Hepatic thermal injury promotes colorectal cancer engraftment in C57/black 6 mice.

Treatment options for liver metastases (primarily colorectal cancer) are limited by high recurrence rates and persistent tumor progression. Surgical approaches to management of these metastases typically use heat energy including electrocautery, argon beam coagulation, thermal ablation of surgical margins for hemostasis, and preemptive thermal ablation to prevent bleeding or to effect tumor destruction. Based on high rates of local recurrence, these studies assess whether local effects of hepatic thermal injury (HTI) might contribute to poor outcomes by promoting a hepatic microenvironment favorable for tumor engraftment or progression due to induction of procancer cytokines and deleterious immune infiltrates at the site of thermal injury. To test this hypothesis, an immunocompetent mouse model was developed wherein HTI was combined with concomitant intrasplenic injection of cells from a well-characterized MC38 colon carcinoma cell line. In this model, HTI resulted in a significant increase in engraftment and progression of MC38 tumors at the site of thermal injury. Furthermore, there were local increases in expression of messenger ribonucleic acid (mRNA) for hypoxia-inducible factor-1α (HIF1α), arginase-1, and vascular endothelial growth factor α and activation changes in recruited macrophages at the HTI site but not in untreated liver tissue. Inhibition of HIF1α following HTI significantly reduced discreet hepatic tumor development (P = 0.03). Taken together, these findings demonstrate that HTI creates a favorable local environment that is associated with protumorigenic activation of macrophages and implantation of circulating tumors. Discrete targeting of HIF1α signaling or inhibiting macrophages offers potential strategies for improving the outcome of surgical management of hepatic metastases where HTI is used.

Implementation of Minimally Invasive Pancreaticoduodenectomy at Low and High-Volume Centers.

BACKGROUND: There is a need to better define the safety of implementing the use of minimally invasive pancreaticoduodenectomy (MIPD) in order to provide evidence for safe application. The objective of this study was to evaluate the mortality associated with the implementation of MIPD across low and high-volume facilities using the National Cancer Database (NCDB). METHODS: Patients in the NCDB with pancreatic cancer diagnosed from 2010-2016 undergoing MIPD were selected. Cumulative MIPD volume for each facility was calculated from the number of MIPD cases performed each year prior to and including the year of a patient's operation. A random effects logistic regression model was used to examine the adjusted association between log-transformed cumulative MIPD volume and 90-day mortality. RESULTS: After controlling for patient, tumor and facility-related variables, there was decreased 90-day mortality as the cumulative MIPD volume increased (OR 0.81; 95% CI 0.69-0.95; P = 0.009). Average annual open pancreaticoduodenectomy (PD) volume was independently protective throughout the implementation phase (OR 0.98; 95% CI 0.97-0.99; P = 0.049). This equates to an average predicted probability of 90-day mortality for the first 5 cumulative MIPD cases of 7.51% at a low-volume facility (5 open PDs per year) versus 4.39% at a high-volume facility (50 open PDs per year). CONCLUSIONS: Using the NCDB, 90-day mortality following MIPD decreased with higher cumulative facility MIPD case volume. Although higher cumulative MIPD case volume was associated with reduced 90-day mortality at both low and high-volume facilities, the higher mortality during the implementation of MIPD is magnified at low-volume facilities. This retrospective analysis demonstrates that MIPD can be safely implemented with low mortality at facilities with high-volume open PD programs.

Statins Inhibit Toll-Like Receptor 4-Mediated Growth of Human Esophageal Adenocarcinoma Cells.

BACKGROUND: Esophageal adenocarcinoma (EAC) is a lethal malignancy with poor prognosis. Pharmacologic inhibitors of inflammation, such as statins, have been shown to decrease the risk of development and progression of esophageal cancer, but the mechanism of this protection is unclear. The objective of this study was to elucidate the effect of statins on toll-like receptor 4-mediated-proliferation of human EAC cells and identify the mechanism responsible for these observed effects. METHODS: Human EAC cells (OE33 and FLO1) were treated with simvastatin or atorvastatin for increasing doses and time periods. Toll-like receptor 4 (TLR4) expression was assessed. Cells were pretreated with statin followed by lipopolysaccharide (LPS). Cell proliferation and expression of signaling proteins were evaluated. FLO1 cells were injected into the flank of nude mice. Mice received intraperitoneal injections of simvastatin, atorvastatin, or control solution and tumor volume was measured. RESULTS: OE33 and FLO1 cells demonstrated decreased TLR4 expression after treatment with simvastatin or atorvastatin for 8 h (P < 0.05). LPS increased proliferation, whereas pretreatment with statin abolished this response (P < 0.05). Statins decreased expression and activation of LPS-induced signaling proteins, including MyD88, TRAF6, Akt, and NF-κB (P < 0.05). Mice receiving daily statin injections demonstrated smaller tumors than control mice (P < 0.001 at day 33). CONCLUSIONS: Treatment of EAC cells with simvastatin or atorvastatin decreases TLR4-mediated proliferation and in vivo tumor growth. Decreased TLR4 expression and subsequent reduction in MyD88-dependent signaling could be a mechanism by which statins act to reduce tumor growth rates.

Secretory Phospholipase A2 IIa Mediates Expression of Growth Factor Receptors in Esophageal Adenocarcinoma.

BACKGROUND: Receptor tyrosine kinases of the epidermal growth factor receptor (EGFR) family such as human epidermal receptor-2 (HER2) are involved in the development and progression of esophageal adenocarcinoma (EAC). Prior studies have demonstrated that group IIa secretory phospholipase A2 (sPLA2 IIa) can function as a ligand for the EGFR family of receptors and lead to an increase in receptor signaling. AIMS: We hypothesized that sPLA2 IIa inhibition downregulates the expression of EGFR and HER-2 in EAC and through this mechanism decreases proliferation in EAC. METHODS: Normal human esophageal epithelium, Barrett's esophagus (BE), and EAC tissue samples were assayed for baseline expression of EGFR, HER-2, and sPLA2 IIa. sPLA2 IIa was attenuated via inhibitor or lentiviral knockdown in esophageal cell lines, and cells were assayed for EGFR and HER2 expression as well as proliferation. FLO1 EAC cells were injected into the flank of nude mice. After randomization, mice received daily group IIA sPLA2 inhibitor or a control solution, and tumor volume was measured with calipers. RESULTS: sPLA2 IIa, EGFR, and HER2 expression increased across the spectrum of normal esophageal epithelium to EAC. sPLA2 IIa inhibition and knockdown decreased the expression of HER-2 and EGFR and proliferation. Mice treated with sPLA2 IIa inhibitor had smaller tumors than controls. CONCLUSIONS: sPLA2 IIa inhibition decreases EGFR and HER2 expression and lowers proliferation of human EAC. The discovery of sPLA2 IIa inhibition's ability to attenuate growth factor receptor signaling underscores the exciting potential of sPLA2 IIa inhibitors as therapeutics in the treatment of EAC.

Dextrose-Containing Carrier Solution for Hyperthermic Intraperitoneal Chemotherapy: Increased Intraoperative Hyperglycemia and Postoperative Complications.

PURPOSE: Intraoperative hyperglycemia is associated with infectious complications in general surgery patients. This study aimed to determine if the use of lactated Ringer's (LR) carrier solution during hyperthermic intraperitoneal chemotherapy (HIPEC) would lower the incidence of intraoperative hyperglycemia and improve postoperative outcomes when compared with a standard 1.5% dextrose peritoneal dialysate carrier solution. PATIENTS AND METHODS: This is a retrospective cohort study of 134 patients who underwent HIPEC at the University of Colorado. Perioperative glucose levels and outcomes were compared between patients who were perfused with 1.5% dextrose peritoneal dialysate carrier solution (n = 68) versus LR carrier solution (n = 66). RESULTS: The study population consisted of patients undergoing HIPEC for appendiceal (50%), colorectal (34%), mesothelioma (8%), and ovarian cancer (5%). Intraoperative severe hyperglycemia (glucose ≥ 180 mg/dL) was significantly more common among patients perfused with a dextrose-containing carrier solution versus those perfused with LR (88% vs. 21%; p < 0.001). Patients in the dextrose cohort had significantly more severe complications (39% vs. 12%; p = 0.034), infectious complications (35% vs. 15%; p = 0.011), and organ space infections (18% vs. 5%: p = 0.026) than the LR cohort. On multivariable analysis, dextrose-containing carrier solution was significantly associated with an increased risk of postoperative infectious complications (HR 5.16; p = 0.006). CONCLUSIONS: Intraoperative hyperglycemia is common when dextrose-containing carrier solution is used during HIPEC, and severe intraoperative hyperglycemia is strongly associated with an increased risk for infectious of complications following HIPEC. LR carrier solution should be routinely used to reduce intraoperative hyperglycemia and its associated risks.

Conversion to open surgery during minimally invasive esophagectomy portends worse short-term outcomes: an analysis of the National Cancer Database.

OBJECTIVE: The objectives were to determine factors associated with conversion to open surgery in patients with esophageal cancer who underwent minimally invasive esophagectomy (MIE, including laparo-thoracoscopic and robotic) and the impact of conversion to open surgery on patient outcomes. METHODS: We included patients from the National Cancer Database with esophageal and gastroesophageal junction cancer who underwent MIE from 2010 to 2015. Patient-, tumor-, and facility-related characteristics as well as short-term and oncologic outcomes were compared between patients who were converted to open surgery and those who underwent successful MIE without conversion to open surgery. Multivariable logistic regression models were used to analyze risk factors for conversion to open surgery from attempted MIE. RESULTS: 7306 patients underwent attempted MIE. Of these patients, 82 of 1487 (5.2%) robotic-assisted esophagectomies were converted to open, compared to 691 of 5737 (12.0%) laparo-thoracoscopic esophagectomies (p < 0.001). Conversion rates decreased significantly over the study period (ptrend = 0.010). Patient age, tumor size, and nodal involvement were independently associated with conversion. Facility minimally invasive cumulative volume and robotic approach were associated with decreased conversion rates. Patients whose MIEs were converted had increased 90-day mortality [Odds Ratio (OR) 1.49; 95% Confidence Interval (CI) 1.10, 2.02], prolonged hospital stay (OR 1.39; 95% CI 1.17, 1.66), and higher rates of unplanned readmission (OR 1.67; 95% CI 1.27, 2.20). No significant differences were found in surgical margins or number of lymph nodes harvested. CONCLUSION: Patients undergoing attempted MIE requiring conversion to open surgery had significantly worse short-term outcomes including postoperative mortality. Patient factors and hospital experience contribute to conversion rates. These findings should inform surgeons and patients considering esophagectomy for cancer.

Hepatic Ablation Promotes Colon Cancer Metastases in an Immunocompetent Murine Model.

OBJECTIVE: To determine the impact of radiofrequency (RF) and microwave (MW) energy compared to direct cautery on metatstatic colon cancer growth. BACKGROUND: Hepatic ablation with MW and RF energy creates a temperature gradient around a target site with temperatures known to create tissue injury and cell death. In contrast, direct heat application (cautery) vaporizes tissue with a higher site temperature but reduced heat gradient on surrounding tissue. We hypothesize that different energy devices create variable zones of sublethal injury that may promote tumor recurrence. To test this hypothesis we applied MW, RF, and cautery to normal murine liver with a concomitant metastatic colon cancer challenge. METHODS: C57/Bl6 mice received hepatic thermal injury with MW, RF, or cautery to create a superficial 3-mm lesion immediately after intrasplenic injection of 50K MC38 colon cancer cells. Thermal imaging recorded tissue temperature during ablation and for 10 seconds after energy cessation. Hepatic tumor location and volume was determined at day 7. RESULTS: Cautery demonstrated the highest maximum tissue temperatures (129°C) with more rapid return to baseline compared to MW or RF energy. All mice had metastasis at the ablation site. Mean tumor volume was significantly greater in the MW (95.3 mm; P = 0.007) and RF (55.7 mm; P = 0.015) than cautery (7.13 mm). There was no difference in volume between MW and RF energy (P = 0.2). CONCLUSIONS: Hepatic thermal ablation promotes colon cancer metastasis at the injury site. MV and RF energy result in greater metastatic volume than cautery. These data suggest that the method of energy delivery promotes local metastasis.

Inhibition of secretory phospholipase A2 IIa attenuates prostaglandin E2-induced invasiveness in lung adenocarcinoma.

Secretory phospholipase A2 IIa (sPLA2 IIa) catalyzes the production of multiple inflammatory mediators that influence the development of lung and other cancers. The most potent of these carcinogenic mediators is prostaglandin E2 (PGE2). We hypothesize that sPLA2 IIa inhibition modulates the production of PGE2, and sPLA2 IIa inhibition exerts its antineoplastic effects via downregulation of PGE2 production. We aim to evaluate these relationships via analysis of PGE2-mediated growth regulation pathways. A549 and H1650 lung adenocarcinoma cells were assayed for PGE2 production in the presence of sPLA2 IIa inhibitor. A549 and H1650 cells were treated with PGE2 and immune blotting was performed to assess ICAM-1 expression and STAT-3 activity. PGE2-induced ICAM-1 expression was measured via immunofluorescence. A549 and H1650 cells were treated with PGE2 in the presence of STAT3 inhibitor and assayed for ICAM-1 expression. A549 cells were treated with PGE2 in the presence ICAM-1 blocking antibody and assayed for invasion. PGE2 stimulation significantly increased the invasiveness and proliferation of lung adenocarcinoma (invasion p < 0.05, proliferation p < 0.05 A549 cells, p < 0.005 H1650 cells). sPLA2 IIa inhibition reduced PGE2 secretion (p < 0.05). PGE2 stimulation significantly upregulated the expression of cell adhesion molecule ICAM-1 and the phosphorylation of anti-apoptotic transcription factor STAT3 (p < 0.05). STAT3 inhibition attenuated ICAM-1 expression demonstrating the dependence of ICAM-1 on the STAT3 pathway (p < 0.05). ICAM-1 blockade attenuated the pro-invasive effects of PGE2 (p < 0.05). sPLA2 IIa inhibition attenuates the potent effects of PGE2-induced invasiveness. This is mediated by decreasing pro-inflammatory and invasion-promoting ICAM-1via the STAT-3 pathway. These data further describe how sPLA2 IIa inhibition mechanistically exerts its anticancer effects and support its use as an antineoplastic agent.

Outcomes After Converted Minimally Invasive to Open Esophagectomy in Patients With Esophageal Cancer.

BACKGROUND: The objective of this study was to evaluate the impact of unplanned conversion to open esophagectomy during minimally invasive esophagectomy (MIE) on postoperative morbidity and mortality for patients with esophageal cancer, as well as to evaluate the variables that influence the need for conversion. METHODS: This study was a retrospective analysis of patients with esophageal cancer who underwent open esophagectomy or MIE by either a laparothoracoscopic approach or a robotic approach from 2016 to 2018 by using the esophagectomy-specific American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database. Poisson regression models were used to analyze 30-day outcomes and risk factors for conversion to open esophagectomy during attempted MIE. RESULTS: A total of 2616 patients were identified. The overall conversion rate for MIE was 6.3%. Compared with completed MIE, patients requiring conversion to open esophagectomy had a significantly increased risk of 30-day mortality (risk ratio, 2.63; 95% confidence interval, 1.03 to 6.69) and experienced a variety of other postoperative complications. Patients requiring conversion to open esophagectomy during MIE also experienced worse perioperative outcomes when compared to patients who underwent planned open esophagectomy. Estimated surgical risk on the basis of the ACS NSQIP Surgical Risk Calculator was the only variable found to be independently associated with conversion from minimally invasive to open esophagectomy (risk ratio, 1.03; 95% confidence interval, 1.01 to 1.04, for each 10% increase in risk score). CONCLUSIONS: Unplanned conversion to open esophagectomy during MIE is associated with significantly greater morbidity and a 2.6-fold increased risk of death when compared with both completed MIE and planned open esophagectomy. The ACS NSQIP Surgical Risk Calculator may help identify patients preoperatively who are at higher risk for conversion to open esophagectomy during MIE.

This Surgical Life - An Exploration of Surgical Department Podcasting.

OBJECTIVE: Surgical departments are increasingly utilizing media to disseminate knowledge, discuss ideas, and mentor future surgeons. Podcasts are a form of media where digitally recorded content can be downloaded or streamed. This study aims (1) to describe the audience reached by a single surgical department podcast and (2) to evaluate what sources of information surgery residency applicants use to formulate a rank list. DESIGN: In Fall 2017, the Rocky Mountain Surgery Podcast (RMSP) was created, produced, and edited by 2 general surgery (GS) residents at a large academic training program. Each episode discussed a topic within GS training and/or educational experiences specific to the program. Interviewing GS applicants for the 2019 match were asked to complete an anonymous voluntary survey on their familiarity and opinion of RMSP and the role of podcasts in the application process. RESULTS: Twenty-two episodes were completed over a 16-month period (October 4, 2017 - February 11, 2019). A total of 7002 individual listens occurred in 644 cities across 46 states. Ninety-eight interviewing applicants responded to the survey (99% response rate), and one-fourth had previously listened to the RMSP. Only half felt that the traditional interview experience provided enough information about a GS program, and a significant majority (97%) stated they would listen to one or more podcast episodes to gain information regarding a GS residency program. CONCLUSIONS: Applicants to GS residency commonly feel inadequate information is gained during the interview process. Podcasts are a tool familiar to applicants that allow for exploration of topics which cannot be adequately addressed in a typical interview day, thus expanding an applicant's knowledge of a GS training program.

Activation of Toll-Like Receptor 2 Promotes Proliferation of Human Lung Adenocarcinoma Cells.

BACKGROUND/AIM: The aim of this study was to evaluate the role of toll-like receptor 2 (TLR2) in the proliferation of human lung cancer cells and identify the signaling pathway that mediates this effect. MATERIALS AND METHODS: Adenocarcinoma (A549 and H1650) and adenosquamous (H125) cells were treated with increasing doses of Pam3CSK4, a TLR2 agonist. Cell proliferation and NF-ĸB activation were evaluated. NF-ĸB was inhibited prior to treatment with Pam3CSK4 and proliferation was assessed. RESULTS: TLR2 expression was significantly higher in A549 and H1650 cells compared to H125 cells (p<0.001). TLR2 stimulation induced proliferation in adenocarcinoma cells only and led to a corresponding increase in NF-ĸB activity (p<0.05). Inhibition of NF-ĸB prior to treatment with Pam3CSK4 attenuated this proliferative response. CONCLUSION: TLR2 activation induced proliferation of lung adenocarcinoma cells through activation of NF-ĸB. Thus, the TLR2 signaling pathway may be a potential therapeutic target in lung adenocarcinoma.

A Comparison of Frailty Measures at Listing to Predict Outcomes After Lung Transplantation.

BACKGROUND: Sarcopenia may be an important predictive factor of outcomes after lung transplantation (LTx). Serum albumin and the 6-minute walk distance (6MWD) have been shown to be a marker of LTx outcomes. We measured sarcopenia, albumin, and 6MWD in a cohort of LTx patients and analyzed the utility of these as markers of outcomes for LTx patients. METHODS: We retrospectively identified LTx recipients from 2013-2018 at our institution who underwent computed tomographic imaging during their listing evaluation. From that image, we measured skeletal muscle cross-sectional surface area at the third lumbar vertebral level, and sarcopenia was diagnosed by established cutoffs. Associations between sarcopenia, albumin, 6MWD, and survival, and hospital length of stay, complications, readmissions, and discharge destination were evaluated. RESULTS: Sarcopenia was found in 72% (95 of 132) of patients, 18% (24 of 131) of patients were hypoalbuminemic, and 41% had a low 6MWD. Survival was not associated with presence of sarcopenia (hazard ratio [HR], 1.06; 95% confidence interval [CI], 0.46-2.42) or low 6MWD (HR, 0.86; 95% CI, 0.410-1.83). Hospital length of stay, complications, readmissions, and discharge destination were not influenced by sarcopenia or 6MWD. In contrast, hypoalbuminemia was independently associated with decreased survival (HR, 2.25; 95% CI, 1.04-4.85) and a higher grade of postoperative complications (P = .04). CONCLUSIONS: Sarcopenia is prevalent in LTx patients. Neither sarcopenia nor 6MWD predicted mortality or short-term outcomes after LTx. This is in contrast to albumin levels, which were inversely associated with survival and complications. Albumin shows promise as an important predictor of mortality and short-term outcomes after LTx.

Palliative Management of Gastric and Esophageal Cancer.

In patients with advanced esophageal or gastric cancer, it is highly likely that palliation of symptoms will become a focus of treatment. Dysphagia and obstruction are the most common complaints, and many of these patients can be treated with endoscopic interventions to alleviate symptoms. Bleeding, perforation, and nutritional issues are common problems. Attempts at palliation should be guided by thoughtful discussions regarding patients' goals of care. Owing to the high morbidity and mortality in patients with limited life expectancy, a strategy of working from the least invasive to the most invasive interventions should be guided by the patient's goals.

Video-Assisted Thoracoscopic Pneumonectomy for Complications of Congenital Pulmonary Venous Stenosis.

Congenital pulmonary venous stenosis is an uncommon congenital heart defect and is a consequence of failed incorporation of the common right or left pulmonary vein into the left atrium during embryologic development. Clinical manifestations include progressive exertional dyspnea, cough, chest pain, and hemoptysis. In this report, we describe a 37-year-old woman with known congenital unilateral pulmonary venous stenosis and a unilateral hypoplastic right pulmonary artery who presented with recurrent episodes of hemoptysis, requiring multiple catheter-based interventions, and symptomatic pleural effusions, requiring multiple large-volume thoracenteses. The patient underwent successful video-assisted thoracoscopic pneumonectomy with resolution of symptoms.

A familial germline mutation in KIT associated with achalasia, mastocytosis and gastrointestinal stromal tumors shows response to kinase inhibitors.

BACKGROUND: Activating mutations of the tyrosine kinase receptor KIT have been described in both mastocytosis and gastrointestinal stromal tumors (GIST), but are usually found in separate domains and often respond differently to signal transduction inhibitors. We describe here a large family with both GIST, mastocytosis, and achalasia. Affected family members have a unique activating mutation in exon 9 of KIT which show promise to a novel signal transduction inhibitor. METHODS: Clinical data was collected from 15 family members, 7 of whom were variably affected with GIST, achalasia and mastocytosis. DNA was prepared from WBC of 12 subjects (6 affected and 6 unaffected) and exons 9, 11, 13 and 17 of KIT were amplified by PCR and directly sequenced. RESULTS: A unique activating single base pair mutation in the extracellular domain of KIT was found in all 6 affected subjects resulting in a K>I amino acid change at codon 509. CONCLUSIONS: In the family reported here, a unique mutation in the extracellular domain leads to receptor activation resulting in GIST and mastocytosis as well as achalasia. Initial data suggests that this activation can be suppressed by signal transduction inhibitors and these patients may benefit from such therapy.

Toll-Like Receptor-4 Is a Mediator of Proliferation in Esophageal Adenocarcinoma.

BACKGROUND: Chronic inflammation from reflux disease has been implicated as part of the development of esophageal adenocarcinoma. Toll-like receptors (TLRs), a component of the innate immune system, have been implicated in mediating hyperplasia and metaplasia in response to inflammatory stimuli. Increased TLR4 in human esophageal cancer has been correlated with its carcinogenesis. We hypothesized that TLR4 mediates proliferation of human esophageal adenocarcinoma cells. METHODS: Normal human esophageal (HET1A) and adenocarcinoma (OE33, FLO-1) cell lines were cultured using standard techniques. TLR4 was measured at baseline and in response to reflux stimuli. All cell lines were treated with the TLR4 agonist lipopolysaccharide for 48 hours, and growth response was measured. Changes in myeloid differentiation primary response 88 (MyD88), tumor necrosis factor receptor associated factor 6 (TRAF6), and nuclear factor-κB (NF-κB) activity were measured during lipopolysaccharide treatment. All cell lines had NF-κB inhibited, and growth rate response was measured. RESULTS: TLR4 was expressed in all cell lines, with increased baseline expression in adenocarcinoma cell lines (p < 0.05). Reflux stimuli increased TLR4 expression (p < 0.01) in normal esophageal cells. After treatment with lipopolysaccharide, all cell lines showed significant increases in proliferation (p < 0.05) due to the NF-κB pathway, and their growth rate was reduced with NF-κB inhibition (p < 0.05). CONCLUSIONS: TLR4 is consistently detectable in esophageal cell lines and most highly expressed in adenocarcinoma. TLR4 expression increases in an inflammatory model of reflux disease. TLR4 activation results in increased proliferation due to the TLR4-MyD88-TRAF6-NF-κB signaling pathway, and inhibition of NF-κB leads to decreased esophageal cell growth. These findings suggest TLR4 may be a target to suppress esophageal cancer growth.

Improved Mortality Associated With the Use of Extracorporeal Membrane Oxygenation.

BACKGROUND: Our objective was to evaluate the association of bridge to transplant (BTT) extracorporeal membrane oxygenation (ECMO) on survival after lung transplantation (LTx) and determine the degree to which transplant center volume affects this relationship. METHODS: Using the United Network for Organ Sharing database, we performed a retrospective cohort study evaluating the survival of patients undergoing LTx between 2005 and 2017. On the basis of previous literature, LTx centers were classified into 3 groups using their average annual LTx volume over the preceding 5 years: less than 25, 25 to 49, and more than 50. Survival of BTT ECMO and non-ECMO patients was analyzed using a log-rank test. Propensity scores for BTT ECMO were calculated, and a weighted proportional hazards model was used to compare BTT ECMO and non-ECMO patients by center volume. RESULTS: There were 20,976 patients who met inclusion criteria, with 611 (2.9%) undergoing BTT ECMO. Overall, BTT ECMO was associated with increased posttransplantation hazard of mortality (hazard ratio, 1.37; 95% confidence interval, 1.14 to 1.64). Kaplan-Meier plots by center volume suggest that BTT ECMO-associated mortality may be mitigated at high-volume LTx centers. In the propensity score-weighted proportional hazards model, we determined that when centers perform more than 35 LTxs per year, the increased hazard of BTT ECMO on mortality is no longer observed. CONCLUSIONS: BTT ECMO can be performed as a bridge to LTx without significantly increasing patient mortality in high-volume centers. Patients undergoing BTT ECMO at LTx centers that perform more than 35 LTxs annually have equivalent mortality to those who do not require ECMO before transplantation.