval of 84.7 months between the prior-CBI and BCS. WB-RT was administered with either conventional fractionation (CF-RT) at 50 Gy in 25 fractions (N = 36) or hypofractionation (HF-RT) at 42.6 Gy in 16 fractions (N = 25). The incidences of implant-related complications (IRC) and their contributing factors were analyzed., Results: After a median follow-up of 43.5 months, the 3-year cumulative incidences of IRC and implant loss were 17.2% and 4.9%, respectively. Among the four (6.6%) patients who opted for implant removal after RT, three were potentially related to RT-related capsular contracture. There was no difference in the 3-year cumulative IRC rates following CF-RT and HF-RT (12.2% and 26.7%, respectively; p = 0.120). The risk factors for IRC included a larger implant size (> 260 cc) and a higher ratio of breast tissue to implant volume., Conclusions: This study demonstrated a favorable safety profile of WB-RT for treatment of breast cancer in Asian women with prior-CBI. The integration of HF-RT following BCS was thought to be a feasible approach., (© 2024. The Author(s), under exclusive licence to The Japanese Breast Cancer Society.)

Triple-negative breast cancer (TNBC) patients are more likely to have BRCA1/2 mutations, with a prevalence rate of about 10-20%. Although several studies have analyzed the oncologic outcomes between BRCA1/2 carriers and non-carriers, the impact on breast cancer patients is still unclear. A retrospective review was performed to determine the long-term outcomes of TNBC patients, focusing on the impact of BRCA1/2 mutations. A total of 953 TNBC patients who underwent primary breast cancer surgery from June 2008 to January 2016 were included. We examined long-term outcomes, including contralateral breast cancer (CBC) incidence, recurrence patterns, and survival rates over a median follow-up of 80.9 months (range 3-152 months). 122 patients (12.8%) had BRCA1/2 mutations. BRCA1/2 mutation carriers were significantly younger at diagnosis and more likely to have a family history of breast/ovarian cancer. CBC incidence at 60, 120, and 150 months was significantly higher in BRCA1/2 mutation carriers compared to non-carriers (P = 0.0250, 0.0063, and 0.0184, respectively). However, there were no significant differences in disease-free survival, overall survival, breast cancer-specific survival, or distant-metastasis-free survival between the two groups. BRCA1/2 mutation status was a significant risk factor for CBC (HR = 6.242, P < 0.0001). Interestingly, among 29 patients with CBC recurrence, 24 patients (82.8%) had recurring TNBC subtype and among the CBC recurrence patients, 19 patients (65.5%) resumed chemotherapy. In the TNBC subtype, appropriate genetic testing and counseling are pivotal for surgical decisions like risk-reducing mastectomy (RRM). Furthermore, long-term surveillance is warranted, especially in BRCA1/2 carriers who did not receive RRM., (© 2024. The Author(s).)

Background: Residual microcalcifications after neoadjuvant chemotherapy (NAC) are challenging for deciding extent of surgery and questionable for impact on prognosis. We investigated changes in the extent and patterns of microcalcifications before and after NAC and correlated them with pathologic response. We also compared prognosis of patients depending on presence of residual microcalcifications after NAC., Methods: A total of 323 patients with invasive breast carcinoma treated with neoadjuvant chemotherapy at Kangbuk Samsung Hospital and Samsung Medical center from March 2015 to September 2018 were included. Patients were divided into four groups according to pathologic response and residual microcalcifications. Non-pCR w/mic group was defined as breast non-pCR with residual microcalcifications. Non-pCR w/o mic group was breast non-pCR without residual microcalcifications. pCR w/mic group was breast pCR with residual microcalcifications. pCR w/o mic group was breast pCR without residual microcalcifications. The first aim of this study is to investigate changes in the extent and patterns of microcalcifications before and after NAC and to correlate them with pathologic response. The second aim is to evaluate oncologic outcomes of residual microcalcifications according to pathologic response after NAC., Results: There were no statistical differences in the extent, morphology, and distribution of microcalcifications according to pathologic response and subtype after NAC (all p > 0.05). With a median follow-up time of 71 months, compared to pCR w/o mic group, the hazard ratios (95% confidence intervals) for regional recurrence were 5.190 (1.160-23.190) in non-pCR w/mic group and 5.970 (1.840-19.380) in non-pCR w/o mic group. Compared to pCR w/o mic group, the hazard ratios (95% CI) for distant metastasis were 8.520 (2.130-34.090) in non-pCR w/mic group, 9.120 (2.850-29.200) in non-pCR w/o mic group. Compared to pCR w/o mic , the hazard ratio (95% CI) for distant metastasis in pCR w/mic group was 2.240 (0.230-21.500) without statistical significance (p = 0.486)., Conclusions: Regardless of residual microcalcifications, patients who achieved pCR showed favorable long term outcome compared to non-pCR group., (© 2024. The Author(s).)

Purpose: Despite the increasing use of immediate breast reconstruction (IBR), its oncologic safety in the setting of neoadjuvant chemotherapy (NACT) needs to be comprehensively clarified in breast cancer management. The objective of the present study was to analyze the oncologic safety of IBR following NACT., Methods: In total, 587 patients with breast cancer who underwent a total mastectomy (TM) with IBR after NACT between 2008 and 2017 at a single institution were retrospectively reviewed. The reviewed patients with IBR following skin-sparing mastectomy (SSM) or nipple-sparing mastectomy (NSM) were matched 1:3 to patients who underwent TM alone after NACT. Matching variables included age, clinical T and N stages before NACT, response to NACT, pathologic T and N stages, and molecular subtypes., Results: After propensity score matching, 95 patients who underwent IBR following SSM/NSM after NACT (IBR group) and 228 patients who underwent TM alone after NACT (TM group) were selected. The median follow-up period was 73 (range, 5-181) months after matching. After matching, there were no significant differences between the two groups in 5-year locoregional recurrence-free survival (88.8% vs. 91.2%, p = 0.516), disease-free survival (67.3% vs. 76.6%, p = 0.099), distant metastasis-free survival (71.9% vs. 81.9%, p = 0.057), or overall survival (84.1% vs. 91.5, p = 0.061) rates. In multivariate analyses, conducting IBR was not associated with increased risks for locoregional recurrence, any recurrence, distant metastasis, or overall death., Conclusion: Our findings suggest that IBR following SSM/NSM elicits comparable long-term oncologic outcomes to those of TM alone in the setting of NACT., Competing Interests: The authors declare that they have no competing interests., (© 2024 Korean Breast Cancer Society.)

Aim: The role of regional nodal irradiation (RNI) after preoperative systemic treatment (PST) with targeted therapy for HER2-positive breast cancer remains uncertain. This study aimed to investigate the impact of RNI on locoregional recurrence (LRR) and disease-free survival (DFS) outcomes after docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP) for PST., Methods: We retrospectively analyzed 255 patients who were treated with six cycles of TCHP between 2016 and 2019. The patients were divided into four groups based on clinical nodal involvement: group A, with no nodal disease; group B, with axillary lymph node (AXL) level I; group C, with AXL level I with II/III; and group D, with supraclavicular or internal mammary nodes., Results: The RNI group had more advanced nodal disease (C/D) than the no RNI group (56.9 % vs. 6.8 %). With a median follow-up of 51.3 months, there were two (0.8 %), three (1.2 %), and 15 (5.9 %) local, regional, and distant metastases, respectively. LRR did not differ significantly according to the RNI (2.6 % vs. 1.0 %, p = 0.651). Group D had the most frequent distant metastases (17.5 %; p = 0.005). The 4-year DFS rate was 92.7 %, and DFS did not improve significantly after RNI (p = 0.074). When stratified by clinical nodal groups and pathological axillary response, RNI had no effect on LRR/DFS outcomes., Conclusion: With a rare incidence of LRR, RNI did not significantly affect LRR or DFS in patients with HER2-positive breast cancer after with PST-TCHP. However, intensive systemic treatment is required for advanced diseases (C/D). Selective de-intensified RNI and intensified systemic treatment should be investigated in future studies., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: Data on subsequent arm lymphedema (SAL) after salvage treatment for locoregional recurrence (LRR) of breast cancer are limited. We conducted a study to evaluate the risk of SAL in patients with LRR., Methods: We reviewed the data of patients with breast cancer who had LRR and were initially diagnosed between January 2003 and December 2017. Among the 214 patients who received curative salvage treatment, most had local (n = 125, 57.9%), followed by regional (n = 73, 34.1%), and locoregional (n = 16, 7.9%) recurrences. A competing risk analysis considering the factors of death and a second LRR were performed to exclude potential malignant lymphedema. We used the Fine-Gray subdistribution hazards model to estimate the hazard ratio (HR) for comparing the risk of SAL., Results: With a median follow-up duration of 41.4 months (interquartile range, 25.6-65.1), 51 patients (23.8%) experienced SAL with a median interval of 9.9 months after treatment. The two-year cumulative incidence of SAL was 12.7%. Among the 18 patients with initial lymphedema, nine (50.0%) developed SAL. Multivariate analysis revealed that a history of lymphedema (HR, 4.61; p < 0.001) and taxane-based salvage chemotherapy (HR, 2.38; p = 0.009) were significantly associated with SAL development., Conclusion: Salvage treatment for LRR-induced SAL was performed in 24% of the patients. A history of initial lymphedema and salvage taxane-based chemotherapy increases the risk of developing SAL. Therefore, close surveillance for the incidence of SAL is required in patients opting for salvage treatment for LRR., Competing Interests: The authors declare that they have no competing interests., (© 2023 Korean Breast Cancer Society.)

This study aimed to evaluate the role of post-mastectomy radiotherapy (PMRT) in T1-2N1 breast cancer. Between 2006 and 2014, a total of 504 patients with T1-2N1 breast cancer were analyzed. PMRT was administered to 71 patients, and 1:2 propensity score matching (PSM) was performed between the PMRT and non-PMRT groups. Loco-regional control (LRC), disease-free survival (DFS), and overall survival (OS) rates were compared according to PMRT status. Thirteen and one loco-regional recurrences were observed in the PMRT and non-PMRT groups, respectively. Before PSM, the 8-year LRC, DFS, and OS rates in the non-PMRT and PMRT groups were 98.5% and 96.5% ( p = 0.426), 89.7% and 91.2% ( p = 0.700), and 91.5% and 92.1% ( p = 0.679), respectively. Corresponding rates were 95.6% and 96.5% ( p = 0.365), 84.1% and 91.2% ( p = 0.185), and 88.4% and 92.1% ( p = 0.276), respectively, after PSM. Multivariate analysis showed that three lymph node metastases were prognostic for LRC and DFS rates and LVI for OS rate. Arm lymphedema developed in 32.4% of patients who received PMRT, which was significantly higher than the non-PMRT group ( p < 0.001). Contributions of PMRT for improvement of treatments outcomes in T1-2N1 breast cancer patients were not evident, while the incidence of arm lymphedema significantly increased after PMRT. Further prospective trials are required to re-evaluate the role of PMRT.

Breast cancer is a prevalent malignancy with increasing incidence, particularly in Asian countries. Classification based on estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status is pivotal in determining treatment. Recent advances have challenged the traditional dichotomy in HER2 classification, prompting investigation into the HER2-low subtype's characteristics and outcomes. This retrospective study analyzed 10,186 non-metastatic hormone receptor (HR)-positive, HER2-negative breast cancer cases treated from 2008 to 2020. Data encompassed clinical, pathological, and treatment information. Oncologic outcomes included disease-free survival (DFS), overall survival (OS), and breast cancer-specific survival (BCSS). In total, 56.5% were HER2-low cases. Differences in patient characteristics were noted, with more BRCA1/2 mutations and higher mastectomy rates in the HER2-low group ( p = 0.002, p < 0.001, respectively). Fewer received adjuvant chemotherapy or radiation therapy, and fewer histologic and nuclear grade 1 tumors were identified (all p < 0.001). With a median follow-up of 64 months (range: 13-174), HER2-low cases exhibited better DFS, OS, and BCSS than HER2-0 cases ( p = 0.012, p = 0.013, and p = 0.013, respectively). Notably, the prognosis differed between premenopausal and postmenopausal subgroups, with BCSS benefitting premenopausal patients ( p = 0.047) and DFS and OS benefitting postmenopausal patients in the HER2-low group ( p = 0.004, p = 0.009, respectively). Multivariate analysis confirmed HER2 status as an independent predictor of these outcomes ( p = 0.010, p = 0.008, and p = 0.014, respectively). This extensive single-center study elucidates the favorable prognosis associated with HER2-low status in HR-positive breast cancer. However, this effect differs among premenopausal and postmenopausal patients, necessitating further research into the underlying tumor biology.

Objective: Pathologic complete response (pCR) of breast cancer after neoadjuvant chemotherapy (NAC) is highly related to molecular subtypes. Patients who achieved tumor pCR after NAC have a better prognosis. However, despite of better prognosis, pCR patients have a potential for recurrence. There is little evidence of risk factors of recurrence in patients with pCR. We aim to analyze factors associated with tumor recurrence in patients who achieved pCR., Methods: This study retrospectively reviewed the data of patients diagnosed with breast cancer who achieved pCR after receiving NAC between January 2009 and December 2018 in Samsung Medical Center. pCR was defined as no residual invasive cancer in the breast and axillary nodes even if there is residual ductal carcinoma in situ (ypT0 or ypTis with ypN0). Breast cancers are classified into 4 subtypes based on hormone receptors (HR) and human epithelial growth factor receptor 2 (HER2) status. Patients who had bilateral breast cancer, ipsilateral supraclavicular or internal mammary lymph node metastasis, inflammatory breast cancer, distant metastasis, unknown subtype, and histologically unique case were excluded from the study., Results: In total 483 patients were included in this study except for patients who corresponded to the exclusion criteria. The median follow-up duration was 59.0 months (range, 0.5-153.3 months). Breast cancer recurred in 4.1% of patients (20 of 483). There was a significant difference in clinical T (P = 0.004) and clinical N (P = 0.034) stage in the Kaplan-Meier curve for disease-free survival. Molecular subtypes (P = 0.573), Ki67 (P = 1.000), and breast surgery type (P = 0.574) were not associated with tumor recurrence in patients who achieved pCR after NAC. In the clinical T stage and clinical N stage, there was a significant difference between recurrence and no-recurrence groups (clinical T stage; P = 0.045, clinical N stage; P = 0.002). Univariable Cox regression revealed statistical significance in the clinical T stage (P = 0.049) and clinical N stage (P = 0.010), while multivariable Cox regression demonstrated non-significance in the clinical T stage (P = 0.320) and clinical N stage (P = 0.073)., Conclusion: Results in this study showed that clinical T, clinical N stage, and molecular subtypes were not statistically significant predictors of recurrence in patients who achieved pCR after NAC. In spite of that, pCR after NAC may be more important than clinical staging and molecular subtype in early breast cancer. In addition, escalated treatments for patients with HER2 + or triple-negative tumors would be considered with a strict patient selection strategy to prevent over-treatment as well as achieve pCR., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Choi, Woen, Jang, Lee, Shin, Kwak, Lee, Chae, Yu, Lee, Kim, Nam and Ryu.)

Background: Breast cancer in young women has been shown to have an aggressive behavior and poor prognosis., Aim: To evaluate the outcomes of young hormone receptor (HR)-positive patients with breast cancer treated with neoadjuvant chemotherapy (NAC), and the oncologic efficacy of gonadotropin-releasing hormone (GnRH) agonists., Methods: This retrospective study involved a prospectively enrolled cohort. We included patients diagnosed with invasive breast cancer who were treated with NAC followed by curative surgery at the Samsung Medical Center and Samsung Changwon Hospital between January 2006 and December 2017. Among patients with HR-positive and human epidermal grow factor 2 (HER2)-negative breast cancer, we analyzed the characteristics and oncology outcomes between the patients equal to or younger than 35 years and the patients older than 35 years., Results: Among 431 patients with NAC and HR-positive/HER2-negative breast cancer, 78 were 35 years old or younger, and 353 patients were older than 35 years. The median follow-up was 71.0 months. There was no statistically significant difference in disease free survival (DFS, P = 0.565) and overall survival ( P = 0.820) between the patients equal to or younger than 35 years and the patients older than 35 years. The two groups differed in that the GnRH agonist was used more frequently in the group of patients equal to or younger than 35 years than in the other group (52.4% vs 11.2%, P < 0.001). Interestingly, for the DFS according to the GnRH agonist in the group of patients equal to or younger than 35 years, patients treated with the GnRH agonist had better DFS ( P = 0.037)., Conclusion: Administration of GnRH agonists might improve the DFS rate of HR-positive/HER2-negative breast cancer in the equal to or younger than 35 years group of patients with NAC., Competing Interests: Conflict-of-interest statement: The authors have no conflicts of interest to declare., (©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.)

Background: Breast cancer is the most common cancer and the most common cause of cancer death in women. Although survival rates have improved, unmet psychosocial needs remain challenging because the quality of life (QoL) and QoL-related factors change over time. In addition, traditional statistical models have limitations in identifying factors associated with QoL over time, particularly concerning the physical, psychological, economic, spiritual, and social dimensions., Objective: This study aimed to identify patient-centered factors associated with QoL among patients with breast cancer using a machine learning (ML) algorithm to analyze data collected along different survivorship trajectories., Methods: The study used 2 data sets. The first data set was the cross-sectional survey data from the Breast Cancer Information Grand Round for Survivorship (BIG-S) study, which recruited consecutive breast cancer survivors who visited the outpatient breast cancer clinic at the Samsung Medical Center in Seoul, Korea, between 2018 and 2019. The second data set was the longitudinal cohort data from the Beauty Education for Distressed Breast Cancer (BEST) cohort study, which was conducted at 2 university-based cancer hospitals in Seoul, Korea, between 2011 and 2016. QoL was measured using European Organization for Research and Treatment of Cancer QoL Questionnaire Core 30 questionnaire. Feature importance was interpreted using Shapley Additive Explanations (SHAP). The final model was selected based on the highest mean area under the receiver operating characteristic curve (AUC). The analyses were performed using the Python 3.7 programming environment (Python Software Foundation)., Results: The study included 6265 breast cancer survivors in the training data set and 432 patients in the validation set. The mean age was 50.6 (SD 8.66) years and 46.8% (n=2004) had stage 1 cancer. In the training data set, 48.3% (n=3026) of survivors had poor QoL. The study developed ML models for QoL prediction based on 6 algorithms. Performance was good for all survival trajectories: overall (AUC 0.823), baseline (AUC 0.835), within 1 year (AUC 0.860), between 2 and 3 years (AUC 0.808), between 3 and 4 years (AUC 0.820), and between 4 and 5 years (AUC 0.826). Emotional and physical functions were the most important features before surgery and within 1 year after surgery, respectively. Fatigue was the most important feature between 1 and 4 years. Despite the survival period, hopefulness was the most influential feature on QoL. External validation of the models showed good performance with AUCs between 0.770 and 0.862., Conclusions: The study identified important factors associated with QoL among breast cancer survivors across different survival trajectories. Understanding the changing trends of these factors could help to intervene more precisely and timely, and potentially prevent or alleviate QoL-related issues for patients. The good performance of our ML models in both training and external validation sets suggests the potential use of this approach in identifying patient-centered factors and improving survivorship care., (©Danbee Kang, Hyunsoo Kim, Juhee Cho, Zero Kim, Myungjin Chung, Jeong Eon Lee, Seok Jin Nam, Seok Won Kim, Jonghan Yu, Byung Joo Chae, Jai Min Ryu, Se Kyung Lee. Originally published in JMIR Public Health and Surveillance (https://publichealth.jmir.org), 24.08.2023.)

Apocrine carcinoma is a rare breast cancer subtype. As such, the genomic characteristics of apocrine carcinoma with triple negative immunohistochemical results (TNAC), which has been treated as triple negative breast cancer (TNBC), have not been revealed. In this study, we evaluated the genomic characteristics of TNAC compared to TNBC with low Ki-67 (LK-TNBC). In the genetic analysis of 73 TNACs and 32 LK-TNBCs, the most frequently mutated driver gene in TNAC was TP53 (16/56, 28.6%), followed by PIK3CA (9/56, 16.1%), ZNF717 (8/56, 14.3%), and PIK3R1 (6/56, 10.71%). Mutational signature analysis showed enrichment of defective DNA mismatch repair (MMR)-related signatures (SBS6 and SBS21) and the SBS5 signature in TNAC, whereas an APOBEC activity-associated mutational signature (SBS13) was more prominent in LK-TNBC (Student's t test, p < 0.05). In intrinsic subtyping, 38.4% of TNACs were classified as luminal A, 27.4% as luminal B, 26.0% as HER2-enriched (HER2-E), 2.7% as basal, and 5.5% as normal-like. The basal subtype was the most dominant subtype (43.8%) in LK-TNBC (p < 0.001), followed by luminal B (21.9%), HER2-E (21.9%), and luminal A (12.5%). In the survival analysis, TNAC had a five-year disease-free survival (DFS) rate of 92.2% compared to 59.1% for LK-TNBC (P = 0.001) and a five-year overall survival (OS) rate of 95.3% compared to 74.6% for LK-TNBC (P = 0.0099). TNAC has different genetic characteristics and better survival outcomes than LK-TNBC. In particular, normal-like and luminal A subtypes in TNAC have much better DFS and OS than other intrinsic subtypes. Our findings are expected to impact medical practice for patients diagnosed with TNAC., (© 2023. The Author(s).)

Purpose: Based on the results of previous trials, de-escalation of axillary surgery after neoadjuvant chemotherapy (NAC) has increased in patients with axillary lymph node (ALN) metastasis at presentation. This study aimed to review the trends of axillary surgery by time period and molecular subtype in patients with ALN metastasis., Methods: We analyzed the rates of sentinel lymph node biopsy (SLNB) and ALN dissection (ALND) based on time period and subtype. The time period was divided into 3 subperiods to determine the rate of axillary surgery type over time (period 1, from 2009 to 2012; period 2, from 2013 to 2016; and period 3, from 2017 to July 2019)., Results: From 2009 to July 2019, 2,525 breast cancer patients underwent surgery. Based on subtype, the ALND rate of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) disease decreased by 13.0% from period 1 to period 3 (period 1, 99.4%; period 2, 97.5%; and period 3, 86.4%; P < 0.001). Conversely, the ALND rate in HR+/HER2+, HR-/HER2+, and triple-negative breast cancer (TNBC) significantly decreased by 43.7%, 48.8%, and 35.2% in period 1, period 2, and period 3, respectively (P < 0.001). In the patient group receiving NAC, HR+/HER2- had a significantly higher ALND rate (84.1%) than HR+/HER2+, HR-/HER2+, and TNBC (60.8%, 62.3%, and 70.7%, respectively; P < 0.001)., Conclusion: The SLNB rate in patients with ALN metastasis has increased over time. However, the ALND rate in HR+/HER2- was significantly higher than in other subtypes., Competing Interests: Conflicts of Interest: No potential conflict of interest relevant to this article was reported., (Copyright © 2023, the Korean Surgical Society.)

Background: Although estrogen receptor (ER) expression levels affect the prognosis of breast cancer, studies about progesterone receptor (PR) expression levels are insufficient, especially in young breast cancer (YBC). The purpose of this study was to compare clinical characteristics and prognosis according to PR expression levels in invasive breast cancer patients., Methods: A prospective cohort study was conducted to identify YBC patients with invasive carcinoma diagnosed at an age of less than 40 years old between 2013 and 2018. Clinicopathologic features and prognosis of ER-positive and human epidermal growth factor receptor 2 (HER2)-negative patients were investigated. Patients were stratified into strong PR (PR-positive cell proportion > 10%), low PR (PR-positive cell proportion = 1~10%), and PR-negative (PR-positive cell proportion < 1%)., Results: Among 458 patients enrolled, 386 (84.3%), 26 (5.7%), and 46 (10.0%) were categorized into strong PR, low PR, and PR-negative groups, respectively. The median follow-up duration was 58.6 months. Compared with the strong PR group, low PR and PR-negative groups were more likely to have high Ki-67 and a high nuclear grade. Low R and PR-negative groups had significantly worse disease-free survival (DFS) and distant metastasis-free survival (DMFS) than the strong PR group ( p = 0.0033, p = 0007). Low PR group had an even higher risk of distant metastasis than PR-negative patients. Low PR patients and PR-negative had significantly lower overall survival (OS) rates than strong PR., Conclusion: Low PR might be a prognostic factor of ER-positive/HER2-negative in YBC.

The development of metal salts-based nanocomposites is highly desired for the Fenton or Fenton-like reaction-based chemodynamic therapy of cancer. Manganese sulfate (MnSO 4 )-dispersed nanoparticles (NPs) were fabricated with a hot-melt extrusion (HME) system for the chemodynamic therapy of colorectal cancer in this study. MnSO 4 was homogeneously distributed in polyethylene glycol (PEG) 6000 (as a hydrophilic polymer) with the aid of surfactants (Span 80 and Tween 80) by HME processing. Nano-size distribution was achieved after dispersing the pulverized extrudate of MnSO 4 -based composite in the aqueous media. The distribution of MnSO 4 in HME extrudate and the interactions between MnSO 4 and pharmaceutical additives were elucidated by Fourier-transform infrared, X-ray diffractometry, X-ray photoelectron spectroscopy, and scanning electron microscopy analyses. Hydroxyl radical generation efficiency by the Fenton-like chemistry capability of Mn 2+ ion was also confirmed by catalytic assays. By using the intrinsic H 2 O 2 in cancer cells, MnSO 4 NPs provided an elevated cellular reactive oxygen species level, apoptosis induction capability, and antiproliferation efficiency. The designed HME-processed MnSO 4 formulation can be efficiently used for the chemodynamic therapy of colorectal cancer.

Purpose: This study aimed to investigate the differences in sleep disturbance changes between patients receiving two hormone therapies ("tamoxifen plus ovarian function suppression group [T+OFS group]" versus "tamoxifen group [T group]") and the chronological changes in sleep disturbances in each group., Methods: Premenopausal women with unilateral breast cancer who underwent surgery and were scheduled to receive hormone therapy (HT) with tamoxifen alone or with tamoxifen plus gonadotropin-releasing hormone (GnRH) agonist for ovarian function suppression were included. The enrolled patients wore an actigraphy watch for two weeks and completed questionnaires (insomnia, sleep quality, physical activity [PA], and quality of life [QOL]) at five time points: immediately before HT and 2, 5, 8, and 11 months after HT., Results: Among the 39 enrolled patients (21 and 18 patients in the T+OFS group and T group, respectively), 25 (17 and 8 patients in the T+OFS group and T group, respectively) were finally analyzed. There were no differences between the two groups in time-dependent changes in insomnia, sleep quality, total sleep time, rapid eye movement sleep rate, QOL, and PA; however, the severity of hot flashes was significantly higher in the T+OFS group than in the T group. Although the interaction between group and time was not significant, insomnia and sleep quality significantly worsened at 2-5 months of HT when changes over time were analyzed within the T+OFS group. In both the groups, PA and QOL were maintained without significant changes., Conclusion: Unlike tamoxifen alone, tamoxifen plus GnRH agonist initially worsened insomnia and sleep quality, but gradually improved with long-term follow-up. Patients who initially experience insomnia during tamoxifen plus GnRH agonist administration can be reassured based on the results of this study, and active supportive care may be used during this period., Trial Registration: ClinicalTrials.gov Identifier: NCT04116827., Competing Interests: The authors declare that they have no competing interests., (© 2023 Korean Breast Cancer Society.)

Purpose: The incidence of early tumor detection is increasing due to popularization of breast cancer screening and the development of imaging techniques. Thus, suitable preoperative localization is required for proper diagnosis and treatment of non-palpable breast lesions. The purpose of this study was to evaluate the efficacy and safety of indocyanine green (ICG)-hyaluronic acid (HA) mixture for lesion localization compared to activated charcoal., Methods: This was a multicenter, randomized, open-label, parallel phase 3 clinical trial performed at four centers in Korea. Female patients scheduled for surgery to remove non-palpable breast lesions were enrolled. One hundred and nine patients were randomly assigned to a control group (activated charcoal: 0.3. - 1 mL) or a study group (ICG-HA mixture, 0.2 mL) for the localization of a breast lesion. The primary endpoint was the accuracy of resection. Secondary endpoints included the technical success rate, histopathological accuracy, skin pigmentation rate, and adverse event rate., Results: A total of 104 patients were eligible for per-protocol analysis (control group, n = 51; study group, n = 53). The accuracy of resection in the study group was not inferior to that of the control group (90.57% vs. 98.04%, 95% confidence interval (CI): -2.31 - 18.91, p = 0.21). There was no statistically significant difference in technical success rate between the two groups (marking on breast skin: p = 0.11, marking on the excised specimen: p = 0.12). However, there were statistically significant differences in histopathological accuracy (0.26 ± 0.13 vs. 0.33 ± 0.17, p = 0.01) and skin pigmentation rate (0.00% vs. 30.77%, p < 0.01). Adverse events were not reported in either group., Conclusions: When localization was performed using ICG-HA, the accuracy of resection was not inferior to that of activated charcoal. However, skin pigmentation rate was significantly lower. In conclusion, ICG-HA is effective and safe for localizing of non-palpable breast lesions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Bang, Choi, Kim, Lee, Lee, Shin, Nam, Lee, Chae, Lee, Ryu and Kim.)

Background: Metaplastic breast cancer (MpBC) is an aggressive histologic type of breast cancer. Although MpBC has a poor prognosis and is responsible for a large proportion of breast cancer mortalities, the clinical features of MpBC compared with invasive ductal carcinoma (IDC) are not well known, and the optimal treatment has not been identified., Methods: We retrospectively reviewed medical records of 155 MpBC patients and 16,251 IDC cases who underwent breast cancer surgery in a single institution between January 1994 and December 2019. The two groups were matched 1:4 by age, tumor size, nodal status, hormonal receptor status, and HER2 status using propensity-score matching (PSM). Finally, 120 MpBC patients were matched with 478 IDC patients. Disease-free survival and overall survival of MpBC and IDC patients both before and after PSM were analyzed by Kaplan-Meier survival, and multivariable Cox regression analysis was performed to identify variables affecting long-term prognosis., Results: The most common subtype of MpBC was triple-negative breast cancer, and nuclear and histologic grades were higher than those of IDC. Pathologic nodal staging of the metaplastic group was significantly lower than that of the ductal group, and more frequent adjuvant chemotherapy was performed in the metaplastic group. Multivariable Cox regression analysis indicated that MpBC was an independent prognostic factor for disease-free survival (HR = 2.240; 95% CI, 1.476-3.399, p = 0.0002) and overall survival (HR = 1.969; 95% CI, 1.147-3.382, p = 0.0140). However, survival analysis revealed no significant difference between MpBC and IDC patients in disease-free survival (HR = 1.465; 95% CI, 0.882-2.432, p = 0.1398) or overall survival (hazard ratio (HR) = 1.542; 95% confidential interval (CI), 0.875-2.718, p = 0.1340) after PSM., Conclusion: Although the MpBC histologic type had poor prognostic factors compared with IDC, it can be treated according to the same principles as aggressive IDC.

Inflammation is a series of host defense processes in response to microbial infection and tissue injury. Inflammatory processes frequently cause extracellular acidification in the inflamed region through increased glycolysis and lactate secretion. Therefore, the immune cells infiltrating the inflamed region encounter an acidic microenvironment. Extracellular acidosis can modulate the innate immune response of macrophages; however, its role for inflammasome signaling still remains elusive. In the present study, we demonstrated that macrophages exposed to an acidic microenvironment exhibited enhanced caspase-1 processing and IL-1β secretion compared with those under physiological pH. Moreover, exposure to an acidic pH increased the ability of macrophages to assemble the NLR family pyrin domain containing 3 (NLRP3) inflammasome in response to an NLRP3 agonist. This acidosis-mediated augmentation of NLRP3 inflammasome activation occurred in bone marrow-derived macrophages but not in bone marrow-derived neutrophils. Notably, exposure to an acidic environment caused a reduction in the intracellular pH of macrophages but not neutrophils. Concordantly, macrophages, but not neutrophils, exhibited NLRP3 agonist-mediated translocation of chloride intracellular channel protein 1 (CLIC1) into their plasma membranes under an acidic microenvironment. Collectively, our results demonstrate that extracellular acidosis during inflammation can increase the sensitivity of NLRP3 inflammasome formation and activation in a CLIC1-dependent manner. Thus, CLIC1 may be a potential therapeutic target for NLRP3 inflammasome-mediated pathological conditions., Competing Interests: Conflicts of Interest: The authors declare no potential conflicts of interest., (Copyright © 2023. The Korean Association of Immunologists.)

This study investigated the feasibility and usability of a personalized mobile health (mHealth) app for self-management during the year following breast cancer surgery. Twenty-nine participants were instructed to use an app and smart band immediately after discharge. Only 18 completed the study. Their perceived necessity and satisfaction for main domains and app were assessed at 1, 2, 4, 6, 9, and 12 months. A self-reporting questionnaire assessed usability at 12 months. Consequently, retention rate as measures of feasibility showed a mean of 75.8%. Exercise and diet management were the most accessed app domains. Perceived necessity was higher than satisfaction. The mean usability score was 80.2. Most participants found the app useful and effective as a delivery for healthcare. Further, 94% of them were willing to pay for and recommend it. Thus, mHealth app can help breast cancer patients improve their healthy behaviors and healthcare further. This study provides insights for designing long-term randomized controlled trials using mHealth interventions.

Purpose: The GenesWell™ breast cancer test (BCT) is a recently developed multigene assay that predicts the risk of distant recurrence in patients with hormone receptor-positive (HR+) and human epidermal growth factor-2 negative (HER2-) early breast cancer (BC). The ability of this assay to predict the response to neoadjuvant chemotherapy (NACT) has not been established to date., Methods: Biopsy specimens from HR+/HER2- BC patients with axillary lymph node (LN) metastasis who underwent NACT were analyzed using the BCT score. The modified BCT score was developed and patients classified into high-and low-response groups. A total of 88 patients were available for the BCT score among the 108 eligible patients. The median follow-up duration was 35.9 (7.8-128.5) months., Results: Among them, 61 (65.1%) had cN1 and 53 (60.2%) had cT1 or cT2 disease. The BCT score was low in 25 (28.4%) patients and high in 63 (71.6%). Among the 50 patients with pathologic complete response or partial response, 41 (82.0%) were in the high BCT score group and 9 (18.0%) were in the low BCT score group. Among the 38 patients with stable or progressive disease, 22 (57.9%) were in the high BCT score group and 16 (42.1%) were in the low BCT score group ( p = 0.025). Ki-67 before NACT was a significant factor for predicting tumor response ( p = 0.006; 3.81 [1.50-10.16]). The BCT score showed a significant response to NACT ( p = 0.016; 4.18 [1.34-14.28]). Distant metastasis-free survival was significantly different between the high- and low-response groups ( p = 0.004)., Conclusion: We demonstrated that the BCT score predicts NACT responsiveness in HR+/HER2- BC with LN metastasis and might help determine whether NACT should be performed. Further studies are required to validate these results., Competing Interests: The authors declare that they have no competing interests., (© 2022 Korean Breast Cancer Society.)

Aim: Both skin-sparing mastectomy (SSM) and nipple-sparing mastectomy (NSM) have been widely adopted. Although postmastectomy radiation therapy (PMRT) can improve clinical outcomes, it can worsen cosmesis following reconstruction. Therefore, identifying risk factors of ipsilateral breast tumor recurrence (IBTR) could help de-escalate PMRT after NSM/SSM in patients with pT1-2 disease., Methods: We retrospectively reviewed patients treated with SSM (N = 400) and NSM (N = 156) in patients with pT1-2N0-1 disease between 2009 and 2016. Seventy-four patients received PMRT with 50-50.4 Gy in 25-28 fractions. The Cox proportional hazards model was used to analyze the prognostic factors of IBTR., Results: With a median follow-up of 66.2 months, 17 IBTR events were observed, with 5-year IBTR-free rate of 97.2%. Although only one IBTR was observed after PMRT, there was no statistical difference in the 5-year IBTR-free rate (PMRT vs. no PMRT, 98.6% vs. 97.0%, p = 0.360). Multivariable analyses demonstrated that age ≤45 years and lymphovascular invasion (LVI) were adverse features of IBTR. The low-risk group (0 risk factor) showed a better 5-year IBTR-free rate than the high-risk group (≥1 risk factor) (100.0% vs. 95.8%, p = 0.003). In the high-risk group, PMRT slightly improved 5-year IBTR-free rate compared with no PMRT (98.6% vs. 95.2%, p = 0.166). In addition, PMRT increased 5-year cumulative incidence of reconstruction failure (10.0% vs. 2.8%, p = 0.001)., Conclusion: We identified risk factors (age and LVI) related to IBTR following upfront SSM/NSM with pT1-2 disease. As a hypothesis-generating study, de-escalation of PMRT by omitting chest wall irradiation in selective patients could improve reconstruction-related complications without compromising oncologic outcomes., Competing Interests: Declaration of interest statement The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

Introduction: The aim of this study was to evaluate the prognostic value of the number of lymph nodes removed in breast cancer patients who undergo axillary lymph node dissection (ALND) after neoadjuvant chemotherapy (NAC). Methods: We included patients who were diagnosed with invasive breast cancer and cytology with proven involved axillary node metastasis at diagnosis and treated with NAC followed by curative surgery at Samsung Medical Center between January 2007 and December 2015. The primary outcomes were disease-free survival (DFS) and overall survival (OS). Results: Among 772 patients with NAC and ALND, there were 285 ypN0, 258 ypN1, 135 ypN2, and 94 ypN3 cases. The median follow-up duration was 69.0 months. The group with less than 10 lymph nodes number (<10 nodes group) included 123 patients and the group with 10 or more lymph nodes number (≥10 nodes group) included 649 patients. There were no significant differences in DFS (p = 0.501) or OS (p = 0.883) between the two groups. In the ypN0 subgroup, the <10 nodes group had worse DFS than ≥10 nodes group (p = 0.024). In the ypN1 subgroup, there were no significant differences in DFS (p = 0.846) or OS (p = 0.774) between the two groups. In the ypN2 subgroup, the <10 nodes group had worse DFS (p = 0.025) and OS (p = 0.031) than ≥10 nodes group Conclusion: In ypN0 and ypN2 subgroups, breast cancer patients with less than 10 lymph nodes number in ALND after NAC might be considered for additional staging or closer surveillance when compared to patients with 10 or more than lymph node.

Background: Given that peak age of breast cancer (BC) is younger in Asians than in Western populations, relatively higher prevalence of pregnancy-associated breast cancer (PABC) has been reported. This study aimed to analyze the characteristics and clinical outcomes of PABC in Korea. Methods: We defined PABC as BC diagnosed during pregnancy or in the first postpartum year. We compared the clinicopathological characteristics and BC outcomes between patients with PABC and non-PABC patients in the prospective YBC cohort from Samsung Medical Center. Results: In total, 1492 patients were initially enrolled, and 1364 patients were included, of which 93 had PABC (6.8%). The median age of patients with PABC was 34 years. Hormone receptor expression was lower (64.6% vs 74.6%) and frequency of HER2 overexpression was higher (26.9% vs 17.6%) in patients with PABC than in non-PABC patients. The 5-year overall survival (OS) rates were 83.2% and 93.4% in patients with PABC and non-PABC patients, respectively (p < 0.001). The 5-year disease-free survival (DFS) rates were 72.2% and 83.8% in PABC and non-PABC patients. Conclusion: Compared to non-PABC patients, patients with PABC had poorer OS and DFS in this prospective cohort. Exploratory biomarker analysis for PABC is warranted.

Purpose: Docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP) regimen is frequently used to treat early and locally advanced human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) in neoadjuvant setting. However, large-scaled real-world evidence did not exist., Materials and Methods: We retrospectively reviewed medical records of patients with early or locally advanced HER2-positive BC who underwent neoadjuvant TCHP followed by curative surgery at Samsung Medical Center between January 2016 and August 2020., Results: Of 447 patients, 316 (70.7%) received breast-conserving surgery and 131 (29.3%) received total mastectomy. In terms of neoadjuvant chemotherapy response, pathologic complete response (pCR) and residual cancer burden (RCB) score were analyzed. The rate of pCR was 64% a class of RCB 0 was observed in 65% of cases, RCB class I in 12%, RCB class II in 14%, and RCB class III in 2%. The 3-year event-free survival rate was 90.6%, BC with pCR occurred in 92.8%, and BC with non-pCR in 86.3% (p=0.016). In terms of distant metastasis, the 3-year distant recurrence-free survival rate was 93.5%; BC with pCR occurred in 95.9% and BC with non-pCR in 89.2% (p=0.013). Mucositis (85.2%), pain (83.2%), and diarrhea (70.5%) were the most common non-hematologic adverse events. In terms of hematologic adverse events, anemia (89.9%) was the most commonly observed adverse events followed by thrombocytopenia (29.8%)., Conclusion: Neoadjuvant TCHP therapy had a pCR rate of 64% and a 3-year event-free survival of 90% in real world experience. In terms of toxicity profile, anemia was frequently observed and adequate management including occasional transfusion was required.

Purpose: The definition of "no tumor on ink" is generally applied for clear resection margin (RM) after breast-conserving surgery (BCS). However, few studies reported the effect of RM in the setting of neoadjuvant chemotherapy (NAC). We investigated the association between RM status and survival outcomes for those who underwent BCS after NAC for breast cancer., Methods: We retrospectively reviewed the data of 2,803 patients who underwent BCS and whole-breast irradiation after NAC between January 2008 and December 2016 from three institutions in South Korea., Results: The 786 patients in the pathologic complete response group (R pCR ) had significantly longer local recurrence-free survival (LRFS) than the 1,949 patients in clear or close RM and non-pCR group (R 0 ) and the 68 patients in involved RM and non-pCR group (R 1 ) (vs. R 0 , p = 0.001; vs. R 1 , p = 0.049). Patients in R 0 showed no benefit in LRFS compared to R 1 on both log-rank test (HR = 1.20; 95% C.I., 0.49-2.93; p = 0.692) and Cox regression analysis (HR = 2.05; 95% C.I., 0.64-6.58; p = 0.227). Subgroup analysis according to tumor subtypes revealed that there was no significant difference in LRFS, distant metastasis-free survival, and recurrence-free survival between the R 0 and R 1 group. Additionally, among 286 patients with pCR with residual ductal carcinoma in situ (DCIS) alone, RM status was not significantly associated with LRFS., Conclusion: Clear RM of specimen does not have benefit on LRFS after NAC. Additionally, for the patients showing pCR with residual DCIS in the breast, margin involvement also did not affect the risk of local recurrence., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose: Surgical margin status is a surrogate marker for residual tumors after breast-conserving surgery (BCS). A comparison of ipsilateral breast tumor recurrence (IBTR) rates between re-excision combined with radiotherapy (excision with RTx) and RTx alone, following the confirmation of ductal carcinoma in situ (DCIS) in the resection margin after BCS, has not been reported previously. Therefore, in the present study, the clinical characteristics of DCIS involvement in the surgical resection margin between excision with RTx and RTx alone were investigated, and the IBTR rate was compared., Methods: We analyzed 8,473 patients treated with BCS followed by RTx between January 2013 and December 2019. Patients were divided into 2 groups based on surgical resection margin status in permanent pathology, and superficial and deep margins were excluded. Patients who underwent re-excision with DCIS confirmed in the resection margin were identified and the IBTR rate was examined., Results: Among 8,473 patients treated with BCS, 494 (5.8%) had positive surgical resection margins. The median follow-up period was 47 months. Among the 494 patients with a positive resection margin, 368 (74.5%) had residual DCIS at the surgical resection margin in the final pathology. Among those with confirmed DCIS at the resection margin, 24 patients (6.5%) were re-excised, and 344 patients (93.5%) underwent RTx after observation. The IBTR rates were 4.2% and 1.2% in the re-excision and observation groups, respectively. IBTR-free survival analysis revealed no significant difference between the excision with RTx and RTx-only groups ( p = 0.262)., Conclusion: The IBTR rate did not differ between the excision with RTx and RTx-only groups when DCIS was confirmed at the resection margins. This suggests that RTx and close observation without re-excision could be an option, even in cases where minimal involvement of DCIS is confirmed on surgical resection., Competing Interests: The authors declare that they have no competing interests., (© 2022 Korean Breast Cancer Society.)

Purpose: Double heterozygosity (DH) for BRCA1 and BRCA2 variant is very rare with only a few cases reported, and most those in Caucasians. In this article, we present seven unrelated cases of DH for BRCA1/2 identified from a single institution in Korea, and describe the characteristics and phenotype of DH individuals compared to those with a single BRCA variant., Materials and Methods: This study included 27,678 patients diagnosed with breast cancer and surgically treated at Samsung Medical Center (SMC) between January 2008 and June 2020. In total, 4,215 high-risk breast cancer patients were tested for the BRCA1/2 genes, and electronic medical records from 456 cases with pathogenic/likely pathogenic variants (PVs/LPVs) were reviewed., Results: A younger mean age at diagnosis was associated with DH than a single variant of BRCA1/2. More triple-negative breast cancer (TNBC) and higher nuclear and histologic grade cancer occurred with DH than BRCA2 variant. All 7 cases of DH were unrelated, and their mutation combinations were different. There were no Ashkenazi founder variants detected., Conclusion: We suggest that patients with DH for BRCA1/2 variants develop breast cancer at a younger age, but the histopathologic features are similar to those of BRCA1.

Purpose: Little is known about the impact of financial toxicity in disease-free breast cancer survivors. We aim to validate the COmprehensive Score for financial Toxicity in Korean (COST-K) and evaluate financial toxicity among disease-free breast cancer survivors., Materials and Methods: We conducted linguistic validation following a standardized methodology recommended by Functional Assessment of Chronic Illness Therapy multilingual translation (FACITtrans). For psychometric validation, we conducted a cross-sectional survey with 4,297 disease-free breast cancer survivors at a tertiary hospital in Seoul, Korea between November 2018 and April 2019. Survivors were asked to complete the COST-K and European Organization for Research and Treatment of Cancer Quality of Life Core 30 (EORTC QLQ-C30) questionnaires. The test-retest reliability, internal consistency, and validity of the COST-K were assessed using standard scale construction techniques., Results: The COST-K demonstrated good internal consistency, with a Cronbach's α of 0.81. The test-retest analysis revealed an intraclass correlation coefficient of 0.78. The COST-K had moderate correlation (r=-0.60) with the financial difficulty item of the EORTC QLQ-C30 and week correlation with the items on acute and chronic symptom burdens (nausea/vomiting, -0.18; constipation, -0.14; diarrhea, -0.14), showing good convergent and divergent validity. The median COST-K was 27 (range, 0 to 44; mean±standard deivation [SD], 27.1±7.5) and about 30% and 5% of cancer survivors experienced mild and severe financial toxicity, respectively. Younger age, lower education, lower household income was associated with higher financial toxicity., Conclusion: The COST-K is a valid and reliable instrument for measuring financial toxicity in disease-free breast cancer survivors. Considering its impact on the health-related quality of life, more studies need to be conducted to evaluate financial toxicity in cancer survivors and design interventions.

Due to the rarity of primary angiosarcoma of the breast, optimal management is based on expert opinion. The aim of this study was to review all primary angiosarcomas of the breast obtained from a single center in terms of clinicopathologic characteristics, treatment, and survival outcomes. From 1997 to 2020, 15 patients with primary angiosarcoma of the breast underwent either mastectomy or wide excision. We analyzed the clinicopathologic data to assess disease-free survival and overall survival. Fifteen women with primary angiosarcoma of the breast were identified. The mean age at diagnosis was 33 years (range: 14-63 years). The overall mean tumor size was 7.7 cm (range 3.5-20 cm). Upon histological grading, there were three cases of low grade, five intermediate grade, six high grade, and one unidentified grade. The five-year disease-free survival rate was 24.4%, and the five-year survival rate was 37.2%. The survival rate of the low-grade patient group was statistically higher than that of the intermediate- or high-grade patient groups ( p = 0.024). Primary angiosarcoma of the breast is a rare aggressive tumor characterized by high grade and poor outcome. Histologic grade appears to be a reliable predictor of survival. There are no standard treatment guidelines; thus, optimal R0 surgical resection remains the best approach. The roles of neoadjuvant, adjuvant chemotherapy, and radiotherapy remain unclear.

1. Mineral excretion is an issue in the poultry industry. The use of micro minerals in nano form can increase bioavailability and decrease excretion rate. However, information concerning the bioavailability of nano manganese (Mn) in broiler chicks is limited.2. This experiment studied the influences of hot-melt extrusion (HME)-processed manganese sulphate on body weight gain, Mn bioavailability, nutrient digestibility and meat quality in broiler chicks fed a corn-soybean meal-based diet as a starter and grower phase. A total of 700 birds (Ross 308, 1-day-old) were randomly placed in 35 cages (20 birds per cage). The broiler chicks were fed one of seven experimental diets, which consisted of a control (without supplemental Mn), different levels of MnSO 4 (IN-Mn60; 60, 120, and 200 mg/kg), or HME MnSO 4 (HME-Mn; 60, 120, and 200 mg/kg).3. There was an increased serum Mn content in broilers fed diet supplemented with HME-Mn. In the grower phase, increased dietary Mn levels elevated the concentrations in the serum, liver, and tibia. There were increases in the excreta Mn content of broilers fed increasing levels. The supplementation of HME-Mn showed a lower percentage of abdominal fat compared with the IN-Mn treatment diets. Supplementation with HME-Mn decreased intramuscular fat compared with the diets supplemented with IN-Mn. The supplementation of HME-Mn decreased the thiobarbituric acid reactive substances (TBARS) at d 6 of age. The HME-Mn source showed a greater decrease in TBARS compared with the IN-Mn treatment.4. In conclusion, HME processing increased bioavailability and could be used as an environmentally friendly method to facilitate lower levels of Mn in the diet of broiler chickens.