Clinicopathological characteristics and eligibility for adjuvant olaparib of germline BRCA1/2 mutation carriers with HER2-negative early breast cancer.

Following the survival benefit demonstrated in the OlympiA trial, one year of adjuvant olaparib is now recommended for all patients with germline BRCA1/2 pathogenic/likely pathogenic variants (PV) and high-risk, HER2-negative early breast cancer after chemotherapy. However, optimal identification of high-risk patients who may derive benefit from this genomically-directed therapy is debated. In this study, we sought to characterize the real-world proportion of gBRCA1/2 PV carriers eligible for adjuvant olaparib according to the OlympiA criteria, and to compare clinicopathologic characteristics and outcomes between eligible and ineligible patients.

Systemic Therapy Advances for HER2-Positive and Triple Negative Breast Cancer: What the Surgeon Needs to Know.

Neoadjuvant systemic therapy (NST) was initially reserved for unresectable patients however it has been increasingly used to facilitate breast conservation, downstage the axilla, and inform adjuvant therapy decisions based on response. For patients with HER2+ and triple-negative breast cancer (TNBC), clinical trials have resulted in the ability to individualize treatment regimens. For HER2+ breast cancer, de-escalation of neoadjuvant regimens to minimize cytotoxic chemotherapy and de-escalation or escalation of adjuvant regimens based on response have been effective. For TNBC, the approval of the combination of chemotherapy plus immunotherapy in the neoadjuvant setting has resulted in a major practice shift and opened the door to many additional treatment questions including de-escalation of the chemotherapy backbone or the adjuvant regimen. For both HER2+ and TNBC, most patients are treated with NST except those with very small tumors. Efforts are also being made to optimally identify patients with T1c tumors who may benefit from more aggressive NST. For patients treated according to or enrolled in NST de-escalation trials, breast conservation (even those who become eligible based on response to NST) and sentinel lymph node biopsy when cN0 at the completion of NST are safe and feasible. Continued involvement of surgeons and multidisciplinary teams in the design and reporting of trials will streamline their adoption into clinical practice. Surgeons need to remain aware of ongoing systemic therapy trials to appropriately select patients for NST and plan for appropriate post-neoadjuvant surgical care.

Implementation of a Trauma-Informed Challenging Interactions Reporting Tool to Improve our Clinical Learning Environment.

PROBLEM: Workplace mistreatment is a contributor to resident burnout; understanding and intervening against mistreatment is one key tool in mitigating burnout. While ACGME survey data alerts programs to general mistreatment trends, those data are not detailed enough to inform local interventions. Our team designed and implemented a Challenging Interactions Reporting Tool (CIRT) to characterize the experiences of our trainees at a granular level and to inform targeted interventions for improvement. APPROACH: Our CIRT was offered to 158 residents in August 2020 via REDCap. Residents submit electronic reports that are reviewed weekly by program leaders who develop action plans for each report. Reporters can identify themselves or can choose to remain anonymous. When "hot spots" for mistreatment are identified in our hospital, we implement a targeted systems-level intervention. OUTCOMES: Residents filed 275 reports between August 2020 and December 2022. Reports represented all training environments and involved all interprofessional members of clinical teams. Residents reported awareness of, use of, and satisfaction with the tool. NEXT STEPS: Our program created the CIRT as a tool to inform local interventions for improving the safety of our clinical learning environment. We continue to disseminate our tool across our hospital's GME programs and are now measuring the impact of our interventions.

Endocrine-Sensitive Disease Rate in Postmenopausal Patients With Estrogen Receptor-Rich/ERBB2-Negative Breast Cancer Receiving Neoadjuvant Anastrozole, Fulvestrant, or Their Combination: A Phase 3 Randomized Clinical Trial.

Importance: Adding fulvestrant to anastrozole (A+F) improved survival in postmenopausal women with advanced estrogen receptor (ER)-positive/ERBB2 (formerly HER2)-negative breast cancer. However, the combination has not been tested in early-stage disease. Objective: To determine whether neoadjuvant fulvestrant or A+F increases the rate of pathologic complete response or ypT1-2N0/N1mic/Ki67 2.7% or less residual disease (referred to as endocrine-sensitive disease) over anastrozole alone. Design, Setting, and Participants: A phase 3 randomized clinical trial assessing differences in clinical and correlative outcomes between each of the fulvestrant-containing arms and the anastrozole arm. Postmenopausal women with clinical stage II to III, ER-rich (Allred score 6-8 or >66%)/ERBB2-negative breast cancer were included. All analyses were based on data frozen on March 2, 2023. Interventions: Patients received anastrozole, fulvestrant, or a combination for 6 months preoperatively. Tumor Ki67 was assessed at week 4 and optionally at week 12, and if greater than 10% at either time point, the patient switched to neoadjuvant chemotherapy or immediate surgery. Main Outcomes and Measures: The primary outcome was the endocrine-sensitive disease rate (ESDR). A secondary outcome was the percentage change in Ki67 after 4 weeks of neoadjuvant endocrine therapy (NET) (week 4 Ki67 suppression). Results: Between February 2014 and November 2018, 1362 female patients (mean [SD] age, 65.0 [8.2] years) were enrolled. Among the 1298 evaluable patients, ESDRs were 18.7% (95% CI, 15.1%-22.7%), 22.8% (95% CI, 18.9%-27.1%), and 20.5% (95% CI, 16.8%-24.6%) with anastrozole, fulvestrant, and A+F, respectively. Compared to anastrozole, neither fulvestrant-containing regimen significantly improved ESDR or week 4 Ki67 suppression. The rate of week 4 or week 12 Ki67 greater than 10% was 25.1%, 24.2%, and 15.7% with anastrozole, fulvestrant, and A+F, respectively. Pathologic complete response/residual cancer burden class I occurred in 8 of 167 patients and 17 of 167 patients, respectively (15.0%; 95% CI, 9.9%-21.3%), after switching to neoadjuvant chemotherapy due to week 4 or week 12 Ki67 greater than 10%. PAM50 subtyping derived from RNA sequencing of baseline biopsies available for 753 patients (58%) identified 394 luminal A, 304 luminal B, and 55 nonluminal tumors. A+F led to a greater week 4 Ki67 suppression than anastrozole alone in luminal B tumors (median [IQR], -90.4% [-95.2 to -81.9%] vs -76.7% [-89.0 to -55.6%]; P < .001), but not luminal A tumors. Thirty-six nonluminal tumors (65.5%) had a week 4 or week 12 Ki67 greater than 10%. Conclusions and Relevance: In this randomized clinical trial, neither fulvestrant nor A+F significantly improved the 6-month ESDR over anastrozole in ER-rich/ERBB2-negative breast cancer. Aromatase inhibition remains the standard-of-care NET. Differential NET response by PAM50 subtype in exploratory analyses warrants further investigation. Trial Registration: ClinicalTrials.gov Identifier: NCT01953588.

Single versus Double Drainage for Immediate Two-Stage Implant-Based Breast Reconstruction: A Propensity Score-Matched Analysis.

BACKGROUND: Reports evaluating plastic surgeons' practices indicate there are conflicting trends regarding the use of one or two drains for implant-based breast reconstruction (IBBR). Our study aimed to perform a matched cohort analysis to examine the postoperative outcomes and complications of immediate IBBR with tissue expander (TE) using two drains versus a single drain. METHODS: A propensity score-matched analysis (nearest neighbor, 1:1 matching) of immediate reconstructions using two versus one drain was conducted. Female patients undergoing immediate two-stage IBBR with TEs between January 2011 and May 2021 were included. The covariables were as follows: BMI, mastectomy weight, lymph node surgery, TE surface, plane of reconstruction, use of acellular dermal matrix products, fluorescence imaging use, and intraoperative TE volume. RESULTS: After matching using propensity scores, 192 reconstructions were included in the final analysis: 96 in each group. The rate of 30-day complications and overall complications during the first phase of IBBR were comparable between groups. The time for drain removal, time to initiate and finalize expansions, and time for TE-to-implant exchange were comparable between groups. Diabetes (OR 3.74, p = 0.025) and an increased estimated blood loss (OR 1.004, p = 0.01) were the only independent predictors for seroma formation. CONCLUSION: In this matched cohort analysis evaluating the role of one versus two drains for two-stage IBBR, we found a comparable rate of complications and surgical outcomes between the two cohorts. Using two drains for immediate IBBR needs to be tailored depending on intraoperative findings. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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.

Axillary Nodal Response to Neoadjuvant T-DM1 Combined with Pertuzumab in a Prospective Phase II Multi-Institution Clinical Trial.

BACKGROUND: Patients with ERBB2 (HER2)-positive breast cancer experience high pathologic complete response (pCR) rates after standard neoadjuvant anti-HER2 systemic therapy. We examined axillary pathologic nodal response to neoadjuvant dual HER2-targeted therapy alone, based on breast pathologic response, in a multi-institution clinical trial. STUDY DESIGN: Patients with HER2-positive breast cancer were enrolled to a phase II single-arm trial, which administered 6 cycles of neoadjuvant trastuzumab emtansine (T-DM1) plus pertuzumab. Rates of pathologic nodal disease (ypN) in patients who were clinically node-negative (cN0) and node-positive (cN1) were analyzed, by residual breast disease (pCR and residual cancer burden [RCB] I to III). RESULTS: One hundred fifty-eight patients completed preoperative treatment and proceeded to surgery. Of 92 patients who were cN0, 48 (52.2%) and 10 (10.9%) experienced breast pCR and RCB I, respectively. Of these, 100% were ypN0. Of 34 with RCB II to III, 26 (76.5%) were ypN0. Of 30 patients who were cN1 with breast pCR, 100% were ypN0; of the 12 patients who were cN1 with RCB I, 66.7% were ypN0; and of the 24 patients who were cN1 with RCB II to III, 25% were ypN0. ypN0 rates were significantly different between patients who did and did not experience a pCR, in both cN0 (p = 0.002) and cN1 (p < 0.001) subgroups. CONCLUSIONS: Patients with HER2-positive breast cancer treated with dual HER2-targeted therapy who experienced a breast pCR or RCB I response were frequently ypN0. These findings support future trials considering omission of axillary surgical staging for patients with HER2-positive breast cancer in neoadjuvant trials of active HER2-targeted regimens, particularly if they experience breast pCR or RCB I.

Positive predictive value of axillary lymph node cortical thickness and nodal, clinical, and tumor characteristics in newly diagnosed breast cancer patients.

PURPOSE: Axillary lymph nodes (LNs) with cortical thickness > 3 mm have a higher likelihood of malignancy. To examine the positive predictive value (PPV) of axillary LN cortical thickness in newly diagnosed breast cancer patients, and nodal, clinical, and tumor characteristics associated with axillary LN metastasis. METHODS: Retrospective review of axillary LN fine needle aspirations (FNAs) performed 1/1/2018-12/31/2019 included 135 axillary FNAs in 134 patients who underwent axillary surgery. Patient demographics, clinical characteristics, histopathology, and imaging features were obtained from medical records. Hypothesis testing was performed to identify predictors of axillary LN metastasis. RESULTS: Cytology was positive in 72/135 (53.3%), negative in 61/135 (45.2%), and non-diagnostic in 2/135 (1.5%). At surgery, histopathology was positive in 84 (62.2%) and negative in 51 (37.8%). LN cortices were thicker in metastatic compared to negative nodes (p < 0.0001). PPV of axillary LNs with cortical thickness ≥ 3 mm, ≥ 3.5 mm, ≥ 4 mm and, ≥ 4.25 mm was 0.62 [95% CI 0.53, 0.70], 0.63 [0.54, 0.72], 0.67 [0.57, 0.76] , and 0.74 [0.64, 0.83], respectively. At multivariable analysis, abnormal hilum (OR = 3.44, p = 0.016) and diffuse cortical thickening (OR = 2.86, p = 0.038) were associated with nodal metastasis. CONCLUSION: In newly diagnosed breast cancer patients, increasing axillary LN cortical thickness, abnormal fatty hilum, and diffuse cortical thickening are associated with nodal metastasis. PPV of axillary LN cortical thickness ≥ 3 mm and ≥ 3.5 mm is similar but increases for cortical thickness ≥ 4 mm. FNA of axillary LNs with cortex < 4 mm may be unnecessary for some patients undergoing sentinel LN biopsy.

Latissimus dorsi flap with immediate fat transfer (LIFT) for autologous breast reconstruction: Single institution experience.

BACKGROUND: Few studies have reported the outcomes of LDF and immediate fat transfer (LIFT) during breast reconstruction. The aim of this study was to compare the perioperative outcomes and complications of LIFT and standard LDF (without immediate fat transfer) for breast reconstruction. METHODS: We retrospectively reviewed charts from patients undergoing autologous breast reconstruction after total mastectomy between 2011 and 2021. We compared intraoperative and postoperative outcomes between groups. RESULTS: One hundred nineteen reconstructions (61.02%) were performed with LIFT, while seventy-six (38.98%) were performed with standard LDF. The median volume of total fat transferred during LIFT was 125-cc [110-170 â€‹cc]. The rates of donor site wound disruption (23.7% versus 12.6%, p â€‹= â€‹0.044) were higher using the standard LDF compared to LIFT. Reconstructions performed with LIFT (HR 4.01, p â€‹< â€‹0.001) were found to be associated with secondary fat grafting procedures. CONCLUSION: LIFT is a safe procedure to enhance the volume of LDF in patients desiring autologous reconstruction without increasing recipient-site morbidity. On a time-to-event analysis, LIFT was associated with the requirement of further revision procedures using secondary fat grafting.

HER2 categorical changes after neoadjuvant chemotherapy: A study of 192 matched breast cancers with the inclusion of HER2-Low category.

Understanding the changes of HER2 expression after neoadjuvant chemotherapy (NAC) in breast cancer (BC) is more important than ever, since it may allow more patients to access the effective therapeutic drugs targeting HER2-low BC. 192 matched pre- and post-NAC BCs were analyzed. HER2 immunohistochemistry (IHC) was re-evaluated with consensus according to the current ASCO/CAP guidelines. Tumors were categorized into HER2-0 (IHC0+), HER2-low (IHC1+ or IHC2+/ISH-) and HER2-positive (IHC3+ or IHC2+/ISH+) subgroups. 55 (28.6 %) patients achieved pathologic complete response (pCR). HER2-low BC accounted for 75/192 (39.1 %) baseline tumors, and 48/133 (36.1 %) residual tumors. In the non-pCR cohort, 53 (39.9 %) patients had HER2 categorical change after NAC, most commonly converting from HER2-low to HER2-0 (20.3 %, n = 27). Among patients with residual tumor, 25.6 % (11/43) of patients with baseline HER2-0 expression experienced a categorical change to HER2-low after NAC, significantly higher (p < 0.05) in the hormone receptor (HR) positive (9/23, 39.1 %) compared to the HR negative tumors (10 %, 2/20). Exploratory analysis failed to reveal a statistically significant difference in disease free survival and overall survival in non-pCR patients with or without HER2 change. Our results suggest that a substantial number of patients may experience HER2 categorical change after NAC, supporting re-testing of HER2 status in post-NAC residual tumors. Retesting HER2 status may be particularly important for evaluating post-NAC HER2-low status, in order to better assess which patients will more likely benefit from therapeutic drugs targeting HER2-low BC.

Breast reconstruction with latissimus dorsi flap: a comprehensive review and case series.

The latissimus dorsi flap (LDF) has gained popularity given its versatile nature and broad applicability in breast reconstruction. Its resurgence has been attributed to its ability to be enhanced using implant or high-volume fat grafting, rendering it a primary option for selected patients. The aim of this review is to tackle current indications and subjects of controversy regarding use of complete-autologous and implant-enhanced LDF in breast reconstruction. Also, a case-series showcasing the authors' experience with this versatile reconstructive option is presented. A search across Web of Science and PubMed MEDLINE from inception through January 3, 2023, was conducted. Articles reporting postoperative outcomes of autologous breast reconstruction with LDF were included. Regarding the case series, electronic medical records of patients who underwent total mastectomy and autologous breast reconstruction with LDF from January 2011 to December 2021 were retrospectively reviewed. Data on demographic and oncologic characteristics, and surgical characteristics and outcomes were extracted. Our review suggests that LDF is suitable for patients who lack alternative donor site, have a history of abdominoplasty or no access to microsurgery, smokers or obese. Latissimus dorsi (LD) harvesting has almost complete shoulder function recovery in the long-term. Thoracodorsal nerve division does not cause volume loss or animation deformity. Multisite multilayer fat grafting, beveling the edges of the skin paddle and fat, folding the LD muscle and plicating the paddle allow adequate projection and contour achievement. Our case-series included 234 reconstructions. Almost half of the patients had immediate fat transfer during reconstruction (51.3%). The rate of recipient site hematoma was 3.0%, seroma was 7.7%, wound disruption 32.1%, wound disruption events requiring unplanned procedures was 13.7%, and surgical site infection (SSI) was 12.4%. The LDF is reliable and safe for immediate or delayed breast reconstruction or salvage after reconstruction failure. Its versatility, reliable anatomy, easy dissection, and relative low complication rate have revived this modality as valuable opportunity for breast reconstruction in this era.

Ecophysiology and interactions of a taurine-respiring bacterium in the mouse gut.

Taurine-respiring gut bacteria produce H2S with ambivalent impact on host health. We report the isolation and ecophysiological characterization of a taurine-respiring mouse gut bacterium. Taurinivorans muris strain LT0009 represents a new widespread species that differs from the human gut sulfidogen Bilophila wadsworthia in its sulfur metabolism pathways and host distribution. T. muris specializes in taurine respiration in vivo, seemingly unaffected by mouse diet and genotype, but is dependent on other bacteria for release of taurine from bile acids. Colonization of T. muris in gnotobiotic mice increased deconjugation of taurine-conjugated bile acids and transcriptional activity of a sulfur metabolism gene-encoding prophage in other commensals, and slightly decreased the abundance of Salmonella enterica, which showed reduced expression of galactonate catabolism genes. Re-analysis of metagenome data from a previous study further suggested that T. muris can contribute to protection against pathogens by the commensal mouse gut microbiota. Together, we show the realized physiological niche of a key murine gut sulfidogen and its interactions with selected gut microbiota members.

A Systematic Review of Breast Implant-Associated Squamous Cell Carcinoma.

Breast augmentation is considered safe, but rare cases of breast implant-associated squamous cell carcinoma (BIA-SCC) have been reported. This study aimed to systematically review published cases of BIA-SCC, providing valuable clinical data. The review included 14 articles and 18 cases of BIA-SCC. An increasing trend in reported BIA-SCC cases was observed, with four cases in the 1990s and 14 cases since 2010. The mean age of affected patients was 56 years, and symptoms typically appeared around 21 years after breast augmentation. Silicone implants used in cosmetic procedures were most commonly associated with BIA-SCC. Implant removal was necessary in all cases, and some patients required a mastectomy. Treatment approaches varied, with the selective use of chemotherapy and/or radiotherapy. The estimated 6-month mortality rate was 11.1%, while the 12-month mortality rate was 23.8%. The estimated 6-month mortality rate should be cautiously interpreted due to the limited sample size. It appears lower than the rate reported by the American Society of Plastic Surgeons, without clear reasons for this discrepancy. This study highlights the importance of enhanced monitoring and information sharing to improve detection and management of BIA-SCC. Healthcare providers should maintain vigilance during the long-term follow-up of breast augmentation patients.

Financial Toxicity Monitoring in a Randomized Controlled Trial of Patient-Reported Outcomes During Cancer Treatment (Alliance AFT-39).

PURPOSE: Financial toxicity (FT) affects 20% of cancer survivors and is associated with poor clinical outcomes. No large-scale programs have been implemented to mitigate FT. We evaluated the effect of monthly FT screening as part of a larger patient-reported outcomes (PROs) digital monitoring intervention. METHODS: PRO-TECT (AFT-39) is a cluster-randomized trial of patients undergoing systemic therapy for metastatic cancer. Practices were randomly assigned 1:1 to digital symptom monitoring (PRO practices) or usual care (control practices). Digital monitoring consisted of between-visit online or automated telephone patient surveys about symptoms, functioning, and FT (single-item screening question from Functional Assessment of Chronic Illness Therapy-COmprehensive Score for financial Toxicity) for up to 1 year, with automated alerts sent to practice nurses for concerning survey scores. Clinical team actions in response to alerts were not mandated. The primary outcome of this planned secondary analysis was development or worsening of financial difficulties, assessed via the European Organisation for Research and Treatment of Cancer QLQ-C30 financial difficulties measure, at any time compared with baseline. A randomly selected subset of patients and nurses were interviewed about their experiences with the intervention. RESULTS: One thousand one hundred ninety-one patients were enrolled (593 PRO; 598 control) at 52 US community oncology practices. Overall, 30.2% of patients treated at practices that received the FT screening intervention developed, or experienced worsening of, financial difficulties, compared with 39.0% treated at control practices (P = .004). Patients and nurses interviewed stated that FT screening identified patients for financial counseling who otherwise would be reluctant to seek, or unaware of the availability of, assistance. CONCLUSION: In this report of a secondary outcome from a randomized clinical trial, FT screening as part of routine digital patient monitoring with PROs reduced the development, or worsening, of financial difficulties among patients undergoing systemic cancer therapy.

Bacteriophages targeting protective commensals impair resistance against Salmonella Typhimurium infection in gnotobiotic mice.

Gut microbial communities protect the host against a variety of major human gastrointestinal pathogens. Bacteriophages (phages) are ubiquitous in nature and frequently ingested via food and drinking water. Moreover, they are an attractive tool for microbiome engineering due to the lack of known serious adverse effects on the host. However, the functional role of phages within the gastrointestinal microbiome remain poorly understood. Here, we investigated the effects of microbiota-directed phages on infection with the human enteric pathogen Salmonella enterica serovar Typhimurium (S. Tm), using a gnotobiotic mouse model (OMM14) for colonization resistance (CR). We show, that phage cocktails targeting Escherichia coli and Enterococcus faecalis acted in a strain-specific manner. They transiently reduced the population density of their respective target before establishing coexistence for up to 9 days. Infection susceptibility to S. Tm was markedly increased at an early time point after challenge with both phage cocktails. Surprisingly, OMM14 mice were also susceptible 7 days after a single phage inoculation, when the targeted bacterial populations were back to pre-phage administration density. Concluding, our work shows that phages that dynamically modulate the density of protective members of the gut microbiota can provide opportunities for invasion of bacterial pathogens, in particular at early time points after phage application. This suggests, that phages targeting protective members of the microbiota may increase the risk for Salmonella infection.

Nutritional and host environments determine community ecology and keystone species in a synthetic gut bacterial community.

A challenging task to understand health and disease-related microbiome signatures is to move beyond descriptive community-level profiling towards disentangling microbial interaction networks. Using a synthetic gut bacterial community, we aimed to study the role of individual members in community assembly, identify putative keystone species and test their influence across different environments. Single-species dropout experiments reveal that bacterial strain relationships strongly vary not only in different regions of the murine gut, but also across several standard culture media. Mechanisms involved in environment-dependent keystone functions in vitro include exclusive access to polysaccharides as well as bacteriocin production. Further, Bacteroides caecimuris and Blautia coccoides are found to play keystone roles in gnotobiotic mice by impacting community composition, the metabolic landscape and inflammatory responses. In summary, the presented study highlights the strong interdependency between bacterial community ecology and the biotic and abiotic environment. These results question the concept of universally valid keystone species in the gastrointestinal ecosystem and underline the context-dependency of both, keystone functions and bacterial interaction networks.

Predictors for Prolonged TE-to-Implant Exchange During Implant-Based Breast Reconstruction: A Single Institution Experience.

BACKGROUND: There is limited evidence regarding the factors causing a prolonged time for tissue expander (TE) exchange into a definitive implant using two-stage implant-based breast reconstruction (IBBR). This study aimed to review our experience with IBBR, focusing on the time for TE-to-implant exchange and determining which factors cause a prolonged time for exchange. METHODS: A retrospective review was performed to include women undergoing immediate two-stage IBBR with TEs after total mastectomy between January 2011 and May 2021. Reconstructions with irradiated TEs were excluded. Cases that had a prolonged time for TE-to-implant exchange were defined as those undergoing exchange longer than 232 days, which corresponds to the 75th percentile of the overall study group. RESULTS: We included 442 reconstructions in our analysis. The median age for our series was 51 years and the median body mass index was 26.43-kg/m2. The median time for TE-to-implant exchange was 155 days [IQR, 107-232]. Cases that had a prolonged time for TE-to-implant exchange were defined as those undergoing exchange on postoperative day 232 or afterward. Diabetes (OR 4.05, p = 0.006), neoadjuvant chemotherapy (OR 2.76, p = 0.006), an increased length of stay (OR 1.54, p = 0.013), and a lengthier time to complete outpatient expansions (OR 1.018, p < 0.001) were independently associated with a prolonged time for exchange. CONCLUSION: As evident from our analysis, the time for exchange is highly heterogeneous among patients. Although several factors affect the timing for TE-to-implant exchange, efforts must be directed to finalize outpatient expansions as soon as possible to expedite the transition into a definitive implant. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .