Outcomes of sentinel node biopsy according to MRI response in an association with the subtypes in cN1-3 breast cancer after neoadjuvant systemic therapy, multicenter cohort study

BACKGROUND

This study investigated the feasibility of sentinel lymph node biopsy (SLNB) after neoadjuvant systemic therapy (NAST) in patients with initially high nodal burden.

METHODS

In the multicenter retrospective cohort, 388 individuals with cN1-3 breast cancer who underwent NAST and had SLNB followed by completion axillary lymph node dissection were included. In an external validation cohort, 267 patients with HER2+ or triple-negative breast cancer (TNBC) meeting similar inclusion criteria were included. Primary outcome was the false-negative rates (FNRs) of SLNB according to the MRI response and subtypes. We defined complete MRI responders as patients who experienced disappearance of suspicious features in the breast and axilla after NAST.

RESULTS

In the multicenter retrospective cohort, 130 (33.5%) of 388 patients were of cN2-3, and 55 (14.2%) of 388 patients showed complete MRI responses. In hormone receptor-positive HER2- (n = 207), complete and non-complete responders had a high FNRs (31.3% [95% CI 8.6-54.0] and 20.9% [95% CI 14.1-27.6], respectively). However, in HER2+ or TNBC (n = 181), the FNR of complete MRI responders was 0% (95% CI 0-0), whereas that of non-complete responders was 33.3% (95% CI 20.8-45.9). When we validated our findings in the external cohort with HER2+ or TNBC (n = 267), of which 34.2% were cN2-3, the FNRs of complete were 7.1% (95% CI 0-16.7).

CONCLUSIONS

Our findings suggest that SLNB can be a reliable option for nodal status evaluation in selected patients who have responded well to NAST, especially in HER2+ and TNBC patients who show a complete MRI response.

Selective omission of sentinel lymph node biopsy in mastectomy for ductal carcinoma in situ: identifying eligible candidates

BACKGROUND

Sentinel lymph node biopsy (SLNB) is recommended for patients with ductal carcinoma in situ (DCIS) undergoing mastectomy, given the concerns regarding upstaging and technical difficulties of post-mastectomy SLNB. However, this may lead to potential overtreatment, considering favorable prognosis and de-escalation trends in DCIS. Data regarding upstaging and axillary lymph node metastasis among these patients remain limited.

METHODS

We retrospectively reviewed patients with DCIS who underwent mastectomy with SLNB or axillary lymph node dissection at Gangnam Severance Hospital between January 2010 and December 2021. To explore the feasibility of omitting SLNB, we assessed the rates of DCIS upgraded to invasive carcinoma and axillary lymph node metastasis. Binary Cox regression analysis was performed to identify clinicopathologic factors associated with upstaging and axillary lymph node metastasis.

RESULTS

Among 385 patients, 164 (42.6%) experienced an invasive carcinoma upgrade: microinvasion, pT1, and pT2 were confirmed in 53 (13.8%), 97 (25.2%), and 14 (3.6%) patients, respectively. Seventeen (4.4%) patients had axillary lymph node metastasis. Multivariable analysis identified age ≤ 50 years (adjusted odds ratio [OR], 12.73; 95% confidence interval [CI], 1.18-137.51; p = 0.036) and suspicious axillary lymph nodes on radiologic evaluation (adjusted OR, 9.31; 95% CI, 2.06-41.99; p = 0.004) as independent factors associated with axillary lymph node metastasis. Among patients aged > 50 years and/or no suspicious axillary lymph nodes, only 1.7-2.3%) experienced axillary lymph node metastasis.

CONCLUSIONS

Although underestimation of the invasive component was relatively high among patients with DCIS undergoing mastectomy, axillary lymph node metastasis was rare. Our findings suggest that omitting SLNB may be feasible for patients over 50 and/or without suspicious axillary lymph nodes on radiologic evaluation.

Tumor-Infiltrating Lymphocyte Level Consistently Correlates with Lower Stiffness Measured by Shear-Wave Elastography: Subtype-Specific Analysis of Its Implication in Breast Cancer

Background: We aimed to elucidate the clinical significance of tumor stiffness across breast cancer subtypes and establish its correlation with the tumor-infiltrating lymphocyte (TIL) levels using shear-wave elastography (SWE). Methods: SWE was used to measure tumor stiffness in breast cancer patients from January 2016 to August 2020. The association of tumor stiffness and clinicopathologic parameters, including the TIL levels, was analyzed in three breast cancer subtypes. Results: A total of 803 patients were evaluated. Maximal elasticity (Emax) showed a consistent positive association with an invasive size and the pT stage in all cases, while it negatively correlated with the TIL level. A subgroup-specific analysis revealed that the already known parameters for high stiffness (lymphovascular invasion, lymph node metastasis, Ki67 levels) were significant only in hormone receptor-positive and HER2-negative breast cancer (HR + HER2-BC). In the multivariate logistic regression, an invasive size and low TIL levels were significantly associated with Emax in HR + HER2-BC and HER2 + BC. In triple-negative breast cancer, only TIL levels were significantly associated with low Emax. Linear regression confirmed a consistent negative correlation between TIL and Emax in all subtypes. Conclusions: Breast cancer stiffness presents varying clinical implications dependent on the tumor subtype. Elevated stiffness indicates a more aggressive tumor biology in HR + HER2-BC, but is less significant in other subtypes. High TIL levels consistently correlate with lower tumor stiffness across all subtypes.

Feasibility of Intraoperative Radiotherapy Tumor Bed Boost in Patients with Breast Cancer after Neoadjuvant Chemotherapy

PURPOSE

This study aimed to assess the feasibility and safety of administering intraoperative radiotherapy (IORT) as a boost during breast-conserving surgery (BCS) following neoadjuvant chemotherapy for patients at high risk of breast cancer recurrence.

MATERIALS AND METHODS

Patients who underwent neoadjuvant chemotherapy received a single 20-Gy dose of IORT during BCS, followed by external beam radiotherapy 4-6 weeks after surgery.

RESULTS

The median follow-up duration was 31.0 months (range, 18.0-59.0 months). Initial tumor sizes had a median of 2.6 cm (range: 0.8-5.3 cm), reducing to 0.3 cm (range: 0-4.0 cm) after neoadjuvant chemotherapy. The most common neoadjuvant chemotherapy regimen was doxorubicin and cyclophosphamide, followed by paclitaxel (n=42, 73.7%). Among 57 patients who received neoadjuvant chemotherapy before BCS and IORT, 2 patients (3.5%) required secondary surgery to achieve negative resection margins due to initially positive margins. Regional lymph node irradiation was performed in 37 (64.9%) patients. There was no grade 3 or higher adverse events, with 4 patients (7.0%) experiencing grade 2 acute radiation dermatitis and 3 (5.3%) having less than grade 2 breast edema. Binary correlation analysis did not reveal statistically significant associations between applicator size or radiation therapy modality and the risk of treatment-related toxicity. Furthermore, chi-square analysis showed that the grade of treatment-related toxicity was not associated with the fractionated regimen (p=0.375).

CONCLUSION

Most patients successfully received IORT as a tumor bed boost after neoadjuvant chemotherapy. Thus, IORT may be a safe and feasible option for patients with advanced-stage breast cancer receiving neoadjuvant chemotherapy.

Predictive Markers of Treatment Response to Neoadjuvant Systemic Therapy with Dual HER2-Blockade

In patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer, achievement of pathologic complete response (pCR) is a known prognostic indicator after neoadjuvant systemic therapy (NAST). We investigated the clinicopathological factors associated with pCR in patients with HER2-positive breast cancer treated with dual HER2-blockade. In this retrospective study, 348 patients with HER2-positive breast cancer who received NAST with docetaxel and carboplatin, combined with trastuzumab and pertuzumab (TCHP), were included. Of the 348 patients with HER2 protein expression data, 278 (79.9%) had HER2 immunochemistry (IHC) 3+. Data on tumor-infiltrating lymphocyte (TIL) levels were available for 305 patients, showing a median TIL level of 20% (IQR 5-50), among which 121 (39.7%) had high TIL levels (≥30%). Estrogen receptor (ER) status (77.9% in ER-negative vs. 47.5% in ER-positive; p < 0.001), HER2 protein expression (71.6% in IHC 3+ vs. 34.3% in IHC 2+; p < 0.001), and TIL levels (71.9% in high vs. 57.6% in low; p = 0.011) were significantly associated with the pCR rate. In addition, we observed a significant link between numerical TIL levels (per 10% increment) and the pCR rate. After adjusting other clinicopathologic factors, ER status (low expression [defined as 1-9% expression] or negative), HER2 IHC 3+ and numerical TIL levels (per 10% increment), and high TIL levels (≥30%) were found to be independent predictors of pCR. Notably, in ER-negative breast cancer, the treatment response was excellent, irrespective of HER2 expression and TIL levels. Conversely, in ER-positive cases, low ER expression, HER2 IHC 3+, and numerical TIL levels or high TIL levels emerged as independent predictors of pCR. Our results suggest that ER expression, HER2 protein expression, and TIL levels serve as valuable predictors of the treatment response to neoadjuvant TCHP.

Breast density reduction as a predictor for prognosis in premenopausal women with estrogen receptor-positive breast cancer: an exploratory analysis of the updated ASTRRA study

BACKGROUND

While the relationship between mammographic breast density reduction (MDR) and endocrine therapy efficacy has been reported in estrogen receptor (ER)-positive breast cancer, it is still unclear in premenopausal women, especially in the case of adding ovarian function suppression (OFS) to antihormone therapy. The authors investigated the impact of MDR on prognosis stratified by treatment based on the updated results of the ASTRRA trial.

MATERIALS AND METHODS

The ASTRRA trial, a randomized phase III study, showed that adding OFS to tamoxifen (TAM) improved survival in premenopausal women with estrogen receptor-positive breast cancer after chemotherapy. The authors updated survival outcomes and assessed mammography before treatment and the annual follow-up mammography for up to 5 years after treatment initiation. Mammographic density (MD) was classified into four categories based on the Breast Imaging-Reporting and Data System. MDR-positivity was defined as a downgrade in MD grade on follow-up mammography up to 2 years after randomization, with pretreatment MD grade as a reference.

RESULTS

The authors evaluated MDR in 944 of the 1282 patients from the trial, and 813 (86.2%) had grade III or IV MD. There was no difference in the MDR-positivity rate between the two treatment groups [TAM-only group (106/476 (22.3%)) vs. TAM+OFS group (89/468 (19.0%)); P =0.217). MDR-positivity was significantly associated with better disease-free survival (DFS) in the TAM+OFS group (estimated 8-year DFS: 93.1% in MDR-positive vs. 82.0% in MDR-negative patients; HR: 0.37; 95% CI: 0.16-0.85; P =0.019), but not in the TAM-only group ( Pinteraction =0.039). MDR-positive patients who received TAM+OFS had a favorable DFS compared to MDR-negative patients who received only TAM (HR: 0.30; 95% CI: 0.13-0.70; P =0.005).

CONCLUSION

Although the proportion of MDR-positive patients was comparable between both treatment groups, MDR-positivity was independently associated with favorable outcomes only in the TAM+OFS group.

Elasticity Values as a Predictive Modality for Response to Neoadjuvant Chemotherapy in Breast Cancer

Shear-wave elastography (SWE) is an effective tool in discriminating malignant lesions of breast and axillary lymph node metastasis in patients with breast cancer. However, the association between the baseline elasticity value of breast cancer and the treatment response of neoadjuvant chemotherapy is yet to be elucidated. Baseline SWE measured mean stiffness (E-mean) and maximum stiffness (E-max) in 830 patients who underwent neoadjuvant chemotherapy and surgery from January 2012 to December 2022. Association of elasticity values with breast pCR (defined as ypTis/T0), pCR (defined as ypTis/T0, N0), and tumor-infiltrating lymphocytes (TILs) was analyzed. Of 830 patients, 356 (42.9%) achieved breast pCR, and 324 (39.0%) achieved pCR. The patients with low elasticity values had higher breast pCR and pCR rates than those with high elasticity values. A low E-mean (adjusted odds ratio (OR): 0.620; 95% confidence interval (CI): 0.437 to 0.878; p = 0.007) and low E-max (adjusted OR: 0.701; 95% CI: 0.494 to 0.996; p = 0.047) were independent predictive factors for breast pCR. Low elasticity values were significantly correlated with high TILs. Pretreatment elasticity values measured using SWE were significantly associated with treatment response and inversely correlated with TILs, particularly in HR+HER2- breast cancer and TNBC.

BRCA1 mutation promotes sprouting angiogenesis in inflammatory cancer-associated fibroblast of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with inferior outcomes owing to its low treatment response and high invasiveness. Based on abundant cancer-associated fibroblasts (CAFs) and frequent mutation of breast cancer-associated 1 (BRCA1) in TNBC, the characteristics of CAFs in TNBC patients with BRCA1 mutation compared to wild-type were investigated using single-cell analysis. Intriguingly, we observed that characteristics of inflammatory CAFs (iCAFs) were enriched in patients with BRCA1 mutation compared to the wild-type. iCAFs in patients with BRCA1 mutation exhibited outgoing signals to endothelial cells (ECs) clusters, including chemokine (C-X-C motif) ligand (CXCL) and vascular endothelial growth factor (VEGF). During CXCL signaling, the atypical chemokine receptor 1 (ACKR1) mainly interacts with CXCL family members in tumor endothelial cells (TECs). ACKR1-high TECs also showed high expression levels of angiogenesis-related genes, such as ANGPT2, MMP1, and SELE, which might lead to EC migration. Furthermore, iCAFs showed VEGF signals for FLT1 and KDR in TECs, which showed high co-expression with tip cell marker genes, including ZEB1 and MAFF, involved in sprouting angiogenesis. Moreover, BRCA1 mutation patients with relatively abundant iCAFs and tip cell gene expression exhibited a limited response to neoadjuvant chemotherapy, including cisplatin and bevacizumab. Importantly, our study observed the intricate link between iCAFs-mediated angiogenesis and chemoresistance in TNBC with BRCA1 mutation.

YAP1 Expression in HR+HER2- Breast Cancer: 21-Gene Recurrence Score Analysis and Public Dataset Validation

BACKGROUND

YAP1, an oncogene in numerous cancers, is a downstream transcription factor of the Hippo pathway. This study focuses on its relationship with the Oncotype Dx (ODX) test risk score (RS) in patients with hormone-receptor-positive, HER2-negative (HR+HER2-) breast cancer.

METHODS

We retrospectively analyzed 401 HR+HER2- breast cancer patients from Gangnam Severance Hospital who underwent ODX tests (May 2014-April 2020). YAP1 nuclear localization was evaluated via immunohistochemical staining and its clinical correlation with clinicopathological parameters, including RS, was analyzed. Public datasets TCGA-BRCA and METABRIC validated clinical outcomes.

RESULTS

YAP1 expression negatively correlated with ODX RS (OR 0.373, p = 0.002). Elevated YAP1 mRNA levels corresponded to better clinical outcomes, specifically in ER-positive patients, with significant results in METABRIC and TCGA-BRCA datasets (p < 0.0001 OS in METABRIC, p = 0.00085 RFS in METABRIC, p = 0.040 DFS in TCGA-BRCA). In subsets with varying ESR1 mRNA expression and pronounced YAP1 expression, superior survival outcomes were consistently observed.

CONCLUSION

YAP1 may be a valuable prognostic marker and potential therapeutic target in HR+HER2- breast cancer patients.

Prognostic impact of radiotherapy-induced-lymphopenia in patients treated with breast-conservative surgery

We investigated a prognostic impact of radiotherapy-induced lymphopenia (RIL) in breast cancer patients treated with breast-conservative surgery (BCS). We included 531 breast cancer patients who were treated with BCS and adjuvant radiotherapy. None of these received (neo)adjuvant chemotherapy. Pre- and post- absolute lymphocyte counts (ALC) were reviewed before and after radiotherapy. The primary endpoint was to evaluate recurrence-free survival (RFS) according to the pre-to-post ALC ratio. Binary logistic regression model was used to identify risk factors for RIL. Either continuous or categorical (> 2.4) pre-to-post ALC ratio was associated with RFS. In 531 patients receiving whole breast irradiation (WBI) and regional nodal irradiation (RNI), RFS was significantly reduced in the patients with high pre-to-post ALC ration (> 2.4). In multivariable analysis, low pre-to-post post ALC ratio was significantly related to decreased RFS in the multivariable analysis (HR 2.293, 95% CIs 1.110-4.735, P = 0.025). In 452 patients treated with WBI alone, high pre-to-post ALC ratio was still significantly associated with decreased RFS in the multivariable analysis (HR 2.708, 95% CIs 1.016-7.218, P = 0.046). In binary logistic regression analysis, RNI was only significant risk factor for clinically meaningful RIL. Our findings show that a markedly decrease in ALC during radiotherapy has a negative prognostic impact.

Ki-67, 21-Gene Recurrence Score, Endocrine Resistance, and Survival in Patients With Breast Cancer

Importance

Both high 21-gene recurrence score (RS) and high Ki-67 level are poor prognostic factors in patients with estrogen receptor (ER)-positive ERBB2-negative (ER+/ERBB-) breast cancer; however, a discrepancy between the 2 has been noted. Survival differences according to these 2 biomarkers are not well known.

Objective

To assess the associations between RS and Ki-67 expression and between Ki-67 expression and recurrence-free survival in patients with ER+/ERBB- breast cancer with low RS.

Design, Setting, and Participants

This cohort study included women treated for ER+/ERBB2- breast cancer who underwent the 21-gene RS test from March 2010 to December 2020 in 2 hospitals in Korea.

Exposures

Recurrence score and Ki-67 level.

Main Outcomes and Measures

A Cox proportional hazards regression model was used to examine the association of Ki-67 with recurrence-free survival (RFS), while a binary logistic regression model was used to examine the association between Ki-67 and secondary endocrine resistance. High Ki-67 expression was defined as 20% or greater, and low genomic risk as an RS of 25 or less. Secondary endocrine resistance was defined as breast cancer recurrence that occurred after at least 2 years of endocrine therapy and during or within the first year after completing 5 years of adjuvant endocrine therapy.

Results

A total of 2295 female patients were included (mean [SD] age, 49.8 [9.3] years), of whom 1948 (84.9%) were in the low genomic risk group and 1425 (62.1%) had low Ki-67 level. The median follow-up period was 40 months (range, 0-140 months). The RS and Ki-67 level had a moderate correlation (R = 0.455; P < .001). Of the patients with low Ki-67 level, 1341 (94.1%) had low RS, whereas 607 of 870 patients with high Ki-67 level (69.8%) had low RS. In patients with low RS, the RFS differed significantly according to Ki-67 level (low Ki-67, 98.5% vs high Ki-67, 96.5%; P = .002). Among the 1807 patients with low genomic risk who did not receive chemotherapy, high Ki-67 level was independently associated with recurrence (hazard ratio, 2.51; 95% CI, 1.27-4.96; P = .008). Recurrence after 3 years differed significantly according to Ki-67 level (low Ki-67, 98.7% vs high Ki-67, 95.7%; P = .003), whereas recurrence within 3 years did not differ (low Ki-67, 99.3% vs high Ki-67, 99.3%; P = .90). In addition, Ki-67 was associated with secondary endocrine resistance in patients with low RS who did not receive chemotherapy (odds ratio, 2.49; 95% CI, 1.13-5.50; P = .02).

Conclusions and Relevance

In this cohort study of patients with ER+/ERBB2- breast cancer, a moderate correlation was observed between Ki-67 and RS, and high Ki-67 level in patients with low genomic risk was associated with increased risk of secondary endocrine resistance.

Investigation of Factors Affecting Adherence to Adjuvant Hormone Therapy in Early-Stage Breast Cancer Patients: A Comprehensive Systematic Review

PURPOSE

Adherence and persistence to adjuvant hormone therapy (AHT) are seldom maintained among early-stage hormone receptor-positive breast cancer (BC) survivors, despite the significant clinical benefits of long-term AHT. As the factors influencing adherence to AHT remain unclear, this study aimed to comprehensively identify such factors and classify them into specific dimensions.

METHODS

PubMed, Cochrane Library, Embase, PsycINFO, and CINAHL were searched for qualified articles. The search mainly focused on three components: early-stage (0-III) BC, oral AHT administration, and adherence to AHT, with keywords derived from MeSH and entry terms. The factors identified were then classified into six categories based on a modified WHO multidimensional model.

RESULTS

Overall, 146 studies were included; the median sample size was 651 (range, 31-40,009), and the mean age of the population was 61.5 years (standard deviation, 8.3 years). Patient- and therapy-related factors were the most frequently investigated factors. Necessity/concern beliefs and self-efficacy among patient-related factors were consistently related to better adherence than depression. Although drug side effects and medication use cannot be modified easily, a refined prescription strategy for the initiation and switching of AHT is likely to increase adherence levels.

CONCLUSION

An effective psychological program that encourages positive views and beliefs about medication and management strategies for each therapy may be necessary to improve adherence to AHT. Social support and a sense of belonging can be enhanced through community participation and social media for better adherence to AHT. Patient-centered communication and appropriate recommendations by physicians may be attributable to better adherence outcomes. Findings from systematically organized factors that influence adherence to AHT may contribute to the establishment of intervention strategies to benefit patients with early-stage BC to achieve optimal health.

Optimal treatment strategy for hormone receptor-positive human epidermal growth factor receptor 2-negative breast cancer patients with 1-2 suspicious axillary lymph node metastases on breast magnetic resonance imaging: upfront surgery vs. neoadjuvant chemotherapy

Background

It is unclear whether upfront surgery or neoadjuvant chemotherapy is appropriate for first treatment in hormone receptor (HR)-positive human epidermal growth factor receptor 2 (HER2)-negative breast cancer patients with 1-2 suspicious axillary lymph node (ALN) metastases on preoperative breast magnetic resonance imaging (MRI).

Method

We identified 282 patients with HR+HER2- breast cancer and 1-2 suspicious ALN metastases on baseline breast MRI (147 received upfront surgery; 135 received neoadjuvant chemotherapy). We evaluated the predictive clinicopathological factors for pN2-3 in the adjuvant setting and axillary pathologic complete response (pCR) in the neoadjuvant setting.

Results

Lymphovascular invasion (LVI)-positive and clinical tumors >3 cm were significantly associated with pN2-3 in patients who received upfront surgery. The pN2-3 rate was 9.3% in patients with a clinical tumor ≤ 3 cm and LVI-negative versus 34.7% in the others (p < 0.001). The pN2-3 rate in patients with a clinical tumor ≤ 3 cm and LVI-negative and in the others were 9.3% versus 34.7% in all patients (p < 0.001), 10.7% versus 40.0% (p = 0.033) in patients aged < 50 years, and 8.5% versus 31.0% in patients aged ≥ 50 years (p < 0.001), respectively. In the neoadjuvant setting, patients with tumor-infiltrating lymphocytes (TILs) ≥ 20% had a higher axillary pCR than those with TILs < 20% (46.7% vs. 15.3%, p < 0.001). A similar significant finding was also observed in patients < 50 years.

Conclusions

Upfront surgery may be preferable for patients aged ≥ 50 years with a clinical tumor < 3 cm and LVI-negative, while neoadjuvant chemotherapy may be preferable for those aged < 50 years with TILs ≥ 20%.

Abstract P4-06-08: HER2-protein expression is a predictive marker for treatment response in patients with HER2-positive breast cancer who received neoadjuvant chemotherapy with dual HER2-blockade

Background In HER2-positive breast cancer, pathologic complete response (pCR) has been known to be a surrogate marker for favorable prognosis after neoadjuvant chemotherapy. We aimed to identify the clinico-pathologic factors related to pCR in patients with HER2-positive breast cancer treated with neoadjuvant dual HER2-targeted therapy. Methods Two-hundred ninty-five patients with HER2-positive breast cancer who received neoadjuvant chemotherapy with docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP) were included in this retrospective analysis. We assessed the association between age, clinical T, N stage, pathologic factors such as histologic grade, hormone receptor (HR), tumor-infiltrating lymphocytes, the membranous expression of HER2 protein evaluated by immunohistochemistry (IHC) and pCR. The fluorescent in situ hybridization (FISH) was performed in a tumor with HER2 score of 2+. Results Of the 295 patients, 195 (66.1%) achieved pCR (ypT0/is and ypN0). Besides, 240 (81.4%) patients were HER2 score of 3+, and 55 (18.6%) patients were HER2 score of 2+. The pCR was frequently observed in patients with HER2 score of 3+ (64 of 176 [73.3%]) than in those with HER2 score of 2+ (19 of 55 [34.5%]), regardless of HR status. After adjusting other clinicopathologic factors, the high HER2 protein expression was only an independent factor for pCR (adjusted OR 3.85, 95% CI, 1.66-8.91, p=0.002). Conclusions Our results suggest that high expression of HER2 protein assessed by IHC is important in predicting neoadjuvant TCHP response in HER2-positive breast cancer.

Citation Format: Soong June Bae, Ji Soo Jang, Yoonwon Kook, Seung Ho Baek, Jee Hung Kim, Sung Gwe Ahn, Joon Jeong. HER2-protein expression is a predictive marker for treatment response in patients with HER2-positive breast cancer who received neoadjuvant chemotherapy with dual HER2-blockade [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-06-08.

Abstract P6-01-03: Tumor-infiltrating lymphocytes (TILs) and 21-gene recurrence score in 1,883 patients with ER+/HER2- breast cancer

Background: In ER+/HER2- breast cancer, several lines of evidence suggest that tumors with high level of tumor-infiltrating lymphocytes (TILs) have a greater chance of obtaining a pathological complete response (pCR) after neoadjuvant chemotherapy. In addition, high 21-gene recurrence score (RS) is associated with an increasing rate of pCR in luminal tumors. We investigated the relationship between TIL and RS in 1,883 patients with early ER+HER2- breast cancer.

Method: In 1,883 ER+ breast cancer patients with 21-gene assay, TIL level was evaluated. Correlation between continuous TIL and RS was investigated. Logistic-regression analysis was performed to identify risk factors for high RS (26). The cut-off for high TIL was 50%. Recurrence-free survival (RFS) was investigated.

Results: A weak positive correlation between TIL level and RS was observed (correlation coefficient=0.283, p&lt; 0.001) in all patients. Average TIL level of the high RS tumors was significantly higher. Two parameters were positively correlated in both two groups classified by age 50 years (correlation coefficient=0.281 in the age 50; correlation coefficient=0.288 in the age&gt;50). Either continuous TILs or binary high TIL level was demonstrated to be an independent factor for high RS. When all patients were divided into 4 groups using TIL and RS (low-RS/low-TIL, low-RS/high-TIL, high-RS/low-TIL, and high-RS/high-TIL), the RFS was worst in the low-TIL/high-RS group (p&lt; 0.001).

Conclusions: Our findings show that TIL level is correlated with RS in ER+ breast cancer regardless of age and suggest that high TIL level can be regarded as a risk factor for high RS. Multigene assay could be integrated in designing clinical trials evaluating immune-check point blockades in luminal breast cancer.

Recurrence-free survival according to RS and TIL

Table 1. 5-years RFS according to TIL and RS

Citation Format: Sung Gwe Ahn, Ji Soo Jang, Yoonwon Kook, Seung Ho Baek, Sae Byul Lee, Soong June Bae, Joon Jeong. Tumor-infiltrating lymphocytes (TILs) and 21-gene recurrence score in 1,883 patients with ER+/HER2- breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-03.

Abstract P2-14-09: Sensory Evaluation of Nipple-Areolar Complex after Nipple-Sparing Mastectomy: A Comparison of Incision Approaches

Background: Since nipple-sparing mastectomy (NSM) has been widely practiced, majority of previous studies have evaluated the effects of Nipple-areolar complex (NAC) preservation on body image adjustment. However, few have evaluated NAC sensation after NSM in a large sample size. This study aims to assess NAC sensation after NSM and compare the results according to different incisional approaches; specifically, inframammary fold (IMF) and peri-areolar.

Methods: Post NSM patients from Oct 2019 to Nov 2021 have been recruited prospectively. A total of 115 patients (IMF 69 and peri-areolar 36) were evaluated for NAC sensory at various time points during follow up within 1.5 to 4 years after surgery. NAC sensation was scored by pin-prick test in a scale of 0 to 2 (0: no sensation, 1: dull sensation, 2: sharp sensation), divided in 5 areas of the NAC and summed up to a total of 10.

Results: In all patients, a median of the pin-prick test total score on NAC was 3 (0-10). Pin-prick test of NAC showed numerically higher NAC sensory score in the IMF incision than in the peri-areolar group without a statistical significance (IMF: Median 4 Mean 3.83 ± 3.04, Peri-areolar Median 2 Mean 2.69 ± 3.64, p=0.062). When sensory scores were evaluated depending on NAC zones (A: Nipple, B: Upper outer, C: Upper inner, D: Lower outer, E: Lower inner) the IMF incision group showed better outcomes in zone B (p=0.015) and E (p=0.043). Simple linear regression analysis showed the possibility of incisional approach, diabetes mellitus (DM) history, previous radiotherapy of ipsilateral breast, post mastectomy radiotherapy (PMRT), adjuvant chemotherapy, tumor to nipple distance and laterality influencing NAC sensory with p&lt; 0.2. When these factors were taken to multiple linear regression analysis, DM history (p=0.045), previous radiotherapy (p=0.001), postop radiotherapy (p=0.001), and adjuvant chemotherapy (p=0.001).

Conclusion: NAC sensory deteriorated postoperatively in general. Scores of NAC sensation were numerically higher in the patients with IMF incision, although the difference was not statistically significant. NAC sensation was negatively affected by DM history, previous ipsilateral breast radiotherapy and post-NSM treatments such as chemotherapy and PMRT. While incision type may improve aesthetic outcomes, additional efforts are necessary to ameliorate the post-NSM NAC desensitization.

Table 1. Patient characteristics

Table 2. Linear regression analysis for clinical factors affecting NAC sensory

Citation Format: Yoonwon Kook, Ji Soo Jang, Seung Ho Baek, Soong June Bae, Sung Gwe Ahn, Joon Jeong. Sensory Evaluation of Nipple-Areolar Complex after Nipple-Sparing Mastectomy: A Comparison of Incision Approaches [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-14-09.

Complications Including Capsular Contracture in Direct-to-Implant Breast Reconstruction With Textured Anatomical Versus Smooth Round Implants: A Single Center Retrospective Analysis

PURPOSE

Implant-based breast reconstruction is the most common reconstruction method used after mastectomy in breast cancer patients. Many studies have compared the smooth round implants and textured anatomical implants. This study aimed to compare the complications, including capsular contracture, between these two implants used in direct-to-implant (DTI) breast reconstruction.

METHODS

This retrospective chart review was performed using a prospectively maintained database from a single center. We identified patients who underwent mastectomy with DTI single-stage breast reconstruction at our hospital between August 2011 and June 2021. The overall complications, including capsular contracture, postoperative infection, seroma, hematoma, implant rupture, implant exposure, rippling, implant malposition, and nipple necrosis, were analyzed.

RESULTS

In total, 340 breasts of 323 patients were reconstructed by the DTI approach using either textured anatomical (n = 203) or smooth round (n = 137) implants. The incidence of overall complications and capsular contracture was significantly lower with smooth round implants than with textured anatomical implants. Multivariate analysis showed that smooth round implants were associated with a reduced risk of overall complications (odds ratio [OR], 0.465; 95% confidence interval [CI], 0.265-0.813) and capsular contracture (OR, 0.475; 95% CI, 0.235-0.962). Particularly, smooth round implants were associated with a decreased risk of overall complications in patients not receiving adjuvant chemotherapy and a decreased risk of capsular contracture in patients with body mass index < 25 kg/m² and in those not receiving adjuvant radiotherapy.

CONCLUSION

Smooth round implants demonstrated a decreased risk of overall complications and capsular contracture when compared with textured anatomical implants. These results may be utilized in counseling patients regarding the advantages and disadvantages of smooth round implants in DTI breast reconstruction.

Resolution of Nonmass Enhancement Extension to the Nipple at Breast MRI after Neoadjuvant Chemotherapy: Pathologic Response and Feasibility for Nipple-sparing Mastectomy

Background Nipple-sparing mastectomy (NSM) is usually contraindicated in patients with nonmass enhancement (NME) extension to the nipple at breast MRI. However, little is known about the feasibility of NSM when NME extension to the nipple resolves after neoadjuvant chemotherapy (NAC). Purpose To evaluate whether NSM is an appropriate surgical procedure for patients in whom NME extension to the nipple resolves after NAC. Materials and Methods This retrospective study included 383 women with NME at baseline MRI who underwent NAC followed by mastectomy between January 2007 and March 2022 at a single institution. NME extension to the nipple was assessed using breast MRI before NAC (hereafter, pre-NAC) and after NAC (hereafter, post-NAC). In 326 women who underwent mastectomy with removal of the nipple-areolar complex, the rate of pathologic analysis-confirmed tumor invasion of the nipple compared with NME extension to the nipple at post-NAC breast MRI was evaluated. Tumor involvement of the nipple was also assessed in those with complete pathologic response at posttreatment MRI. Furthermore, the outcomes in 57 women undergoing NSM were investigated, particularly in patients with NME extension to the nipple at initial diagnosis. Results Of the 326 women who underwent mastectomy with removal of the nipple-areolar complex (mean age, 49 years ± 9.4 [SD]), 217 patients (67%) showed NME extension to the nipple on pre-NAC MRI scans. Among the 153 women (70%) in whom the NME extension to the nipple resolved after NAC, the rate of pathologic analysis-confirmed tumor invasion of the nipple was 2.6% (four of 153 women; 95% CI: 0, 6.5). No pathologic analysis-confirmed tumor invasion of the nipple was detected in 31 women with complete response at MRI. Of the 57 women who underwent NSM, 12 (21%) with resolution of NME extension to the nipple after NAC had no relapse during the median follow-up of 31 months (range, 11-80 months). Conclusion Pathologic analysis-confirmed tumor invasion of the nipple was rare in women with resolution of nonmass enhancement extension to the nipple after neoadjuvant chemotherapy (NAC). Therefore, nipple-sparing mastectomy could be feasible in this population, especially in those with complete MRI response to NAC. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Lee in this issue.

Radiation dose-event relationship after intraoperative radiotherapy as a boost in patients with breast cancer

Purpose

Intraoperative radiotherapy (IORT) can be used as a boost in combination with external whole breast irradiation. This study reports the clinical and dosimetric factors associated with IORT-related adverse events (AE).

Methods and materials

Between 2014 and 2021, 654 patients underwent IORT. A single fraction of 20 Gy was prescribed to the surface of the tumour cavity using the mobile 50-kV X-ray source. For skin dose measurement, at least four optically stimulated luminescent dosimeter (OSLD) chips were annealed and attached to the skin edge in the superior, inferior, medial, and lateral locations during IORT. Logistic regression analyses were conducted to identify factors associated with IORT-related AE.

Results

With a median follow-up period of 42 months, 7 patients experienced local recurrence, resulting in a 4-year local failure-free survival rate of 97.9%. The median skin dose measured by OSLD was 3.85 Gy (range, 0.67-10.89 Gy), and a skin dose of > 6 Gy was observed in 38 patients (2%). The most common AE was seroma (90 patients, 13.8%). We also found that 25 patients (3.9%) experienced fat necrosis during follow-up, and among them, 8 patients underwent biopsy or excision to exclude local recurrence. IORT-related late skin injury occurred in 14 patients, and a skin dose > 6 Gy was significantly associated with IORT-induced skin injury (odds ratio 4.942, 95% confidence interval 1.294-18.871, p = 0.019).

Conclusions

IORT was safely administered as a boost to various populations of patients with breast cancer. However, several patients may experience severe skin injuries, and for older patients with diabetes, IORT should be performed with caution.

Association of Body Mass Index With 21-Gene Recurrence Score Among Women With Estrogen Receptor-Positive, ERBB2-Negative Breast Cancer

IMPORTANCE

Body mass index (BMI) may affect the 21-gene recurrence score (RS) in patients with ER-positive, ERBB2-negative breast cancer. If high BMI increases genomic risk in ER-positive, ERBB2-negative breast cancer, weight control will become more important.

OBJECTIVE

To assess the association between RS and BMI according to age groups and address BMI as a factor associated with high RS.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included 2295 patients with ER-positive, ERBB2-negative breast cancer who had undergone a multigene assay between March 29, 2010, and December 31, 2020, in 2 hospitals. All of the study patients were Korean women, and the median follow-up period was 45 months (range, 1-40 months). The correlations between continuous RS and BMI were investigated. A high BMI was defined as a body mass index greater than or equal to 25. In the younger age group (age ≤45 years), a high RS was defined as an RS of greater than 20.

EXPOSURES

Body mass index.

MAIN OUTCOMES AND MEASURES

The Pearson correlation coefficient was used to estimate the association between RS and BMI. A multivariable binary logistic model was used to identify high RS.

RESULTS

Among the 2295 women included (mean [SD] age, 49.8 [4.00] years; range, 22-81 years), 776 were aged 45 years or younger; RS and BMI were weakly correlated (correlation coefficient, 0.119; P < .001) in this younger group. Among them, the proportion of patients with an RS greater than 20 was significantly higher in the high BMI group than in the normal BMI group (45.5% [46 of 101] vs 27.3% [184 of 675]; P < .001). In the multivariable analysis, high BMI was an associated factor for high RS (odds ratio, 2.06; 95% CI, 1.28-3.32; P = .003). The 21-gene multigene assay-guided chemotherapy rate was significantly higher in patients with high BMI (30.7% [31 of 101] vs 20.2% [136 of 674]; P = .02).

CONCLUSIONS AND RELEVANCE

In this cohort study of women aged 45 years or younger, high BMI was associated with higher RS in those with ER-positive, ERBB2-negative breast cancer; further studies are necessary to examine the underlying mechanisms.

Prognostic Value of Neutrophil-to-Lymphocyte Ratio and Early Standardized Uptake Value Reduction in Patients With Breast Cancer Receiving Neoadjuvant Chemotherapy

PURPOSE

We investigated the treatment response and prognosis using the neutrophil-to-lymphocyte ratio (NLR) and standardized uptake value (SUV) of ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) in neoadjuvant settings.

METHODS

Baseline NLR and maximum SUV (SUV_max) were retrospectively analyzed in 273 females with breast cancer who received neoadjuvant chemotherapy followed by surgery. Of these, 101 patients underwent ¹⁸F-FDG PET after 3-4 neoadjuvant chemotherapy cycles, which allowed the measurement of ΔSUV_max, an early reduction in SUV_max. NLR and early SUV_max reduction (ΔSUV_max) were classified as low and high, respectively, relative to the median values.

RESULTS

The mean NLR was lower, and the mean ΔSUV_max was higher in patients with pathologic complete response (pCR) than in those with residual tumors. The ΔSUV_max was an independent variable associated with pCR. Furthermore, the high NLR group had poor recurrence-free survival (RFS) and overall survival. Among patients with ΔSUV_max data, high NLR (adjusted hazard ratio, 2.82; 95% confidence intervals [CI], 1.26-6.28; P = 0.016) and low ΔSUV_max (adjusted hazard ratio, 2.39; 95% CI, 1.07-5.34; P = 0.037) were independent prognostic factors for poor RFS. The categorization of the patients into four groups according to the combination of NLR and ΔSUV_max showed that patients with high NLR and low ΔSUV_max had significantly poorer RFS.

CONCLUSION

Baseline NLR and ΔSUV_max were significantly associated with the prognosis of patients with breast cancer who received neoadjuvant chemotherapy. These results suggest that metabolic non-responders with defective immune systems have worse survival outcomes.

Correlation of Yes-Associated Protein 1 with Stroma Type and Tumor Stiffness in Hormone-Receptor Positive Breast Cancer

Simple Summary

YAP1 is an oncogene that can be activated by matrix stiffness, as it can act as a mechanotransducer. So far, only in vitro studies regarding YAP1 activation and matrix stiffness are present. We confirmed the activation of YAP1 in breast cancer using human breast cancer tissue and immunohistochemistry. Tumor stiffness was quantified by shear-wave elastography. Nuclear localization of YAP1 showed correlation with tumor stiffness in hormone-receptor positive (HR+) breast cancer. Also, tumors with non-collagen-type stroma showed an association between YAP1 expression and tumor stiffness. YAP1 expression, along with tumor stiffness, may serve as a prognostic candidate in HR+ breast cancer.

Abstract

(1) Background: Yes-associated protein 1 (YAP1) is an oncogene activated under the dysregulated Hippo pathway. YAP1 is also a mechanotransducer that is activated by matrix stiffness. So far, there are no in vivo studies on YAP1 expression related to stiffness. We aimed to investigate the association between YAP1 activation and tumor stiffness in human breast cancer samples, using immunohistochemistry and shear-wave elastography (SWE). (2) Methods: We included 488 patients with treatment-naïve breast cancer. Tumor stiffness was measured and the mean, maximal, and minimal elasticity values and elasticity ratios were recorded. Nuclear YAP1 expression was evaluated by immunohistochemistry and tumor-infiltrating lymphocytes (TILs); tumor-stroma ratio (TSR) and stroma type of tumors were also evaluated. (3) Results: Tumor stiffness was higher in tumors with YAP1 positivity, low TILs, and high TSR and was correlated with nuclear YAP1 expression; this correlation was observed in hormone receptor positive (HR+) tumors, as well as in tumors with non-collagen-type stroma. (4) Conclusions: We confirmed the correlation between nuclear YAP1 expression and tumor stiffness, and nuclear YAP1 expression was deemed a prognostic candidate in HR+ tumors combined with SWE-measured tumor stiffness.

CD39+ tissue-resident memory CD8+ T cells with a clonal overlap across compartments mediate antitumor immunity in breast cancer

Despite being a standard treatment option in breast cancer, immune checkpoint inhibitors (ICIs) are only efficacious for a subset of patients. To gain a better understanding of the antitumor immune response in breast cancer, we examined the heterogeneity of CD8⁺ T cells in tumors, metastatic lymph nodes (mLNs), and peripheral blood from patients with early breast cancer (n = 131). Among tissue-resident memory CD8⁺ T (T_RM) cells, including virus- and tumor-specific CD8⁺ T cells, CD39 expression was observed in a tumor-specific and exhausted subpopulation in both tumors and mLNs. CD39⁺ T_RM cells from tumors and mLNs exhibited a phenotypic similarity and clonally overlapped with each other. Moreover, tumor or mLN CD39⁺ T_RM cells clonally overlapped with CD39^- T_RM and non-T_RM cells in the same compartment, implying a tissue-specific differentiation process. These inter-subpopulationally overlapping CD39⁺ T_RM clonotypes were frequently detected among effector memory CD8⁺ T cells in peripheral blood, suggesting a systemic clonal overlap. CD39⁺ T_RM cell enrichment was heterogeneous among molecular subtypes of breast cancer, which is associated with the different role of antitumor immune responses in each subtype. In vitro blockade of PD-1 and/or CTLA-4 effectively restored proliferation of CD39⁺ T_RM cells and enhanced cytokine production by CD8⁺ T cells from tumors or mLNs, particularly in the presence of CD39⁺ T_RM enrichment. This suggests that CD39⁺ T_RM cells have a capacity for functional restoration upon ICI treatment. Thus, our study indicates that CD39⁺ T_RM cells with a clonal overlap across compartments are key players in antitumor immunity in breast cancer.

Anaemia and pathologic complete response rate according to carboplatin dose in HER2+ breast cancer treated with neoadjuvant TCHP

Grade 3/4 anaemia, which is mainly induced by carboplatin, frequently occurs in patients treated with neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP). However, dose reduction of carboplatin may raise concerns about the oncological outcome. This study investigated the pathologic complete response (pCR) rate, occurrence of grade 3/4 anaemia, and transfusion rate according to carboplatin dose in patients treated with neoadjuvant TCHP. We retrospectively analysed 294 patients treated with neoadjuvant TCHP between April 2015 and December 2020. Case matching was performed using propensity score matching. Among patients treated with neoadjuvant TCHP, carboplatin area under the plasma concentration-time curve 6 (AUC6) was used in 234 patients (79.6%) and upfront carboplatin AUC5 was used in 60 patients (20.4%). No significant difference in pCR rate was found between the two groups (AUC6: 70.9%, AUC5: 80.0%). In both oestrogen receptor-positive (ER+) and ER- patients, no significant differences were observed between the AUC6 and AUC5 groups (ER+: 54.3% vs. 50.0%, ER-: 81.7% vs. 86.0%). The case-matched cohort showed consistent findings. The AUC5 group had lower frequencies of grade 3/4 anaemia (18.3% vs. 34.2%) and transfusion events (10.0% vs. 21.8%) than the AUC6 group. Compared with AUC5, carboplatin at AUC6 would associate with a 2.7-fold increased risk of grade 3 or 4 chemotherapy-induced anaemia. Carboplatin AUC5 has comparable cytotoxic effects to carboplatin AUC6 in patients with HER2+ breast cancer treated with six cycles of neoadjuvant TCHP, with fewer complications associated with clinically meaningful anaemia. AUC5 may be the optimal carboplatin dose to reduce TCHP-induced anaemia in patients with HER2+ breast cancer treated with TCHP.

Effects of Single Nucleotide Polymorphisms and Mediterranean Diet in Overweight or Obese Postmenopausal Women With Breast Cancer Receiving Adjuvant Hormone Therapy: A Pilot Randomized Controlled Trial

Background and Aims

Weight management is recommended in overweight or obese breast cancer patients, as they have an increased risk of cancer recurrence and poor prognosis. Furthermore, identifying the relationships between genetic factors and nutrition could help suggest possible individualized nutritional solutions in weight management. The objective of this pilot randomized controlled trial was to investigate the influence of two obesity-associated single nucleotide polymorphisms and the Mediterranean diet intervention on weight loss and modification of nutrient intake and metabolic parameters in overweight or obese, postmenopausal, breast cancer patients receiving adjuvant hormone therapy.

Methods

Seventy-eight breast cancer patients were randomly assigned to the Mediterranean diet (MeDiet) group or control group, and seventy-one were finally analyzed. Body composition, nutrient intake, and metabolic parameters were assessed at baseline and after the 8-week intervention. Fat mass and obesity-associated (FTO) rs7185735 and melanocortin-4 receptor (MC4R) rs476828 variants were genotyped.

Results

We found that both variants did not influence weight loss or improvement of metabolic parameters within the Mediterranean diet intervention. Intake of saturated fatty acid (SFA) and trans fat was significantly increased in C carriers compared with the TT genotype of MC4R rs476828 only in the control group (p = 0.002 for SFA; p = 0.016 for trans fat), whereas no significant difference was observed between genotypes in the MeDiet group. There were statistically significant interactions between MC4R rs476828 and dietary intervention for changes in SFA intake (p = 0.009) and trans fat intake (p = 0.049).

Conclusion

Our data suggest that considering the effects of genotype may be more necessary when the Mediterranean diet is not followed and that this diet may have a protective role against the effects of certain genotypes. Further studies are required to determine the potential mechanism of the observed gene-diet interaction.

Clinical Trial Registration

[www.ClinicalTrials.gov], identifier [NCT04045392].

Abstract 2542: Unraveling heterogeneity of tumor microenvironment of TNBC patients by meta-analysis of 6 breast cancer scRNAseq studies

Breast cancer can be classified into several types. Among them, triple-negative breast cancer (TNBC) is breast cancer that does not express estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Since targeted therapy for breast cancer relies on the three receptors, treatment outcomes have been worst in TNBCs. However, clinical benefit of immune-checkpoint inhibitors (ICIs) with chemotherapy over chemotherapy alone was demonstrated in the KEYNOTE-355 and IMPASSION-130 trials in terms of overall survival, opening new avenue for patients with metastatic PD-L1+ TNBC. After several studies with ICIs, researchers found that the tumor microenvironment affects the response rate of immunotherapies.

Therefore, to unravel the heterogeneity of tumor microenvironment of TNBC patients, we collected 28 TNBC samples from 6 public single cell RNA sequencing breast cancer studies.

Results: From 124,301 cells populating tumors and tumor-microenvironment (TMEs), we first identified epithelial cells separately. Using epithelial cells alone, we identified the Baylor-proposed TNBC molecular subtype of each patient. This approach with epithelial cells revealed that 3 basal-like immune-activated (BLIA), 11 basal-like immune-suppressed (BLIS), 5 luminal- androgen receptor (LAR), and 9 unclassified subtypes. By comparing cell number and cell-cell interactions, the heterogeneity of TME-consisting cell populations between the TNBC subtypes was analyzed. Analysis of tumor-infiltrating lymphocytes revealed their difference in activation, expansion, and exhaustion programs across patients. Among the subtypes, the LAR subtype had less amount of exhausted CD8+ T cells and regulatory T cells. This finding was consistent with cell-cell interaction analysis. In the case of the LAR subtype, the interaction between regulatory T cells and CD8 T cells was less active than other subtypes. Also, the interaction between cytotoxic cells (T cells and NK cells) and regulatory T cells was less active in the LAR subtype. Additionally, tumor cells in the LAR subtype seem to inhibit cytotoxic cells to a lesser extent. When we repeated our analyses using whole cells including epithelial and immune-stromal cells, the molecular subtypes of each subject were changed (7 of 19, 36.8%). 4 of 11 BLIS were changed to BLIA, 1 of 11 BLIS were changed to mesenchymal (MES), and 2 of 5 LAR were changed to MES. Characteristics of immune cells in the epithelial-based LAR subtype were conserved in the whole cells-based MES.

Conclusions:This extensive meta-analysis of public single cell RNA sequencing analysis enhances our knowledge about the heterogeneity and dynamics of the tumor microenvironment. These results offer insights about potential diagnostic and therapeutic targets for TNBC depending on their subtypes.

Citation Format: Kyungsoo Kim, Sung Gwe Ahn, Soong June Bae, Chihhao Chu, Jung Hwan Ji, Jee Hung Kim, Joon Jeong. Unraveling heterogeneity of tumor microenvironment of TNBC patients by meta-analysis of 6 breast cancer scRNAseq studies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2542.

Breast density reduction as a predictor for prognosis in premenopausal women with hormone receptor–positive breast cancer: A retrospective analysis of the ASTRRA study

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Background: While the relationship between mammographic breast density (MD) decline and anti-hormone therapy efficacy has been reported in estrogen-receptor (ER)-positive breast cancer, it is still unclear in premenopausal women and in the case of adding ovarian function suppression (OFS) to anti-hormone therapy. We aimed to investigate the MD reduction (MDR) rate and impact of MDR on prognosis stratified by treatment from the updated result of the ASTRRA trial. Methods: ASTRRA trial, a randomized phase 3 study, showed that adding ovarian function suppression (OFS) to tamoxifen (TAM) improved survival in premenopausal women with ER+ breast cancer after chemotherapy. We updated survival outcomes with a median follow-up of 108 months. We assessed mammography taken before treatment and the follow-up mammography taken annually for up to five years after initiation of treatment. MD was classified into four categories based on the Breast Imaging Reporting and Data System. MDR positivity was defined as a downgrade in MD among follow-up mammography up to two years after randomization, with the pretreatment MD grade as a reference. Results: Among the 1,293 patients from ASTRRA trial, we successfully evaluated MDR in 947 patients, of which 796 (83.4%) belong to high MD (grade C or D). The patient characteristics were similar between the entire ASTRRA trial and the subgroup with available MDR. There was no difference in MDR-positive rate between two treatment groups (106 of 477 [22.2%] in TAM-only group vs. 87 of 470 [18.5%] in TAM + OFS group, P =.156). MDR-positivity was significantly associated with better disease-free survival (DFS) in TAM + OFS group (estimated 8-year DFS: 92.9% in MDR-positive vs. 82.2% in MDR-negative, P =.013), but did not in TAM-only group (estimated 8-year DFS: 80.3% in MDR-positive vs. 80.2% in MDR-negative, P =.927; Pinteraction =.025). Simialr trends were observed in terms of recurrence-free survival, distant metastasis-free survival (DMFS), locoregional-free survival, and overall survival. In addition, MDR-positivity was an independent factor for favorable DFS (adjusted hazard ratio [HR], 0.37; 95% CI, 0.16 to 0.86; P =.021) and DMFS (adjusted HR, 0.35; 95% CI, 0.13 to 0.98; P =.045) in TAM + OFS group. Conclusions: Although the proportion of patients with MDR-positive was comparable between the two treatment groups, MDR-positive was independently associated with favorable outcomes only in TAM + OFS group. Future work is warranted to verify the mechanism by which the association between MDR and clinical benefit differs according to the treatment group. Clinical trial information: NCT00912548.

Primary endocrine resistance of ER+ breast cancer with ESR1 mutations interrogated by droplet digital PCR

We investigated the patterns of recurrence and primary endocrine resistance according to estrogen receptor (ER) alpha gene (ESR1) mutations, as assessed by digital droplet (dd) PCR, in patients with non-metastatic ER+ breast cancer. We collected 121 formalin-fixed paraffin-embedded (FFPE) surgical specimens from ER+ breast cancer patients who had relapsed after surgery. Genomic DNA was extracted from the FFPE samples and ESR1 mutations were evaluated using ddPCR. ESR1 mutations were detected in 9 (7.4%) of 121 primary breast cancer specimens. The median recurrence-free interval and overall survival were significantly lower in patients with ESR1 mutations than in those without. Of the patients treated with ET (N = 98), eight had ESR1 mutations. Of these, six (75.0%) had primary endocrine resistance and two (25.0%) had secondary endocrine resistance. By contrast, only 22 of 90 (24.4%) patients without ESR1 mutations had primary endocrine resistance. A multivariable model showed that an ESR1 mutation is a significant risk factor for primary endocrine resistance. Our findings provide clinical evidence that the presence of rare ESR1 mutant clones identified by ddPCR in primary tumors is associated with primary endocrine resistance in an adjuvant setting.

Association between TP53 mutation and high 21-gene recurrence score in estrogen receptor-positive/HER2-negative breast cancer

We investigated the association between TP53 mutation and 21-gene recurrence score (RS) in ER-positive/HER2-negative breast cancer (BC) using data from 141 patients who underwent TP53 sequencing and Oncotype DX^® tests. We detected TP53 mutations in 18 (12.8%) patients. Most patients with TP53 mutation had a high 21-gene RS (≥26). The average 21-gene RS was higher in TP53 mutant tumors. Multivariate analysis showed that mutated TP53 is an independent factor for a high 21-gene RS. Mutated TP53 remained closely associated with high 21-gene RS in patients with low pathological risk (n = 103). In the ER⁺/PR⁺/HER2-negative subset (n = 356) of The Cancer Genome Atlas, the non-luminal A intrinsic subtype was more prevalent in the group with mutant TP53. mRNA levels of p53-regulated senescence gatekeeper and cell cycle-related genes were increased in BC with mutated TP53. Mutational analysis of TP53 helped identify endocrine-resistant tumors.

Abstract P2-12-13: Pathologic complete response rate according to the carboplatin dose in patients with non-metastatic HER2+ breast cancer treated with neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP)

Purpose In the patients treated with neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP) regimen, grade 3-4 anemia occurs frequently during the treatment course. Anemia develops mainly by cytotoxic drug including carboplatin. By contrast, dose reduction of carboplatin could raise concerns about the oncologic outcome. We compared the pathologic complete response (pCR) rate and grade 3-4 anemia/transfusion rate according to the dose of carboplatin among the patients undergoing neoadjuvant TCHP. Method We retrospectively analyzed 294 patients who treated with neoadjuvant TCHP between Apr 1, 2015 and Dec 31, 2020. Clinicopathological features were collected by electronic medical record review. Hemoglobin levels were measured at baseline, before each cycle of chemotherapy, and after the chemotherapy completion. Multivariable binary logistic regression analysis was performed to identify predictive factors for grade 3-4 anemia and transfusion event. Result In a total of 294 patients, neoadjuvant TCHP with carboplatin AUC6 were initiated in 234 (79.6%, 234 of 294), whereas upfront carboplatin AUC5 were concurrently administered in 60 (20.4%, 60 of 294). There was no statistical difference in the pCR rate between the two groups (70.9% in the AUC6, 80.0% in the AUC5; p=0.159). In the both ER+ and ER-, there were no significant differences between the AUC6 and AUC5 (54.3% and 50.0% in the ER+; 81.7% and 86.0% in the ER-). Tumor and nodal stage were not different between the two groups. The AUC5 group had less grade 3-4 anemia (18.3%, 11 of 60 vs 34.2%, 80 of 234) and transfusion event (10.0%, 6 of 60 vs 21.8%, 51 of 234) compared with the AUC6 group. Multivariable analysis demonstrated that baseline hemoglobin level under 12g/dL and ≥2g/dL hemoglobin down after first chemotherapy are independent risk factors for grade3-4 anemia or blood transfusion before surgery. Conclusion The pCR rate was not different according to the initial carboplatin dose in the HER2+ breast cancer treated with neoadjuvant TCHP. We suggest that the dose of carboplatin could be optimized as AUC5 to reduce TCHP-induced anemia and transfusion rate among Asian HER2-positive breast cancer patients treated with TCHP. Baseline low hemoglobin level under 12 g/dL or rapid hemoglobin down after first cycle are risk factors for TCHP-induced anemia.

Table 1.The pathologic complete response (pCR) rate, distribution of anemia grade and transfusion rate according to AUCVariablesAUC6AUC5TotalP-valueOverall (N=294)0.159pCR166 (70.9%)48 (80.0%)214 (72.8%)Non-pCR68 (29.1%)12 (20.0%)80 (27.2%)Total234 (100.0%)60 (100.0%)294 (100.0%)ER-positive (N=102)0.793pCR50 (54.3%)5 (50.0%)55 (53.9%)Non-pCR42 (45.7%)5 (50.0%)47 (16.1%)Total92 (100.0%)10 (100.0%)102 (100.0%)ER-negative (N=192)0.487pCR116 (81.7%)43 (86.0%)159 (82.8%)Non-pCR26 (18.3%)7 (14.0%)33 (17.2%)Total142 (100.0%)50 (100.0%)192 (100.0%)Anemia grade (N=294)0.0181 or 2154 (65.8%)49 (81.7%)203 (69.0%)3 or 480 (34.2%)11 (18.3%)91 (31.0%)Transfusion (N=294)0.039No183 (78.2%)54 (90.0%)237 (80.6%)Yes51 (21.8%)6 (10.0%)57 (19.4%)

Citation Format: Jung Hwan Ji, Soong June Bae, Seul-Gi Kim, Min Hwan Kim, Gun-Min Kim, Joohyuk Sohn, Jee Hung Kim, Sung Gwe Ahn, Joon Jeong. Pathologic complete response rate according to the carboplatin dose in patients with non-metastatic HER2+ breast cancer treated with neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-12-13.

Abstract P1-08-11: Clinical relevance of host immunity in patients with breast cancer who received neoadjuvant chemotherapy

Background Host immunity plays a key role in breast cancer progression. It seems that the neutrophil-to-lymphocyte ratio (NLR) may reflect the systemic host immunity, and tumor-infiltrating lymphocytes (TILs) may reflect the localized host immunity. This study aimed to analyze the clinical relevance of host immunity combining NLR and TILs to treatment efficacy and survival.Methods We assessed the pre-treatment NLR and TILs from core-biopsy samples in 461 patients with breast cancer who received neoadjuvant chemotherapy. The patients were assigned into two groups: the intact host immunity group (NLR &lt; 2.75 and TILs ≥ 30%) and the defective host immunity group (the remainder; NLR &gt; 2.75 or TILs &lt; 30%). We investigated the pathologic complete response (pCR) and recurrence-free survival (RFS) according to host immunity.ResultsOf the total, 141 (30.6%) patients belong to the intact host immunity group, and 320 (69.4%) patients belong to the defective host immunity group. A pCR was achieved in 76 (53.9%) of 141 patients in the intact host immunity group, whereas a pCR was achieved in 96 (30.0%) of 320 patients in the defective host immunity group (P&lt;0.001). The intact host immunity was an independent predictor for high pCR (adjusted odds ratio [OR], 2.65; 95% confidence interval [CI], 1.74-4.03). Furthermore, the Cox proportional hazards regression models revealed that the intact host immunity obtained an independent prognostic value for favorable RFS after adjusted for clinicopathologic factors including pCR (adjusted hazard ratio [HR], 0.33; 95% CI, 0.11-0.98; P=0.045).ConclusionHost immunity based on the combined analysis of NLR and TILs provides information regarding the treatment response and prognosis in patients with breast cancer receiving neoadjuvant chemotherapy. There is a need for a new therapeutic strategy to activate the immune system in patients with defective host immunity. 2

Citation Format: Soong June Bae, Jung Hwan Ji, Chihhao Chu, Yoon Jin Cha, Jee Hung Kim, Sung Gwe Ahn, Joon Jeong. Clinical relevance of host immunity in patients with breast cancer who received neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-08-11.

Abstract P4-05-08: 18F-FDG uptake of visceral adipose tissue on preoperative PET/CT as a predictive marker for breast cancer recurrence

Background: Glucose utilisation of visceral adipose tissue (VAT) reflects inflammatory activities, which promote tumour cell growth and carcinogenesis. The impact of the VAT-inflammatory response on survival outcomes in breast cancer is not known. We investigated survival outcomes in breast cancer patients based on the standardised uptake value (SUV) in VAT using 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT). Methods: We retrospectively enrolled breast cancer patients (stages I-III) treated at the Gangnam Severance Hospital between 2007 and 2010. Metabolic activities of VAT and tumour were calculated based on FDG uptake, and the clinical characteristics and survival outcomes were comparatively analysed in the high-SUV and low-SUV groups. Results: The SUV of VAT (SUV-VAT) was obtained for 148 patients. With no significant intergroup differences in clinical characteristics, high SUV-VAT was associated with poor recurrence-free survival (RFS; hazard ratio [HR] 2.754, 95% confidence interval [CI] 1.090-6.958, P=0.032) and distant metastasis-free survival (DMFS; HR 3.500, 95% CI 1.224-10.01, P=0.019). Multivariate analysis showed that high SUV-VAT was a significant clinical factor for both poor RFS and DMFS (P=0.023 and P=0.039, respectively). SUV-tumour was significantly associated with RFS (P=0.0388), but not DMFS (P=0.0718). Conclusion: The glucose metabolism of VAT, assessed by 18F-FDG PET/CT, is a prognostic biomarker of adverse outcomes and of primary tumour metabolism in breast cancer. The glucose utilisation of VAT may reflect the degree of inflammation associated with breast cancer recurrence and metastasis. Keywords: breast cancer, visceral adipose tissue, inflammation, 18F-FDG, PET/CT, glycolysis, metastasis, recurrence

Citation Format: Pill Sun Paik, Chang Ik Yoon, Hyun Jeong Kim, Yoon Jin Cha, Dooreh Kim, Soong June Bae, Sung Gwe Ahn, Joon Jeong, Woo-Chan Park, Young Hoon Ryu, Tae Joo Jeon, Chai Won Kim. 18F-FDG uptake of visceral adipose tissue on preoperative PET/CT as a predictive marker for breast cancer recurrence [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-05-08.

From cadaveric and animal studies to the clinical reality of robotic mastectomy: a feasibility report of training program

Robotic nipple-sparing mastectomy (RNSM) provides better cosmetic outcomes and improves the quality of life of women with breast cancer. However, this has not been widely adapted due to the lack of well-structured training programs. The present study aimed to report the establishment of cadaveric and animal skill laboratory training programs for RNSM and the participants’ perception on the training programs. We performed 24 RNSMs using 11 cadavers and one porcine model. Then, the skill laboratory characteristics were reviewed. Five trainers and 10 trainees participated in the programs. The first four cadaveric RNSMs with latissimus dorsi flaps and implants were performed using the da Vinci Si® system. We performed 14 and six RNSMs using the Xi® and SP® systems, respectively. The scores for questionnaires on the satisfaction with the training consisted of the trainees’ perceived goals in attending the course, teaching/learning environment, and teaching staff performance. The scores were excellent. Cadaveric or porcine RNSM skill laboratory training may be essential programs that can provide safe and efficient training.

Application of the 21-Gene Recurrence Score in Patients with Early HR-Positive/HER2-Negative Breast Cancer: Chemotherapy and Survival Rate According to Clinical Risk

Simple Summary

It is important to address the influence of 21-gene Recurrence Score (RS) on chemotherapy decision-making stratified by clinical risk in patients with hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative early breast cancer. Our study presented that the application of the 21-gene RS assay significantly reduced the chemotherapy rate in patients with high clinical risk. Meanwhile, there was no significant difference in the chemotherapy rate according to the implementation of the 21-gene RS assay in those with low clinical risk. Furthermore, we observed no difference in prognosis according to the application of 21-gene RS for either clinical risk. These results suggest that the 21-gene RS could be considered more positively in HR+/HER2- patients with high clinical risk to reduce chemotherapy rates without increasing the occurrence of relapse.

Abstract

We assessed the impact of 21-gene Recurrence Score (RS) assay on chemotherapy decision-making according to binary clinical risk stratification in patients with hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative early breast cancer. We included patients with tumors measuring 1–5 cm, N0-1, and HR+/HER2- breast cancer who underwent surgery followed by adjuvant treatment. The clinical risk was determined by a modified version of Adjuvant! Online. We performed propensity score matching (PSM) according to the application of 21-gene RS separately in the low and high clinical risk groups. Before PSM, 342 (39.0%) of 878 patients were classified as having high clinical risk. In the high clinical risk group, 21-gene RS showed a significantly reduced chemotherapy rate of 39.3%, without increasing the recurrence. After PSM, the 21-gene RS application significantly reduced chemotherapy rate by 34.0% in 200 patients with high clinical risk (21-gene RS application, 32.0% vs. no 21-gene RS application, 66.0%, p < 0.001). There was also no significant difference in RFS according to 21-gene RS status in the high clinical risk group (log-rank test, p = 0.467). These results support the usefulness of the 21-gene RS to reduce the chemotherapy rate without adversely affecting prognosis in a high clinical risk group.

Added value of abbreviated breast magnetic resonance imaging for assessing suspicious microcalcification on screening mammography-a prospective study

OBJECTIVES

To investigate the added diagnostic value of abbreviated breast magnetic resonance imaging (MRI) for suspicious microcalcifications on screening mammography.

METHODS

This prospective study included 80 patients with suspicious calcifications on screening mammography who underwent abbreviated MRI before undergoing breast biopsy between August 2017 and September 2020. The abbreviated protocol included one pre-contrast and the first post-contrast T1-weighted series. MRI examinations were interpreted as either positive or negative based on the visibility of any significant enhancement. The positive predictive value (PPV) was compared before and after the MRI.

RESULTS

Of the 80 suspicious microcalcifications, 33.8% (27/80) were malignant and 66.2% (53/80) were false positives. Abbreviated MRI revealed 33 positive enhancement lesions, and 25 and two lesions showed true-positive and false-negative findings, respectively. Abbreviated MRI increased PPV from 33.8 (27 of 80 cases; 95% CI: 26.2%, 40.8%) to 75.8% (25 of 33 cases; 95% CI: 62.1%, 85.7%). A total of 85% (45 of 53) false-positive diagnoses were reduced after abbreviated MRI assessment.

CONCLUSIONS

Abbreviated MRI added significant diagnostic value in patients with suspicious microcalcifications on screening mammography, as demonstrated by a significant increase in PPV with a potential reduction in unnecessary biopsy.

KEY POINTS

• Abbreviated breast magnetic resonance imaging increased the positive predictive value of suspicious microcalcifications on screening mammography from 33.8 (27/80 cases) to 75.8% (25/33 cases) (p < .01). • Abbreviated magnetic resonance imaging helped avoid unnecessary benign biopsies in 85% (45/53 cases) of lesions without missing invasive cancer.

Diagnostic Accuracy of Nonmass Enhancement at Breast MRI in Predicting Tumor Involvement of the Nipple: A Prospective Study in a Single Institution

Background Although nonmass enhancement (NME) extension to the nipple at preoperative MRI frequently leads to sacrifice of the nipple-areolar complex (NAC), its correlation with pathologically confirmed NAC involvement is unclear. Purpose To evaluate the diagnostic accuracy of using NME extension to the subareolar region at breast MRI to predict pathologic nipple involvement and the eligibility for nipple-sparing mastectomy. Materials and Methods From November 2017 to November 2019, the authors prospectively enrolled participants with breast cancer and NME within 2 cm of the nipple at breast MRI who underwent surgery that included removal of the NAC. The authors evaluated NME extensions that were ipsilateral and contiguous with the biopsy-proven tumor lesions on images acquired during the early contrast phases. Pathologic nipple involvement and the distance from the nipple to the nearest cancer cell were evaluated by using serial vertical sectioning of the area extending from the entire NAC to the tumor. The primary end point was the positive predictive value (PPV) of NME, which was calculated as follows: (number with pathologic nipple invasion and NME extension to the nipple at breast MRI/number with NME extension to the nipple at breast MRI) × 100. Results Of 64 women (mean age, 52 years ± 9.8 [standard deviation]), 49 (77%) had NME extension to the nipple at breast MRI. The PPV of NME extension to the nipple was 86% (42 of 49 women; 95% CI: 73, 94). Among the 15 participants without NME extension to the nipple, only one (7%) had pathologic nipple involvement. The diagnostic accuracy of using NME extension to the nipple was 88% (56 of 64 women; 95% CI: 77, 95). The radiologic distance correlated well with the pathologic distance (Spearman correlation coefficient = 0.71, P = .003). Conclusion Nonmass enhancement extension to the nipple base at preoperative MRI has a high positive predictive value for identifying tumor involvement of the nipple, a contraindication to nipple-sparing mastectomy. © RSNA, 2021 Online supplemental material is available for this article.

Axillary response according to neoadjuvant single or dual human epidermal growth factor receptor 2 (HER2) blockade in clinically node-positive, HER2-positive breast cancer

Incorporating dual human epidermal growth factor receptor 2 (HER2) blockade into neoadjuvant systemic therapy (NST) led to higher response in patients with HER2-positive breast cancer. However, axillary response to treatment regimens, including single or dual HER2 blockade, in patients with clinically node-positive breast cancer remains uncertain. Our study aimed to examine the pathologic axillary response according to the type of NST, that is, single or dual HER2 blockade. In our study, 546 patients with clinically node-positive, HER2-positive breast cancer who received NST followed by axillary surgery were retrospectively selected and divided into three groups: chemotherapy alone, chemotherapy + trastuzumab and chemotherapy + trastuzumab with pertuzumab. The primary outcome was the axillary pathologic complete response (pCR). Among 471 patients undergoing axillary lymph node dissection, the axillary pCR rates were 43.5%, 74.5% and 68.8% in patients who received chemotherapy alone, chemotherapy + trastuzumab and chemotherapy + trastuzumab with pertuzumab, respectively. There was no difference in axillary pCR rates between patients who received single or dual HER2 blockade (P = .379). Among patients receiving chemotherapy + trastuzumab, patients without breast pCR had the greatest risk for residual axillary metastases (relative risk, 9.8; 95% confidence interval, 3.2-14.9; P < .0001). In conclusion, adding trastuzumab to chemotherapy increased the axillary pCR rate in patients with clinically node-positive, HER2-positive breast cancer; furthermore, dual HER2-blockade with trastuzumab and pertuzumab did not elevate the axillary response compared with trastuzumab alone. Breast pCR could be a strong predictor for axillary pCR in clinically node-positive patients treated with HER2-targeting therapy.

Clinical and genomic assessment of PD-L1 SP142 expression in triple-negative breast cancer

PURPOSE

The SP142 PD-L1 assay is a companion diagnostic for atezolizumab in metastatic triple-negative breast cancer (TNBC). We strove to understand the biological, genomic, and clinical characteristics associated with SP142 PD-L1 positivity in TNBC patients.

METHODS

Using 149 TNBC formalin-fixed paraffin-embedded tumor samples, tissue microarray (TMA) and gene expression microarrays were performed in parallel. The VENTANA SP142 assay was used to identify PD-L1 expression from TMA slides. We next generated a gene signature reflective of SP142 status and evaluated signature distribution according to TNBCtype and PAM50 subtypes. A SP142 gene expression signature was identified and was biologically and clinically evaluated on the TNBCs of TCGA, other cohorts, and on other malignancies treated with immune checkpoint inhibitors (ICI).

RESULTS

Using SP142, 28.9% of samples were PD-L1 protein positive. The SP142 PD-L1-positive TNBC had higher CD8+ T cell percentage, stromal tumor-infiltrating lymphocyte levels, and higher rate of the immunomodulatory TNBCtype compared to PD-L1-negative samples. The recurrence-free survival was prolonged in PD-L1-positive TNBC. The SP142-guided gene expression signature consisted of 94 immune-related genes. The SP142 signature was associated with a higher pathologic complete response rate and better survival in multiple TNBC cohorts. In the TNBC of TCGA, this signature was correlated with lymphocyte-infiltrating signature scores, but not with tumor mutational burden or total neoantigen count. In other malignancies treated with ICIs, the SP142 genomic signature was associated with improved response and survival.

CONCLUSIONS

We provide multi-faceted evidence that SP142 PDL1-positive TNBC have immuno-genomic features characterized as highly lymphocyte-infiltrated and a relatively favorable survival.

Visit-to-visit changes in fasting blood sugar and the risk for cardiovascular disease and mortality in the Korean population: a nationwide population-based cohort study

OBJECTIVE

The importance of continuous monitoring of fasting blood sugar (FBS) levels of diabetic patients has been established.

MATERIALS AND METHODS

An observational prospective study was conducted. Our analysis included 1,700,796 individuals from the nationwide South Korean National Health Insurance System cohort. FBS variability was measured by standard deviation (SD).

RESULTS

Kaplan-Meier curves demonstrated elevated disease probability in the higher FBS fluctuation group compared with the lower FBS fluctuation group. After adjusting for confounding variables, Cox proportional hazards analysis showed that the hazard ratios of 411 individuals in the highest quartile of SD variation of FBS were 1.77 (95% confidence interval 1.37-2.28, p<0.001) compared with the lowest quartile of SD variation of FBS. The impact of FBS fluctuation on the risk of cardiovascular diseases (CVDs), cerebrovascular diseases, CVD mortality and all-cause mortality in the highest quartiles of diabetic and non-diabetic individuals was statistically significant.

CONCLUSIONS

Visit-to-visit FBS variability has prognostic value for predicting micro- and macrovascular disease, cardiovascular mortality, and all-cause mortality.

Real-World Clinical Outcomes of Biosimilar Trastuzumab (CT-P6) in HER2-Positive Early-Stage and Metastatic Breast Cancer

Background

The trastuzumab biosimilar CT-P6 has demonstrated equivalent efficacy and comparable safety to reference trastuzumab (RTZ) in clinical trials of human epidermal growth factor receptor 2 (HER2)-positive early breast cancer (EBC). Here, we present the first real-world comparison of CT-P6 versus RTZ with dual HER2-targeted therapy for the neoadjuvant and palliative first-line treatment with HER2-positive EBC and metastatic breast cancer (MBC) patients in two tertiary hospitals in Korea.

Methods

We retrospectively investigated medical records in the Severance Breast Cancer Registry in Korea. We identified patients with HER2-positive EBC (n=254) who had received neoadjuvant chemotherapy with RTZ or CT-P6, plus pertuzumab, carboplatin and docetaxel (TCHP) and untreated stage IV MBC (n=103) who had received palliative first-line treatment with RTZ or CT-P6, plus pertuzumab and docetaxel (THP) between May 2014 and December 2019. The primary endpoints were pathologic complete response (pCR) in the EBC and progression-free survival (PFS) in the MBC cohort. Overall survival (OS), overall response rate (ORR), disease control rate (DCR), and cardiac safety were secondary endpoints.

Results

A similar percentage of EBC patients achieved a pCR with CT-P6 versus RTZ (74.4% [93/125]) vs 69.8% [90/129], p=0.411). For patients with MBC, median follow-up duration was 23.0 and 41.0 months for CT-P6 and RTZ groups, respectively; median PFS did not differ significantly between two groups (13.0 vs 18.0 months, 95% confidence intervals (CIs) 0.0-26.6 vs 11.3-24.7, p=0.976). The ORR, DCR, and cardiac safety profiles did not also show significant difference efficacy outcomes between two groups.

Conclusions

These real-world data suggest that biosimilar trastuzumab CT-P6 has similar effectiveness and cardiac safety to RTZ in HER2-positive EBC and MBC patients, when administered as part of dual HER2-targeted therapy with pertuzumab plus chemotherapy in the neoadjuvant or palliative setting.

The association between the expression of nuclear Yes-associated protein 1 (YAP1) and p53 protein expression profile in breast cancer patients

Background

Yes-associated protein 1 (YAP1) is a key effector molecule regulated by the Hippo pathway and described as a poor prognostic factor in breast cancer. Tumor protein 53 (TP53) mutation is well known as a biomarker related to poor survival outcomes. So far clinical characteristics and survival outcome according to YAP1 and TP53 mutation have been poorly identified in breast cancer.

Patients and methods

Retrospectively, 533 breast tumor tissues were collected at the Seoul St Mary’s hospital and Gangnam Severance Hospital from 1992 to 2017. Immunohistochemistry with YAP1 and p53 specific antibodies were performed, and the clinical data were analyzed.

Results

Mutant p53 pattern was associated with aggressive tumor features and advanced anatomical stage. Inferior overall survival (OS) and recurrence free survival (RFS) were related with mutant p53 pattern cases with low nuclear YAP1 expression (P = 0.0009 and P = 0.0011, respectively). Multivariate analysis showed that mutant p53 pattern was an independent prognostic marker for OS [hazard ratios (HR): 2.938, 95% confidence intervals (CIs): 1.028–8.395, P = 0.044] and RFS (HR: 1.842, 95% CIs: 1.026–3.304). However, in cases with high nuclear YAP1 expression, there were no significantly difference in OS and RFS according to p53 staining pattern.

Conclusion

We found that mutant p53 pattern is a poor prognostic biomarker in breast tumor with low nuclear YAP1 expression. Our findings suggest that interaction between nuclear YAP1 and p53 expression pattern impact survival outcomes.

Body mass index and absolute lymphocyte count predict disease-free survival in Korean breast cancer patients

Background

Our study evaluated the association between body mass index (BMI) and absolute lymphocyte count (ALC) in breast cancer patients and healthy females. Additionally, we determined the prognostic value of these factors in breast cancer.

Methods

We retrospectively identified 1225 primary invasive breast cancer patients and 35,991 healthy females. Factors including BMI and complete blood count associated with disease-free survival (DFS) were assessed using a multi-variable Cox proportional hazard model.

Results

BMI and ALC were positively correlated in breast cancer patients and healthy females (both P < 0.001). In multi-variable analysis, overweight or obese participants had worse DFS (hazards ratio [HR], 1.98; 95% confidence interval [CI], 1.34–2.92; P = 0.001) than underweight or normal-weight individuals, but patients with high ALC had better DFS than those with low ALC (HR, 0.43; 95% CI, 0.29–0.65; P < 0.001). After risk stratification according to BMI/ALC, high-risk patients with high BMI/low ALC had worse DFS than others (HR, 2.48; 95% CI, 1.70–3.62; P < 0.001).

Conclusions

BMI and ALC were positive correlated, but their effect on breast cancer prognosis was opposite. Patients with high BMI/low ALC had worse DFS than others. Underlying mechanisms for effect of BMI/ALC on breast cancer prognosis should be studied in the future.

Clinical Features of Breast Cancer in South Korean Patients with Germline TP53 Gene Mutations

Purpose

Li-Fraumeni syndrome (LFS) is a rare autosomal cancer syndrome caused by a germline mutation in the TP53 gene. Breast cancer in LFS patients is of various subtypes; however, limited data are available on the clinicopathological features of these subtypes and their appropriate treatments. This study aimed to review the clinical features and treatments for breast cancer in South Korean patients with germline TP53 mutations.

Methods

Data on the clinicopathological features and treatment of all breast cancer patients with LFS were collected retrospectively from the available database of 4 tertiary hospitals in the Republic of Korea.

Results

Twenty-one breast cancer cases in 12 unrelated women with confirmed germline TP53 mutations were included in the study. The median age at diagnosis was 33.5 years. The histopathological diagnosis included invasive ductal carcinoma (n = 16), ductal carcinoma in situ (n = 3), and malignant phyllodes tumor (n = 2). While 42% and 31% of the cases were positive for estrogen and progesterone receptors, respectively, 52.6% were human epidermal growth factor receptor 2 (HER2) positive, and 21% were triple-negative. The treatments included mastectomy (52%) and breast-conserving surgery (38%). Five patients underwent radiotherapy (RT). The median follow-up period was 87.5 (8–222) months. There were 3 ipsilateral and 4 contralateral breast recurrences during the follow-up, and 8 patients developed new primary cancers. In the post-RT subgroup, there were 2 ipsilateral and 2 contralateral breast recurrences in 1 patient, and 4 patients had a new primary cancer.

Conclusion

As reported in other countries, breast cancer in LFS patients in South Korea had an early onset and were predominantly but not exclusively positive for HER2. A multidisciplinary approach with adherence to the treatment guidelines, considering mastectomy, and avoiding RT is encouraged to prevent RT-associated sequelae in LFS patients.

Author Correction: Validation of Clinical Treatment Score post-5 years (CTS5) risk stratification in premenopausal breast cancer patients and Ki-67 labelling index

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

High Nuclear Expression of Yes-Associated Protein 1 Correlates With Metastasis in Patients With Breast Cancer

Background

Yes-associated protein 1 (YAP1) is a transcription factor regulated by the Hippo pathway and functions as an oncogene in various solid tumors under dysregulated Hippo pathway. However, the role of YAP1 in breast cancer remains controversial. Here, we investigated the impact of different levels of nuclear YAP1 expression on the clinical characteristics and survival outcome in patients with breast cancer.

Patients and Methods

Retrospectively obtained 455 breast tumor samples at Gangnam Severance Hospital were examined for YAP1 expression by immunohistochemistry, and the clinical data were analyzed. External validation was performed using a retrospective cohort and tissues in 482 patients from Severance Hospital.

Results

High nuclear YAP1 expression was associated with hormone receptor negativity and aggressive tumor behavior, including lymph node metastasis, high Ki67 labeling index and inferior distant metastasis-free survival (DMFS, hazard ratio [HR] 2.271, 95% confidence intervals [CIs] 1.109–4.650, P = 0.0249), and also confirmed inferior disease free survival (HR 3.208, 95% CIs 1.313–7.833, P = 0.0105) in external validation cohort. In patients with triple-negative breast cancer (TNBC), high nuclear YAP1 expression was an independent significant determinant of poor DMFS (HR 2.384, 95% CIs 1.055–5.386, P = 0.0367).

Conclusion

Our findings suggest that nuclear YAP1 expression is a biomarker of adverse prognosis and a potential therapeutic target in patients with breast cancer, especially in TNBC.

Abstract PS13-13: The value of shear-wave elastography for prediction of treatment response to neoadjuvant chemotherapy in patients with breast cancer

Introduction Recently, Shear-wave elastography (SWE) has been known to be useful for the diagnosis of breast cancer and lymph node metastasis. However, little is known about whether SWE can predict the response to neoadjuvant chemotherapy in patients with breast cancer. This study aimed to investigate the relationship between treatment response and elasticity values. Method Pre-treatment shear-wave elastography was performed in 394 patients who underwent neoadjuvant chemotherapy followed by surgery at Gangnam Severance Hospital from January 2012 to May 2020. We evaluated the pathologic complete response (pCR, defined as ypTis/T0, No) according to elasticity values such as ‘Mean stiffness’, ‘Minimum stiffness’, ‘Maximum stiffness’, and ‘Ratio’. Results A total of 394 patients, 147 (37.3%) achieved pCR. All elasticity values were significantly lower in patients with pCR after neoadjuvant chemotherapy than those with the residual invasive tumor. In the multivariable analysis, the mean stiffness (OR 0.995; 95% CIs, 0.989-1.000; P=0.039) and the maximum stiffness (OR 0.995; 95% CIs, 0.990-0.999; P=0.024) were independent predictive factors for pCR after adjusting clinic-pathologic factors. Besides, the tumor-infiltrating lymphocytes (TILs) evaluated in biopsy samples were inversely correlated with pre-treatment mean stiffness (CC -0.053, P=0.044), and elasticity ratio (CC-0.288, P=0.033). Conclusion In this study, pre-treatment elasticity values measured by SWE were significantly associated with pCR in breast cancer. Our results suggest that SWE can be a useful diagnostic tool for predicting treatment response in patients with breast cancer who will receive neoadjuvant chemotherapy.

Citation Format: Soong June Bae, Min Ji Kim, Yoon Jin Cha, Na Lae Eun, Dooreh Kim, Janghee Lee, Sung Gwe Ahn, Eon Ju Son, Joon Jeong. The value of shear-wave elastography for prediction of treatment response to neoadjuvant chemotherapy in patients with breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS13-13.

Abstract PS10-02: A good prognosis of endocrine-dependent tumors among residual invasive cancer after anti-HER2 therapy: CALGB 40601 (Alliance) and validation studies

Background: Patients with HER2+ breast cancer who have residual disease after neoadjuvant anti-HER2 plus chemotherapy have a high risk of recurrence and benefit from adjuvant trastuzumab emtansine (T-DM1). We hypothesize that endocrine-responsive residual tumors after neoadjuvant treatments may have good outcomes among patients receiving only adjuvant endocrine therapy plus trastuzumab. Using paired pre- and post-treatment samples from CALGB 40601 and other neoadjuvant cohorts that did not include adjuvant T-DM1, we investigated survival by pretreatment and residual disease ESR1 and PgR gene expression in CALGB 40601, and by estrogen receptor (ER) and progesterone receptor (PR) immunohistochemistry (IHC) in the other cohorts. We considered endocrine-responsive tumors those with ER and/or PR expression by gene expression or IHC.

Methods: CALGB 40601 is a randomized neoadjuvant trial of single vs. dual HER2-targeting (trastuzumab and/or lapatinib added to paclitaxel). We only included those patients who had not suffered from disease progression or death during their preoperative treatments. In total, 77 patients with paired pretreatment and residual disease tumors were profiled by mRNA sequencing and studied. Cutoffs for ESR1 and PgR mRNA expression mimicking clinical positivity were obtained using 265 pretreatment CALGB 40601 tumors (and 1,045 TCGA samples for ESR1). We also examined ER and PR IHC in paired tumors from 202 patients treated at 4 different collaborating institutions; all had residual disease after neoadjuvant HER2 targeting plus chemotherapy. We considered ER- or PR-positive as ≥10% positively staining cells. The primary endpoint was EFS, defined as the time from randomization to event in CALGB 40601 and from the first systemic therapy to event in the 4-institution validation cohort.

Results: In 77 patients from CALGB 40601 with paired (pretreatment/residual disease) specimens, 38 (49.3%) had ESR1+/ESR1+ tumors. The EFS was superior in the ESR1+/ESR1+ (n=38) group than in the remaining others (the log-rank test, p=0.011). The 5- and 7-year EFS rates for the ESR1+/ESR1+ (n=38) were 92.1% and 89.2%, whereas the rates were uniformly &lt; 70% in the others. In particular, the 5-year EFS rate among 11 patients with ESR1+/ESR1- tumors was 61.4%. This remained significant in multivariable analysis with clinical stage and treatment arm; the hazard ratio (HR) for EFS in ESR1+/ESR1+ versus all others was 0.29 (95% CI, 0.09-0.90). In ESR1+/ESR1+ tumors, 5-year EFS rates were high for those whose residual disease and also being PgR+ (n=32) or PAM50 LumA or Normal-like (n=34) (93.8% and 97.1%, respectively). In the institutional validation cohort, pretreatment /residual disease ER(+)/ER(+) tumors (n=113) had superior 3-year EFS versus all others (p=0.010). At a median follow-up of 35.9 months, the 3-year EFS rates for ER(+)/ER(+) and all other groups were 96.6% and 82.6%, respectively. This remained strongly significant in multivariable analysis with clinical stage; the HR for EFS in ER(+)/ER(+) versus all other groups was 0.28 (95% CI, 0.09-0.88). Among 46 who also had PR+ in the residual disease, the 3-year EFS was 100.0%.

Conclusions: HER2+ patients with ER+ pretreatment and ER+ residual disease after neoadjuvant chemotherapy + HER2-targeting have a very good survival outcome despite not receiving additional anti-HER2 targeting with T-DM1. This may provide a simple mechanism to better tailor therapy within residual disease patients using serial ER measurements.

Citation Format: Sung Gwe Ahn, Aranzazu Fernandez-Martinez, Mei-Yin C. Polley, Soong June Bae, Seho Park, Núria Chic, Fara Brasó-Maristany, Benedetta Conte, Valentina Guarneri, Maria Vittoria Dieci, Gaia Griguolo, PierFranco Conte, Joon Jeong, Aleix Prat, Lisa A. Carey, Charles M Perou. A good prognosis of endocrine-dependent tumors among residual invasive cancer after anti-HER2 therapy: CALGB 40601 (Alliance) and validation studies [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS10-02.

Repeat Sentinel Lymph Node Biopsy for Ipsilateral Breast Tumor Recurrence After Breast Conserving Surgery With Sentinel Lymph Node Biopsy: Pooled Analysis Using Data From a Systematic Review and Two Institutions

Introduction: Best surgical approach of axillary staging remains controversial in locally recurrent breast cancer. We evaluated the reliability of repeat sentinel lymph node biopsy (reSLNB) in patients with ipsilateral breast tumor recurrence (IBTR) after breast conserving surgery (BCS) with sentinel lymph node biopsy (SLNB) in terms of identification rate (IR) and false negative rate (FNR). To address the FNR, we identified patients who underwent sequential axillary lymph node dissection (ALND) after reSLNB.

Methods: A systematic search of PubMed, EMBASE, and Cochrane Library were conducted to identify patient-level data from articles. We searched for data of patients who underwent BCS with SLNB for primary breast cancer and who underwent sequential ALND after reSLNB due to local recurrence. Patients data was also identified by the same criteria at two institutions.

Results: In total, 197 peer-reviewed publications were obtained, of which 20 included patients who met the eligibility criteria. Data from 464 patients were collected. From the two institutions, 31 patients were identified. A total of 495 patients were pooled. The IR of reSLNB was 71.9% (356/495). To address the FNR of reSLNB, 171 patients who underwent ALND after reSLNB were identified. The FNR and accuracy of reSLNB were 9.4% (5/53) and 97.1% (165/170), respectively.

Conclusion: Our pooled data analysis showed that the FNR of reSLNB is lower than 10%, indicating that this operation is a reliable axillary surgery in patients with IBTR after they underwent BCS.