Carbon savings associated with changing surgical trends in total knee arthroplasty in England: a retrospective observational study using administrative data.

BACKGROUND: Best practice pathways for common surgical procedures, including total knee arthroplasty (TKA), have the potential to improve patient outcomes and reduce carbon emissions. We aimed to estimate the reduction in carbon emissions due to changing trends in the care of patients undergoing TKA in England. METHODS: This was a retrospective analysis of Hospital Episode Statistics data from 1 April 2013 to 31 March 2022 on adults undergoing elective primary TKA in England. The carbon footprint for each patient was calculated using carbon factors for multiple steps in the pathway, including ipsilateral knee arthroscopies in the year preceding the TKA, outpatient attendances, the index TKA, revisions of the TKA performed within 180 days of the index procedure, length of hospital stay and emergency readmissions. RESULTS: A total of 648,861 TKA operations were identified. Over the study period, the median length of stay reduced from four to three days, the proportion of patients undergoing ipsilateral knee arthroscopies performed within a year before TKA surgery fell from 5.9% to 0.5% and the number of early revisions and emergency readmissions also fell. The per-patient carbon footprint reduced from 378.8kgCO2e to 295.2kgCO2e over this time. If all the study patients had the same carbon footprint as the average patient in 2021/2022, 32.4kilotons CO2e would have been saved, enough to power 29,509 UK homes for one year. CONCLUSIONS: Practices that were introduced primarily to improve patient outcomes can contribute to a reduction in the carbon footprint.

Outcomes for Children With Vascular Ring Repair Using a Simple Surgical Approach.

INTRODUCTION: Vascular Rings (VRs) are congenital malformations of the aortic arch that can compress the trachea and esophagus producing symptoms. Approximately, 5%-10% of patients experience persistent symptoms postrepair and 9% require reintervention. There are various approaches to repair-simple ligation and division of the ring or more complex procedures. Our objective was to describe outcomes for VR repair using a "simple" surgical approach. METHODS: We identified patients who underwent VR repair from 2012 to 2022 at our institution. Clinical and surgical data, demographics, intraoperative, and postoperative outcomes were extracted from their electronic medical records. Outcomes were analyzed and regression analysis was used to identify risk factors for residual symptoms after repair. RESULTS: Ninety three patients with VR repair were included. Prevalence of symptoms were reduced following surgery (80% preoperative versus 13% postoperative, P 0.03). Tracheomalacia also decreased from 16% to 7% postrepair. No deaths were reported in our cohort and 2% of our patients required reintervention. Multivariable regression analysis showed that preoperative tracheomalacia was associated with having persistent symptoms after VR repair (odds ratio 6.2, 95% CI 1.02-37.6). CONCLUSIONS: Our institutional experience using a simple surgical approach showed a significant decrease in symptoms, a very low reintervention rate and no mortality. Preoperative tracheomalacia can be a risk factor for persistent symptoms postrepair. We believe a simple surgical approach for children with complete VR repair can be effective in relieving symptoms.

Standardization of the Norwood Procedure Improves Outcomes in a Medium-Sized Volume Center.

The Norwood operation has become common practice to palliate patients with hypoplastic left heart structures. Surgical technique and postoperative care have improved; yet, there remains significant attrition prior to stage II palliation. The objective of this study is to report outcomes before and after standardizing our approach to the Norwood operation. Patients who underwent the Norwood operation at Children's of Alabama were identified, those who underwent hybrid palliation operations were excluded. Pre- (2015-2020) and post- (2020-January 2023) standardization groups were compared and outcomes analyzed. Ninety-one patients were included (pre-standardization 44 (48.3%) and 47 (51.7%) post-standardization). There were no differences in baseline and intraoperative characteristics at Norwood between the pre- and post-standardization groups. Compared with pre-standardization, post-standardization was associated with decreased time to extubation (OR 0.87, 95%CI 0.79-0.96), inotrope duration (OR 0.92, 95%CI 0.86-0.98) and hospital length of stay (OR 0.98, 95%CI 0.96-0.99). There was a trend toward decreased cardiac arrest, reintervention rates, and interstage mortality for the post-standardization group. A standardized approach to complex neonatal cardiac operations such as the Norwood procedure may improve morbidity and decrease hospital resource utilization. We recommend establishing protocols at an institutional level to optimize outcomes in such high-risk patient populations.

Surgical pulmonary arterioplasty at bidirectional cavopulmonary anastomosis leads to favorable pulmonary hemodynamics at final stage palliation.

Objective: Pulmonary arterioplasty (PA plasty) at bidirectional cavopulmonary anastomosis (BDCA) is associated with increased morbidity, but outcomes to final stage palliation are unknown. We sought to determine the influence of PA plasty on pulmonary artery growth and hemodyamics at Fontan. Methods: We retrospectively reviewed clinical data and outcomes for BDCA patients from 2006 to 2018. PA plasty was categorized by extent (type 1-4), as previously described. Outcomes included pulmonary artery reintervention and mortality before final palliation. Results: Five hundred eighty-eight patients underwent BDCA. One hundred seventy-nine patients (30.0%) underwent concomitant PA plasty. Five hundred seventy (97%) patients (169 [94%] PA plasty) survived to BDCA discharge. One hundred forty out of 570 survivors (25%) required PA/Glenn reintervention before final stage palliation (59 out of 169 [35%]) PA plasty; 81 out of 401 (20%) non-PA plasty; P < .001). Twelve-, 24-, and 36-month freedom from reintervention after BDCA was 80% (95% CI, 74-86%), 75% (95% CI, 69-82%), and 64% (95% CI, 57-73%) for PA plasty, and 95% (95% CI, 93-97%), 91% (95% CI, 88-94%), and 81% (95% CI, 76-85%) for non-PA plasty (P < .001). Prefinal stage mortality was 37 (6.3%) (14 out of 169 PA plasty; 23 out of 401 non-PA plasty; P = .4). Five hundred four (144 PA plasty and 360 non-PA plasty) patients reached final stage palliation (471 Fontan, 26 1.5-ventricle, and 7 2-ventricular repair). Pre-Fontan PA pressure and pulmonary vascular resistance were 10 mm Hg (range, 9-12 mm Hg) and 1.6 mm Hg (range, 1.3-1.9 mm Hg) in PA plasty and 10 mm Hg (range, 8-12 mm Hg) and 1.5 mm Hg (range, 1.3-1.9 mm Hg) in non-PA plasty patients, respectively (P = .29, .6). Fontan hospital mortality, length of stay, and morbidity were similar. Conclusions: PA plasty at BDCA does not confer additional mortality risk leading to final palliation. Despite increased pulmonary artery reintervention, there was reliable pulmonary artery growth and favorable pulmonary hemodynamics at final stage palliation.

Association of day-case rates with post COVID-19 recovery of elective laparoscopic cholecystectomy activity across England.

INTRODUCTION: The aim of this study was to investigate the safety of day-case laparoscopic cholecystectomy, and the association between day-case rates and, post the COVID-19 pandemic, recovery of activity to prepandemic levels for integrated care boards (ICBs) in England. METHODS: This was a retrospective observational study of the Hospital Episodes Statistics (HES) data set. Elective laparoscopic cholecystectomies for the period 1 January 2019 to 31 December 2022 were identified. Activity levels for 2022 were compared with those for the whole of 2019 (baseline). Day-case activity was identified where the length of stay recorded in the HES was zero days. RESULTS: Data were available for 184,252 patients across the 42 ICBs in England, of which 120,408 (65.3%) were day-case procedures. By December 2022, activity levels for the whole of England had returned to 88.2% of prepandemic levels. The South West region stood out as having recovered activity levels to the greatest extent, with activity at 97.3% of prepandemic levels during 2022. The South West also had the highest postpandemic day-case rate at 74.9% of all patients seen as a day-case during 2022; this compares with an England average of 65.3%. At an ICB level, there was a significant correlation between day-case rates and postpandemic activity levels (r = 0.362, p = 0.019). There was no strong or consistent evidence that day-case surgery had poorer patient outcomes than inpatient surgery. CONCLUSIONS: Recovery of elective laparoscopic cholecystectomy activity has been better in South West England than in other regions. Increasing day-case rates may be important if ICBs in other regions are to increase activity levels up to and beyond prepandemic levels.

Factors associated with conversion from day-case to in-patient elective inguinal hernia repair surgery across England: an observational study using administrative data.

PURPOSE: Elective primary inguinal hernia repair surgery is increasingly being conducted as a day-case procedure. However, some patients planned for day-case surgery have to stay in hospital for at least one night. The aim of this study was to identify the factors associated with conversion from day-case to in-patient management for elective inguinal hernia repair surgery. METHODS: This was an exploratory retrospective analysis of observational data from the Hospital Episode Statistics dataset for England. All patients aged ≥ 17 years undergoing a first elective inguinal hernia repair between 1st April 2014 and 31st March 2022 that was planned as day-case surgery were identified. The exposure of interest was discharged on the day of admission (day-case) or requiring overnight stay. The primary outcome of interest was 30-day emergency readmission with an overnight stay. For reporting, providers were aggregated to an Integrated Care Board (ICB) level. RESULTS: A total of 351,528 planned day-case elective primary inguinal hernia repairs were identified over the eight-year study period. Of these, 45,305 (12.9%) stayed in hospital for at least one night and were classed as day-case to in-patient stay conversions. Patients who converted to in-patient stay were older, had more comorbidities, and were more likely to have bilateral surgery and be operated on by a low-annual volume surgeon. Post-procedural complications were strongly associated with conversion. Across the 42 ICBs in England, model-adjusted conversion rates varied from 3.3% to 21.3%. CONCLUSIONS: There was considerable variation in conversion to in-patient stay rates for inguinal hernia repair across ICBs in England. Our findings should help surgical teams to better identify patients suitable for day-case inguinal hernia repair and plan discharge services more effectively. This should help to reduce the variation in conversion rates.

Hybrid Thrombectomy and Central Extracorporeal Membrane Oxygenation for Massive Pulmonary Embolism in a Child.

We describe a hybrid thrombectomy and central extracorporeal membrane oxygenation for a child in cardiogenic shock due to a massive pulmonary embolism.

Unwarranted variation and the goal of net zero for the NHS in England: exploring the link between efficiency working, patient outcomes and carbon footprint.

In 2020 the NHS in England set a target of reaching net zero carbon emissions by 2040. Progress has already been made towards this goal, with substantial reductions in the use of environmentally harmful anaesthetic gases, such as desflurane, in recent years. Where an effective replacement already exists, changing practice to use low carbon alternatives is relatively easy to achieve, but much greater challenges lie ahead. The Getting It Right First Time (GIRFT) programme is a clinically-led, data-driven clinical improvement initiative with a focus on reducing unwarranted variation in clinical practice and patient outcomes. Reducing unwarranted variation can improve patient care and service efficiency, and can also support the drive to net zero. In this article we set out what the GIRFT programme is doing to support sustainable healthcare in England, why it is uniquely positioned to support this goal and what the future challenges, barriers, enablers and opportunities are likely to be in the drive to net zero.

Loss of the mitochondrial citrate carrier, Slc25a1/CIC disrupts embryogenesis via 2-Hydroxyglutarate.

Biallelic germline mutations in the SLC25A1 gene lead to combined D/L-2-hydroxyglutaric aciduria (D/L-2HGA), a fatal systemic disease uniquely characterized by the accumulation of both enantiomers of 2-hydroxyglutaric acid (2HG). How SLC25A1 deficiency contributes to D/L-2HGA and the role played by 2HG is unclear and no therapy exists. Both enantiomers act as oncometabolites, but their activities in normal tissues remain understudied. Here we show that mice lacking both SLC25A1 alleles exhibit developmental abnormalities that mirror human D/L-2HGA. SLC25A1 deficient cells undergo premature senescence, suggesting that loss of proliferative capacity underlies the pathogenesis of D/L-2HGA. Remarkably, D- and L-2HG directly induce senescence and treatment of zebrafish embryos with the combination of D- and L-2HG phenocopies SLC25A1 loss, leading to developmental abnormalities in an additive fashion relative to either enantiomer alone. Metabolic analyses further demonstrate that cells with dysfunctional SLC25A1 undergo mitochondrial respiratory deficit and remodeling of the metabolism and we propose several strategies to correct these defects. These results reveal for the first time pathogenic and growth suppressive activities of 2HG in the context of SLC25A1 deficiency and suggest that targeting the 2HG pathway may be beneficial for the treatment of D/L-2HGA.

Day-case and in-patient elective inguinal hernia repair surgery across England: an observational study of variation and outcomes.

PURPOSE: Elective primary inguinal hernia repair surgery is increasingly being conducted as a day-case procedure. However, in England there is evidence of wide variation in day-case rates across hospitals. Reducing the extent of this variation has the potential to support more efficient use of resources (e.g., clinician time, hospital beds) and help the recovery of elective surgical activity following the COVID-19 pandemic. The aims of this study were to explore the extent of variation in day-case rates across healthcare providers in England and to evaluate the safety of day-case elective primary inguinal hernia repair surgery. METHODS: This was an exploratory, retrospective analysis of observational data from the Hospital Episode Statistics data set for England. All patients aged ≥ 17 years undergoing a first elective inguinal hernia repair between 1st April 2014 and 31st March 2022 were identified. The exposure of interest was day-case or in-patient stay, and the primary outcome of interest was 30-day emergency readmission with an overnight stay. For reporting, providers were aggregated to an Integrated Care Board (ICB) level. RESULTS: A total of 413,059 elective primary inguinal hernia repairs were identified over the 8-year study period. Of these, 326,833 (79.1%) were day-case procedures. During the most recent financial year (2021-22), the highest day-case rate for an ICB was 93.8% and the lowest 66.1%. After adjusting for covariates, day-case surgery was associated with significantly lower rates of 30-day emergency readmission (odds ratio (OR) 0.61, 95% confidence interval (CI) 0.58-0.64, p < 0.001) and for the secondary outcomes 180-day mortality and haemorrhage, infection and pain at 30-day post-discharge. Rates of 30-day emergency readmission were significantly lower in ICBs with high rates of day-case surgery (OR 0.84, 95% CI 0.74-0.96, p < 0.001) than in ICBs with low rates of day-case surgery, although rates of post-procedural haemorrhage within 30 days of discharge were significantly higher in trusts with high day-case rates (OR 1.20, 95% CI 1.04-1.40, p = 0.015). CONCLUSIONS: For the outcomes studied, we found no consistent evidence that day-case elective inguinal hernia repair was unsafe for selected patients. Currently, there is substantial variation between ICBs in terms of delivering day-case surgery. Reducing this variability may help address the current pressures on the NHS in elective surgery.

ß-hydroxybutyrate is a metabolic regulator of proteostasis in the aged and Alzheimer disease brain.

Loss of proteostasis is a hallmark of aging and Alzheimer disease (AD). Here, we identify ß-hydroxybutyrate (ßHB), a ketone body, as a regulator of protein solubility in the aging brain. ßHB is a small molecule metabolite which primarily provides an oxidative substrate for ATP during hypoglycemic conditions, and also regulates other cellular processes through covalent and noncovalent protein interactions. We demonstrate ßHB-induced protein insolubility across in vitro, ex vivo, and in vivo mouse systems. This activity is shared by select structurally similar metabolites, is not dependent on covalent protein modification, pH, or solute load, and is observable in mouse brain in vivo after delivery of a ketone ester. Furthermore, this phenotype is selective for pathological proteins such as amyloid-ß, and exogenous ßHB ameliorates pathology in nematode models of amyloid-ß aggregation toxicity. We have generated a comprehensive atlas of the ßHB-induced protein insolublome ex vivo and in vivo using mass spectrometry proteomics, and have identified common protein domains within ßHB target sequences. Finally, we show enrichment of neurodegeneration-related proteins among ßHB targets and the clearance of these targets from mouse brain, likely via ßHB-induced autophagy. Overall, these data indicate a new metabolically regulated mechanism of proteostasis relevant to aging and AD.

Hybrid Norwood for Hypoplastic Left Heart Syndrome With Rare Aortic Arch Anatomy.

We describe the hybrid Norwood as first-stage palliation for a patient with hypoplastic left heart syndrome, right aortic arch, right descending aorta, bilateral ductus arteriosus, and left innominate artery arising from the left ductus.

Surgical Experience With Nine Cases of Obstructed Right Aortic Arch.

BACKGROUND: Right-sided aortic arch obstruction is an extremely rare congenital anomaly. A variety of surgical approaches have been described. This study reviews our institutional experience over the last 30 years. METHODS: Our surgical database at the University of Alabama at Birmingham and Children's Hospital of Alabama from 1992 to 2022 was reviewed to include all patients who underwent surgical repair for right-sided aortic arch obstruction. RESULTS: A total of nine patients underwent surgical repair for right-sided aortic arch obstruction. Surgical approach was via thoracotomy (n = 2, 22%), sternotomy (n = 5, 56%), or combined (n = 2, 22%). Primary extended end-to-end anastomosis was utilized for patients with discrete coarctation (n = 1, 11%), reverse subclavian flap for coarctation with associated distal arch hypoplasia (n = 2, 22%), GORE-TEX® tube graft for circumflex aorta (n = 1, 11%), and aortic arch advancement (n = 5, 56%) with or without patch augmentation for those with an interrupted or severely hypoplastic aortic arch. Reintervention was required in one patient (11%) for recoarctation. All patients were discharged in good condition. There was no hospital mortality and at 10.5 years (mean) follow-up there was one late death. CONCLUSION: Right aortic arch obstruction is a rare entity. Surgical approach should be tailored to the anatomy and associated intracardiac defects. Preoperative imaging with a CT angiogram is useful for operative planning. Sternotomy with single-stage primary repair is safe, effective, and our preferred surgical approach for patients with right aortic arch obstruction and associated intracardiac pathology.

A high-density 3-dimensional culture model of human glioblastoma for rapid screening of therapeutic resistance.

Glioblastoma is among the most lethal cancers, with no known cure. A multitude of therapeutics are being developed or in clinical trials, but currently there are no ways to predict which patient may benefit the most from which drug. Assays that allow prediction of the tumor's response to anti-cancer drugs may improve clinical decision-making. Here, we present a high-density 3D primary cell culture model for short-term testing from resected glioblastoma tissue that is set up on the day of surgery, established within 7 days and viable for at least 3 weeks. High-density 3D cultures contain tumor and host cells, including microglia, and retain key histopathological characteristics of their parent tumors, including proliferative activity, expression of the marker GFAP, and presence of giant cells. This provides a proof-of-concept that 3D primary cultures may be useful to model tumor heterogeneity. Importantly, we show that high-density 3D cultures can be used to test chemotherapy response within a 2-3-week timeframe and are predictive of patient response to Temozolomide therapy. Thus, primary high-density 3D cultures could be a useful tool for brain cancer research and prediction of therapeutic resistance.

Identifying drivers of breast cancer metastasis in progressively invasive subpopulations of zebrafish-xenografted MDA-MB-231.

Cancer metastasis is the primary cause of the high mortality rate among human cancers. Efforts to identify therapeutic agents targeting cancer metastasis frequently fail to demonstrate efficacy in clinical trials despite strong preclinical evidence. Until recently, most preclinical studies used mouse models to evaluate anti-metastatic agents. Mouse models are time-consuming and expensive. In addition, an important drawback is that mouse models inadequately model the early stages of metastasis which plausibly leads to the poor correlation with clinical outcomes.Here, we report an in vivo model based on xenografted zebrafish embryos where we select for progressively invasive subpopulations of MDA-MB-231 breast cancer cells. A subpopulation analogous to circulating tumor cells found in human cancers was selected by injection of MDA-MB-231 cells into the yolk sacs of 2 days post-fertilized zebrafish embryos and selecting cells that migrated to the tail. The selected subpopulation derived from MDA-MB-231 cells were increasingly invasive in zebrafish. Isolation of these subpopulations and propagation in vitro revealed morphological changes consistent with activation of an epithelial-mesenchymal transition program. Differential gene analysis and knockdown of genes identified gene-candidates (DDIT4, MT1X, CTSD, and SERPINE1) as potential targets for anti-metastasis therapeutics. Furthermore, RNA-splicing analysis reinforced the importance of BIRC5 splice variants in breast cancer metastasis. This is the first report using zebrafish to isolate and expand progressively invasive populations of human cancer cells. The model has potential applications in understanding the metastatic process, identification and/or development of therapeutics that specifically target metastatic cells and formulating personalized treatment strategies for individual cancer patients.

Social Participation's Association with Falls and Frailty in Malaysia: A Cross-Sectional Study.

BACKGROUND: The global population is ageing rapidly, with the most dramatic increases in developing countries like Malaysia. Older people are at increased risk of multimorbidity, frailty and falls. OBJECTIVES: In this study we aimed to determine the relationship between social participation, frailty and falls in Malaysia. DESIGN, SETTING, AND PARTICIPANTS: This was a cross-sectional study of individuals aged 55 years and above selected from the electoral rolls of three Klang Valley parliamentary constituencies through stratified random sampling. They were invited to take part in a questionnaire and physical assessment as part of the Malaysian Elders Longitudinal Research (MELoR) study. MEASUREMENTS: Fallers were individuals who had fallen in the previous year. Frailty was defined as meeting ≥3 of: low body mass index, reduced cognition, low physical activity, low hand-grip strength, and slow walking speed. Social participation was determined from employment status, social network, and community activity. Binomial logistic regression multivariant analysis was performed to identify links between the measures of social participation and falls and frailty. RESULTS: The mean age of the 1383 participants was 68.5 years, with 57.1% female. Within the population, 22.9% were fallers and 9.3% were frail. Social isolation (OR= 2.119; 95% CI=1.351-3.324), and non-engagement in community activities (OR=2.548; 95% CI=1.107-5.865) were associated with increased frailty. Falls increased with social isolation (OR=1.327; 95% CI=1.004-1.754). CONCLUSIONS: Previous studies have shown social participation to be linked to frailty and falls risk, and social isolation to be a predictor of falls. In this study frailty was associated with all three social participation measures and history of falls was associated with social isolation.

Safety of day-case paediatric tonsillectomy in England: an analysis of administrative data for the Getting It Right First Time programme.

We used the Hospital Episodes Statistics database to investigate unwarranted variation in the rates Trusts discharged children the same day after scheduled tonsillectomy and associations with adverse postoperative outcomes. We included children aged 2-18 years who underwent tonsillectomy between 1 April 2014 and 31 March 2019. We stratified analyses by category of Trust, non-specialist or specialist, defined as without or with paediatric critical care facilities, respectively. We adjusted analyses for age, sex, year of surgery and aspects of presentation and procedure type. Of 101,180 children who underwent tonsillectomy at non-specialist Trusts, 62,926 (62%) were discharged the same day, compared with 24,138/48,755 (50%) at specialist Trusts. The adjusted proportion of children discharged the same day as tonsillectomy ranged from 5% to 100% at non-specialist Trusts and 9% to 88% at specialist Trusts. Same-day discharge was not independently associated with an increased rate of 30-day emergency re-admission at non-specialist Trusts but was associated with a modest rate increase at specialist Trusts; adjusted probability 8.0% vs 7.7%, odds ratio (95%CI) 1.14 (1.05-1.24). Rates of adverse postoperative outcomes were similar for Trusts that discharged >70% children the same day as tonsillectomy compared with Trusts that discharged <50% children the same day, for both non-specialist and specialist Trust categories. We found no consistent evidence that day-case tonsillectomy is associated with poorer outcomes. All Trusts, but particularly specialist centres, should explore reasons for low day-case rates and should aim for rates >70%.

WNK1 Enhances Migration and Invasion in Breast Cancer Models.

Metastasis is the major cause of mortality in patients with breast cancer. Many signaling pathways have been linked to cancer invasiveness, but blockade of few protein components has succeeded in reducing metastasis. Thus, identification of proteins contributing to invasion that are manipulable by small molecules may be valuable in inhibiting spread of the disease. The protein kinase with no lysine (K) 1 (WNK1) has been suggested to induce migration of cells representing a range of cancer types. Analyses of mouse models and patient data have implicated WNK1 as one of a handful of genes uniquely linked to invasive breast cancer. Here, we present evidence that inhibition of WNK1 slows breast cancer metastasis. We show that depletion or inhibition of WNK1 reduces migration of several breast cancer cell lines in wound healing assays and decreases invasion in collagen matrices. Furthermore, WNK1 depletion suppresses expression of AXL, a tyrosine kinase implicated in metastasis. Finally, we demonstrate that WNK inhibition in mice attenuates tumor progression and metastatic burden. These data showing reduced migration, invasion, and metastasis upon WNK1 depletion in multiple breast cancer models suggest that WNK1 contributes to the metastatic phenotype, and that WNK1 inhibition may offer a therapeutic avenue for attenuating progression of invasive breast cancers.

An AIB1 Isoform Alters Enhancer Access and Enables Progression of Early-Stage Triple-Negative Breast Cancer.

AIB1Δ4 is an N-terminally truncated isoform of the oncogene amplified in breast cancer 1 (AIB1) with increased expression in high-grade human ductal carcinoma in situ (DCIS). However, the role of AIB1Δ4 in DCIS malignant progression has not been defined. Here we CRISPR-engineered RNA splice junctions to produce normal and early-stage DCIS breast epithelial cells that expressed only AIB1Δ4. These cells showed enhanced motility and invasion in 3D cell culture. In zebrafish, AIB1Δ4-expressing cells enabled invasion of parental cells when present in a mixed population. In mouse xenografts, a subpopulation of AIB1Δ4 cells mixed with parental cells enhanced tumor growth, recurrence, and lung metastasis. AIB1Δ4 chromatin immunoprecipitation sequencing revealed enhanced binding to regions including peroxisome proliferator-activated receptor (PPAR) and glucocorticoid receptor (GR) genomic recognition sites. H3K27ac and H3K4me1 genomic engagement patterns revealed selective activation of breast cancer-specific enhancer sites by AIB1Δ4. AIB1Δ4 cells displayed upregulated inflammatory response genes and downregulated PPAR signaling gene expression patterns. In the presence of AIB1Δ4 enabler cells, parental cells increased NF-κB and WNT signaling. Cellular cross-talk was inhibited by the PPARγ agonist efatutazone but was enhanced by treatment with the GR agonist dexamethasone. In conclusion, expression of the AIB1Δ4-selective cistrome in a small subpopulation of cells triggers an "enabler" phenotype hallmarked by an invasive transcriptional program and collective malignant progression in a heterogeneous tumor population. SIGNIFICANCE: A minor subset of early-stage breast cancer cells expressing AIB1Δ4 enables bulk tumor cells to become invasive, suggesting that selective eradication of this population could impair breast cancer metastasis.