BACKGROUND:Robot-assisted nipple-sparing mastectomy (R-NSM) was developed to minimize visible scarring and improve the quality of life in patients with breast cancer. However, despite its increasing adoption, evidence regarding its oncologic outcomes remains sparse. This study aimed to compare the oncologic outcomes of R-NSM and conventional nipple-sparing mastectomy (C-NSM). METHODS:We retrospectively reviewed patients who underwent NSM with immediate breast reconstruction for breast cancer between 2019 and 2022. Risk-reducing cases were excluded. R-NSM and C-NSM groups were compared after propensity score matching using a nearest-neighbor algorithm, matching each patient in the R-NSM group to up to five controls without replacement. RESULTS:Before matching, the R-NSM group more frequently had hormone receptor-positive/human epidermal growth factor receptor 2-negative tumors, lower Ki-67 indices, and no neoadjuvant chemotherapy. After propensity score matching, most clinicopathologic variables were well balanced between groups. During a median follow-up of 37.5 months for R-NSM and 42.6 months for C-NSM, no locoregional recurrence, distant metastasis, or death occurred in the R-NSM group, whereas all seven recurrences (3.5%) occurred in the C-NSM group. Kaplan-Meier analysis showed no significant differences in locoregional recurrence-free survival, distant metastasis-free survival, or disease-free survival between groups, although all observed oncologic events occurred in the C-NSM group. CONCLUSION:R-NSM demonstrated oncologic outcomes comparable to those of C-NSM, with no recurrence or mortality despite a sufficiently long follow-up. These findings support R-NSM as a feasible and oncologically sound surgical option for appropriately selected patients with early-stage breast cancer.

Background:The GenesWell BCT is a prognostic assay that integrates the expression of six prognostic and three reference genes with clinicopathological factors (tumor size and nodal status) to generate a BCT Score. The BCT Score is used to predict the risk of recurrence in early breast cancer. We excluded clinical variables and developed a gene-only version of the BCT Gene Score to evaluate its independent prognostic performance. Methods:We assessed the prognostic value of the BCT Gene Score in a cohort of patients with ER+/HER2- early breast cancer using available Oncotype DX Recurrence Score (RS) data. The primary endpoint was concordance between the assays and recurrence-free survival (RFS). Results:We analyzed 759 samples from five Korean institutions. Risk classification concordance between the BCT Gene Score and the BCT Score was 81.2%, whereas concordance with the Oncotype DX RS was 74.2%, indicating moderate agreement. All three scores were significantly associated with RFS (p < 0.05). Combining the BCT and BCT Gene Scores improved prognostic stratification compared with either score alone. Patients classified as high risk by both scores exhibited the poorest prognosis, whereas those classified as low risk by both scores exhibited the most favorable outcomes. Among patients with low RS, those reclassified as high risk by the BCT Gene Score exhibited significantly worse RFS. Conclusions:The BCT Gene Score exhibits independent prognostic utility and complements the original BCT Score. Risk stratification may be enhanced by incorporating both scores, ultimately guiding more precise treatment decisions in ER+/HER2- early breast cancer.

Extracellular vesicle-derived mRNAs (EV-mRNAs) are emerging analytes for liquid biopsy research, but their reliable detection is limited by low RNA abundance and co-isolated nucleic acids. We compared five EV isolation approaches to identify a suitable workflow for EV-mRNA profiling using the NanoString nCounter platform in breast cancer. EV preparations from pooled plasma were evaluated for particle yield, RNA recovery, and transcript detection using the nCounter Breast Cancer 360 panel with pre-amplification. RNase A pretreatment and post-extraction DNase I treatment were used to assess extra-vesicular RNA and residual DNA contributions. DNase I treatment markedly reduced total counts and detected transcripts, highlighting the importance of minimizing residual DNA-derived signals in pre-amplified EV-mRNA analysis. Among the tested approaches, miRCURY (MIR) retained the highest number of detected transcripts after nuclease treatment and was selected for downstream profiling. This workflow was applied to plasma samples from healthy donors (n = 36), breast cancer patients without recurrence (n = 36), and breast cancer patients with recurrence (n = 31), followed by RT-qPCR assessment in an independent cohort. CCL5 and HIST1H3H were identified as exploratory breast cancer-associated EV-mRNA candidates, with CCL5 also showing a recurrence-associated pattern. These findings support MIR-based isolation with DNase I treatment as a practical workflow for NanoString-based EV-mRNA profiling in clinical plasma samples.

BACKGROUND:Perceived financial toxicity (FT) is an increasingly recognized concern among cancer survivors. However, its association with long-term oncologic outcomes, particularly after completion of active treatment, remains underexplored. METHODS:We conducted a prospective cohort study of 4163 breast cancer survivors from a tertiary cancer center in South Korea. Eligible participants were within 18 months of diagnosis, had completed surgery and any adjuvant chemotherapy or radiotherapy, and had no evidence of recurrence at enrollment. Perceived FT was assessed using the Comprehensive Score for Financial Toxicity (COST) questionnaire. FT was defined by a COST score <26. Primary outcome was recurrence-free survival (RFS), and secondary outcomes included all-cause mortality and quality-of-life (QoL) domains. Multivariable Cox proportional hazard models adjusted for age, stage, treatment, and socioeconomic factors. RESULTS:Among the cohort, 2109 (50.7 %) patients reported perceived FT after active treatment. FT was independently associated with increased risk of recurrence or death (HR 1.42, 95 % CI 1.08-1.87), and higher all-cause mortality (HR 1.74, 95 % CI 1.02-2.97). FT was also associated with significantly worse emotional functioning, social functioning, and future outlook. CONCLUSIONS:Perceived financial toxicity following active breast cancer treatment was associated with worse oncologic and quality-of-life outcomes, regardless of objective socioeconomic status. These findings underscore the need for routine assessment of perceived financial burden during survivorship care and targeted financial interventions, even in patients without traditionally defined financial vulnerability.

Objective: Accurate prediction of breast cancer (BC) recurrence after curative treatment is essential for optimizing surveillance strategies and personalized patient management. We aimed to prospectively validate a previously developed artificial intelligence (AI)–based BC recurrence prediction model in a real-world clinical setting.Methods: This prospective validation study included BC patients who underwent curative surgery followed by adjuvant therapy at a tertiary cancer center. The AI model integrated clinicopathologic variables and longitudinal follow-up data, including laboratory and imaging findings, to estimate individualized 2-year recurrence risk. Patients were stratified into low- and high-risk groups based on a predefined risk threshold. Model performance was evaluated using recurrence outcomes during follow-up.Results: Of 829 patients initially identified, 529 met eligibility criteria, and 400 were randomly selected. Among them, 391 were classified as low-risk and 9 as high-risk. Significant differences in clinicopathologic factors (T/N stage, ER, PR, HER2, Ki-67) were observed between groups, excluding age, adjuvant radiotherapy, and targeted therapy. During follow-up, 7 patients (1.8%) experienced recurrence, 6 in the low-risk group (1.5%) and 1 in the high-risk group (11.1%).Conclusion: This prospective validation demonstrates that the AI-based model can effectively identify BC patients at low risk of recurrence in a real-world clinical setting. The model shows potential as a clinical decision support tool to guide individualized surveillance strategies, although further multi-center studies with larger high-risk populations are warranted to enhance sensitivity and generalizability.

Axillary surgery in breast cancer has progressively shifted from radical clearance to selective de-escalation. Sentinel lymph node biopsy (SLNB) replaced axillary lymph node dissection (ALND) as the standard, markedly reducing morbidity while maintaining oncologic safety. More recently, randomized trials have challenged even the necessity of SLNB in certain patients, reflecting a broader movement toward optimization rather than maximal intervention. Evidence can be grouped according to the burden of sentinel node metastasis. Micrometastasis-focused trials (IBCSG 23-01, AATRM) showed that omission of ALND in patients with one or more micrometastases (≤ 2 mm) did not compromise survival or locoregional control. Mixed-burden trials (ACOSOG Z0011, AMAROS) included patients with 1-2 positive sentinel lymph nodes, regardless of micrometastatic or macrometastatic size, and confirmed the safety of avoiding ALND when appropriate systemic therapy and radiotherapy are given. Macrometastasis trials (SENOMAC, SINODAR-ONE, POSNOC) extended these findings to patients with 1-2 macrometastases (≥ 2 mm), demonstrating that ALND omission is still safe even in higher-burden disease. In parallel, de-escalation has advanced further. SOUND and INSEMA established non-inferiority of observation vs. SLNB in clinically node-negative (cN0), imaging-negative tumors, while ongoing studies such as NAUTILUS are validating these results in Asian populations. In the neoadjuvant setting, SLNB is standard for cN0 patients and feasible in clinically node-positive patients who convert to cN0 after neoadjuvant chemotherapy. Ongoing trials (ASICS, EUBREAST-01, ASLAN) are exploring whether axillary surgery can be omitted entirely in excellent responders, particularly in human epidermal growth factor receptor 2-positive and triple-negative breast cancer. The collective data indicate a clear trend. Axillary surgery should be optimized to disease biology, systemic therapy response, and patient quality of life.

Breast cancer incidence is increasing worldwide, leading to a growing population of survivors and raising questions about optimal surveillance strategies. Current guidelines do not recommend routine imaging for asymptomatic breast cancer survivors, yet advances in diagnostic technologies may enable earlier detection of distant metastases and potentially improve outcomes. The aim of this study was to evaluate the association between symptom status at the time of distant metastasis detection and post-metastasis overall survival in breast cancer patients. We retrospectively reviewed 7,840 women who underwent surgery for primary breast cancer at Samsung Medical Center between 2010 and 2014 and identified 316 patients who subsequently developed distant metastases. Patients were classified as asymptomatic (n = 204, 64.6

PURPOSE:Young patients with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative tumors often exhibit poor outcomes. This study evaluated whether BRCA mutation contributes to prognosis by comparing oncologic outcomes according to BRCA status. MATERIALS AND METHODS:We conducted a retrospective study of a prospective institutional cohort. Among 1,025 patients 40 years and younger with ER-positive, HER2-negative breast cancer who underwent BRCA1/2 testing, 967 patients were included (excluding low ER expression). Ninety-eight patients (10.1%) were BRCA mutation carriers. Propensity score matching (1:4) and multivariate Cox regression were performed using covariates differing between groups. RESULTS:BRCA mutation carriers showed more aggressive features. They had worse distant metastasis-free survival (DMFS) compared with noncarriers (hazard ratio [HR], 2.40, P < .001), with a greater risk in late DMFS beyond 5 years (HR, 3.50, P < .001). These findings persisted after adjustment (DMFS HR, 1.76, P = .038, late DMFS HR, 2.84, P = .009). Overall survival was not significantly different. Bone was the most common first site of metastasis in BRCA carriers, whereas noncarriers more frequently showed metastasis to multiple sites. In exploratory subgroup analysis, luminal A-like BRCA carriers consistently showed the poorest survival among the four subgroups. CONCLUSION:In luminal-type YBC excluding low ER expression, BRCA carriers demonstrated more aggressive features and significantly worse distant metastasis outcomes. These findings support the need for long-term surveillance and consideration of tailored treatment strategies, including PARP inhibitors, in this high-risk population.

The clinical significance of residual mammographic microcalcifications after neoadjuvant systemic therapy in human epidermal growth factor receptor 2 (HER2)-positive (HER2+) breast cancer remains unclear. Traditionally, persistent calcifications have prompted wide excisions or mastectomies under the assumption that they indicate residual disease. However, accumulating evidence suggests that calcifications may persist as treatmentrelated or biologically-attenuated changes, rather than as viable carcinomas, particularly in the era of dual HER2-directed therapy. Recent Korean studies demonstrate that patients with favorable radiologic response who achieve pathologic complete response maintain excellent local control after breast-conserving surgery, even when residual calcifications are present. A large multicenter cohort study reported a 5-year local recurrence-free survival rate of 97.4% and a validated prediction model showed strong discriminatory performance. This Brief Communication synthesizes emerging evidence on the biological basis and clinical implications of residual calcifications after neoadjuvant therapy, with emphasis on recent Korean data. Current evidence supports a response-adapted surgical approach in selected patients, emphasizing clip-guided excision of the invasive index lesion and consistent delivery of whole-breast irradiation rather than routine removal of the entire pretreatment calcification field in patients with HER2+ breast cancer. Prospective validation with a longterm follow-up is warranted to further refine patient selection and confirm the safety of this strategy in clinical practice.

BackgroundEndocrine therapy (ETx) for hormone receptor–positive breast cancer frequently induces menopausal symptoms that may compromise treatment adherence. However, longitudinal symptom trajectories compared with natural menopausal progression remain unclear.MethodsThis longitudinal cohort study included 5,734 women from two prospective cohorts. Menopausal symptoms were assessed using the Menopause Rating Scale (MRS). Women with breast cancer (n=2,583) were recruited from the Breast Cancer Information Grand Round for Survivorship cohort, and women without breast cancer (n=3,151) from the Kangbuk Samsung Health Study. Linear mixed-effects models estimated longitudinal changes in MRS scores according to breast cancer status, menopausal status, and ETx use. Difference-in-differences (DiD) analyses used premenopausal women without breast cancer as the reference group.ResultsAmong premenopausal women, ETx was associated with greater increases in total MRS scores compared with women without breast cancer (DiD 3.30; 95% CI, 2.04–4.58 at 1 year). Premenopausal women receiving ETx experienced sustained symptom increases over 3 years, particularly those receiving ovarian function suppression. Regimens including gonadotropin-releasing hormone agonists were associated with the greatest increases in symptom burden. Among postmenopausal women, ETx was associated with modest changes in total MRS scores but a significant increase in urogenital symptoms (DiD 0.71; 95% CI, 0.26–1.16).ConclusionsETx for breast cancer is associated with sustained increases in menopausal symptoms beyond those observed during natural menopause. The excess symptom burden is most pronounced among premenopausal women receiving ovarian function suppression. These findings highlight the importance of proactive symptom monitoring and supportive care strategies to improve long-term adherence to endocrine therapy.

This study aimed to identify prognostic factors and to stratify recurrence risk using a prognostic model incorporating the identified factors in patients with residual triple-negative breast cancer (TNBC) following neoadjuvant systemic therapy (NST). A retrospective analysis was conducted using data from a prospectively collected single-institution database. Eligible patients had residual TNBC after NST and curative surgery between 2007 and 2020 and completed planned postoperative radiotherapy. Prognostic factors for disease-free survival (DFS) were identified using multivariable Cox proportional hazards regression. Risk groups were stratified according to the number of these factors. A total of 347 patients were included. With a median follow-up of 61.6 months, the 5-year DFS and overall survival rates were 62.5

Background and purposeRecent trials have demonstrated the safety of sentinel lymph node biopsy (SLNB) omission in selected patients with early breast cancer. However, criteria for identifying patients suitable for partial breast irradiation (PBI) without surgical axillary evaluation remain undefined. This study aimed to identify the candidates for PBI in pT1 breast cancer patients.Materials and methodsA retrospective analysis was conducted on 5,097 patients with pT1 breast cancer who underwent breast surgery with axillary evaluation between 2016 and 2020. All patients had clinically node-negative disease (cN0) confirmed by preoperative axillary ultrasound. Univariable and multivariable logistic regression analyses were used to identify independent predictors of axillary lymph node metastasis (ALNM).ResultsThe overall ALNM rate was 13.9% (708/5,097). The mean age was 51.3 years. Multivariable analysis identified lymphovascular invasion (LVI) as the strongest independent predictor (odds ratio [OR] 5.57, 95% confidence interval [CI] 4.61–6.74, p < 0.001), and LVI-positive patients (14.3%) had a 42.1% ALNM rate. pT1c stage was also a significant independent predictor (OR 2.13, 95% CI 1.71–2.65, p < 0.001). A simple classification using LVI and tumor size stratified patients into three groups: low-risk (LVI-negative, tumor ≤1.0 cm; 40.1% of patients), intermediate-risk (LVI-negative, tumor >1.0 cm; 45.7%), and high-risk (LVI-positive; 14.3%). The corresponding ALNM rate was 4.9%, 13.0%, and 42.1%, respectively.ConclusionsPatients with pT1a-b tumors without LVI represent a low-risk population with an axillary metastasis rate below 5%. These findings suggest the feasibility of PBI in this low-risk subgroup without SLNB, warranting validation through prospective randomized trials.

PURPOSE:Long-term outcome comparisons between invasive lobular carcinoma (ILC) and invasive carcinoma of no special type (NST, historically referred to as invasive ductal carcinoma) remain inconsistent, particularly in patients with low-proliferative hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) disease. This study evaluated the long-term outcomes of ILC and NST in a pathologically defined, low-proliferative, HR+/HER2- (luminal A-like) cohort. METHODS:This retrospective, single-institution study included patients with HR+/HER2- breast cancer and Ki-67 ≤ 20% who underwent surgery between 2008 and 2015. Patients with mixed histopathology, those who underwent palliative surgery, or those who received neoadjuvant chemotherapy were excluded. Survival was analyzed using the Kaplan-Meier method and multivariable Cox regression. A secondary 24-month landmark analysis included patients who were alive, disease-free, under observation, and receiving endocrine therapy 24 months after surgery. RESULTS:Among 3,439 patients, 3,156 had NST and 283 had ILC. Compared with NST, ILC was associated with a higher rate of synchronous bilateral breast cancer, a more advanced pathological stage, and a lower nuclear grade. In the comprehensive cohort, breast cancer-specific survival did not differ significantly (log-rank p = 0.081), whereas disease-free survival (DFS) and distant metastasis-free survival (DMFS) were worse in patients with ILC (log-rank p < 0.001 and p = 0.005, respectively). After adjustment for measured clinicopathological factors, these differences were no longer statistically significant (DFS: adjusted hazard ratio [HR], 1.27; 95% confidence interval [CI], 0.91-1.79; p = 0.164; DMFS: adjusted HR, 1.38; 95% CI, 0.83-2.30; p = 0.210). Detailed biomarker analyses showed similarly high estrogen receptor expression in both groups and lower exact Ki-67 values in ILC. The 24-month landmark analysis revealed the same overall pattern. CONCLUSION:In this low-proliferative HR+/HER2- cohort, ILC showed less favorable unadjusted long-term DFS and DMFS than NST, but these differences were attenuated and were no longer statistically significant after adjustment for measured clinicopathological characteristics.

PURPOSE:While the benefit of neoadjuvant chemotherapy (NAC) has been established in human epidermal growth factor receptor 2 (HER2)-positive and triple-negative breast cancers, its effectiveness in achieving pathological complete response (pCR) and optimal patient selection in estrogen receptor (ER)-positive, HER2-negative breast cancers remain less clearly defined. This study aimed to identify immunohistochemistry (IHC)-based predictors of pCR and to develop a scoring model for ER-strong positive/HER2-negative breast cancer. METHODS:Data from a prospective cohort were retrospectively analyzed. We included 522 patients with ER-strong positive/HER2-negative tumors who received NAC and surgery between 2008 and 2021. IHC markers including progesterone receptor (PR), Ki-67, epidermal growth factor receptor (EGFR), cytokeratin 5/6 (CK5/6), and p53 were evaluated to identify predictors of pCR. Independent predictors of pCR from multivariate logistic regression were used to develop a weighted 4-point model. Model performance was assessed using receiver operating characteristic analysis. The prognostic impact of pCR was evaluated using Kaplan-Meier and Cox regression analyses. RESULTS:Independent predictors of pCR included PR-negative status, positivity for basal-like markers (EGFR or CK5/6), and Ki-67 ≥ 50%. The scoring model demonstrated good discrimination for pCR (area under the curve = 0.754). pCR rates increased stepwise, with scores of 4.9% (low), 10.7% (intermediate), and 36.2% (high). In the high-score group, pCR was significantly associated with improved disease-free survival (hazard ratio [HR], 0.09; p = 0.023) and distant metastasis-free survival (HR, 0.11; p = 0.035), whereas no significant survival differences according to pCR status were observed in the low and intermediate score groups. CONCLUSION:This IHC-based model predicts pCR and helps identify subgroups in which pCR is associated with meaningful survival benefit following NAC in ER-positive/HER2-negative breast cancers. High-scoring patients may benefit from NAC, while patients with low- or intermediate-scores may be better managed with surgery and endocrine therapy. This model may support personalized treatment decisions regarding NAC.

BACKGROUND:Patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer who achieve a pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) generally have favorable outcomes. However, in the hormone receptor-positive/HER2-positive (HR+/HER2+) subtype, prognostic heterogeneity may persist even after pCR. In particular, the role of gonadotropin-releasing hormone agonist (GnRHa) for ovarian function suppression in premenopausal patients remains unclear. We aimed to identify prognostic factors and evaluate the clinical impact of GnRHa in this population. METHODS:We performed a retrospective analysis of prospectively collected cohorts from Samsung Medical Center and Asan Medical Center. A total of 332 premenopausal patients with HR+/HER2+ breast cancer who achieved pCR after anti-HER2 containing NAC (2008 - 2021) were included. Patients were categorized according to GnRHa use during adjuvant endocrine therapy. The primary endpoints were disease-free survival (DFS) and distant metastasis-free survival (DMFS), analyzed using Cox proportional hazards regression and the Kaplan-Meier method. RESULTS:Among 332 patients, 218 (65.7%) did not receive GnRHa and 114 (34.3%) did. With a median follow-up of 65.8 months, clinical nodal stage (cN3) was identified as an independent adverse prognostic factor for both DFS (HR 5.92, p < 0.001) and DMFS (HR 13.60, p < 0.001). In contrast, GnRHa use was not significantly associated with survival outcomes. Patients with cN3 disease showed significantly worse outcomes than those with cN0-2 (5-year DFS: 80.0%% vs 96.2%; DMFS: 87.5% vs 97.9%). No clear survival differences were observed according to GnRHa use. Subgroup analyses showed no significant association between GnRHa and survival, although a trend toward improved outcomes was observed in the cN3 subgroup. CONCLUSION:Prognostic heterogeneity persists among premenopausal HR+/HER2+ patients achieving pCR, with baseline nodal status as a key determinant of outcomes. GnRHa was not associated with improved survival overall, although a potential benefit in high-risk subgroups cannot be excluded. These findings support a risk-adapted approach to adjuvant endocrine therapy rather than uniform intensification.

Purpose: Lobular carcinoma in situ (LCIS) is a noninvasive lesion associated with an increased risk of invasive cancer. Since its removal from the tumor, node, metastasis classification in the 8th edition of the American Joint Committee on Cancer (AJCC) guidelines, the clinical management of LCIS has shifted from surgery to surveillance. However, studies focusing on the risk and associated factors for invasive cancer development in pure LCIS without ductal carcinoma in situ (DCIS) or invasive cancer remain limited. Methods: We retrospectively analyzed 106 patients diagnosed with pure LCIS between 2008 and 2018. This study evaluated the effect of tamoxifen use and histologic type on the development of invasive cancer. Results: All 106 patients underwent surgery, and nine (8.5%) developed invasive cancer over a median follow-up of 67.5 months. The incidence of invasive cancer was lower in the tamoxifen group (6.3%, n = 4) than in the non-tamoxifen group (11.9%, n = 5), although this difference was not statistically significant (p = 0.266). Pleomorphic LCIS had a significantly higher incidence of invasive cancer (30.0%, n = 3) than classic LCIS (6.3%, n = 6) (p = 0.045). Multivariable Cox regression analysis showed no significant difference in the risk of invasive cancer according to tamoxifen use (hazard ratio [HR], 2.031; 95% confidence interval [CI], 0.544-7.579; p = 0.292). However, pleomorphic LCIS showed a trend toward an increased risk of invasive cancer compared to classic LCIS (HR, 3.856; 95% CI, 0.922-16.126; p = 0.064). Conclusion: Postoperative tamoxifen did not significantly lower invasive cancer development in patients with pure LCIS. Pleomorphic LCIS may carry a higher risk than classic LCIS. These findings require tailored follow-up and treatment strategies based on the histologic subtype of LCIS.

BACKGROUND/OBJECTIVES: Dietary supplement use is common among breast cancer survivors, but studies on Asian populations remain limited. This study investigated dietary supplement use among Korean breast cancer survivors, distinguishing between vitamin/ mineral (VM) and non-vitamin/non-mineral (NVNM) supplements. SUBJECTS/METHODS: This cross-sectional study included 1,136 stage I-III breast cancer survivors from 12 Korean hospitals, who survived more than 6 mon post-surgery. The participants completed a questionnaire on post-diagnostic dietary supplement use. Stepwise logistic regression was applied, calculating odds ratios (ORs) and 95% confidence intervals (CIs) to identify the demographic and clinical factors associated with VM and NVNM use. RESULTS: Seventy percent of survivors reported supplement use, with 25% using a single product. The most common VM supplements were multivitamins/minerals, vitamin D, and vitamin C, while the most common NVNM supplements included omega-3 fatty acids, probiotics, and ginseng. Survivors with higher education and greater physical activity were more likely to use VM supplements (ORs [95% CIs], 2.74 [1.76-4.25] for college graduates or above vs. middle school or below; 1.38 [1.02-1.88] for the most active group vs. the least active group). NVNM use was associated with higher education, greater physical activity levels, and a history of smoking (ORs [95% CIs], 2.29 [1.46-3.58] for college graduates or above vs. middle school or below; 1.52 [1.13-2.06] for the most active group vs. the least active group; 2.00 [1.23-3.25] for ever smokers vs. never smokers). Survivors who had undergone chemotherapy were also more likely to use NVNM supplements than those who had not (OR [95% CI], 1.37 [1.02-1.84]). CONCLUSION: Seventy percent of Korean breast cancer survivors used dietary supplements in this study. VM use was associated with higher education and physical activity, while higher NVNM use was associated with higher education, greater physical activity, a history of smoking, and chemotherapy.

BACKGROUND/OBJECTIVES:Isoflavones are estrogen-like compounds found in plants and their health effects remain equivocal. We investigated dietary isoflavone intake and its associated factors in Korean breast cancer survivors, with a comparison to cancer-free women. SUBJECTS/METHODS:The usual dietary intake of breast cancer survivors (n = 981, mean age 52 yrs) in 9 hospitals between 2012 and 2019 was assessed using 3-day food records or food frequency questionnaires (FFQs). They were age-matched to 2,943 cancer-free women who completed FFQs as part of a nationwide study conducted between 2012 and 2016. We used the flavonoid database of common Korean foods and the Phenol-Explorer database to estimate isoflavone intake. The contribution of each food or food group to the total isoflavone intake was calculated. The adjusted least-squares means of dietary isoflavone intake according to lifestyle and clinical factors were calculated using generalized linear models. RESULTS:Breast cancer survivors had a higher mean dietary isoflavone intake (23.59 mg/day) than cancer-free women (17.81 mg/day). Major food sources, including tofu, soybeans, and doenjang, contributed to over 70% of the isoflavone intake in both groups. When we estimated dietary isoflavone intake according to lifestyle characteristics, isoflavone intake increased with higher scores of adherence to the American Cancer Society dietary guidelines but decreased with increasing body mass index in both groups. Among cancer-free women, dietary isoflavone intake was higher among those who had never smoked and among dietary supplement users. Among breast cancer survivors, dietary isoflavone intakes did not vary with clinical characteristics, including time since surgery and estrogen receptor status. CONCLUSION:Breast cancer survivors were more likely to consume isoflavones than age-matched cancer-free women. Dietary isoflavone intake was associated with healthy lifestyle characteristics in women both with and without breast cancer. Further research is needed to understand the role of the higher isoflavone intake among breast cancer survivors compared to cancer-free women on their prognosis.