Validation of the Finite Element Model versus Biomechanical Assessments of Dental Implants and Total Knee Replacements.

Computer modeling and simulation (CM&S) technology is widely used in the medical device industry due to its advantages such as reducing testing time and costs. However, the developer's parameter settings during the modeling and simulation process can have a significant impact on the results. This study developed a test model for the rotational shear strength of dental implants and the constraint force of total knee replacements based on CM&S technology and proposes ideal parameters to ensure reliability. For dental implants, the load area and sliding contact conditions were considered, and for total knee replacements, the friction coefficient, medial-lateral displacement, valgus-varus rotation, and elastic modulus were considered. By comparing the simulation results and mechanical tests, boundary conditions with an error rate of less than 1.5% were selected. When a jig (gripper and collector) was applied with the same boundary conditions, an error rate of 48~22% occurred; otherwise, it was confirmed that the error rate was within 10~0.2%. The FE model was verified with an error of 2.49 to 3% compared to the mechanical test. The friction coefficient variable had the greatest influence on the results, accounting for 10 to 13%, and it was confirmed that valgus-varus rotation had a greater influence on the results than medial-lateral displacement. Relatively, the elastic modulus of the insert had the least effect on the results. These research results are expected to make CM&S techniques useful as a medical device digital development tool (M3DT) in the development of total knee replacements and dental implants.

Biomechanical and Biological Assessment of Polyglycelrolsebacate-Coupled Implant with Shape Memory Effect for Treating Osteoporotic Fractures.

Poly(glycerol sebacate) is a biocompatible elastomer that has gained increasing attention as a potential biomaterial for tissue engineering applications. In particular, PGS is capable of providing shape memory effects and allows for a free form, which can remember the original shape and obtain a temporary shape under melting point and then can recover its original shape at body temperature. Because these properties can easily produce customized shapes, PGS is being coupled with implants to offer improved fixation and maintenance of implants for fractures of osteoporosis bone. Herein, this study fabricated the OP implant with a PGS membrane and investigated the potential of this coupling. Material properties were characterized and compared with various PGS membranes to assess features such as control of curing temperature, curing time, and washing time. Based on the ISO 10993-5 standard, in vitro cell culture studies with C2C12 cells confirmed that the OP implant coupled with PGS membrane showed biocompatibility and biomechanical experiments indicated significantly increased pullout strength and maintenance. It is believed that this multifunctional OP implant will be useful for bone tissue engineering applications.

Feasibility of 3D-Printed Locking Compression Plates with Polyether Ether Ketone (PEEK) in Tibial Comminuted Diaphyseal Fractures.

The applicability of a polyether ether ketone locking compression plate (PEEK LCP) fabricated using FDM (fused deposition modeling)-based 3D printing to treat actual patients was studied. Three different tests-bending, axial compression, and axial torsion-were conducted on tibial non-osteoporotic comminuted diaphyseal fracture samples fixed with the commercial titanium alloy LCP and 3D-printed PEEK LCP. Comparing the outcomes of these tests revealed that the commercial titanium alloy LCP underwent plastic deformation in the bending and axial torsion tests, though the LCP did not fail even when an external force greater than the maximum allowable load of the tibia fixture of the LCP was applied. Elastic deformation occurred in the 3D-printed PEEK LCP in the bending and axial torsion tests. However, deformation occurred even under a small external force, and its stiffness was 10% compared to commercial titanium alloy LCP. Thus, 3D-printed PEEK LCP can be applied to the fracture conditions in non-weight-bearing regions. The experimental results reveal detailed insights into the treatment of actual patients by considering the stiffness and high toughness of 3D-printed PEEK LCP.

Safe Optimal Tear Drop View for Spinopelvic Fixation Using a Three-Dimensional Reconstruction Model of the Pelvis.

Background: Spinopelvic fixation (SPF) has been a challenge for surgeons despite the advancements in instruments and surgical techniques. C-arm fluoroscopy-guided SPF is a widely used safe technique that utilizes the tear drop view. The tear drop view is an image of the corridor from the posterior superior iliac spine to the anterior inferior iliac spine (AIIS) of the pelvis. This study aimed to define the safe optimal tear drop view using three-dimensional reconstruction of computed tomography images. Methods: Three-dimensional reconstructions of the pelvises of 20 individuals were carried out. By rotating the reconstructed model, we simulated SPF with a cylinder representing imaginary screw. The safe optimal tear drop view was defined as the one embracing a corridor with the largest diameter with the inferior tear drop line not below the acetabular line and the lateral tear drop line medial to the AIIS. The distance between the lateral border of the tear drop and AIIS was defined as tear drop index (TDI) to estimate the degree of rotation on the plane image. Tear drop ratio (TDR), the ratio of the distance between the tear drop center and the AIIS to TDI, was also devised for more intuitive application of our simulation in a real operation. Results: All the maximum diameters and lengths were greater than 9 mm and 80 mm, respectively, which are the values of generally used screws for SPF at a TDI of 5 mm and 10 mm in both sexes. The TDRs were 3.40 ± 0.41 and 3.35 ± 0.26 in men and women, respectively, at a TDI of 5 mm. The TDRs were 2.26 ± 0.17 and 2.14 ± 0.12 in men and women, respectively, at a TDI of 10 mm. Conclusions: The safe optimal tear drop view can be obtained with a TDR of 2.5 to 3 by rounding off the measured values for intuitive application in the actual surgical field.

Design Optimization of Additive Manufactured Edgeless Simple Cubic Lattice Structures under Compression.

This study proposed an optimization framework and methodologies to design edgeless lattice structures featuring fillet and multipipe functions. Conventional lattice structures typically experience stress concentration at the sharp edges of strut joints, resulting in reduced mechanical performance and premature failure. The proposed approach aimed to improve the compression behavior of lattice structures by introducing edgeless features. Through finite element analysis, the optimized fillet edgeless simple cubic unit cell with a fillet radius to strut radius ratio of 0.753 showed a 12.1% improvement in yield stress and a 144% reduction in stress concentration. To validate the finite element analysis, experimental compressive tests were conducted, confirming that the introduction of edgeless functions improved the compressive strength of lattice structures manufactured through additive manufacturing. The optimized fillet edgeless simple cubic lattice structure exhibited the most effective improvement. This approach has promising potential for lattice structure applications.

Chloride Diffusion by Build Orientation of Cementitious Material-Based Binder Jetting 3D Printing Mortar.

Binder jetting 3D printing (BJ3DP) is used to create geometrical and topology-optimized building structures via architectural geometric design owing to its high degree of freedom in geometry implementation. However, building structures require high mechanical and durability performance. Because of the recent trend of using 3D printing concrete as a structural component in reinforcing bars, its durability with respect to chloride penetration needs to be reviewed. Therefore, in this study, the compressive strength and durability of the chloride diffusion of cement-based 3D-printed output were evaluated. In addition, to confirm the performance difference based on the build orientation, the compressive strength and chloride diffusion were evaluated with respect to the build direction and transverse direction. The experimental results show that the compressive strength was approximately 22.1-26.5% lower in the transverse direction than in the build direction and that the chloride diffusion coefficient was approximately 186.1-407.1% higher in the transverse direction. Consequently, when a structure that requires long-term durability is produced using BJ3DP, it is necessary to examine the design and manufacturing methods in relation to the build orientation in advance.

Degradation Mechanisms of Solid Oxide Fuel Cells under Various Thermal Cycling Conditions.

A critical issue to tackle before successful commercialization of solid oxide fuel cells (SOFCs) can be achieved is the long-term thermal stability required for SOFCs to operate reliably without significant performance degradation despite enduring thermal cycling. In this work, the impact of thermal cycling on the durability of NiO-yttria-stabilized zirconia-based anode-supported cells is studied using three different heating/cooling rates (1, 2, and 5 °C min-1) as the temperature fluctuated between 400 and 700 °C. Our experiments simulate time periods when power from SOFCs is not required (e.g., as might occur at night or during an emergency shutdown). The decay ratios of the cell voltages are 8.8% (82 µV h-1) and 19.1% (187 µV h-1) after thermal cycling testing at heating/cooling rates of 1 and 5 °C min-1, respectively, over a period of 1000 h. The results indicate SOFCs that undergo rapid thermal cycling experience much greater performance degradation than cells that experience slow heating/cooling rates. The changes in total resistance for thermally cycled cells are determined by measuring the Rpol of the electrodes (whereas the ohmic resistances of the cells remain unchanged from their initial value), signifying that electrode deterioration is the main degradation mechanism for SOFCs under thermal cycling. In particular, fast thermal cycling leads to severe degradation in the anode part of SOFCs with substantial agglomeration and depletion of Ni particles seen in our characterizations with field emission-scanning electron microscopy and electron probe microanalysis. In addition, the mean particle size in the cathode after thermal cycling testing increases from 0.104 to 0.201 µm for the 5 °C min-1 cell. Further, the presence of Sr-enriched regions is more significant in the La0.6Sr0.4Co0.2Fe0.8O3-δ cathode after fast thermally cycled SOFCs.

Conventional versus helical blade screw insertion following the removal of the femoral head screw: a biomechanical evaluation using trochanteric gamma 3 locking nail versus PFN antirotation.

OBJECTIVE: When a hip screw needs to be changed, choosing between the conventional (C-type) and helical blade (H-type) types is difficult. In this biomechanical study, we compared these two screw types relative to the type of the initial screw used. METHODS: C- or H-type screws were inserted (leading screw) in three types of polyurethane bone models (Sawbone, Pacific Research Laboratories, Inc., Washington, USA: 130 × 180 × 40 mm) of different bone mineral densities (pounds per cubic feet [PCF] 5, 80 kg/m3; PCF 10, 160 kg/m3; and PCF 15, 240 kg/m3), and then successively or alternately inserted (following screw) after the leading screw removal. An original model (original C and H) of a leading screw without removal was created as a control. The strengths of resistance to pullout (PO) and rotational stress were measured. For each experimental condition, there were 30 experimental models. RESULTS: The original C screw was superior in PO strength, and the original H-type screw was superior in rotational strength. When the C- or H-type screw was the leading screw, using the C-type screw again as the following screw (C1-C2, H1-C2) showed the greatest resistance to PO, and using the H-type screw as the following screw (C1-H2, H1-H2) showed superior resistance to rotational strength. However, the rotational strength of the C2 screw decreased by more than 50% compared with that of the original C screw. Moreover, the PO and rotational strengths of the H2 screw decreased to less than 30% overall compared with those of the original H screw. CONCLUSION: The H-type screw should be used for second-time screw insertion procedures in cases where it is difficult to choose between PO and rotational strengths.

Surgical outcomes are hampered after endoscopic ultrasonography-guided ethanol lavage and/or Taxol injection in cystic lesions of the pancreas.

BACKGROUNDS/AIMS: Endoscopic ultrasonography-guided ethanol lavage and Taxol injection (EUS-ELTI) for pancreatic cystic lesions have been recently performed in some medical centers. The aim of this study was to optimize patient selection and analyze outcomes of patients who underwent surgeries after EUS-ELTI for pancreatic cystic lesions. METHODS: Among 310 patients who underwent EUS-ELTI between January 2007 and December 2014, 23 underwent surgeries after EUS-ELTI owing to incomplete treatment and/or adverse events. Surgical outcomes of patients who underwent surgeries after EUSELTI were evaluated. Clinical outcomes of patients who underwent surgeries after EUS-ELTI were then retrospectively compared with those of patients who underwent upfront surgery for left-sided pancreatic lesions without an EUS-ELTI procedure. RESULTS: The pathology revealed degenerated cysts in 12 patients, mucinous cyst neoplasms in five, neuroendocrine tumors in two, intraductal papillary mucinous neoplasm (IPMN) in one, solid pseudopapillary tumor in one, pancreatic ductal adenocarcinoma arising from an IPMN in one, and hepatoid carcinoma in one. Twelve patients underwent laparoscopic distal pancreatectomy and five patients underwent open distal pancreatectomy. When clinical outcomes were retrospectively compared between patients who underwent laparoscopic distal pancreatectomy after EUS-ELTI and those who did not receive an EUS-ELTI procedure, the spleen-preserving rate was 0% in the EUS-ELTI group and 61.7% (365/592) in the control group (p < 0.001). CONCLUSIONS: Surgical outcomes are compromised after EUS-ELTI for cystic tumor of the pancreas. Further studies are needed to investigate the efficacy and safety of the EUS-ELTI procedure.

Design Optimization of Lattice Structures under Compression: Study of Unit Cell Types and Cell Arrangements.

Additive manufacturing enables innovative structural design for industrial applications, which allows the fabrication of lattice structures with enhanced mechanical properties, including a high strength-to-relative-density ratio. However, to commercialize lattice structures, it is necessary to define the designability of lattice geometries and characterize the associated mechanical responses, including the compressive strength. The objective of this study was to provide an optimized design process for lattice structures and develop a lattice structure characterization database that can be used to differentiate unit cell topologies and guide the unit cell selection for compression-dominated structures. Linear static finite element analysis (FEA), nonlinear FEA, and experimental tests were performed on 11 types of unit cell-based lattice structures with dimensions of 20 mm × 20 mm × 20 mm. Consequently, under the same relative density conditions, simple cubic, octahedron, truncated cube, and truncated octahedron-based lattice structures with a 3 × 3 × 3 array pattern showed the best axial compressive strength properties. Correlations among the unit cell types, lattice structure topologies, relative densities, unit cell array patterns, and mechanical properties were identified, indicating their influence in describing and predicting the behaviors of lattice structures.

The Effective Fixation Level for Cosmetic Lateral Canthoplasty.

BACKGROUND: In previous reports of lateral canthoplasty, the components of the inferior retinaculum were mostly secured to the lateral orbital rim at a level around the pupil or superior limbus. However, that level is not adjustable in young patients who want to lengthen the short palpebral fissure for cosmetic purposes. Moreover, the anchoring method based on the palpebral portion can also be inconvenient and ineffective. Thus, the authors report an effective fixation level of the lateral orbital rim to lengthen and widen the lateral palpebral fissure. METHODS: From June 2015 to August 2017, 202 women and 44 men underwent cosmetic lateral canthoplasty (mean age 28.4 ±â€Š2.8 years old). The lower lid component of the lateral retinaculum was identified and selectively released through a small incision at the lateral commissure. Then, the released retinaculum was secured to the periosteum of the inner aspect of the lateral orbital wall. The fixation level corresponded to the most concave portion or immediately below the most concave point (1 to 2 mm below). RESULTS: Cosmetic lateral canthoplasty was successfully performed in all cases. No severe complications were observed. There were some minor complications. In most cases, the lateral palpebral fissure was naturally reshaped into a wider and brighter contour. Almost all of the patients were satisfied with the results of the treatment. CONCLUSIONS: The anchoring procedure at the most concave portion of the lateral orbital rim, which corresponds to the level of the inferior edge of the limbus or medial epicanthus, consistently resulted in a brighter and wider shape of the lateral palpebral fissure. Fixation based on the bony portion, compared to palpebral portion, offers several advantages as follows: effective lengthening and widening the lateral palpebral fissure; ease of application; symmetry with consistent final results; and minimal occurrences of overcorrection and undercorrection.

Prognostic comparison of the longitudinal margin status in distal bile duct cancer: R0 on first bile duct resection versus R0 after additional resection.

BACKGROUND: This study investigated survival differences following intra-operative frozen-section examination of bile duct resection margins and final longitudinal margin status (LMS) in distal bile duct cancer (BDC). METHODS: One hundred and ninety-three patients underwent Whipple's operation for curative resection of distal BDC from 2008 to 2016. Patients were sorted into two and three groups according to LMS of the frozen-sections and the final pathological specimen results: R0 on first bile duct resection (primary R0), R0 after additional resection (secondary R0), and no evidence of residual carcinoma (FR0), carcinoma in situ or high-grade dysplasia (FR1-CIS/HGD), or invasive carcinoma (FR1-INV). Survival and prognostic factors according to LMS were analyzed. RESULTS: The final R0 ratio increased from 82.3% to 90.1% through additional resection. The 5-year overall survival (OS) of primary and secondary R0 were 60.8%, 46.1% (P = 0.969). And disease-free survival of primary and secondary R0 were 54.6%, 54.9% (P = 0.903). The 5-year OS after FR0, FR1-CIS/HGD, FR1-INV were 59.3%, 59.5%, 14.3% (P = 0.842). LMS of the bile duct was an independent prognostic factor by multivariable analyses. CONCLUSIONS: If R0 of final LMS was achieved, it would help to improve survival regardless of R0 through additional resection. And, it should be avoided remaining invasive cancer at the longitudinal margin whenever possible.

The feasibility of robotic left-side hepatectomy with comparison of laparoscopic and open approach: Consecutive series of single surgeon.

BACKGROUND: Recent studies report safety and effectiveness of robotic hepatectomy. In present study, we describe our initial experiences with robotic hepatectomy, focusing on left-side procedures. METHODS: A retrospective review was conducted of 13, 10, and 11 consecutive patients who underwent robotic, laparoscopic, and open left-side hepatectomy by the single surgeon. RESULTS: There were no significant differences in the estimated blood loss, application of Pringle maneuver, postoperative hospital stays, number of IV analgesic injections, or postoperative complications between the robotic and laparoscopic groups. The robotic group had a smaller number of patients applied a Pringle maneuver (8.3 vs 90.9%, P < 0.001), a shorter postoperative hospital stays (7.0 vs 9.0 days, P = 0.044), and a less use of IV analgesics (2.8 vs 8.2, P = 0.005) than the open group. CONCLUSIONS: From our initial experiences, a robotic left-side hepatectomy seems to be a feasible and safe procedure when compared with the laparoscopic and open left-side hepatectomies.

Validation of the Eighth American Joint Committee on Cancer Staging System for Distal Bile Duct Carcinoma.

PURPOSE: T category of the eighth edition of the American Joint Committee on Cancer (AJCC) staging system for distal bile duct carcinoma (DBDC) was changed to include tumor invasion depth measurement, while the N category adopted a 3-tier classification system based on the number of metastatic nodes. MATERIALS AND METHODS: To validate cancer staging, a total of 200 surgically resected DBDCs were staged and compared according to the seventh and eighth editions. RESULTS: T categories included T1 (n=37, 18.5%), T2 (n=114, 57.0%), and T3 (n=49, 24.5%). N categories included N0 (n=133, 66.5%), N1 (n=50, 25.0%), and N2 (n=17, 8.5%). Stage groupings included I (n=33, 16.5%), II (n=150, 75.0%), and III (n=17, 8.5%). The overall 5-year survival rates (5-YSRs) of T1, T2, and T3 were 59.3%, 42.4%, and 12.2%, respectively. T category could discriminate patient survival by both pairwise (T1 and T2, p=0.011; T2 and T3, p < 0.001) and overall (p < 0.001) comparisons. The overall 5-YSRs of N0, N1, and N2 were 47.3%, 17.0%, and 14.7%, respectively. N category could partly discriminate patient survival by both pairwise (N0 and N1, p < 0.001; N1 and N2, p=0.579) and overall (p < 0.001) comparisons. The overall 5-YSRs of stages I, II, and III were 59.0%, 35.4%, and 14.7%, respectively. Stages could distinguish patient survival by both pairwise (I and II, p=0.002; II and III, p=0.015) and overall (p < 0.001) comparisons. On multivariate analyses, T and N categories (p=0.014 and p=0.029) and pancreatic invasion (p=0.006) remained significant prognostic factors. CONCLUSION: The T andNcategories of the eighth edition AJCC staging system for DBDC accurately predict patient prognosis.

Clinicopathologic Characteristics and Optimal Surgical Treatment of Duodenal Gastrointestinal Stromal Tumor.

BACKGROUND: The clinicopathologic characteristics of duodenal gastrointestinal stromal tumor (GIST) were unclear and the optimal surgical procedure for duodenal GIST remains poorly defined. We aimed to analyze clinicopathological characteristics, survival outcomes based on the surgical procedure, and recommend optimal surgical treatment for duodenal GIST. METHODS: From July 2000 to April 2017, 118 patients with localized duodenal GIST underwent curative surgical resection at a single institution. We retrospectively reviewed the clinicopathological characteristics and survival outcomes. RESULTS: The 5-year overall survival (OS) and disease-free survival (DFS) rates were 94.9 and 79.2%, respectively. On multivariate analysis, the mitotic count was a statistically significant prognostic factor for DFS. Limited resection (LR) was performed in 20 patients with GIST in the first or fourth portion of the duodenum. Both LR and pancreaticoduodenectomy (PD) were performed in 98 patients with GIST in second or third portion of the duodenum. The patients in the LR group had less late complications than in the PD group and no postoperative newly developed diabetes mellitus. The minimally invasive LR (MI-LR) group had a shorter duration of surgery and shorter length of postoperative hospital stay. CONCLUSION: LR is a feasible and effective surgical treatment for patients with small-sized and antimesenteric-sided duodenal GIST in terms of late complications and postoperative diabetic complications. MI-LR has better perioperative outcomes than open LR. Therefore, we should consider MI-LR as an optimal surgical treatment for selected patients with duodenal GIST.

Robot resection of a choledochal cyst with Roux-en-y hepaticojejunostomy in adults: Initial experiences with 22 cases and a comparison with laparoscopic approaches.

BACKGROUNDS/AIMS: In adult choledochal cysts, complete excision of cyst with Roux-en-Y hepaticojejunostomy by laparoscopy is typically been performed, but there is now a trend towards adopting robot-assisted resection. METHODS: From January 2014 to December 2017, 22 patients who underwent robotic procedure were classified as Group 1, and 34 patients who underwent the same laparoscopic procedure as Group 2. In addition, from September 2009 to July 2011, 13 patients who underwent laparoscopic procedure were classified as Group 3. The perioperative outcomes and short-term postoperative morbidity levels were evaluated in three groups. RESULTS: In all groups, there were more women than men, and the mean age and BMI did not differ significantly. Since 2014, jejunojejunostomy was performed extracorporeally and the mean operation time was shorter in Group 1 (258.5±52.9 min) and Group 2 (236.2±62.9 min) than Group 3 (395.2±85.9 min). [p=0.00 (1 vs 3), 0.00 (2 vs 3)] The median hospital stay was 7 days in Group 1 and 2, and shorter than 9 days in Group 3. [p=0.00 (1 vs 3), 0.011 (2 vs 3)] In Group 1, there were three postoperative complications, which included cholangitis, bile leakage and umbilical herniation, respectively). In Group 2, there were seven of postoperative complications, which included choledochojejunostomy site stricture & intrahepatic duct stone, choledochojejunostomy site stone, jejunal branch bleeding, portal vein thrombus, acute pancreatitis, adhesive ileus, and A-loop syndrome. In Group 3, there were three of postoperative complications, which included 2 hepaticojejunostomy site stricture and 1 paralytic ileus. CONCLUSIONS: Robot-assisted resection of a choledochal cyst with Roux-en-y hepaticojejunostomy is a safe and feasible approach with short-term results that are comparable to those of laparoscopic surgery.

Pancreatectomy for a secondary metastasis to the pancreas: A single-institution experience.

The aim of the present study was to evaluate the short- and long-term outcomes of secondary metastasis to the pancreas in terms of overall survival (OS) and disease-free survival (DFS) after pancreatectomy.This retrospective study included 29 patients who underwent pancreatectomy for secondary metastasis to the pancreas between December 1995 and August 2016.The study group was divided into renal cell carcinoma (RCC) (17 patients) and non-RCC (12 patients). The non-RCC group had 5 cases of colorectal cancer and 7 of another primary origin. The OS for the whole cohort was 86.2% at 1 year, 63.2% at 3 years, and 46.7% at 5 years. There was no significant difference between the 2 groups at 1, 3, and 5 years survival and OS. In subgroup analysis of patients who underwent curative resection, there was no significant difference in OS between the 2 groups at 1, 3, and 5 years. However, there was a significant difference in recurrence rate at 3 years (P = .035). Pathologic analysis showed that the non-RCC group had significantly more positive lymph node metastasis than the RCC group (P = .002).Pancreatectomy for secondary metastasis has promising short- and long-term outcomes in terms of OS and DFS.

Transduodenal ampullectomy for ampullary tumors - single center experience of consecutive 26 patients.

PURPOSE: Transduodenal ampullectomy (TDA) has been reported in a limited number of cases and in a small number of case series. The aim of this study was to analyze perioperative and long-term oncological outcomes of patients with ampullary tumors who underwent TDA in a single large-volume center. METHODS: Through a retrospective review of data from 2004 to 2016, we identified 26 patients who underwent TDA at Asan Medical Center. RESULTS: Eleven of 26 patients underwent TDA for T1 and carcinoma in situ (high-grade dysplasia) cancer; these patients are still alive without recurrence. A major in-hospital complication (3.8%) occurred in 1 case, but there was no case of 90-day mortality. In addition, none of the patients was diagnosed as having newly developed diabetes mellitus after TDA. No significant differences were found between open and laparoscopic-TDA in terms of operation time, painkiller use, and hospital stay. CONCLUSION: TDA is a feasible and effective surgical procedure for the treatment of selected patients with ampullary tumors. It is an alternative treatment option in cases of ampullary tumors not amenable to endoscopic papillectomy or pancreaticoduodenectomy.

Chronologic changes in clinical and survival features of pancreatic ductal adenocarcinoma since 2000: A single-center experience with 2,029 patients.

BACKGROUND: To identify chronologic changes in clinical and survival features of pancreatic ductal adenocarcinoma based on diagnosis and treatment strategy development since 2000. METHODS: Among 2,029 patients enrolled in this study, 746 and 1,283 were treated between 2000 and 2009 (group 1) and between 2010 and 2016 (group 2), respectively. We used patient clinicopathologic, biologic, and molecular factors to assess the prognostic factors. RESULTS: Group 2 had a better survival outcome than group 1 (median survival time: 24.9 versus 18.4 months; 5-year survival rate: 27.6% versus 22.3%). The tendency for early diagnosis (lower CA19-9 levels, smaller size, and earlier T stage), use of neoadjuvant chemotherapy, decreased morbidity, early recovery (lesser hospital stay and more minimally invasive surgery), and standardization of surgical techniques appeared to improve patient survival. Multivariable analysis for prognosis revealed that tumor biologic factors (increased preoperative serum CA19-9 level, tumor size, tumor differentiation, N stage, and presence of lymphovascular invasion), operational factors (status of the resection margin, type of operation, and year of operation), and genetic factors (K-ras mutations) correlated with patient survival. CONCLUSION: Early diagnosis and combined efforts, such as neoadjuvant chemotherapy and an established system of patient care, have gradually enhanced patient survival after operative resection for pancreatic ductal adenocarcinoma. Hence, multiplex prognostic parameters could provide additional information for improved prognostic estimation of pancreatic cancer exhibiting heterogeneous results.

Diagnostic value of chromogranin A in pancreatic neuroendocrine tumors depends on tumor size: A prospective observational study from a single institute.

BACKGROUND: Chromogranin A has recently been recommended as the most practical tumor marker in patients with pancreatic neuroendocrine tumors. However, the diagnostic effectiveness of circulating chromogranin A levels remains controversial. Here, we aimed to assess the clinical diagnostic value of plasma chromogranin A levels for pancreatic neuroendocrine tumors. METHODS: Between June 2012 and June 2015, 110 consecutive patients with a suspected pancreatic neuroendocrine tumor were prospectively enrolled. We evaluated the diagnostic value of the chromogranin A assay for differentiating pancreatic neuroendocrine tumors from other tumors. The plasma chromogranin A levels in the pancreatic neuroendocrine tumor patients were examined according to various clinicopathologic factors. RESULTS: A total of 65 patients were diagnosed as having pancreatic neuroendocrine tumors, whereas 45 had other tumors. The median chromogranin A level in pancreatic neuroendocrine tumor cases was higher than that in cases of other tumors (pancreatic neuroendocrine tumors: 126.62 ng/mL, other tumors: 69.82 ng/mL). The sensitivity, specificity, and accuracy of the chromogranin A assay for pancreatic neuroendocrine tumor diagnosis were 49.2%, 77.8%, and 60.9%, respectively. The chromogranin A levels after operative resection were reduced or were confirmed as being within the normal range (78.9%) in most cases. Moreover, the chromogranin A level in pancreatic neuroendocrine tumors cases was correlated with tumor size based on comparisons with other tumors in the pancreas (P = .038). The sensitivity, specificity, and accuracy of the chromogranin A assay for large tumors were greater, at 64.3%, 100.0%, and 81.5%, respectively. CONCLUSION: In clinical settings, the identification of pancreatic neuroendocrine tumors is vital for the development of therapeutic strategies. In large pancreatic tumors, the measurement of chromogranin A levels is very useful for distinguishing pancreatic neuroendocrine tumors from other tumors in the pancreas.