Je Lee

Abstract P2-09-19: Zerumbone suppresses IL-1b-induced cell migration and invasion through inhibition of IL-8 expression and MMP3 expression in human triple negative breast cancer cells

Background: Inflammation is a key regulatory process in breast cancer progression and severity. Several studies have demonstrated that prolonged exposure of breast tumor cells to inflammatory cytokines leads to epithelial-mesenchymal transitions (EMT), which is the principle mechanism involved in metastasis and tumor invasion. Disruption of the signaling pathways involved in EMT may therefore provide an effective treatment strategy for currently difficult to treat or untreatable cancers such as TNBC. The interleukin (IL)-1 plays a pivotal role on breast cancer proliferation, invasion and/or inflammation. Here, we investigated the correlation of MMP-3 and IL-8 on IL-1b-induced cell migration and invasion as well as the inhibitory effect of zerumbone on IL-1β-induced MMP-3 and IL-8. Methods: Triple negative breast cancer cells (Hs578T and MDA-MB231) were cultured DMEM with 10% FBS and 1% antibiotics. The levels of IL-8 and MMP-3 mRNA were analyzed by real-time PCR. The levels of secreted IL-8 and MMP-3 protein expression were analyzed by ELISA and western blot analysis, respectively. Cell viabilities by drug were analyzed by MTT assay. Cell invasion and migration was detected by Boyden chamber assay. Results: The level of IL-8 and MMP-3 mRNA and protein expression significantly increased by IL-1β treatment in both Hs578T cells and MDA-MB231 cells. In addition, IL-1β-induced cell migration and invasion also increased in Hs578T and MDA-MB231 cells. On the other hand, the levels of basal and IL-1β-induced IL-8 and MMP-3 expression were decreased by zerumbone. Conclusion: IL-1β induces the migration and invasion of breast cancer cells through IL-8 and MMP-3 expression. These effects are significantly suppressed by zerumbone. Therefore, we suggest that zerumbone may act as a useful therapeutic agent for treatment of triple negative breast cancer. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-09-19.

P5-14-02: Clinicopathologic and Prognostic Difference of Screen Detected Breast Cancer Compared with Symptomatic Breast Cancer.

Background: Breast cancer screening program makes it possible to detect early cancer, thus to reduce breast cancer mortality. The authors studied clinicopathologic characteristics and prognosis of screen detected invasive breast cancer compared with symptomatic breast cancer. Furthermore, we compared the result according to molecular subtypes (luminal A, luminal B, Her2, triple negative), so intended to identify the role of screening in each subtypes. Material and Methods: From January 2002 to June 2008, 3141 patients who underwent operation for the treatment of invasive ductal carcinoma(NOS) at Samsung medical center were included. Among them, 1025 patient were screen detected, 2116 patient were symptomatic, out of screening over 2 years. We reviewed the medical records retrospectively. Result: Screen detected breast cancer was associated with older patients, smaller tumor size, more hormone receptor- positive, less lymph node involvement, lower stage and reduced mortality compared with symptomatic breast cancer (P Conclusion: Compared to symptomatic breast cancer patients, screen detected breast cancer patients have favorable pathological and molecular characteristics, so better outcomes. According to the molecular subtype, only in luminal A subtype, screen detected breast cancer shows both overall and disease free survival benefit, and also acts as an independent prognostic factor itself. So, screening program seems to have a different efficacy depending on the molecular subtype of breast cancer Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-14-02.

Abstract P6-09-08: Identification of ESR1 mutation in breast cancers using targeted ultra-deep sequencing data analysis

Introduction: Estrogen Receptor 1 (ESR1) gene encodes an estrogen receptor, which regulates cell proliferation and promotes tumor progression in estrogen receptor(ER)-positive breast cancer (BC). Therefore, endocrine therapy that inhibiting ER downstream signal, is the most effective treatment strategy in ER-positive BC. However, about 25% of patients with primary disease and almost all patients with metastases will present with or eventually develop endocrine resistance. And genetic alteration of ESR1 is now identified as the endocrine resistance mechanism. However, a few data from clinical trials or public data base exists and could not reflect real world clinic. Therefore, we aimed to identify the frequency and type of ESR1 genetic alterations in BCs through this large scaled study. Methods: We performed targeted ultra-deep sequencing (CancerSCAN™) using BC tissue specimens. This sequencing was covered entire coding area of ESR1 gene and also detected copy number alteration and translocation of ESR1. Results: Targeted ultra-deep sequencing of ESR1 was performed using 618 BC tissues. Of 618 tissue samples, 253(40.9%) were MBCs, 362(58.6%) were early BCs (EBCs) and 3 were not identified. In terms of subtypes, 220 ER-positive BCs, 122 ER-positive and HER2-positive BCs, 119 HER2-positive and 153 triple-negative BCs (TNBCs) were included. BCs from patients under 40 year-old were 277(44.8%)(Median: 43.0, range: 23.5 -75.6). ESR1 genetic alterations were identified in 21 BCs (5 EBCs and 16 MBCs). In EBCs, 3 cases were observed in TNBCs and 2 cases were in ER-positive BCs (2.6% and 1.2%, respectively). All five EBC were treatment naive status. Of 16 cases of ESR1 alterations in MBCs, 10 cases of ESR1 alterations were detected in ER-positive BCs (17.6%), 5cases in ER and HER2-positive BCs(6.7%) and 1 in HER2-positive BCs (1.2%). All ER-positive MBCs were treated with more than one line of endocrine therapy. Most commonly detected genetic alteration was single nucleotide variant (SNV) (15 of 21, 71.4%). Thirteen were in ligand binding domain and two cases occurred in activation function-1 (AF-1) domain (P79A and G145S). D538G and V392I were most frequently mutated loci followed by Y537N (3, 3 and 2 cases, respectively) and only metastatic ER-positive BCs harbored ESR1 activating mutation. Four copy number (CN) amplification in 2 ER-positive and 2 ER and HER2-positive BCs, one CN deletion in TNBC and one ESR1 fusion in ER and HER2-positive BC were also detected (19.0%, 4.8% and 4.8%, respectively). In frame ESR1 fusion was occurred between ESR1 and NPHS1 genes. Conclusion: In this experimental study, ESR1 genetic alterations were frequently detected in ER-positive MBC but ER-negative or EBC also harbored. The type of genetic alterations varied including SNVs, CN alterations and translocation and ESR1-NPHS1 fusion is the novel genetic alteration that has not been reported. To identify the role of ESR1 genetic alteration in ER-negative BCs and novel translocation, further functional validation would be warranted (Clinical trials.gov Number :NCT02591966). Citation Format: Kim J-Y, Park K, Park W-Y, Nam SJ, Kim SW, Lee JE, Lee SK, Jung HH, Yu JH, Ahn JS, Im Y-H, Park YH. Identification of ESR1 mutation in breast cancers using targeted ultra-deep sequencing data analysis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-09-08.

Abstract P6-09-36: Tamoxifen resistance: EGFR expression in hormone receptor-positive and HER2 negative breast cancer

Purpose: Crosstalk between growth factor receptor tyrosine kinases (RTKs) and the estrogen receptor (ER) represents one of the most important mechanisms of endocrine resistance. EGFR and HER2 have been recognized as prominent factors associated with endocrine resistance. Most previous studies did not identify subgroups by HER2 overexpression and/or included breast cancer with HER2 overexpression. Accordingly, we analyzed HR positive (HR+) tumors without HER2 overexpression (HER2-). Methods: We analyzed the clinical data of 2,166 patients with HR+HER2- breast tumors, between January 2007 and July 2013.We included only patients who had endocrine therapy with tamoxifen. Immunostaining for EGFR was interpreted as positive when at least 10% of the tumor cells showed moderate to strong membrane staining. Results: EGFR expression (EGFR+) was present in 109 patients (5%). EGFR expression was significantly associated with more advanced stage and higher grades. In the univariate analyses, EGFR+ tumors were associated with poorer prognosis than EGFR- tumors (5-year DFS, EGFR+ vs. EGFR-, 91.2% vs. 96.6%, P Conclusion: EGFR expression could be prognostic factor in hormone receptor-positive and HER2 negative breast cancer, for tamoxifen resistance. Citation Format: Bae SY, Nam SJ, Lee SK, Kim SW, Lee JE, Yu JH. Tamoxifen resistance: EGFR expression in hormone receptor-positive and HER2 negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-36.

Abstract P1-02-11: Clinical utility of serial monitoring of circulating tumor DNA (ctDNA)in patients with neoadjuvant chemotherapy (NAC) for locally advanced breast cancer (LABC)

Introduction: Circulating tumor DNA (ctDNA) is a new biomarker which could guide further treatment. Characterization of tumor mutation profiles is required for informed choice of therapy, given that biological agents target specific pathways and effectiveness may be modulated by specific mutations. It would have clinical utility for neoadjuvant setting also. Thus, we assess the potency of ctDNA to predict tumor response to neoadjuvant chemotherapy(NAC) in locally advanced breast cancer(LABC). Methods: We performed targeted deep sequencing of 30 plasma DNAs and 10 matched germline DNAs from 10 LABC patients. Serial plasma DNAs were collected at diagnosis, after 1st NAC and curative surgery. For the target enrichment, we designed RNA baits covering a total of ~202kb regions of human genome including a total of 83 cancer-related genes. We constructed the sequencing libraries according to the optimized protocol that we recently reported and sequenced on Illumina HiSeq2500 aiming a mean sequencing depth of ~10,000. After excluding unmapped reads, PCR duplicates and off-target reads, the coverage depths for plasma DNA and germline DNA samples were 2,627x and 4,833x on average, respectively. NAC response was measured by residual cancer burden(RCB) score, calculated as a continuous index combining pathologic measurements of primary tumor and nodal metastases for prediction of distant relapse-free survival. Results: We analyzed ctDNA and primary tumor tissues from 10 patients with LABC scheduled NAC followed by operation in Samsung Medical Center. Of ten LABCs, one excluded from analysis because of angiosarcoma of breast. Five samples were triple-negative breast cancers (BCs), 2 were HER2 positive BCs and others were ER positive BCs. In tumor response, 1 patient had pathologic complete response (pCR), 1 had RCB class I, 4 and 3 patients did RCB class II and III. Of 83 genes, in analysis of ctDNA at BC diagnosis, we found 2 to 6 mutations in each samples and 3 mutations were detected averagely. Most common mutation was TP53 (6 patients), followed by PIK3CA mutation. By measuring these mutations in serial ctDNA, we found that ctDNA had disappeared after first cycle of NAC in patient with pCR. In two patients with RCB class I, ctDNA had decreased by more than 10 percent (the level of ctDNA(pg/ml): 455.9 to 30.4, 5.8 to 0.0) of primary plasma sample after first NAC. Two patients increased level of ctDNA had tumor response with RCB class III and one patient had distant tumor recurrence within 3 months after curative surgery. However, correlation between the level of ctDNA and initial stage was not observed. Conclusions: This preliminary result suggests that serial monitoring of ctDNA would be a potiential surrogate marker to predict tumor response and recurrence during NAC in LABC patients. Further results with long-term outcomes are warranted. Citation Format: Kim J-Y, Park D, Jung HH, Bae SY, Yu JH, Lee SK, Kim SW, Lee JE, Nam SJ, Ahn JS, Im Y-H, Park YH. Clinical utility of serial monitoring of circulating tumor DNA (ctDNA)in patients with neoadjuvant chemotherapy (NAC) for locally advanced breast cancer (LABC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-02-11.

Abstract P3-14-12: Oncologic outcomes of immediate breast reconstruction after neoadjuvant chemotherapy in breast cancer patients: A matched case control study

Introduction: Although the indication for total mastectomy (TM) with immediate breast reconstruction (IBR) has been expanded, IBR after neoadjuvant chemotherapy (NACT) is still controversy. We assumed that TM with IBR after NACT is feasible surgical treatment in breast cancer patients. Methods: A retrospective review of breast cancer patients who underwent TM with IBR after NACT between 2008 and 2015 at a single center was conducted. These cases were matched by 1:5 to patients who underwent mastectomy alone after NACT. Matching variables included age, clinical T and N staging before NACT, response to NACT, and pathologic staging after NACT. Pathological stage was followed by seventh American Joint Committee on Cancer (AJCC) classification. Results: Overall, 31 patients were identified in the TM with IBR group (Study group) and 85 patients (Control group) were matched. In the study group, 13 (41.9%) patients underwent nipple-sparing mastectomy (NSM) and 18 (58.1%) underwent skin-sparing mastectomy (SSM). Median follow-up duration was 29.2 (7-31) and 38.8 (11-85) months for the study and control group, respectively. Median age was 37.0 (26-57) and 40.0 (24-56) years for the study and control group, respectively. The clinicopathologic characteristics of both groups are summarized in Table1. Disease-free survival (p=0.520), local recurrence-free survival (p=0.610), distant metastasis-free survival (p=0.795), and over survival (p=0.971) did not differ significantly between two groups. Conclusion: TM with IBR after NACT is feasible surgical treatment option in breast cancer patients. Citation Format: Ryu JM, Lee JE, Kim SW, Yu J, Rayzah M, Lee SK, Mansoor A, Bae SY, Park S, Paik H-J, Kim I, Bang SI, Jeon BJ, Mun G-H, Pyon J-K. Oncologic outcomes of immediate breast reconstruction after neoadjuvant chemotherapy in breast cancer patients: A matched case control study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-14-12.

Abstract P1-05-15: Multi-omics and immuno-oncology profiling reveal distinct molecular signatures of young Asian breast cancers

Breast cancers (BC) in younger, premenopausal patients (YBC) tend to be more aggressive with worse prognosis, higher chance of relapse and poorer response to endocrine therapies compared to breast cancers in older patients. The proportion of YBC (age ≤ 40) among BC in East Asia is estimated to be 16-32%, significantly higher than the 7% reported in Western countries. To characterize the molecular bases of Asian YBC, we have performed whole-exome sequencing (WES) and whole-transcriptome sequencing (WTS) on tumor and matched normal samples from 134 Korean BC patients consisting of 74 YBC cases (age ≤ 40) and 60 OBC cases (age > 40). We then performed comparison analyses and integrative analyses with the TCGA BC cohort consisting of 1,116 tumors from primarily Caucasian patients, also grouped by age into YBC (age ≤ 40), IBC (40 60). Somatic mutation prevalence analysis identified 7 significantly mutated genes and the same top three genes – TP53, GATA3 and PIK3CA – were reported by the TCGA BC study. To identify differentially expressed (DE) genes and pathways in YBCs vs. OBCs, we performed logistic regression analyses while controlling for the confounding effects of tumor purity and stage. We were surprised to see a significant overlap in DE pathways between a comparison of adjacent normal tissues in younger vs. older TCGA cohorts and a comparison of YBC vs. OBC tumors, indicating that normal tissue compartment could contribute to observed differences between bulk tumors. To separately examine molecular signatures from tumor, stroma and normal compartments, we used non-negative matrix factorization (NMF) analyses to virtually dissect bulk tumor expression data and identified 14 factors including 3 factors associated with normal tissues, 1 factor associated with stroma and 1 factor associated with tumor infiltrating lymphocytes (TIL). Integrative analyses of tumor associated factors and DE pathways revealed that estrogen response, endocrine therapy resistance, and oxidative phosphorylation pathways are up-regulated in YBCs compared to OBCs while cell cycle and proliferation pathways are up-regulated in Asian OBCs. Interestingly, many immune and inflammation pathways correlated with the TIL factor were significantly upregulated in OBCs vs. YBCs. Using gene expression signatures representing distinct immune cell types, we classified our cohort into four subtypes of varying TIL activities and observed significant enrichment of the TIL-high subtype in OBCs compared to YBCs. These observations were confirmed by IHC analyses of four TIL markers (CD45, CD4, CD8 and CD163) in 120 tumors. To our knowledge, this is the first large-scale multi-omics study of Asian breast cancer and would significantly contribute to the compendium of molecular data available for studying young breast cancers. The major landmarks in the molecular landscape looked similar across BCs of different ethnicities and ages, however, we have identified a number of distinguishing molecular characteristics associated with Asian YBC. The sources for some signatures were further traced to non-tumor intrinsic compartments, indicating that tumor microenvironment may play potentially important roles in driving the carcinogenesis of young breast cancers. Citation Format: Kan Z, Ding Y, Cho S, Lee S-H, Powell E, Jung HH, Chung W, Deng S, Choi Y-l, Kim J, Park W-Y, Vizcarra P, Fernandez-Banet J, Nichols T, Ram S, Lee SK, Kim SW, Lee JE, Ching KA, Kim J-Y, Ahn JS, Im Y-H, Nam SJ, Park YH. Multi-omics and immuno-oncology profiling reveal distinct molecular signatures of young Asian breast cancers [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-05-15.

Abstract P1-11-01: Depression and anxiety after adjuvant ovarian function suppression in premenopausal breast cancer patients

Purpose The results of the Suppression of Ovarian Function Trial (SOFT) and the Tamoxifen and Exemestane Trial (TEXT) showed that ovarian function suppression (OFS) in premenopausal early breast cancer patients improves disease control. However, mood swings after OFS is one of the chief complaints to make patients stop undergoing endocrine therapy. Studies about complications of OFS in breast cancer patients are not established well. We designed this randomized controlled trial to evaluate psychological functioning of patients after undergoing adjuvant OFS by goserelin. Patients and Methods We randomly assigned 64 premenopausal women with hormone receptor positive early breast cancer to the tamoxifen or tamoxifen plus goserelin group for a period of 1 year. Participants were screened for depression and generalized anxiety disorder using Hamilton Rating Scale for Depression (HAMD), Hamilton Rating Scale for Anxiety (HAM-A), Anxiety Sensitivity Index (ASI) and Albany panic and phobia questionnaire (APPQ) at baseline, 6 months and 12 months. Brain-derived Neurotrophic Factor (BDNF) levels were measured, as well. The results were analyzed by using a linear mixed model and a generalized linear mixed model. Results Thirty two patients were distributed in each group, equally. Linear mixed-mixed model analyses revealed that, compared with HAM-A scores of each group at baseline, HAM-A scores at 12 months showed increments (p=0.0078). Among HAM-A questions, Questions for intellectual, sensory and autonomic status were scored significantly high at 12 months (p=0.0018, p=0.0132, p=0.0006). Platelet BDNF levels reported a statistically significant rise at 12 months (p=0.0006). There was no significant time-by-study group effect in all scales. Conclusion Compared with the patients without OFS, patients with Goserelin showed no difference in anxiety or depression scales. Thought the levels of anxiety of each group at 12 months were increased, they do not indicate medical interventions. Patients with increased levels of BDNF at 12 months are expected to have good recovery from anxious and depressive symptoms. Citation Format: Yi HW, Nam SJ, Kim SW, Lee JE, Lee SK, Bae SY, Park S, Paik H-J, Ryu JM. Depression and anxiety after adjuvant ovarian function suppression in premenopausal breast cancer patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-11-01.

Abstract P2-08-19: Prognostication of HER family gene expression collaborate with ESR1 expression in patients with triple negative breast cancer

Background: Triple-negative breast cancer (TNBC) consists of heterogeneous sub-population. Although many investigators made an effort to categorize and classify TNBCs using genetic expressions, it is still needed to be defined for prognostication Traditionally, HER family genes have been known to contribute mammalian glands formation and breast cancer generation as well as ESR gene. Moreover, target agents for HER family genes have been already developed. Accordingly, we investigated the expression profiles of HER family genes with ESR in patients with TNBC to categorize into sub-types and determine the prognostic value of HER family genes in search of clinical implications. Methods : We investigated the results of the nCounter expression assay (NanoString®) for ERBB1, ERBB2, ERBB3, ERBB4 and ESR1 using mRNA extract from paraffin-embedded tumor tissues in 203 patients diagnosed as TNBC. We used the results of nCounter expression assay using 84 TNBC tissues for validation and 52 breast cancer tissues diagnosed as other subtypes to control the expression assay results of these five genes. Results: Two-hundred and three patients were diagnosed as TNBC from 2000 to 2004 and received adjuvant chemotherapy after curative surgery. Eighty-four TNBC patients for validation set and 52 patients diagnosed as other subtypes for control set were selected from the patients diagnosed as breast cancer from 2005 to 2010 and received curative surgery. Through analyzing 5 genes using the nCounter expression profiles from 203 TNBC tissues, we found that increased expression of ERBB4 was associated with poor prognosis by survival analysis (5 year disease recurrence free survival (DRFS), low vs. high expression [cut-off: median]: 90.1% vs. 80.2%; p =.002). This trend was still remained in validation set composed of TNBC (5 year DRFS, low vs. high expression [cut-off : median]: 61.1% vs. 44.0%), whereas was not observed in other subtypes of breast cancer (44.4% vs. 80.8%). The Kaplan-Meier estimates of the rates of 5 year DRFS in the subgroups classified according to the level of 5 genes expression showed that the group of higher expression of all HER family genes and lower expression of ESR1 gene had dismal prognosis rather than other groups in patients with TNBC (5 year DRFS, this group vs. others: 50.0% vs. 88.2%; p Conclusions: The expression profile of HER family genes could be used as a prognostic marker in patients with TNBC. Further study is needed to identify the expression profiles of HER family gene as predictive marker of HER targeting treatment in patients with TNBC. Citation Format: Kim J-Y, Ahn T, Jung HH, Park K, Do I-G, Kil WH, Kim SW, Lee JE, Nam SJ, Ahn JS, Park YH, Im Y-H. Prognostication of HER family gene expression collaborate with ESR1 expression in patients with triple negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-19.

Abstract P3-01-03: Optimal concentration of indocyanine green in near-infrared fluorescence guided sentinel lymph node biopsy in breast cancer

Background: Near-infrared (NIR) fluorescence-guided sentinel lymph node biopsy (SLNB) using indocyanine green (ICG) has been successfully applied in various kinds of cancers, especially in breast cancer. Optimizing the concentration of ICG without using human serum albumin in natural lymphatic system is still required. Methods: 25mg of ICG was diluted with distilled water (DW) or normal saline (NS). Dilution concentrations used for measurement were 0.25μg/mL, 0.5μg/mL, 2.5μg/mL, 5.0μg/mL, 25μg/mL, and 250μg/mL. The brightness of fluorescence was measured by an image system called Visual Navigator (SH System, Korea). We used graphic software (GIMP, version 2.8.14, The GIMP Team) to measure the brightness. We assumed that drained serous lymphatics from a breast cancer patient can reflect a natural lymphatic condition injected with ICG in the operation field. Drained lymphatics were mixed to reduce the concentration of ICG by half that was diluted with DW or NS. We also measured the brightness of fluorescence diluted with DW or NS that was mixed with drained lymphatics. After this screening test, we subdivided the range which brightness was measured as 100 and adjusted the intensity of illumination for more specific results. Results: Highest brightness values were measured as 100 between 2.5μg/mL and 25μg/mL concentration of ICG with DW dilution in screening settings, and the values of brightness were measured as 100 between 2.5μg/mL and 5.0μg/mL concentration of ICG with NS dilution. When drained lymphatics were mixed together, the values of brightness were measured as 100 between 2.5μg/mL and 25μg/mL concentration of ICG with DW or NS dilution. After subdividing the ICG concentration to 2.5μg/mL, 3.13μg/mL, 5.0μg/mL, 6.25μg/mL, 12.5μg/mL and 25μg/mL with adjusting the intensity of illumination, the highest brightness value was measured as 76 in 5.0μg/mL concentration of ICG with DW dilution. When diluting with NS, the highest brightness value was measured as 61 in 5.0μg/mL ICG concentration. After mixing with drained lymphatics, the highest brightness value was both 79 in 5.0μg/mL concentration of ICG with DW and NS dilution. Conclusions: This study showed a practically optimal ICG concentration range in fluorescence guided SLNB. The optimal range of ICG concentration is from 3.13μg/mL to 6.25μg/mL with DW or NS dilution. Although 5.0μg/mL met the best result, adjustment for individual settings may be considered. Citation Format: Paik H-J, Yi HW, Park S, Ryu JM, Nam SJ, Lee JE, Kil WH, Lee SK, Bae SY, Kim SW. Optimal concentration of indocyanine green in near-infrared fluorescence guided sentinel lymph node biopsy in breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-01-03.