Postoperative outcomes and costs of laparoscopic versus robotic distal pancreatectomy: a propensity-matched analysis.

BACKGROUND: Minimally invasive distal pancreatectomy (MIDP) has established advantages over the open approach. The costs associated with robotic DP (RDP) versus laparoscopic DP (LDP) make the robotic approach controversial. We sought to compare outcomes and cost of LDP and RDP using propensity matching analysis at our institution. METHODS: Patients undergoing LDP or RDP between 2000 and 2021 were retrospectively identified. Patients were optimally matched using age, gender, American Society of Anesthesiologists status, body mass index, and tumor size. Between-group differences were analyzed using the Wilcoxon signed-rank test for continuous data, and the McNemar's test for categorical data. Outcomes included operative duration, conversion to open surgery, postoperative length of stay, pancreatic fistula rate, pseudocyst requiring intervention, and costs. RESULTS: 298 patients underwent MIDP, 180 (60%) were laparoscopic and 118 (40%) were robotic. All RDPs were matched 1:1 to a laparoscopic case with absolute standardized mean differences for all matching covariates below 0.10, except for tumor type (0.16). RDP had longer operative times (268 vs 178 min, p < 0.01), shorter length of stay (2 vs 4 days, p < 0.01), fewer biochemical pancreatic leaks (11.9% vs 34.7%, p < 0.01), and fewer interventional radiological drainage (0% vs 5.9%, p = 0.01). The number of pancreatic fistulas (11.9% vs 5.1%, p = 0.12), collections requiring antibiotics or intervention (11.9% vs 5.1%, p = 0.12), and conversion rates (3.4% vs 5.1%, p = 0.72) were comparable between the two groups. The total direct index admission costs for RDP were 1.01 times higher than for LDP for FY16-19 (p = 0.372), and 1.33 times higher for FY20-22 (p = 0.031). CONCLUSIONS: Although RDP required longer operative times than LDP, postoperative stays were shorter. The procedure cost of RDP was modestly more expensive than LDP, though this was partially offset by reduced hospital stay and reintervention rate.

Comparison of Spleen-Preservation Versus Splenectomy in Minimally Invasive Distal Pancreatectomy.

BACKGROUND: Spleen-preservation during minimally invasive distal pancreatectomy (MIDP) can be technically challenging and remains controversial. Our primary aim was to compare MIDP and splenectomy with spleen-preserving MIDP. Secondarily, we compared two spleen-preserving techniques. METHODS: Adults undergoing MIDP (2007-2021) were retrospectively included in this single-center study. Intraoperative and postoperative outcomes between spleen-preservation and splenectomy and between the two spleen-preserving techniques were compared using the Mann-Whitney U test for continuous data, and Fisher's exact test for categorical data. RESULTS: Of the 293 patients who underwent MIDP, preservation of the spleen was intended in 208 (71%) patients. Spleen-preservation was achieved in 174 patients (84%) via the Warshaw technique (130; 75%) or vessel-preservation (44; 25%). The spleen-preserving group had shorter length of stay (3 vs 4 days, p < 0.01), fewer conversions to open (1 vs 12, p < 0.01) and less blood loss (p < 0.01) compared to the splenectomy group. Operative (OR) times were comparable (229 vs 214 min, p = 0.67). Except for the operative time, which was longer for the Warshaw technique (245 vs 183 min, p = 0.01), no other differences between the two spleen-preserving techniques were found. At a median follow-up of 43 (IQR 18-79) months after spleen-preservation, only 2 (1.1%) patients had required splenectomy (1 partial splenectomy for infarct/abscess after Warshaw, 1 for variceal bleeding after vessel-preserving). CONCLUSIONS: Spleen-preservation is not associated with increased risk of blood loss, longer hospital stay, conversion, nor lengthy OR times. Late splenectomy is very rarely required. Given the immune consequences of splenectomy, spleen-preservation should be strongly considered in MIDP.

Clinical features and postoperative survival in patients with sporadic versus multiple endocrine neoplasia type 1-related pancreatic neuroendocrine tumors: An international cohort study.

BACKGROUND: The optimal surgical management of pancreatic neuroendocrine tumors in patients with multiple endocrine neoplasia type 1 is controversial. This study sought to compare clinicopathologic characteristics and outcomes of multiple endocrine neoplasia type 1-associated and sporadic pancreatic neuroendocrine tumors from a large multi-national database. METHODS: A multi-institutional, international database of patients with surgically resected pancreatic neuroendocrine tumors was analyzed. The cohort was divided into 2 groups: those with multiple endocrine neoplasia type 1 versus those with sporadic disease. Clinicopathologic comparisons were made. Overall and disease-free survival were analyzed. Propensity score matching was used to reduce bias. RESULTS: Of 651 patients included, 45 (6.9%) had multiple endocrine neoplasia type 1 and 606 sporadic pancreatic neuroendocrine tumors. Multiple endocrine neoplasia type 1-associated pancreatic neuroendocrine tumors were more common in younger patients and associated with multifocal disease at the time of surgery and higher T-stage. Lymph node involvement and the presence of metastasis were similar. Total pancreatectomy rate was 5-fold higher in the multiple endocrine neoplasia type 1 cohort. Median survival did not differ (disease-free survival 126 months multiple endocrine neoplasia type 1 vs 198 months sporadic, P > .5). After matching, survival remained similar (overall survival not reached in either cohort, disease-free survival 126 months multiple endocrine neoplasia type 1 vs 198 months sporadic, P > .5). Equivalence in overall survival and disease-free survival persisted even when patients who underwent subtotal and total pancreatectomy were excluded. CONCLUSION: Multiple endocrine neoplasia type 1-associated pancreatic neuroendocrine tumors are more common in younger patients and are associated with multifocality and higher T-stage. Survival for patients with multiple endocrine neoplasia type 1-associated pancreatic neuroendocrine tumors is comparable to those with sporadic pancreatic neuroendocrine tumors, even in the absence of radical pancreatectomy. Consideration should be given to parenchymal-sparing surgery to preserve pancreatic function.

Similar Outcomes in Minimally Invasive versus Open Management of Primary Pancreatic Neuroendocrine Tumors: A Regional, Multi-Institutional Collaborative Analysis.

In pancreatic neuroendocrine tumors (PNETs), the impact of minimally invasive (MI) versus open resection on outcomes remains poorly studied. We queried a multi-institutional pancreatic cancer registry for patients with resected non-metastatic PNET from 1996−2020. Recurrence-free (RFS), disease-specific survival (DSS), and operative complications were evaluated. Two hundred and eighty-two patients were identified. Operations were open in 139 (49%) and MI in 143 (51%). Pancreaticoduodenectomy was performed in 77 (27%, n = 23 MI), distal pancreatectomy in 184 (65%, n = 109 MI), enucleation in 13 (5%), and total pancreatectomy in eight (3%). Median follow-up was 50 months. Thirty-six recurrences and 13 deaths from recurrent disease yielded 5-year RFS and DSS of 85% and 95%, respectively. On multivariable analysis, grade 1 (HR 0.07, p < 0.001) and grade 2 (HR 0.20, p = 0.002) tumors were associated with improved RFS, while T3/T4 tumors were associated with worse RFS (OR 2.78, p = 0.04). MI resection was not associated with RFS (HR 0.53, p = 0.14). There was insufficient mortality to evaluate DSS with multivariable analysis. Of 159 patients with available NSQIP data, incisional surgical site infections (SSIs), organ space SSIs, Grade B/C pancreatic fistulas, reoperations, and need for percutaneous drainage did not differ by operative approach (all p > 0.2). Nodal harvest was similar for MI versus open distal pancreatectomies (p = 0.16) and pancreaticoduodenectomies (p = 0.28). Minimally invasive surgical management of PNETs is equivalent for oncologic and postoperative outcomes.

Evaluation of Outcomes Following Surgery for Locally Advanced Pancreatic Neuroendocrine Tumors.

Importance: Although outcome of surgical resection of liver metastases from pancreatic neuroendocrine tumors (PNETs) has been extensively studied, little is known about surgery for locally advanced PNETs; it was listed recently by the European neuroendocrine tumor society as a major unmet need. Objective: To evaluate the outcome of patients who underwent surgery for locally aggressive PNETs. Design, Setting, and Participants: This retrospective single-center case series reviewed consecutive patients who underwent resection of T3/T4 PNETs at a single academic institution. Data collection occurred from 2003 to 2018. Data analysis was performed in August 2019. Main Outcomes and Measures: Disease-free survival (primary outcome) and overall mortality (secondary outcome) were assessed with Kaplan-Meier analysis. Recurrence risk (secondary outcome, defined as identification of tumor recurrence on imaging) was assessed with Cox proportional hazard models adjusting for covariates. Results: In this case series, 99 patients with locally advanced nondistant metastatic PNET (56 men [57%]) with a mean (SEM) age of 57.0 (1.4) years and a mean (SEM) follow-up of 5.3 (0.1) years underwent surgically aggressive resections. Of those, 4 patients (4%) underwent preoperative neoadjuvant treatment (including peptide receptor radionuclide therapy and chemotherapy); 18 patients (18%) underwent pancreaticoduodenectomy, 68 patients (69%) had distal or subtotal pancreatic resection, 10 patients (10%) had total resection, and 3 patients (3%) had other pancreatic procedures. Additional organ resection was required in 86 patients (87%): spleen (71 patients [71%]), major blood vessel (17 patients [17%]), bowel (2 patients [2%]), stomach (4 patients [4%]), and kidney (2 patients [2%]). Five-year disease-free survival was 61% (61 patients) and 5-year overall survival was 91% (91 patients). Of those living, 75 patients (76%) had an Eastern Cooperative Oncology Group score of less than or equal to 1 at last followup. Lymph node involvement (HR, 7.66; 95% CI, 2.78-21.12; P < .001), additional organ resected (HR, 6.15; 95% CI, 1.61-23.55; P = .008), and male sex (HR, 3.77; 95% CI, 1.68-8.97; P = .003) were associated with increased risk of recurrence. Functional tumors had a lower risk of recurrence (HR, 0.23; CI, 0.06-0.89; P = .03). Required resection of blood vessels was not associated with a significant increase recurrence risk. Conclusions and Relevance: In this case series, positive lymph node involvement and resection of organs with tumor involvement were associated with an increased recurrence risk. These subgroups may require adjuvant systemic treatment. These findings suggest that patients with locally advanced PNETs who undergo surgical resection have excellent disease-free and overall survival.

Neoadjuvant Capecitabine/Temozolomide for Locally Advanced or Metastatic Pancreatic Neuroendocrine Tumors.

OBJECTIVES: The combination chemotherapy regimen capecitabine/temozolomide (CAPTEM) is efficacious for metastatic well-differentiated pancreatic neuroendocrine tumors (PNETs), but its role in the neoadjuvant setting has not been established. METHODS: The outcomes of all patients with locally advanced or resectable metastatic PNETs who were treated with neoadjuvant CAPTEM between 2009 and 2017 at 2 high-volume institutions were retrospectively reviewed. RESULTS: Thirty patients with locally advanced PNET (n = 10) or pancreatic neuroendocrine hepatic metastases (n = 20) received neoadjuvant CAPTEM. Thirteen patients (43%) exhibited partial radiographic response (PR), 16 (54%) had stable disease, and 1 (3%) developed progressive disease. Twenty-six (87%) patients underwent resection (pancreatectomy [n = 12], combined pancreatectomy and liver resection [n = 8], or major hepatectomy alone [n = 6]); 3 (18%) declined surgery despite radiographic PR, and 1 (3%) underwent aborted pancreatoduodenectomy. Median primary tumor size was 5.5 cm, and median Ki-67 index was 3.5%. Rates of PR were similar across tumor grades (P = 0.24). At median follow-up of 49 months, median progression-free survival was 28.2 months and 5-year overall survival was 63%. CONCLUSIONS: Neoadjuvant CAPTEM is associated with favorable radiographic objective response rates for locally advanced or metastatic PNET and may facilitate selection of patients appropriate for surgical resection.

Pancreatic grade 3 neuroendocrine tumors behave similarly to neuroendocrine carcinomas following resection: a multi-center, international appraisal of the WHO 2010 and WHO 2017 staging schema for pancreatic neuroendocrine lesions.

BACKGROUND: In 2017, the WHO updated their 2010 classification of pancreatic neuroendocrine tumors, introducing a well-differentiated, highly proliferative grade 3 tumor, distinct from neuroendocrine carcinomas. The aim of this study was to investigate the clinical significance of this update in a large cohort of resected tumors. METHODS: Using a multicenter, international dataset of patients with pancreatic neuroendocrine lesions, patients were classified both according to the WHO 2010 and 2017 schema. Multivariable survival analyses were performed, and the models were evaluated for discrimination ability and goodness of fit. RESULTS: Excluding patients with a known germline MEN1 mutation and incomplete data, 544 patients were analyzed. The performance of the WHO 2010 and 2017 models was similar, however surgically resected grade 3 tumors behaved very similarly to neuroendocrine carcinomas. CONCLUSION: The addition of a grade 3 NET classification may be of limited utility in surgically resected patients, as these lesions have similar postoperative survival compared to carcinomas. While the addition may allow for a more granular evaluation of novel treatment strategies, surgical intervention for high grade tumors should be considered judiciously.

Management of Ileal Neuroendocrine Tumors with Liver Metastases.

PURPOSE: Assessment of treating metastatic ileal neuroendocrine tumors (NETs) with complete resection of primary tumor, nodal and liver metastases, plus administration of long-acting somatostatin analogues (SSAs). METHODS: A prospective database was queried for patients with ileal or pancreatic NETs with pathology-confirmed liver metastases and tumor somatostatin receptors. Patients did not have MEN-1 and had no previous treatment. The impacts of SSA treatment on the primary outcome of survival and secondary outcome of progression-free survival were assessed with Kaplan-Meier analysis. Log rank test was used to compare overall and progression-free survival among groups. RESULTS: Seventeen ileal NET patients and 36 pancreatic NET patients who underwent surgical resection between 2001 and 2018, who had pathology-confirmed liver metastases and confirmed tumor somatostatin receptors, did not have MEN-1, and had no previous treatment were identified. Median follow-up for patients with ileal NETs was 80 months (range 0-197 months) and 32 months (range 1-182 months) for pancreatic NETs. Five-year survival was 93% and 72% for ileal and pancreatic NET, respectively. Progression-free 5-year survival was 70% and 36% for ileal and pancreatic NET, respectively. Overall 5-year survival for pNETs was greater in those patients treated with SSA (79%) compared to those who underwent surgery alone (34%, p < 0.01). The average ECOG score was low for surviving patients with ileal (0.15) and pancreatic NET (0.73) indicating a good quality of life. CONCLUSIONS: Resection of primary lymph node and liver metastatic ileal or pancreatic NETs followed with continued SSAs is associated with an excellent progression-free and overall survival and minimal side effects.

Isolated pancreatic tail remnants after transgastric necrosectomy can be observed.

BACKGROUND: Severe necrotizing pancreatitis may result in midbody necrosis and ductal disruption leaving an isolated pancreatic tail. The purpose of this study was to characterize outcomes among patients with an isolated tail remnant who underwent transgastric drainage or necrosectomy (endoscopic or surgical) and determine the need for subsequent operative management. MATERIALS AND METHODS: Patients with necrotizing pancreatitis and retrogastric walled-off collections treated by surgical transgastric necrosectomy or endoscopic cystgastrostomy ± necrosectomy between 2009 and 2017 were identified by a retrospective chart review. All available preprocedure and postprocedure imaging was reviewed for evidence of isolated distal pancreatic tail remnants. RESULTS: Seventy-four patients were included (40 surgical and 34 endoscopic). All the patients in the surgical group underwent laparoscopic transgastric necrosectomy; the endoscopic group consisted of 26 patients for pseudocyst drainage and eight patients for necrosectomy. A disconnected pancreatic tail was identified in 22 (29%) patients (13 laparoscopic and nine endoscopic). After the creation of the "cystgastrostomy," there were no external fistulas despite the viable tail. Of the 22 patients, four patients developed symptoms at a median of 23 months (two, recurrent episodic pancreatitis; two, intractable pain). Two patients (both initially in endoscopic group) ultimately required distal pancreatectomy and splenectomy at 24 and 6 months after index procedure. CONCLUSIONS: Patients with a walled-off retrogastric collection and an isolated viable tail are effectively managed by a transgastric approach. Despite this seemingly "unstable anatomy," the creation of an internal fistula via surgical or endoscopic "cystgastrostomy" avoids external fistulas/drains and the short-term necessity of surgical distal pancreatectomy. A very small subset requires intervention for late symptoms.

Monitoring gastric myoelectric activity after pancreaticoduodenectomy for diet "readiness".

Postoperative delayed gastric emptying (DGE) is a frustrating complication of pancreaticoduodenectomy (PD). We studied whether monitoring of postoperative gastric motor activity using a novel wireless patch system can identify patients at risk for DGE. Patients ( n = 81) were prospectively studied since 2016; 75 patients total were analyzed for this study. After PD, battery-operated wireless patches (G-Tech Medical) that acquire gastrointestinal myoelectrical signals are placed on the abdomen and transmit data by Bluetooth. Patients were divided into early and late groups by diet tolerance of 7 days [enhanced recovery after surgery (ERAS) goal]. Subgroup analysis was done of patients included after ERAS initiation. The early and late groups had 50 and 25 patients, respectively, with a length of stay (LOS) of 7 and 11 days ( P < 0.05). Nasogastric insertion was required in 44% of the late group. Tolerance of food was noted by 6 versus 9 days in the early versus late group ( P < 0.05) with higher cumulative gastric myoelectrical activity. Diminished gastric myoelectrical activity accurately identified delayed tolerance to regular diet in a logistical regression analysis [area under the curve (AUC): 0.81; 95% confidence interval (CI), 0.74-0.92]. The gastric myoelectrical activity also identified a delayed LOS status with an AUC of 0.75 (95% CI, 0.67-0.88). This stomach signal continued to be predictive in 90% of the ERAS cohort, despite earlier oral intake. Measurement of gastric activity after PD can distinguish patients with shorter or longer times to diet. This noninvasive technology provides data to identify patients at risk for DGE and may guide the timing of oral intake by gastric "readiness." NEW & NOTEWORTHY Limited clinical indicators exist after pancreaticoduodenectomy to allow prediction of delayed gastric emptying (DGE). This study introduces a novel, noninvasive, wireless patch system capable of accurately monitoring gastric myoelectric activity after surgery. This system can differentiate patients with longer or shorter times to a regular diet as well as provide objective data to identify patients at risk for DGE. This technology has the potential to individualize feeding regimens based on gastric activity patterns to improve outcomes.

MYC regulates ductal-neuroendocrine lineage plasticity in pancreatic ductal adenocarcinoma associated with poor outcome and chemoresistance.

Intratumoral phenotypic heterogeneity has been described in many tumor types, where it can contribute to drug resistance and disease recurrence. We analyzed ductal and neuroendocrine markers in pancreatic ductal adenocarcinoma, revealing heterogeneous expression of the neuroendocrine marker Synaptophysin within ductal lesions. Higher percentages of Cytokeratin-Synaptophysin dual positive tumor cells correlate with shortened disease-free survival. We observe similar lineage marker heterogeneity in mouse models of pancreatic ductal adenocarcinoma, where lineage tracing indicates that Cytokeratin-Synaptophysin dual positive cells arise from the exocrine compartment. Mechanistically, MYC binding is enriched at neuroendocrine genes in mouse tumor cells and loss of MYC reduces ductal-neuroendocrine lineage heterogeneity, while deregulated MYC expression in KRAS mutant mice increases this phenotype. Neuroendocrine marker expression is associated with chemoresistance and reducing MYC levels decreases gemcitabine-induced neuroendocrine marker expression and increases chemosensitivity. Altogether, we demonstrate that MYC facilitates ductal-neuroendocrine lineage plasticity in pancreatic ductal adenocarcinoma, contributing to poor survival and chemoresistance.

Incidental Angiosarcoma of the Pancreas: A Case Report of a Rare, Asymptomatic Tumor.

Background: Angiosarcoma of the pancreas is a very rare neoplasm accounting for 0.1% of pancreatic malignancies. This tumor is biologically very aggressive and frequently diagnosed at an unresectable stage. Case Presentation: Herein, we report a case of an incidentally discovered angiosarcoma that was removed with a robotic distal pancreatectomy and discuss the current literature on this rare disease. Conclusion: This is the fifth reported case of primary angiosarcoma of the pancreas and the first case to be identified incidentally. Unlike the other cases where survival was limited due to advanced disease, the patient presented here underwent surgical resection and remains disease free after 1 year of follow-up.

Major bile duct injury requiring operative reconstruction after laparoscopic cholecystectomy: a follow-on study.

BACKGROUND: Bile duct injury (BDI) after laparoscopic cholecystectomy (LC) has significant cost impact and is a significant source of morbidity and mortality. We undertook a population-based assessment of the national experience with BDI between 2001 and 2011 and compared this to our report for the prior decade. METHODS: Using the nationwide inpatient sample (NIS) for 2001-2011, we identified patients who underwent LC or partial cholecystectomy, with and without biliary reconstruction. Data were analyzed using methods that accounted for the hierarchical, stratified random sampling of the NIS. Both univariate modeling and multivariate modeling were performed. RESULTS: LCs increased from 71.1 % in 2001 to 79.0 % in 2011 (p < 0.0001). Annual mortality decreased from 0.56 to 0.38 % (p = 0.002). In 2001, 0.11 % of LCs were associated with biliary reconstruction versus 0.09 % in 2011 (p = 0.15) with rates ranging from 0.08 to 0.12 %. The need for reconstruction was associated with an average in-hospital mortality rate of 4.4 %. Mortality rates from LC remained consistent across the study period (average mortality, 0.10 %, p = 0.57). Under multivariate analysis, admission to rural or urban non-teaching centers was associated with a decreased rate of injury; the majority of major BDIs were admitted from clinic or outpatient settings. These results are consistent with results from the prior decade. Neither emergent admission nor race was associated with increased odds of BDI, and this differs from our prior analysis. CONCLUSION: LC continued to increase in utilization between 2001 and 2011. Although rates of BDI have decreased, the need for reconstruction continues to be associated with a significant mortality. In addition, mortality related to biliary reconstruction is also higher than previously published series and may reflect the complexity of managing biliary injury as well as the higher likelihood of these patients having comorbid conditions.

Characteristics predicting clinical improvement and cure following laparoscopic adrenalectomy for primary aldosteronism in a large cohort.

BACKGROUND: Surgical resection is the standard of care for unilateral adrenal adenomas and hyperplasia resulting in primary aldosteronism (PA). Resolution of PA following surgery is variable and some patients continue to require some or all of their antihypertensives. Prior studies have investigated factors contributing to "cure" of PA (defined as no hypertension [HTN] medications required postoperatively). These models are a tool in patient selection, yet fail to consider the benefit of some reduction in medications, resolution of hypokalemia, or reduction in blood pressure which may improve long-term cardiovascular and renal outcomes. We sought to investigate factors contributing to postoperative improvement or complete resolution following surgery. METHODS: This is a retrospective review of prospectively collected data on 58 adrenalectomies performed for PA from December 1999 to April 2013 at a single center. Patient demographics, PA characteristics, labs, and imaging studies were evaluated, as well as operative characteristics. Mean systolic and diastolic blood pressures were calculated over several visits after discharge, and postoperative antihypertensive regimen was recorded. Patients were stratified by cured vs not cured and then again by improved vs not improved based on differences in pre- and postoperative values. Aldosteronoma Resolution Score was also calculated for each patient. RESULTS: Median age was 52.6 years, with 44.8% women and an average duration of HTN of 13.5 years. Average body mass index (BMI) was 31.5 kg/m(2); 74% of the lesions were adenomas. Patients with complications had higher BMIs than those without (36.9 vs 28.7 kg/m(2), P = .02). In comparing improved (n = 42, 72%) vs not improved (n = 16, 28%) patients, preoperative systolic blood pressure (147.5 vs 159.7 mm Hg, P = .047) and serum creatinine (.94 vs 1.32 mg/dL, P = .016) were higher in the not improved group. Cured (n = 13) vs not cured (n = 45) patients differed in terms of BMI (27.4 vs 32.7, P = .009), duration of HTN (9.1 vs 14.9 years, P = .020), and number of preoperative antihypertensives (2.1 vs 3.7, P = .002). Aldosteronoma Resolution Score was significantly higher in cured patients (3.2 vs 1.0, P < .01). CONCLUSIONS: A significant number of patients who are not cured by adrenalectomy for PA will still benefit from surgery. Obesity, duration of HTN, and number of medications may predict cure, yet fail to detect a population of patients with overall improvement. Attention to serum creatinine may help in distinguishing this population of patients.

Disruption of interleukin-1 signaling improves the quality of wound healing.

In this study, we investigated the role of interleukin (IL)-1 signaling in wound healing. IL-1 receptor type I (IL-1R) knockout (KO) mice showed reduced fibrosis in both cutaneous and deep tissue wounds, which was accompanied by a reduction in inflammatory cellular infiltration in cutaneous but not in deep tissue wounds. There were no differences in either total collagenolytic activity or in the expression of selected matrix metalloproteinases or tissue inhibitors of metalloproteinases between the wound fluids from wild-type or IL-1R KO mice. However, wound fluids from IL-1R KO mice contained lower levels of IL-6 compared with wild-type controls. In addition, the infusion of IL-6 into wounds in IL-1R KO mice did not increase fibrosis. Skin wounds in IL-1R KO animals had lower levels of collagen and improved restoration of normal skin architecture compared with skin wounds in wild-type mice. However, neither the tensile strength of incisional skin wounds nor the rate of closure of excisional wounds differed between IL-1R KO and wild-type animals. The reduced fibrotic response in wounds from IL-1R KO mice could be reproduced by the administration of an IL-1R antagonist. These findings suggest that pharmacological interference with IL-1 signaling could have therapeutic value in the prevention of hypertrophic scarring and in the treatment of fibrotic diseases.