Society of Surgical Oncology Breast Disease Site Working Group Statement on Contralateral Mastectomy: Indications, Outcomes, and Risks.

Rates of contralateral mastectomy (CM) among patients with unilateral breast cancer have been increasing in the United States. In this Society of Surgical Oncology position statement, we review the literature addressing the indications, risks, and benefits of CM since the society's 2017 statement. We held a virtual meeting to outline key topics and then conducted a literature search using PubMed to identify relevant articles. We reviewed the articles and made recommendations based on group consensus. Patients consider CM for many reasons, including concerns regarding the risk of contralateral breast cancer (CBC), desire for improved cosmesis and symmetry, and preferences to avoid ongoing screening, whereas surgeons primarily consider CBC risk when making a recommendation for CM. For patients with a high risk of CBC, CM reduces the risk of new breast cancer, however it is not known to convey an overall survival benefit. Studies evaluating patient satisfaction with CM and reconstruction have yielded mixed results. Imaging with mammography within 12 months before CM is recommended, but routine preoperative breast magnetic resonance imaging is not; there is also no evidence to support routine postmastectomy imaging surveillance. Because the likelihood of identifying an occult malignancy during CM is low, routine sentinel lymph node surgery is not recommended. Data on the rates of postoperative complications are conflicting, and such complications may not be directly related to CM. Adjuvant therapy delays due to complications have not been reported. Surgeons can reduce CM rates by encouraging shared decision making and informed discussions incorporating patient preferences.

Factors Associated With Node-Positive Disease in Estrogen Receptor-Positive Breast Cancer Patients.

INTRODUCTION: Larger tumor size and shorter tumor-to-nipple distance at diagnosis are associated with greater risk of lymph node involvement in breast cancer. However, the relationship between receptor subtype status and lymph node metastasis remains unclear. Our objective was to examine the association between primary tumor size, location, and nodal metastasis across estrogen receptor (ER)+/ progesterone receptor (PR)+/ human epidermal growth factor receptor 2 (HER2)-, ER+/PR-/HER2-, ER+/PR+/HER2+, and ER+/PR-/HER2+ tumors. METHODS: A single-institution retrospective chart review was conducted of breast cancer patients diagnosed between 1998 and 2019 who underwent nodal evaluation during primary surgery. Neoadjuvant chemotherapy, pure ductal carcinoma in situ, inflammatory, recurrent, metastatic, bilateral, multicentric, and multifocal disease were excluded. Descriptive statistics (proportions and frequencies for categorical variables and medians [Q1-Q3] for continuous variables) were used to summarize patient characteristics. Kruskal-Wallis test was applied to test the association of outcome variables and continuous variables. Chi-square test or Fisher exact test was applied to test the association of outcome variables and categorical variables. RESULTS: Six hundred eighteen ER + patients had a median tumor size of 1.7 cm (1.1-2.5 cm). Two hundred ninety six out of 618 (47.9%) were node-positive and 188/618 (30.4%) had axillary dissection. Eighty four point three percent of patients were ER+/PR+/HER2-, 6.31% were ER+/PR-/HER2-, 6.96% were ER+/PR+/HER2+, and 1.13% were ER+/PR-/HER2+. Median tumor size was significantly larger in node-positive cases compared to node-negative cases in ER+/PR+/HER2-, ER+/PR+/HER2+, and ER+/PR-/HER2- subgroups. In ER+/PR+/HER2-patients, median tumor-nipple distance was significantly shorter in node-positive patients compared to node-negative patients. Upper outer quadrant location was significantly associated with nodal positivity in ER+/PR-/HER2- patients. CONCLUSIONS: Across ER + patients, the significance between tumor size, location, and lymph node positivity varied significantly when differentiating by PR and HER2 status.

Factors Predictive of Positive Lymph Nodes for Breast Cancer.

BACKGROUND: Axillary node status is an important prognostic factor in breast cancer. The primary aim was to evaluate tumor size and other characteristics relative to axillary disease. MATERIALS AND METHODS: Single institution retrospective chart review of stage I-III breast cancer patients collected demographic and clinical/pathologic data from 1998-2019. Student's t-test, Chi-squared test (or Fisher exact test if applicable), and logistic regression models were used for testing the association of pN+ to predictive variables. RESULTS: Of 728 patients (mean age 59 yrs) with mean follow up of 50 months, 86% were estrogen receptor +, 10% Her2+, 78% ER+HER2-negative, and 10% triple-negative. In total, 351/728 (48.2%) were pN+ and mean tumor size was larger in pN+ cases compared to pN- cases (mean = 27.7 mm versus 15.5 mm) (p < 0.001). By univariate analysis, pN+ was associated with lymphovascular invasion (LVI), higher grade, Her2, and histology (p < 0.005). Tumor-to-nipple distance was shorter in pN+ compared to pN- (45 mm v. 62 mm; p< 0.001). Age < 60, LVI, recurrence, mastectomy, larger tumor size, and shorter tumor-nipple distance were associated with 3+ positive nodes (p < 0.05). CONCLUSIONS: Larger tumor size and shorter tumor-nipple distance were associated with higher lymph node positivity. Age less than 60, LVI, recurrence, mastectomy, larger tumor size, and shorter tumor-nipple distance were all associated with 3+ positive lymph nodes.

Tumor Characteristics Associated with Axillary Nodal Positivity in Triple Negative Breast Cancer.

Larger-size primary tumors are correlated with axillary metastases and worse outcomes. We evaluated the relationships among tumor size, location, and distance to nipple relative to axillary node metastases in triple-negative breast cancer (TNBC) patients, as well as the predictive capacity of imaging. We conducted a single-institution, retrospective chart review of stage I-III TNBC patients diagnosed from 1998 to 2019 who underwent upfront surgery. Seventy-three patients had a mean tumor size of 20 mm (range 1-53 mm). All patients were clinically node negative. Thirty-two patients were sentinel lymph node positive, of whom 25 underwent axillary lymph node dissection. Larger tumor size was associated with positive nodes (p < 0.001): the mean tumor size was 14.30 mm in node negative patients and 27.31 mm in node positive patients. Tumor to nipple distance was shorter in node positive patients (51.0 mm) vs. node negative patients (73.3 mm) (p = 0.005). The presence of LVI was associated with nodal positivity (p < 0.001). Tumor quadrant was not associated with nodal metastasis. Ultrasound yielded the largest number of suspicious findings (21/49), with sensitivity of 0.25 and specificity of 0.40. On univariate analysis, age younger than 60 at diagnosis was also associated with nodal positivity (p < 0.002). Comparative analyses with other subtypes may identify biologic determinants.

Surgeon and Radiologist Evaluation of Electromagnetic Chip Localization for Benign and Malignant Breast Lesions.

BACKGROUND: SmartClipTM is a food and drug administration-approved, electromagnetic chip (EMC) localization system that provides three-dimensional navigation for the excision of soft tissue lesions. The purpose of this study was to analyze the accuracy and feasibility of EMC radiologic and surgical localization for benign and malignant breast lesions. PATIENTS AND METHODS: An institutional review board-approved, single institution, prospective study from October 2020 to September 2022 of 38 women undergoing breast conserving surgery with EMC localization of a single lesion > 5 mm on mammogram (MMG) or ultrasound (US) imaging. Surveys from performing breast radiologists and breast surgeons were collected after image-guided localization and surgical excision. RESULTS: Seventy-six survey responses from nine radiologists and four surgeons were received. The deployment needle and EMC were highly visible in 86.8% and 76.3% of procedures, respectively. There was no difficulty in deployment for 92.1% of procedures. The EMC was in the correct location on postdeployment MMG in 97.4% of cases. Three instances of EMC migration occurred, one 1 cm from target lesion. The targeted mass and EMC were within the surgical specimen in 97.4% of cases. On specimen radiograph, 39.5% of the EMCs were 0-1 mm from the center of the target lesion, 18.4% were within 2-4 mm, and 23.7% were within 5-10 mm. Mean operating room time for all cases was 65 min. One case required US to localize the target due to console malfunction. CONCLUSION: There was successful EMC deployment by radiologists with accurate visualization and successful surgical excision in most cases. The EnVisioTM SmartClipTM system is a reproducible and accurate localization method for benign and malignant breast lesions.

Breast Conservation Surgery and Mastectomy Have Similar Locoregional Recurrence After Neoadjuvant Chemotherapy: Results From 1462 Patients on the Prospective, Randomized I-SPY2 Trial.

Neoadjuvant chemotherapy (NAC) increases rates of successful breast-conserving surgery (BCS) in patients with breast cancer. However, some studies suggest that BCS after NAC may confer an increased risk of locoregional recurrence (LRR). We assessed LRR rates and locoregional recurrence-free survival (LRFS) in patients enrolled on I-SPY2 (NCT01042379), a prospective NAC trial for patients with clinical stage II to III, molecularly high-risk breast cancer. Cox proportional hazards models were used to evaluate associations between surgical procedure (BCS vs mastectomy) and LRFS adjusted for age, tumor receptor subtype, clinical T category, clinical nodal status, and residual cancer burden (RCB). In 1462 patients, surgical procedure was not associated with LRR or LRFS on either univariate or multivariate analysis. The unadjusted incidence of LRR was 5.4% after BCS and 7.0% after mastectomy, at a median follow-up time of 3.5 years. The strongest predictor of LRR was RCB class, with each increasing RCB class having a significantly higher hazard ratio for LRR compared with RCB 0 on multivariate analysis. Triple-negative receptor subtype was also associated with an increased risk of LRR (hazard ratio: 2.91, 95% CI: 1.8-4.6, P < 0.0001), regardless of the type of operation. In this large multi-institutional prospective trial of patients completing NAC, we found no increased risk of LRR or differences in LRFS after BCS compared with mastectomy. Tumor receptor subtype and extent of residual disease after NAC were significantly associated with recurrence. These data demonstrate that BCS can be an excellent surgical option after NAC for appropriately selected patients.

Factors Influencing Lymph Node Positivity in HER2/neu+ Breast Cancer Patients.

Axillary lymph node metastases are a key prognostic factor in breast cancer treatment. Our aim was to evaluate how tumor size, tumor location, and imaging results correlate to axillary lymph node diseases for patients with stage I-III HER2/neu+ breast cancer. This is a single-institution retrospective chart review of female breast cancer patients diagnosed with primary invasive Her2/neu+ breast cancer who were treated with upfront surgical resection from 2000-2021. Of 75 cases, 44/75 (58.7%) had nodal metastasis, and there was a significant association of larger tumor size to nodal metastases (p ≤ 0.001). Patients with negative nodes had a smaller mean tumor size (n = 30; 15.10 mm) than patients with positive nodes (n = 45; 23.9 mm) (p = 0.002). Preoperative imaging detected suspicious nodes in 36 patients, and ultrasound detected the most positive nodes (14/18; p = 0.027). Our data confirms that tumor size at diagnosis is correlated with a higher likelihood of axillary involvement in patients with Her2/neu+ breast cancer; notably, a large proportion of Her2/neu+ breast cancers have metastatic involvement of axillary lymph nodes even with small primary lesions.

Intraoperative Fluorescence Guidance for Breast Cancer Lumpectomy Surgery.

Fluorescence Guidance for Lumpectomy SurgeryThis prospective trial of 406 patients assessed margin status with and without pegulicianine fluorescence-guided surgery (pFGS) for stages 0 to 3 breast cancers. The use of pFGS met prespecified thresholds for removal of residual tumor and specificity but did not meet the prespecified threshold for sensitivity.

Association of Residual Ductal Carcinoma In Situ With Breast Cancer Recurrence in the Neoadjuvant I-SPY2 Trial.

Importance: Pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) in breast cancer strongly correlates with overall survival and has become the standard end point in neoadjuvant trials. However, there is controversy regarding whether the definition of pCR should exclude or permit the presence of residual ductal carcinoma in situ (DCIS). Objective: To examine the association of residual DCIS in surgical specimens after neoadjuvant chemotherapy for breast cancer with survival end points to inform standards for the assessment of pathologic complete response. Design, Setting, and Participants: The study team analyzed the association of residual DCIS after NAC with 3-year event-free survival (EFS), distant recurrence-free survival (DRFS), and local-regional recurrence (LRR) in the I-SPY2 trial, an adaptive neoadjuvant platform trial for patients with breast cancer at high risk of recurrence. This is a retrospective analysis of clinical specimens and data from the ongoing I-SPY2 adaptive platform trial of novel therapeutics on a background of standard of care for early breast cancer. I-SPY2 participants are adult women diagnosed with stage II/III breast cancer at high risk of recurrence. Interventions: Participants were randomized to receive taxane and anthracycline-based neoadjuvant therapy with or without 1 of 10 investigational agents, followed by definitive surgery. Main Outcomes and Measures: The presence of DCIS and EFS, DRFS, and LRR. Results: The study team identified 933 I-SPY2 participants (aged 24 to 77 years) with complete pathology and follow-up data. Median follow-up time was 3.9 years; 337 participants (36%) had no residual invasive disease (residual cancer burden 0, or pCR). Of the 337 participants with pCR, 70 (21%) had residual DCIS, which varied significantly by tumor-receptor subtype; residual DCIS was present in 8.5% of triple negative tumors, 15.6% of hormone-receptor positive tumors, and 36.6% of ERBB2-positive tumors. Among those participants with pCR, there was no significant difference in EFS, DRFS, or LRR based on presence or absence of residual DCIS. Conclusions and Relevance: The analysis supports the definition of pCR as the absence of invasive disease after NAC regardless of the presence or absence of DCIS. Trial Registration: ClinicalTrials.gov Identifier NCT01042379.

The Breast Cancer Screening and Timing of Breast MRI-Experience in a Genetic High-Risk Screening Clinic in a Comprehensive Cancer Center.

For women with genetic risk of breast cancer, the addition of screening breast MRI to mammography has become a standard. The order and interval of annual imaging can be variable among providers. To evaluate the clinical implications related to the timing, we conducted a chart review on a cohort of women (N = 276) with high-risk (BRCA1, BRCA2, CDH1, PTEN and TP53) and moderate high-risk (ATM and CHEK2) predisposition to breast cancer in a 48-month follow up. The estimated MRI detection rate in the entire group is 1.75% (18 per 1000 MRI tests). For the high-risk group, the estimated rate is 2.98% (30 per 1000 MRI tests). Many women discovered their genetic risk at an age much older (average age of the high-risk group was 48 years) than the age recommended to initiate enhanced screening (age 20 to 25 years). In total, 4 of the 11 primary breast cancers detected were identified by screening MRI within the first month after initial visit, which were not detected by previous mammography, suggesting the benefit of initiating MRI immediately after the discovery of genetic risk. Breast screening findings for women with Lynch syndrome and neurofibromatosis type 1 were also included in this report.

Identification of Immunogenic MHC Class II Human HER3 Peptides that Mediate Anti-HER3 CD4+ Th1 Responses and Potential Use as a Cancer Vaccine.

The HER3/ERBB3 receptor is an oncogenic receptor tyrosine kinase that forms heterodimers with EGFR family members and is overexpressed in numerous cancers. HER3 overexpression associates with reduced survival and acquired resistance to targeted therapies, making it a potential therapeutic target in multiple cancer types. Here, we report on immunogenic, promiscuous MHC class II-binding HER3 peptides, which can generate HER3-specific CD4+ Th1 antitumor immune responses. Using an overlapping peptide screening methodology, we identified nine MHC class II-binding HER3 epitopes that elicited specific Th1 immune response in both healthy donors and breast cancer patients. Most of these peptides were not identified by current binding algorithms. Homology assessment of amino acid sequence BLAST showed >90% sequence similarity between human and murine HER3/ERBB3 peptide sequences. HER3 peptide-pulsed dendritic cell vaccination resulted in anti-HER3 CD4+ Th1 responses that prevented tumor development, significantly delayed tumor growth in prevention models, and caused regression in multiple therapeutic models of HER3-expressing murine tumors, including mammary carcinoma and melanoma. Tumors were robustly infiltrated with CD4+ T cells, suggesting their key role in tumor rejection. Our data demonstrate that class II HER3 promiscuous peptides are effective at inducing HER3-specific CD4+ Th1 responses and suggest their applicability in immunotherapies for human HER3-overexpressing tumors.

Influential Factors on Risk-reduction Mastectomy in a High-risk Breast Cancer Population With Genetic Predispositions.

BACKGROUND: Carriers of deleterious mutations in breast cancer predisposition genes are presented with critical choices regarding cancer risk management. Risk-reduction mastectomy is a major preventative strategy in this population. Understanding the decision-making process for prophylactic mastectomy is essential in patient-centered care for high-risk carriers and patients with breast cancer. We sought to provide insight into influential factors underlying preventative surgery decisions among individuals with high breast cancer risk. MATERIALS AND METHODS: We conducted a retrospective chart review of pathogenic carriers of high-risk breast cancer genes who presented to the Moffitt GeneHome clinic between March 2017 and June 2020. Associations between preventative mastectomy choice and influence variables were analyzed via unadjusted and adjusted logistic regression models. RESULTS: Of 258 high-risk mutation carriers, 104 (40.3%) underwent risk-reduction mastectomy. A significantly higher proportion of mastectomy patients reported prior history of breast cancer (68.9% vs. 16.5%; P < .001) and history of other risk-reduction or noncancer-related surgeries (61.7% vs. 25.8%; P < .001). Significant predictors affecting surgery decision included previous breast cancer history (adjusted odds ratio [aOR], 10.48; 95% confidence interval [CI], 5.59-19.63; P < .0001), other risk-reduction or noncancer-related surgical history (aOR, 4.65; 95% CI, 2.28-9.47; P < .0001), and age at presentation to the genetics clinic (< 35 years old: aOR, 2.77; 95% CI, 1.04-7.4; P = .042; 35-55 years old: aOR, 2.48; 95% CI, 1.19-5.18; P = .016). CONCLUSIONS: Preventive mastectomy decisions are highly personal and complex. In our sample, we observed prior history or concurrent breast cancer, history of other risk-reduction surgery or noncancer-related surgery, and younger age at presentation to the GeneHome clinic to be predictive of mastectomy uptake.

Clinical Presentation, Diagnosis and Prognosis of Pregnancy-Associated Breast Cancer.

Breast cancer in pregnancy is a rare entity generally presenting as a persistent breast mass, but is often a delayed finding due to the expected physiologic changes in the breast related to pregnancy and lactation. The preferred diagnostic workup of a persistent breast mass involves a combination of mammographic and ultrasonographic evaluation in addition to tissue diagnosis via core biopsy ; breast MRI is not recommended. Surgical excision should be reserved for definitive treatment in order to minimize fetal exposure to anesthesia. Evaluation for distant metastatic spread can be performed using radiographs and ultrasound to limit fetal radiation exposure . Similar to the non-pregnant patient, prognosis is primarily driven by tumor biology, however, there is limited and conflicting data regarding the impact of pregnancy on breast cancer outcomes with a distinct difference in survival among patients with breast cancer during pregnancy compared to those diagnosed postpartum.

Narrowing the focus: Therapeutic cell surface targets for refractory triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is defined as a type of breast cancer with lack of expression of estrogen receptor, progesterone receptor and human epidermal growth factor 2 protein. In comparison to other types of breast cancer, TNBC characterizes for its aggressive behavior, more prone to early recurrence and a disease with poor response to molecular target therapy. Although TNBC is identified in only 25%-30% of American breast cancer cases annually, these tumors continue to be a therapeutic challenge for clinicians for several reasons: Tumor heterogeneity, limited and toxic systemic therapy options, and often resistance to current standard therapy, characterized by progressive disease on treatment, residual tumor after cytotoxic chemotherapy, and early recurrence after complete surgical excision. Cell-surface targeted therapies have been successful for breast cancer in general, however there are currently no approved cell-surface targeted therapies specifically indicated for TNBC. Recently, several cell-surface targets have been identified as candidates for treatment of TNBC and associated targeted therapies are in development. The purpose of this work is to review the current clinical challenges posed by TNBC, the therapeutic approaches currently in use, and provide an overview of developing cell surface targeting approaches to improve outcomes for treatment resistant TNBC.

Metabolic reprogramming augments potency of human pSTAT3-inhibited iTregs to suppress alloreactivity.

Immunosuppressive donor Tregs can prevent graft-versus-host disease (GVHD) or solid-organ allograft rejection. We previously demonstrated that inhibiting STAT3 phosphorylation (pSTAT3) augments FOXP3 expression, stabilizing induced Tregs (iTregs). Here we report that human pSTAT3-inhibited iTregs prevent human skin graft rejection and xenogeneic GVHD yet spare donor antileukemia immunity. pSTAT3-inhibited iTregs express increased levels of skin-homing cutaneous lymphocyte-associated antigen, immunosuppressive GARP and PD-1, and IL-9 that supports tolerizing mast cells. Further, pSTAT3-inhibited iTregs significantly reduced alloreactive conventional T cells, Th1, and Th17 cells implicated in GVHD and tissue rejection and impaired infiltration by pathogenic Th2 cells. Mechanistically, pSTAT3 inhibition of iTregs provoked a shift in metabolism from oxidative phosphorylation (OxPhos) to glycolysis and reduced electron transport chain activity. Strikingly, cotreatment with coenzyme Q10 restored OxPhos in pSTAT3-inhibited iTregs and augmented their suppressive potency. These findings support the rationale for clinically testing the safety and efficacy of metabolically tuned, human pSTAT3-inhibited iTregs to control alloreactive T cells.

Evaluation of 2014 margin guidelines on re-excision and recurrence rates after breast conserving surgery: A multi-institution retrospective study.

INTRODUCTION: A 2014 consensus statement from the Society of Surgical Oncology and American Society for Radiation Oncology supported "no ink on tumor" as an adequate margin for breast conserving therapy (BCT). This study evaluates this statement in a multi-institution cohort. METHODS: A retrospective review of BCT cases at 3 comprehensive cancer centers was performed. Women age >18 receiving BCT for T1-2 breast cancer from 2008-2012 were included. Pre-2014, all sites considered 2 mm adequate. Estimated re-excision rates using the 2014 guidelines were calculated and factors predictive of re-excision were analyzed. RESULTS: 542 patients (545 lumpectomies) were eligible. Using a ≥2 mm margin standard, 32.8% of patients underwent re-excision compared to 14.1% after 2014 (p < 0.0001). Tumor size (p= 0.003), grade (p=0.015), and lymphovascular invasion (p=0.021) were predictive of re-excision. Patients with additional intraoperative margins excised were less likely to require reoperation (p=0.002). Local recurrence was unaffected by re-excision after mean followup of 66 months. CONCLUSIONS: The 2014 margin guidelines markedly reduce re-excision rates. There is no difference in local recurrence for patients after re-excision for a close margin versus without Powered.

A Framework for Pilot Testing Health Risk Video Narratives.

Narrative messages may be superior to didactic messages when providing educational information due to their natural format for information sharing, ability to engage audiences, and engender positive thoughts about the message. Although narrative messages are gaining popularity in health promotion, little guidance exists regarding the development phase. Our team created a psychosocial narrative video intervention grounded in the Health Belief Model to increase breast cancer survivors' attendance at genetic counseling after treatment. Here we report the use of Learner Verification (LV) during an iterative video development process. Using LV, we conducted individual semi-structured interviews with patients and providers, after they viewed the video. Demographic information was analyzed using descriptive statistics, and verbatim interview transcripts were used to conduct a two-phase qualitative content analysis. Patient and provider participants (n = 30) believed the video was attractive, relatable, and informative, and they identified areas for improvement including narrative coherence, changes to text and graphical information, and including more specific information. LV framework elicited audience feedback on the video intervention relevant to theoretical principles of narrative interventions, and highlighted audience preferences. In this study, LV interviews tapped into theoretical constructs of narratives and facilitated the iterative intervention design process.

Implant-sparing Mastectomy: An Alternative for Women Undergoing Mastectomy With Retropectoral Implants.

INTRODUCTION: Implant-sparing mastectomy (ISM) is a skin-sparing mastectomy that preserves a retropectoral implant and potentially eliminates the need for tissue expansion or complex reconstruction. This study aimed to determine oncologic and surgical outcomes and reconstructive patterns in patients undergoing ISM. PATIENTS AND METHODS: A single-institution, retrospective review of patients undergoing ISM from 2006 to 2018 was performed. Patient/tumor characteristics, stage, adjuvant therapy use, 90-day complication rates, reconstruction type, and disease recurrence were collected. RESULTS: A total of 121 ISMs in 73 women were performed. Seventy (57.9%) ISMs were for breast cancer (BC) treatment and 51 (42.1%) for prophylaxis. Among BC cases, 72.3% were cT1/cT2 and 73.8% were cN0; 72.3% received systemic therapy and 33.8% received radiation therapy. There were 3 deaths owing to BC at the median follow-up of 35 months. Among 5 recurrences, only 1 was local. There was no BC identified after prophylactic ISM. Total 90-day complication rate per ISM was 15.7%. Rates were 0.8% for both seroma and wound infection, 2.5% for wound dehiscence, 3.3% for hematoma, and 8.2% for skin necrosis. The majority (72.6%) of patients required only implant exchange for reconstruction. Overall use of autologous reconstruction was low (12.3%); 77.8% of flaps were performed in patients receiving radiation therapy. CONCLUSION: ISM is a unique approach for patients pursuing mastectomy for BC treatment or prevention with equivalent oncologic outcomes and complication rates to mastectomy with reconstruction. Reconstruction for the majority was markedly simplified by elimination of tissue expansion while maintaining a low rate of flap reconstruction.