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Background: Although randomized controlled trials on neoadjuvant chemotherapy for gastric cancer have included some T1-staged tumors, overall survival (OS) has not been analyzed for this subset. Due to the low negative predictive value of clinical staging and the benefits of neoadjuvant chemotherapy for locally advanced disease, identifying patient groups with early-stage gastric cancer that may benefit from neoadjuvant chemotherapy is of merit., Aims: The objective of this study was to evaluate the relationship between OS and sequence of surgical therapy for clinical T1 gastric cancer., Methods: The 2017 National Cancer Database was used to compare patients who had surgery-first and those who received neoadjuvant chemotherapy for T1-stage gastric cancer. OS was analyzed using a parametric regression survival-time model adjusted for covariates. The effects of these covariates on OS based on surgical sequence were examined., Results: 11,219 patients were included, of which 10,191 underwent surgery as their first or only treatment. When adjusted for covariates, neoadjuvant chemotherapy followed by curative-intent surgery was significantly associated with increased risk of death (HR 1.15, 95% CI 1.01-1.31, P = .030). In multivariate analysis, clinical N0 stage, non-minorities, and patients with high socioeconomic status had improved OS if they did not have neoadjuvant chemotherapy and instead had upfront surgery., Conclusion: Neoadjuvant chemotherapy is associated with decreased OS for early-stage gastric adenocarcinoma, even for patients with clinically positive nodal disease. In addition, the lack of survival improvement with a surgery-first approach in patients with disparities deserves further study., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Neurofibromatosis type I (NF1) is an autosomal dominant genetic disorder associated with characteristic skin findings, as well as a fourfold increase in risk of malignancy. NF1 patient malignancies commonly include the central and peripheral nervous system, but these patients are also at high risk of developing gastrointestinal (GI) tumors. While most often these GI tumors are benign upper GI neurofibromas; clinicians should have a high suspicion for malignant tumors, degeneration into a malignant peripheral nerve sheath tumor or less common associated malignancies such as well-differentiated neuroendocrine tumor (formerly carcinoid tumor), when patients present with multiple GI tumors. Our patient underwent a Whipple for symptomatic neurofibromas associated with NF1 and was unexpectedly discovered to have a metastatic duodenal well-differentiated neuroendocrine tumor. The patient is a 66-year-old man with NF1 who presented with hematemesis and was found to have large gastric neurofibromas and an ampullary neurofibroma based on endoscopy and radiological imaging. Another ostensive neurofibroma was noted distally. A pancreatoduodenectomy was performed. Pathological examination identified the neurofibromas but the tumor measuring 1.4cm and arising from the minor duodenal papilla was, in fact, a synchronous well-differentiated neuroendocrine tumor metastatic to regional lymph nodes, consistent with pT2 pN1, Stage IIIB cancer. NF1 patients with multiple GI tumors are at an increased risk for malignancy. Therefore, a high index of suspicion for malignancy in any patient with NF1 presenting with gastrointestinal symptoms has implications for a surgeon, warranting not only a further diagnostic investigation, but also an appropriate surgical intervention and sampling for nodal spread. Because of the possibility of a simultaneous cancer, it is crucial to assess all suspicious tumors even if the masses appear endoscopically benign.

Background: The impact of the COVID-19 pandemic has spread beyond those infected with SARS-CoV-2. Its widespread consequences have affected cancer patients whose surgeries may be delayed in order to minimize exposure and conserve resources., Methods: Experts in each surgical oncology subspecialty were selected to perform a review of the relevant literature. Articles were obtained through PubMed searches in each cancer subtype using the following terms: delay to surgery, time to surgery, outcomes, and survival., Results: Delays in surgery > 4 weeks in breast cancer, ductal carcinoma in situ, T1 pancreatic cancer, ovarian cancer, and pediatric osteosarcoma, negatively impacted survival. Studies on hepatocellular cancer, colon cancer, and melanoma (Stage I) demonstrated reduced survival with delays > 3 months., Conclusion: Studies have shown that short-term surgical delays can result in negative impacts on patient outcomes in multiple cancer types as well as in situ carcinoma . Conversely, other cancers such as gastric cancer, advanced melanoma and pancreatic cancer, well-differentiated thyroid cancer, and several genitourinary cancers demonstrated no significant outcome differences with surgical delays.

Background and Objectives: ERCP prior to pancreaticoduodenectomy is unnecessary in select patients. When performed, it should be in conjunction with endoscopic ultrasound (EUS) to increase diagnostic sensitivity and allow for metal stent placement. The aim of this study was to determine differences in endoscopic practice patterns at community medical centers (CMC) and a comprehensive pancreaticobiliary referral center (PBRC)., Methods: Retrospective cohort study of all patients seen at a PBRC for endoscopic and/or surgical management of potentially resectable malignant distal biliary obstruction from 1/2011 to 6/2014., Results: Of 75 patients, 30 underwent endoscopic management at a CMC and 45 were initially managed at our PBRC. ERCP was attempted in 92% of patients. EUS was performed more frequently (100% vs. 13.3 %, P < 0.0001), ERCP was more successful (93% vs. 69%, P = 0.02), and metal stent placement more likely (41% vs. 5%, P = 0.005) at our PBRC compared to a CMC. The majority (81%) of patients undergoing initial endoscopy at a CMC required repeat endoscopy at our PBRC., Conclusions: Patients who are candidates for pancreaticoduodenectomy frequently undergo ERCP. At a CMC, ERCP is often unsuccessful, is rarely accompanied by EUS, and often requires repeat endoscopy. Our findings support regionalizing the management of suspected pancreatic malignancy into dedicated specialty centers. J. Surg. Oncol. 2016;113:647-651. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Importance: Debate continues regarding whether to further restrict resident duty hour policies, but little high-level evidence is available to guide policy changes., Objective: To inform decision making regarding duty hour policies, the Flexibility in Duty Hour Requirements for Surgical Trainees (FIRST) Trial is being conducted to evaluate whether changing resident duty hour policies to permit greater flexibility in work hours affects patient postoperative outcomes, resident education, and resident well-being., Design, Setting, and Participants: Pragmatic noninferiority cluster-randomized trial of general surgery residency programs with 2 study arms. Participating in the study are Accreditation Council for Graduate Medical Education (ACGME)-approved US general surgery residency programs (n = 118), their affiliated hospitals (n = 154), surgical residents and program directors, and general surgery patients from July 1, 2014, to June 30, 2015, with additional patient safety outcomes collected through June 30, 2016. The data collection platform for patient outcomes is the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP), thus only hospitals participating in the ACS NSQIP were included., Interventions: In the usual care arm, programs adhered to current ACGME resident duty hour standards. In the intervention arm, programs were allowed to deviate from current standards regarding maximum shift lengths and minimum time off between shifts through an ACGME waiver., Main Outcomes and Measures: Death or serious morbidity within 30 days of surgery measured through ACS NSQIP, as well as resident satisfaction and well-being measured through a survey delivered at the time of the 2015 American Board of Surgery in Training Examination (ABSITE)., Results: A total of 118 general surgery residency programs and 154 hospitals were enrolled in the FIRST Trial and randomized. Fifty-nine programs (73 hospitals) were randomized to the usual care arm and 59 programs (81 hospitals) were randomized to the intervention arm. Intent-to-treat analysis will be used to estimate the effectiveness of assignment to the intervention arm on patient outcomes, resident education, and resident well-being compared with the usual care arm. Several sensitivity analyses will be performed to determine whether there were differential effects when examining only inpatients, high-risk patients, and emergent/urgent cases., Conclusions and Relevance: To our knowledge, the FIRST Trial is the first national randomized clinical trial of duty hour policies. Results of this study may be informative to policymakers and other stakeholders engaged in restructuring graduate medical training to enhance the quality of patient care and resident education., Trial Registration: clinicaltrials.org Identifier: NCT02050789.

Background: Concerns persist regarding the effect of current surgical resident duty-hour policies on patient outcomes, resident education, and resident well-being., Methods: We conducted a national, cluster-randomized, pragmatic, noninferiority trial involving 117 general surgery residency programs in the United States (2014-2015 academic year). Programs were randomly assigned to current Accreditation Council for Graduate Medical Education (ACGME) duty-hour policies (standard-policy group) or more flexible policies that waived rules on maximum shift lengths and time off between shifts (flexible-policy group). Outcomes included the 30-day rate of postoperative death or serious complications (primary outcome), other postoperative complications, and resident perceptions and satisfaction regarding their well-being, education, and patient care., Results: In an analysis of data from 138,691 patients, flexible, less-restrictive duty-hour policies were not associated with an increased rate of death or serious complications (9.1% in the flexible-policy group and 9.0% in the standard-policy group, P=0.92; unadjusted odds ratio for the flexible-policy group, 0.96; 92% confidence interval, 0.87 to 1.06; P=0.44; noninferiority criteria satisfied) or of any secondary postoperative outcomes studied. Among 4330 residents, those in programs assigned to flexible policies did not report significantly greater dissatisfaction with overall education quality (11.0% in the flexible-policy group and 10.7% in the standard-policy group, P=0.86) or well-being (14.9% and 12.0%, respectively; P=0.10). Residents under flexible policies were less likely than those under standard policies to perceive negative effects of duty-hour policies on multiple aspects of patient safety, continuity of care, professionalism, and resident education but were more likely to perceive negative effects on personal activities. There were no significant differences between study groups in resident-reported perception of the effect of fatigue on personal or patient safety. Residents in the flexible-policy group were less likely than those in the standard-policy group to report leaving during an operation (7.0% vs. 13.2%, P<0.001) or handing off active patient issues (32.0% vs. 46.3%, P<0.001)., Conclusions: As compared with standard duty-hour policies, flexible, less-restrictive duty-hour policies for surgical residents were associated with noninferior patient outcomes and no significant difference in residents' satisfaction with overall well-being and education quality. (FIRST ClinicalTrials.gov number, NCT02050789.).

Importance: There is a paucity of data assessing the effect of increased surgical duration on the incidence of venous thromboembolism (VTE)., Objective: To examine the association between surgical duration and the incidence of VTE., Design, Settings, and Participants: Retrospective cohort of 1,432,855 patients undergoing surgery under general anesthesia at 315 US hospitals participating in the American College of Surgeons National Surgical Quality Improvement Program from 2005 to 2011., Exposure: Duration of surgery., Main Outcomes and Measures: The rates of deep vein thrombosis (DVT), pulmonary embolism (PE), and VTE within 30 days of the index operation. Surgical duration was standardized across Current Procedural Terminology codes using a z score. Outcomes were compared across quintiles of the z score. Multiple logistic regression models were developed to examine the association while adjusting for patient demographics, clinical characteristics, and comorbidities., Results: The overall VTE rate was 0.96% (n = 13,809); the rates of DVT and PE were 0.71% (n = 10,198) and 0.33% (n = 4772), respectively. The association between surgical duration and VTE increased in a stepwise fashion. Compared with a procedure of average duration, patients undergoing the longest procedures experienced a 1.27-fold (95% CI, 1.21-1.34; adjusted risk difference [ARD], 0.23%) increase in the odds of developing a VTE; the shortest procedures demonstrated an odds ratio of 0.86 (95% CI, 0.83-0.88; ARD, -0.12%). The robustness of these results was substantiated with several sensitivity analyses attempting to minimize the effect of outliers, concurrent complications, procedural differences, and unmeasured confounding variables., Conclusions and Relevance: Among patients undergoing surgery, an increase in surgical duration was directly associated with an increase in the risk for VTE. These findings may help inform preoperative and postoperative decision making related to surgery.

Objective: The objective was to assess the presence and extent of venous thromboembolic (VTE) surveillance bias using high-quality clinical data., Background: Hospital VTE rates are publicly reported and used in pay-for-performance programs. Prior work suggested surveillance bias: hospitals that look more for VTE with imaging studies find more VTE, thereby incorrectly seem to have worse performance. However, these results have been questioned as the risk adjustment and VTE measurement relied on administrative data., Methods: Data (2009-2010) from 208 hospitals were available for analysis. Hospitals were divided into quartiles according to VTE imaging use rates (Medicare claims). Observed and risk-adjusted postoperative VTE event rates (regression models using American College of Surgeons National Surgical Quality Improvement Project data) were examined across VTE imaging use rate quartiles. Multivariable linear regression models were developed to assess the impact of hospital characteristics (American Hospital Association) and hospital imaging use rates on VTE event rates., Results: The mean risk-adjusted VTE event rates at 30 days after surgery increased across VTE imaging use rate quartiles: 1.13% in the lowest quartile to 1.92% in the highest quartile (P < 0.001). This statistically significant trend remained when examining only the inpatient period. Hospital VTE imaging use rate was the dominant driver of hospital VTE event rates (P < 0.001), as no other hospital characteristics had significant associations., Conclusions: Even when examined with clinically ascertained outcomes and detailed risk adjustment, VTE rates reflect hospital imaging use and perhaps signify vigilant, high-quality care. The VTE outcome measure may not be an accurate quality indicator and should likely not be used in public reporting or pay-for-performance programs.

Acute cholecystitis is defined as inflammation of the gallbladder and is usually caused by obstruction of the cystic duct. Cholescintigraphy is the most sensitive imaging modality for cholecystitis. The gold standard treatment of acute cholecystitis is laparoscopic cholecystectomy. Operating early in the disease course decreases overall hospital stay and avoids increased complications, conversion to open procedures, and mortality. Cholecystitis during pregnancy is a challenging problem for surgeons. Operative intervention is generally safe for both mother and fetus, given the improved morbidity of the laparoscopic approach compared with open, although increased caution should be exercised in women with gallstone pancreatitis., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background: Hospital-specific and surgeon-specific public reporting of performance measures is expanding largely due to calls for transparency from the public and oversight agencies. Surgeons continue to voice concerns regarding public reporting. Surgeons' perceptions of hospital-level and individual-level public reporting have not been assessed. This study (1) evaluated surgeons' perceptions of public reporting of surgical quality; and (2) identified specific barriers to surgeons' acceptance of public reporting., Methods: All surgeons (n=185) at 4 hospitals (university, children's, 2 community hospitals), representing all surgical specialties, received a 41-item anonymous Internet-based survey. Twenty follow-up qualitative interviews were conducted to assess surgeons' interpretation of findings., Results: The survey response rate was 66% (n=122). Most surgeons supported public reporting of quality metrics at the hospital level (80%), but opposed individual reporting (53%, P<0.01). Fewer surgeons expected that individual (26%) or hospital (47%) public reporting would improve outcomes (P<0.01). Few indicated that their practice would change with hospital (11%) or individual (18%) public reporting (P=0.20). Primary concerns regarding public reporting at the hospital level included patients misinterpreting data, surgeons refusing high-risk patients, and outcome metric validity. Individual-surgeon level concerns included outcome metric validity, adequate sample sizes, and patients misinterpreting data. To make public reporting more acceptable, surgeons recommended patient education, simplified data presentation, continued risk-adjustment refinement, and internal review before public reporting., Conclusions: Surgeons expressed concerns about public reporting of quality metrics, particularly reporting of individual surgeon performance. These concerns must be addressed to gain surgeons' acceptance and to use public reporting to improve health care quality.

The role of regulatory T cells (T(regs)) in human colon cancer (CC) remains controversial: high densities of tumor-infiltrating T(regs) can correlate with better or worse clinical outcomes depending on the study. In mouse models of cancer, T(regs) have been reported to suppress inflammation and protect the host, suppress T cells and protect the tumor, or even have direct cancer-promoting attributes. These different effects may result from the presence of different T(reg) subsets. We report the preferential expansion of a T(reg) subset in human CC with potent T cell-suppressive, but compromised anti-inflammatory, properties; these cells are distinguished from T(regs) present in healthy donors by their coexpression of Foxp3 and RORγt. T(regs) with similar attributes were found to be expanded in mouse models of hereditary polyposis. Indeed, ablation of the RORγt gene in Foxp3(+) cells in polyp-prone mice stabilized T(reg) anti-inflammatory functions, suppressed inflammation, improved polyp-specific immune surveillance, and severely attenuated polyposis. Ablation of interleukin-6 (IL-6), IL-23, IL-17, or tumor necrosis factor-α in polyp-prone mice reduced polyp number but not to the same extent as loss of RORγt. Surprisingly, loss of IL-17A had a dual effect: IL-17A-deficient mice had fewer polyps but continued to have RORγt(+) T(regs) and developed invasive cancer. Thus, we conclude that RORγt has a central role in determining the balance between protective and pathogenic T(regs) in CC and that T(reg) subtype regulates inflammation, potency of immune surveillance, and severity of disease outcome.

Objectives: Nearly 80% of general surgery residents (GSR) pursue Fellowship training. We hypothesized that fellowships coexisting with general surgery residencies do not negatively impact GSR case volumes and that fellowship-bound residents (FBR) preferentially seek out cases in their chosen specialty ("early tracking")., Methods: To test our hypotheses, we analyzed the Accreditation Council for Graduate Medical Education Surgical Operative Log data from 2009 American Board of Surgery qualifying examination applicants (N = 976). General surgery programs coexisted with 35 colorectal (CR), 97 vascular (Vasc), 80 minimally invasive (MIS), and 12 Endocrine (Endo) fellowships. We analyzed (1) operative cases for general surgery residency programs with and without coexisting Fellowships, comparing caseloads for FBR and all GSR and (2) operative cases of FBR in their chosen specialties compared to all other GSR. Group means were compared using ANOVA with significance set at P < 0.01., Results: Coexisting fellowships had minimal impact on GSR caseloads. Endocrine fellowships actually enhanced case volumes for all residents. CR impact was neutral while MIS and vascular fellowships resulted in small declines. Endo, CR, and Vasc but not MIS FBR performed significantly more cases in their future specialties than their GSR counterparts, consistent with self-directed, prefellowship tracking. Tracking seems to be additive and FBR do not sacrifice other GSR cases., Conclusions: Our data establish that the impact of Fellowships on GSR caseloads is minimal. Our data confirm that FBR seek out cases in their future specialties ("early tracking").

The Society for Surgery of the Alimentary Tract's (SSAT) mission is to advance the science and practice of surgery in the treatment of digestive disease. An essential core value of the SSAT is multidisciplinary collaboration with both its sister societies in the Digestive Disease Week (DDW) Council and other surgical societies in Gastrointestinal Surgery. In order to achieve the society's goals, the strategic plan rests on the society's values of interdisciplinary collaboration, scholarship, education, and discovery. The strategic plan also creates a meritocracy system to foster the development of future leaders for both the SSAT and the broader house of surgery. In the short term, this plan will: Re-organize committee structure and reporting responsibilities; Clarify committee goals and deliverables; Facilitate member participation in the committees and governance of the society; Enhance member services by utilizing enhanced communication strategies; Accelerate efforts to meet the Maintenance of Certification needs of the membership; Re-focus the SSAT's energy on Quality and Outcome Assessment of GI surgery; Clarify and standardize the methodology for allocating funds for new projects. Over the course of the next few years, the SSAT will: Develop a financial model that increases revenue to support the expanded tasks the society intends to undertake; Play an active role in developing the evolving training paradigms for gastrointestinal surgeons through the continuum from residency, fellowship, and early mentored practice; Continue to support development of surgeon scientists through Career Development Award; Enhance relationship with the SSAT Foundation; Continue to improve the experience of members attending DDW; Develop surgeons interested in public policy to be leaders at a national level. The strategic plan is ambitious, and the current leadership realizes that all the tasks and objectives cannot be accomplished in 1 year. There is much to do in order to keep the SSAT the premier professional society for gastrointestinal surgery. Changes in the external environment may require modifications of the priorities or the plan itself in the coming years. Implicit in this plan is the need for annual review by the Board of Trustees at the May Board Meeting so that modifications can be made as the world around us changes.

Background: Program directors in surgery are now facing the challenge of incorporating the ACGME's practice-based learning and improvement (PBLI) competency into residency curriculum. We introduced a comprehensive PBLI experience for postgraduate year 2 (PGY2) residents designed to integrate specific competency goals (ie, quality improvement, clinical thinking, and self-directed learning) within the context of residents' clinical practice., Study Design: Fourteen PGY2 residents participated in a 3-week PBLI curriculum consisting of 3 components: complex clinical decision making, individual learning plan, and quality improvement (QI). To assess how effectively the curriculum addressed these 3 competencies, residents rated their understanding of PBLI by answering a 12-question written survey given pre- and post-rotation. Resident satisfaction was assessed through standard post-rotation evaluations., Results: Analysis of the pre- and post-rotation surveys from the 14 participants showed an increase in all measured elements, including knowledge of PBLI (p < 0.001), ability to assess learning needs (p < 0.001), set learning goals (p < 0.001), understanding of QI concepts (p = 0.001), and experience with QI projects (p < 0.001). Fourteen QI projects were developed. Although many residents found the creation of measurable learning goals to be challenging, the process of identifying strengths and weaknesses enhanced the resident's self-understanding and contributed to overall satisfaction with the rotation., Conclusions: The initial implementation of our PBLI curriculum demonstrated that residents report personal progress in their clinical decision making, self-directed learning, and familiarity with QI. This comprehensive PBLI curriculum was accepted by surgical residents as a valuable part of their training. We are encouraged to continue a clinically grounded PBLI experience for PGY2 residents., (Copyright (c) 2010 American College of Surgeons. Published by Elsevier Inc. All rights reserved.)

Liver resection is the current standard treatment for patients with both primary and metastatic liver cancer. The principal causes of morbidity and mortality after liver resection are related to blood loss (typically between 0.5 and 1 L), especially in cases where transfusion is required. Blood transfusions have been correlated with decreased long-term survival, increased risk of perioperative mortality and complications. The goal of this study was to evaluate different designs of a radiofrequency (RF) electrode array for use during liver resection. The purpose of this electrode array is to coagulate a slice of tissue including large vessels before resecting along that plane, thereby significantly reducing blood loss. Finite Element Method models were created to evaluate monopolar and bipolar power application, needle and blade shaped electrodes, as well as different electrode distances. Electric current density, temperature distribution, and coagulation zone sizes were measured. The best performance was achieved with a design of blade shaped electrodes (5 x 0.1 mm cross section) spaced 1.5 cm apart. The electrodes have power applied in bipolar mode to two adjacent electrodes, then switched sequentially in short intervals between electrode pairs to rapidly heat the tissue slice. This device produces a ~1.5 cm wide coagulation zone, with temperatures over 97 masculineC throughout the tissue slice within 3 min, and may facilitate coagulation of large vessels.

Background: Improved outcomes have been associated with the use of adjuvant therapy after resection of pancreas adenocarcinoma. However, the frequency with which patients receive adjuvant therapy and the factors impacting its use remain largely undefined. We hypothesized that nonutilization of adjuvant therapy was primarily associated with patient comorbidity and onset of postoperative complications., Methods: A prospectively maintained database was reviewed to identify patients who underwent potentially curative resection of histologically confirmed pancreas adenocarcinoma at our institution from January 1996 to May 2007. Clinicopathological data and postoperative treatment history were collected to identify variables associated with receipt of adjuvant therapy., Results: Of 119 patients, 33% did not receive adjuvant therapy. The frequency with which patients underwent adjuvant therapy did not change over time. On multivariate analysis, patient age 70 years or greater, major postoperative complications, distal pancreatectomy, absence of nodal metastases, and absence of perineural invasion were associated with decreased utilization of adjuvant therapy., Discussion: One-third of patients in this contemporary dataset of patients did not go on to receive adjuvant therapy. The likelihood of receiving adjuvant treatment is negatively impacted by the course of postoperative recovery. Moreover, the fact that adjuvant therapy was undertaken less often for older patients and patients with favorable pathological features highlights the selection bias impacting the decision to pursue postoperative therapy for this disease. This selective utilization of postoperative therapy for patients with adverse oncological characteristics is likely to bias any retrospective analysis attempting to measure the efficacy of adjuvant treatment for pancreas adenocarcinoma.

Background: The use of staging laparoscopy has been highly institutional dependent. We sought to assess the incidence of occult intra-abdominal metastases identified at the time of staging laparoscopy for patients with either potentially resectable or locally advanced pancreatic adenocarcinoma (LAPC). We also compared the rate of occult metastases in patients who underwent staging laparoscopy versus laparotomy., Methods: Patients were confirmed to have potentially resectable or LAPC at a multidisciplinary hepatopancreaticobiliary conference. Patients with potentially resectable lesions were initially explored via staging laparoscopy or laparotomy, based on surgeon preference., Results: Over a 4-year period, 25 patients with potentially resectable tumors and 33 patients with LAPC were staged with laparoscopy, with an equivalent prevalence of occult metastases found at laparoscopy (28% potentially resectable vs. 33% LAPC, P = 0.8). Fifty-two patients with potentially resectable lesions were explored initially via laparotomy. Occult peritoneal metastases were more likely to be detected in patients with potentially resectable tumors that were explored via laparoscopy than via laparotomy (32% vs. 10%, P = 0.018)., Conclusions: Staging laparoscopy is more likely than open exploration to detect occult metastases. Current preoperative imaging inadequately identifies unresectable pancreatic adenocarcinoma; therefore, all patients with potentially resectable disease should undergo staging laparoscopy., (Copyright 2009 Wiley-Liss, Inc.)

Microwave ablation (MWA) is a minimally invasive technique increasingly used for thermal therapy of liver tumors. Effective MWA requires efficient interstitial antennas that destroy tumors and a margin of healthy tissue, in situ, while minimizing damage to the rest of the organ. Previously, we presented a method for optimizing MWA antenna designs by coupling finite element method models of antennas with a real-coded, multiobjective genetic algorithm. We utilized this procedure to optimize the design of a minimally invasive choke antenna that can be used to create near-spherical ablation zones of adjustable size (radius 1-2 cm) by adjusting treatment durations and a sliding structure of the antenna. Computational results were validated with experiments in ex vivo bovine liver. The optimization procedure yielded antennas with reflection coefficients below -30 dB, which were capable of creating spherical ablation zones up to 2 cm in radius using 100 W input power at 2.45 GHz with treatment durations under 2 min.

Purpose: Radiofrequency ablation (RFA) is a common treatment modality for surgically unresectable tumors. However, there is a high rate of both local and systemic recurrence., Experimental Design: In this preclinical study, we sought to enhance the antitumor effect of RFA by combining it with huKS-IL2 immunocytokine [tumor-specific monoclonal antibody fused to interleukin-2 (IL2)] in mice bearing CT26-KS colon adenocarcinoma. Mice were treated with RFA, huKS-IL2 via intratumoral injection, or combination therapy., Results: Treatment of mice bearing s.c. tumors with RFA and huKS-IL2 resulted in significantly greater tumor growth suppression and enhanced survival compared with mice treated with RFA or huKS-IL2 alone. When subtherapeutic regimens of RFA or huKS-IL2 were used, tumors progressed in all treated mice. In contrast, the combination of RFA and immunocytokine resulted in complete tumor resolution in 50% of mice. Treatment of a tumor with RFA and intratumoral huKS-IL2 also showed antitumor effects against a distant untreated tumor. Tumor-free mice after treatment with RFA and huKS-IL2 showed immunologic memory based on their ability to reject subsequent challenges of CT26-KS and the more aggressive parental CT26 tumors. Flow cytometry analysis of tumor-reactive T cells from mice with complete tumor resolution showed that treatment with RFA and huKS-IL2 resulted in a greater proportion of cytokine-producing CD4 T cells and CD8 T cells compared with mice treated with RFA or huKS-IL2 alone., Conclusions: These results show that the addition of huKS-IL2 to RFA significantly enhances the antitumor response in this murine model, resulting in complete tumor resolution and induction of immunologic memory.

Objective: Few studies have analyzed the impact of mentoring on general surgical graduates' future career choices. We attempted to characterize the impact mentoring had on choices made by graduates from our residency program regarding surgical subspecialty training., Methods: A 32 item web survey was sent to 99 graduates of a university general surgery program, who matriculated between 1985 and 2007. The intent of the questionnaire was to evaluate influences on future subspecialty choice. Focusing on the influence of mentoring, we compared graduates who indicated that an influential mentor was an important factor in their decision (MENTOR) to those respondents who ranked this factor as unimportant (OTHER). Results were analyzed using Fisher's exact test with significance determined at p < or = 0.05., Results: A total of 83 respondents (84%) answered the questionnaire (61 men, 18 women, 4 not indicated). Of these respondents, 61 (75%) indicated that an influential mentor was important or very important in choosing their specialty field (MENTOR). The most common fields of the mentors were general surgery (22%), surgical oncology (15%), and plastic surgery (13%). Protégés indicated that their decision to pursue a subspecialty was most influenced by the following mentor characteristics: demonstrating expertise (77%), being a role model (72%), and practicing professional integrity (70%). In the MENTOR group, the vast majority of respondents [72% (43/60)] were in the same field as their mentor (P = <0.0001). Protégés also tended to practice in the same setting as their mentor: All (8/8) of those who identified a mentor in a non-academic practice were also currently in a non-academic practice (P = 0.002). Respondents in a non-academic practice were more likely than those in academic practice to have identified their mentor before or during medical school [59% (20/34) versus 8% (2/26)]. Alternatively, 62% (16/26) of academic practitioners identified their mentor during their PGY 2 or 3 y compared to only 21% (7/34) of those in a non-academic practice (P = 0.003)., Conclusion: Mentored surgical residency graduates were likely to enter the same specialty and practice type as their mentor. Also, the timing of identifying a mentor was strongly correlated with future practice type. With increasing concerns about "the impending disappearance of the general surgeon" along with increasing growth in surgical sub-specialization, it is essential that all types of surgeons provide early and sustained mentorship to medical students and residents to help shape the future of surgery.

Background: In the absence of symptoms related to their primary tumor, patients with stage IV colorectal cancer can undergo medical treatment with their primary tumor in situ. In these patients, bowel obstruction is the most common primary tumor-related complication. We hypothesized that left-sided, circumferential, near-obstructing lesions and/or inability to advance the colonoscope beyond the primary tumor are associated with symptomatic bowel obstruction and are indications for prophylactic primary tumor resection (PTR) or colonic diversion., Patients and Methods: The medical oncology database of the University of Wisconsin Hospital was retrospectively reviewed. Inclusion criteria were presentation with stage IV colorectal cancer without previous treatment. Student's t-test and Fisher's exact test were used to compare continuous and noncontinuous variables, respectively., Results: Forty-nine patients met the inclusion criteria. None underwent colonic diversion or stenting during the course of their disease. At presentation, nine patients underwent PTR for obstructive symptoms. Forty percent of patients with high-risk colonoscopic lesions required PTR at presentation, compared with 3% of patients without high-risk findings. No patients with high-risk colonoscopic findings and/or left-sided lesions who did not undergo PTR at presentation developed symptoms of obstruction during medical therapy., Conclusion: In stage IV colorectal cancer, circumferential, near-obstructing lesions and inability to advance the colonoscope beyond the primary tumor are common colonoscopic findings and are associated with obstructive symptoms at the time of diagnosis. Left-sided lesions and/or high-risk colonoscopic findings do not predict bowel obstruction during medical treatment and should not be indications for prophylactic PTR or colonic diversion in asymptomatic patients.

We measured the ex vivo electrical conductivity of eight human metastatic liver tumours and six normal liver tissue samples from six patients using the four electrode method over the frequency range 10 Hz to 1 MHz. In addition, in a single patient we measured the electrical conductivity before and after the thermal ablation of normal and tumour tissue. The average conductivity of tumour tissue was significantly higher than normal tissue over the entire frequency range (from 4.11 versus 0.75 mS cm(-1) at 10 Hz, to 5.33 versus 2.88 mS cm(-1) at 1 MHz). We found no significant correlation between tumour size and measured electrical conductivity. While before ablation tumour tissue had considerably higher conductivity than normal tissue, the two had similar conductivity throughout the frequency range after ablation. Tumour tissue conductivity changed by +25% and -7% at 10 Hz and 1 MHz after ablation (0.23-0.29 at 10 Hz, and 0.43-0.40 at 1 MHz), while normal tissue conductivity increased by +270% and +10% at 10 Hz and 1 MHz (0.09-0.32 at 10 Hz and 0.37-0.41 at 1 MHz). These data can potentially be used to differentiate tumour from normal tissue diagnostically.

Introduction: An increasing number of women are entering the field of general surgery. Because surgical devices have traditionally been targeted at men, we hypothesized that, due to smaller hand size, female general surgery residents would have significantly more difficulty utilizing the "one size fits all" handles of disposable laparoscopic (lap) devices when compared with male residents., Methods: General surgery residents were anonymously surveyed at four university general surgery training programs. Participants were asked to describe their use of four disposable lap instruments: the lap stapler, lap Harmonic scalpel (Ethicon, Inc., Somerville, New Jersey), lap LigaSure (Valleylab, Boulder, Colorado), and lap retrieval bag. Data were tabulated and analyzed, comparing male with female residents for each instrument as well as according to glove size., Results: A total of 120 residents were asked to participate with 65 anonymous responses (28 women and 37 men). Women's median glove size was significantly smaller than men's (6.5 vs. 7.5, p<0.0001), whereas the clinical year and number of lap cases were not significantly different. Women reported the following devices more awkward than their male counterparts: lap stapler, lap Harmonic scalpel, and the lap LigaSure. Women were more likely to use two hands and describe these devices as "always awkward." When results were analyzed by glove size independently of gender we found that, with increasing glove size, residents were more likely to describe these devices as easy to use and used these devices with only one hand., Conclusions: Current disposable lap devices are not designed for individuals with small hands. Women have significantly smaller hands than their male counterparts and have difficulty with the "one size fits all" lap device handles. With the increasing number of women entering general surgery programs, this problem will likely persist until devices are designed for surgeons with small hand sizes.

Cryoablation is a minimally invasive ablation technique for primary and metastatic hepatic tumors. Inadequate freezing around large blood vessels due to the warm blood flow can lead to local recurrence, and thus, necessitates close application of a cryoprobe to the large blood vessels. In this study, we constructed a perfusion model with an ex vivo bovine liver and ablated the tissue around a large blood vessel with one or two cryoprobes applied to the side of the vessel. The finite-element computer model developed in our previous study was modified to include a blood vessel and its convective heat transfer to the vicinity of the blood vessel. We compared the predicted simulation results to those acquired from this ex vivo perfusion model. The results indicate that blood vessels act as a heat source and generate steep temperature profiles in the area next to the large blood vessel. After validation, the maximum allowable distance between the cryoprobe and the large blood vessel for successful cryoablation was presented. The results of this study should be considered when placing cryoprobes in the vicinity of large blood vessels.

Background: Hilar cholangiocarcinoma is an uncommon tumor with a poor prognosis. We sought to evaluate recurrence patterns and prognostic factors for disease-specific and disease-free survival in patients with surgically resected hilar cholangiocarcinoma in a single institution over the last 21 years., Methods: From 1985 to 2006, all patients with hilar cholangiocarcinoma referred to a tertiary surgical clinic were evaluated. Demographic data, tumor characteristics, and outcome were analyzed retrospectively. Outcome was compared in patients treated in a recent era (1995-2006) compared with an earlier era (1985-1994)., Results: Of 91 patients evaluated, 22 patients (24%) had unresectable disease at presentation. Of the 69 patients submitted to laparotomy, resection was possible in 55% and the curative (R0) resection rate was 63%. In patients submitted to exploration, the operative (60 day) morbidity and mortality rates were 26% and 3%. Median disease-specific (DSS) and disease-free survival (DFS) were 29 and 20 months, respectively (median FU, 29 months.). In patients undergoing R0 resection, the median survival was prolonged (65 months). In the more recent era, resectability rates improved (69% vs. 17%; P = 0.0002), and this was associated with an improvement in median survival (30 vs. 4 months; P < 0.001). Factors predictive of improved disease-specific and disease-free survival included negative histologic margins, concomitant hepatic lobectomy, lack of nodal disease, well-differentiated histology, and an earlier tumor stage (P < 0.05). Concomitant liver resection was associated with a higher R0 resection rate (P = 0.006) and improved DSS and DFS (P = 0.005). In addition, concomitant liver resection was associated with a decreased incidence of initial recurrence in liver (P = 0.031)., Conclusions: In patients with hilar cholangiocarcinoma, concomitant hepatic resection is associated with improved DFS, DSS, and decreased hepatic recurrence. Therefore, hepatectomy combined with bile duct resection should be considered standard treatment.

Objective: To analyze physician work production over a 5-year period to discover trends in productivity., Summary Background Data: Surgical workforce calculations over the past 25 years have projected major oversupply as well as looming shortages. Recent studies indicate that demand for surgical services will increase over the next two decades as the population ages and develops age related chronic diseases. This study examines actual physician productivity to determine whether there is capacity for increased work output in response to projected increases in demand., Methods: Physician productivity data as measured by relative value units were obtained from the Medical Group Management Association Physician Compensation Reports for a 5-year period. Surgeons were compared with nonsurgeons and across subspecialties., Results: Surgeon and nonsurgeon productivity in terms of relative value units remained relatively stable over the study period; surgical:nonsurgical productivity per provider was 1.30-1.46:1., Conclusions: Surgeons produce a significant amount of the total work in multi-specialty medical groups. These results may indicate that the surgical and general surgical workforce has reached a plateau with respect to clinical productivity. Predicted increases in demand for procedure-based work to care for the aging population are likely to be difficult to meet with the available workforce.

Hepatic resection is currently the standard treatment for liver cancer. During hepatic resection part of the liver containing the tumor is surgically removed. This type of surgery is accompanied by high blood loss of approximately 0.6-1.35 L. Blood loss is associated with increased complication rates, prolonged hospital stay, and reduced patient survival, especially when transfusion is required. Other researchers have suggested using radiofrequency (rf) or microwave ablation to coagulate a tissue slice before resection to reduce blood loss, but conventional devices typically take several hours. We developed a device consisting of a linear array of blade-shaped, 1 cm wide radiofrequency (rf) electrodes 1.5 cm apart. Bipolar rf power is applied between pairs of adjacent electrodes, leading to high tissue temperatures between the electrodes that promote coagulation of large vessels (>3 mm) in the resection plane. Rapid switching of applied power between pairs of adjacent electrodes allows simultaneous heating and coagulation of the entire resection plane within 3-6 min. In seven in vivo trials in a porcine model, resection along a plane pre-coagulated with the device resulted in little (<20 mL) to no blood loss, while coagulating all vessels (up to 4.5 mm diameter in this study). Average treatment time (from placement of the device to transection) was 6.8+/-0.5 min when four electrodes were used, and 11.3+/-1.2 min when 5-7 electrodes were used. This device may reduce blood loss related morbidity during resection and reduce treatment time by coagulating all vessels in the resection plane.

We describe the application of a Bayesian variable-number sample-path (VNSP) optimization algorithm to yield a robust design for a floating sleeve antenna for hepatic microwave ablation. Finite element models are used to generate the electromagnetic (EM) field and thermal distribution in liver given a particular design. Dielectric properties of the tissue are assumed to vary within +/- 10% of average properties to simulate the variation among individuals. The Bayesian VNSP algorithm yields an optimal design that is a 14.3% improvement over the original design and is more robust in terms of lesion size, shape and efficiency. Moreover, the Bayesian VNSP algorithm finds an optimal solution saving 68.2% simulation of the evaluations compared to the standard sample-path optimization method.

A new ultrawideband (UWB) microwave method to estimate tumor size based upon detection of the tumor/liver interface is proposed. This method involves monitoring the response of a broadband pulse launched down a coaxial treatment antenna and radiated into the tumor. By monitoring the peak in the returned signal, and estimating the propagation velocity within the tumor, the location of the tumor/liver interface can be determined and the size of a spherical lesion estimated. The feasibility of this technique is demonstrated by finite element (FE) electromagnetic simulations of a spherical tumor in the liver. Robustness to noise is also investigated as well as the effects of insertion depth. The promising outcome of this feasibility study suggests that further development of this technique should be pursued.

Background: Few studies have examined whether women and men identify the same factors as important in choosing their specialty. We sought to evaluate whether the factors influencing residents' choice of surgical specialty differed by gender., Study Design: A 32-item Web survey, designed to elucidate which factors motivated residents to seek fellowship training, was sent to 99 graduates of a university general surgery program, all of whom matriculated between 1985 and 2006., Results: A total of 74 (75%) respondents replied (16 women, 58 men). There was a higher proportion of men who pursued fellowship training than women (69% versus 38%, p=0.04), but there was no significant difference in those who were currently in academic practice (men, 46% versus women, 27%, p=0.2). Both genders were equally likely to respond that interest in and intellectual appeal of their field, clinical opportunities in that field, and having an influential mentor during residency were important in choosing their future specialty. But significantly more women listed lifestyle as an important factor in choosing their future careers (69% versus 43%, p=0.03). When respondents' data from the most recent decade were analyzed, there was no difference between genders in completion of fellowship training or in those in academic practice. But lifestyle continued to be more important to women., Conclusions: Both genders were influenced by many similar factors when deciding to pursue subspecialty training, but women were more likely than men to be influenced by their perception of the lifestyle associated with their career choice. These findings suggest that general surgical residency programs might improve efforts to recruit women by addressing the perception of the lifestyle associated with choosing a surgical career.

Background: Negative surgical margins minimize the risk of local recurrence after breast-conserving surgery. Intraoperative frozen section analysis (FSA) is one method for margin evaluation. We retrospectively analyzed records of patients who received breast-conserving therapy with intraoperative FSA of the lumpectomy cavity to assess re-excision rates and local control., Methods: Records were retrospectively reviewed for individuals who underwent breast-conserving surgery for ductal carcinoma in situ (DCIS) or invasive carcinoma between 1993 and 2003. Inclusion criteria were a minimum of 2 years follow-up and intact tumor at the time of operation. The major outcome measure was local recurrence. The Kaplan-Meier test was used to evaluate local recurrence rates between groups., Results: 290 subjects with an average age of 57.2 years (range 27-89) underwent 292 lumpectomies with FSA. 11.3% had DCIS, 73.3% had infiltrating ductal, 5.8% had infiltrating lobular, and 9.6% exhibited other forms of invasive carcinoma. 70 subjects underwent additional resection at the time of breast surgery, 16 underwent subsequent re-excision, and 17 underwent subsequent mastectomy. At a median follow-up of 53.4 months (range 5.8-137.8), there were six local recurrences (2.74%) in patients who had breast-conserving procedures and two local recurrences in patients who underwent mastectomy. There were no statistically significant associations among local recurrence rate, tumor size, nodal status, or overall stage. Local recurrences were higher in patients with DCIS compared with invasive carcinoma, and tumors >2cm., Conclusions: Intraoperative FSA allows resection of suspicious or positive margins at the time of lumpectomy and results in low rates of local recurrence and re-excision. The low local recurrence rate reported here is comparable to those reported with other margin assessment techniques.

Background: Lobular intraepithelial neoplasia (LIN) is associated with an increased risk of breast malignancy. The significance of LIN diagnosed at core needle biopsy (CNB) is unclear, although many groups recommend surgical excision to rule out lesions, which would require immediate, definitive therapy. Current management options include clinical/mammographic observation and surgical excision. The necessity of routine surgical excision remains controversial due to conflicting opinions on the biological behavior of lobular lesions, diagnostic confusion regarding histopathology, and uncertainty of their association with high-risk lesions. The purpose of this report was to review the published data regarding the incidence of high-risk lesions associated with LIN diagnosed at CNB to clarify the indications for surgical excision., Materials and Methods: A PubMed search was performed to identify all published articles in English addressing management of LIN diagnosed at CNB., Results: The 19 studies that form the basis of this report included a total of 504 subjects. Although the studies differed greatly in their content and methods, they were analyzed as a group for the presence of criteria deemed by the authors to be the most important information to include in a study regarding this issue and thus a reasonably good indicator of the quality of the literature. All of the studies were retrospective, nearly half were nonconsecutive series, and no study reported clear inclusion criteria for surgical excision versus observation. Limitations of the reviewed studies included their retrospective nature, small number of subjects, inconsistent inclusion criteria, and selection bias regarding surgical excision., Conclusions: Based on the reviewed literature, it is difficult to reach a firm evidence-based conclusion regarding optimal management of LIN diagnosed at CNB. Associated high-risk lesions increase the risk of upgrade, but there are no mammographic predictors. The available retrospective literature suggests that some cases of LIN are associated with higher-risk lesions identified on surgical excision but does not support routine excision for all patients.

Hepatic malignancies have historically been treated with surgical resection. Due to the shortcomings of this technique, there is interest in other, less invasive, treatment modalities, such as microwave hepatic ablation. Crucial to the development of this technique is the accurate knowledge of the dielectric properties of human liver tissue at microwave frequencies. To this end, we characterized the dielectric properties of in vivo and ex vivo normal, malignant and cirrhotic human liver tissues from 0.5 to 20 GHz. Analysis of our data at 915 MHz and 2.45 GHz indicates that the dielectric properties of ex vivo malignant liver tissue are 19 to 30% higher than normal tissue. The differences in the dielectric properties of in vivo malignant and normal liver tissue are not statistically significant (with the exception of effective conductivity at 915 MHz, where malignant tissue properties are 16% higher than normal). Also, the dielectric properties of in vivo normal liver tissue at 915 MHz and 2.45 GHz are 16 to 43% higher than ex vivo. No statistically significant differences were found between the dielectric properties of in vivo and ex vivo malignant tissue (with the exception of effective conductivity at 915 MHz, where malignant tissue properties are 28% higher than normal). We report the one-pole Cole-Cole parameters for ex vivo normal, malignant and cirrhotic liver tissue in this frequency range. We observe that wideband dielectric properties of in vivo liver tissue are different from the wideband dielectric properties of ex vivo liver tissue, and that the in vivo data cannot be represented in terms of a Cole-Cole model. Further work is needed to uncover the mechanisms responsible for the observed wideband trends in the in vivo liver data.

Effective eradication of established tumor and generation of a lasting systemic immune response are the goals of cancer immunotherapy. The objective of this phase IB study was to assess the safety and toxicity of treatment to metastatic tumor underlying the skin with the DNA encoding interleukin-12 (IL-12). This treatment strategy allowed the patient's own tumor to serve as a source of autologous antigen in the tumor microenvironment. We proposed that IL-12 protein produced by the transfected cells would result in the generation of both a local and systemic antitumor response. The tumor was treated with either three or six intratumoral injections of plasmid containing IL-12 DNA. This treatment strategy resulted in no significant local or systemic toxicity. The treatment did not result in an increase in serum IL-12 protein. The size of the treated lesion decreased significantly (greater than 30%) in five of the 12 patients. However, nontreated subcutaneous lesions or other disease did not decrease in size.

We propose a new method to study high temperature tissue ablation using an expanded bioheat diffusion equation. An extra term added to the bioheat equation is combined with the specific heat into an effective (temperature dependent) specific heat. It replaces the normal specific heat term in the modified bioheat equation, which can then be used at temperatures where water evaporation is expected to occur. This new equation is used to numerically simulate the microwave ablation of bovine liver and is compared to experimental ex vivo results.

The liver is a common site of disease for both primary and metastatic cancer. Since most patients have a disease that is not amenable to surgical resection, tumor ablation modalities are increasingly being used for treatment of liver cancer. This review describes the current status of ablative technologies used as alternatives for resection, clinical experience with these technologies, currently available devices and design rules for the development of new devices and the improvement of existing ones. It focuses on probe design for radiofrequency ablation, microwave ablation and cryoablation, and compares the advantages and disadvantages of each ablation modality.

Cryoablation is a widely used method for the treatment of nonresectable primary and metastatic liver tumors. A model that can accurately predict the size of a cryolesion may allow more effective treatment of tumor, while sparing normal liver tissue. We generated a computer model of tissue cryoablation using the finite-element method (FEM). In our model, we considered the heat transfer mechanism inside the cryoprobe and also cryoprobe surfaces so our model could incorporate the effect of heat transfer along the cryoprobe from the environment at room temperature. The modeling of the phase shift from liquid to solid was a key factor in the accurate development of this model. The model was verified initially in an ex vivo liver model. Temperature history at three locations around one cryoprobe and between two cryoprobes was measured. The comparison between the ex vivo result and the FEM modeling result at each location showed a good match, where the maximum difference was within the error range acquired in the experiment (< 5 degrees C). The FEM model prediction of the lesion size was within 0.7 mm of experimental results. We then validated our FEM in an in vivo experimental porcine model. We considered blood perfusion in conjunction with blood viscosity depending on temperature. The in vivo iceball size was smaller than the ex vivo iceball size due to blood perfusion as predicted in our model. The FEM results predicted this size within 0.1-mm error. The FEM model we report can accurately predict the extent of cryoablation in the liver.

Purpose: We examined in vivo particle-mediated epidermal delivery (PMED) of cDNAs for gp100 and granulocyte macrophage colony-stimulating factor (GM-CSF) into uninvolved skin of melanoma patients. The aims of this phase I study were to assess the safety and immunologic effects of PMED of these genes in melanoma patients., Experimental Design: Two treatment groups of six patients each were evaluated. Group I received PMED with cDNA for gp100, and group II received PMED with cDNA for GM-CSF followed by PMED for gp100 at the same site. One vaccine site per treatment cycle was biopsied and divided for protein extraction and sectioning to assess transgene expression, gold-bead penetration, and dendritic cell infiltration. Exploratory immunologic monitoring of HLA-A2(+) patients included flow cytometric analyses of peripheral blood lymphocytes and evaluation of delayed-type hypersensitivity to gp100 peptide., Results: Local toxicity in both groups was mild and resolved within 2 weeks. No systemic toxicity could be attributed to the vaccines. Monitoring for autoimmunity showed no induction of pathologic autoantibodies. GM-CSF transgene expression in vaccinated skin sites was detected. GM-CSF and gp100 PMED yielded a greater infiltration of dendritic cells into vaccine sites than did gp100 PMED only. Exploratory immunologic monitoring suggested modest activation of an antimelanoma response., Conclusions: PMED with cDNAs for gp100 alone or in combination with GM-CSF is well tolerated by patients with melanoma. Moreover, pathologic autoimmunity was not shown. This technique yields biologically active transgene expression in normal human skin. Although modest immune responses were observed, additional investigation is needed to determine how to best utilize PMED to induce antimelanoma immune responses.

We measured tissue temperature changes during ex vivo microwave ablation (MWA) procedures for bovine liver tissue. Tissue temperature increased rapidly at the beginning of the MW power application. It came to a plateau at 100 degrees C to 104 degrees C before it increased again. We split the changes of tissue temperature versus time into four phases. This suggests that tissue temperature changes may be directly related to tissue water related phenomena during MWA, including evaporation, diffusion, condensation and tissue water composition. An additional analysis indicated the lesion boundary at approximately 50 degres C to 60 degrees C temperature. We also measured the water content of ablated tissue lesions and examined the relationship of tissue water content and tissue temperature by mapping temperature to remaining tissue water after ablation. The results demonstrate significant tissue water content changes and lead to a better understanding of tissue water movement.

Phantoms are often used to simulate tissue during the development, testing and calibration of medical devices. In order to infer the specific absorption rate (SAR) and resistive heating in phantoms from temperature measurements, the specific heat capacity and density of the phantom are needed. Stauffer et al (2003 Int. J. Hyperth. 19 89-101) developed several phantoms that mimic dielectric properties of liver tissue at 915 MHz. However, thermal properties of the phantoms were not presented. We have measured specific heat capacities and densities for these phantoms. We also present dielectric properties for these phantoms measured from 0.7 to 20 GHz, including 2.45 GHz--a commonly used frequency for microwave hyperthermia and ablation.

We report a novel coaxial antenna for hepatic microwave ablation. This device uses a floating sleeve, that is, a metal conductor electrically isolated from the outer connector of the antenna coaxial body, to achieve a highly localized specific absorption rate pattern that is independent of insertion depth. This floating sleeve coaxial dipole antenna has low power reflection in the 2.4-GHz IMS band. Ex vivo experiments confirm our numerical simulation results. Index Terms-Ablation, coaxial aperture antennas, finite element methods, floating sleeve, microwave heating.

We measured the specific heat of liver tissue in vitro by uniformly heating liver samples between two electrodes. We insulated the samples by expanded polystyrene, and corrected for heat loss and water loss. The specific heat of the liver is temperature-dependent, and increases by 17% at 83.5 degrees C (p < 0.05), compared to temperatures below 65 degrees C. The average specific heat was 3411 J kg(-1)K(-1) at 25 degrees C, and 4187 J kg(-1)K(-1) at 83.5 degrees C. Water loss from the samples was significant above 70 degrees C, with approximately 20% of reduction in sample mass at 90 degrees C.

Background: An axisymmetric finite element method (FEM) model was employed to demonstrate important techniques used in the design of antennas for hepatic microwave ablation (MWA). To effectively treat deep-seated hepatic tumors, these antennas should produce a highly localized specific absorption rate (SAR) pattern and be efficient radiators at approved generator frequencies., Methods and Results: As an example, a double slot choked antenna for hepatic MWA was designed and implemented using FEMLABtrade mark 3.0., Discussion: This paper emphasizes the importance of factors that can affect simulation accuracy, which include boundary conditions, the dielectric properties of liver tissue, and mesh resolution.