National Cluster-Randomized Trial of Duty-Hour Flexibility in Surgical Training.

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.).

ERCP in potentially resectable malignant biliary obstruction is frequently unsuccessful when performed outside of a comprehensive pancreaticobiliary center.

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.

Association between hospital imaging use and venous thromboembolism events rates based on clinical data.

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.

Neoadjuvant Chemotherapy is Associated With Decreased Survival in Early-Stage Gastric Cancer.

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.

Surgeons' perceptions of public reporting of hospital and individual surgeon quality.

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.

Feast or famine? The variable impact of coexisting fellowships on general surgery resident operative volumes.

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").

Synchronous Upper Intestinal Neurofibromas and Duodenal Periampullary Well-Differentiated Neuroendocrine Tumor Associated With Neurofibromatosis 1.

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.

Impact of selection bias on the utilization of adjuvant therapy for pancreas adenocarcinoma.

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.

What is Elective Oncologic Surgery in the Time of COVID-19? A Literature Review of the Impact of Surgical Delays on Outcomes in Patients with Cancer.

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.

Colonoscopic findings and tumor site do not predict bowel obstruction during medical treatment of stage IV colorectal cancer.

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.

Surgical career choices: the vital impact of mentoring.

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.

Staging laparoscopy enhances the detection of occult metastases in patients with pancreatic 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.

Electrical conductivity measurement of excised human metastatic liver tumours before and after thermal ablation.

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.

Resection of hilar cholangiocarcinoma: concomitant liver resection decreases hepatic recurrence.

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.

Design optimization of a robust sleeve antenna for hepatic microwave ablation.

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 phase I study of immunization using particle-mediated epidermal delivery of genes for gp100 and GM-CSF into uninvolved skin of melanoma patients.

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.

One size does not fit all: current disposable laparoscopic devices do not fit the needs of female laparoscopic surgeons.

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.

Feasibility study of tumor size estimation through time domain peak monitoring.

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.

Dielectric properties of human normal, malignant and cirrhotic liver tissue: in vivo and ex vivo measurements from 0.5 to 20 GHz using a precision open-ended coaxial probe.

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.

Expanding the bioheat equation to include tissue internal water evaporation during heating.

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.