Heavy metals in ENDS: a comparison of open versus closed systems purchased from the USA, England, Canada and Australia.

INTRODUCTION: Electronic nicotine delivery systems (ENDS) are known to contain heavy metals such as lead (Pb), nickel (Ni) and chromium (Cr). The presence of heavy metals in ENDS may be due to contamination of e-liquids or leaching from elements of the ENDS device. This study investigates differences in ENDS metal concentrations between product type, year of purchase, country of purchase and e-liquid flavour. METHODS: Various open-system (refill e-liquids; n=116) and closed-system (prefilled with e-liquid; n=120) products were purchased in 2017 and 2018 from the USA, England, Canada and Australia. Electrothermal atomic absorption spectroscopy was used to analyse each product for Pb, Ni and Cr. Multiple linear regression and Kruskal-Wallis non-parametric statistical tests were conducted using GraphPad. RESULTS: Linear regression showed system type, year of purchase (not supported by Kruskal-Wallis), country of purchase and flavour type each had significant impacts on heavy metal concentrations. Open-system e-liquid samples showed no quantifiable levels of heavy metals. Closed-system samples contained concerningly high concentrations of Pb, Ni and Cr. Closed-system samples from the USA commonly displayed higher average heavy metal concentrations than those from England. Some fruit and mint-flavoured closed-system products showed higher heavy metal concentrations than tobacco-flavoured products. CONCLUSION: The presence of heavy metals only in closed-system products suggests that metals may be leaching from ENDS device parts. Highly variable heavy metal concentrations between ENDS products demonstrate that various product characteristics may affect the degree of leaching and that there is a need for further regulation of these products.

Clinicopathologic analysis of intraductal papillary neoplasm of bile duct: Korean multicenter cohort study.

BACKGROUND: IPNB is very rare disease and most previous studies on IPNB were case series with a small number due to low incidence. The aim of this study is to validate previously known clinicopathologic features of intraductal papillary neoplasm of bile duct (IPNB) based on the first largest multicenter cohort. METHODS: Among 587 patients previously diagnosed with IPNB and similar diseases from each center in Korea, 387 were included in this study after central pathologic review. We also reviewed all preoperative image data. RESULTS: Of 387 patients, 176 (45.5%) had invasive carcinoma and 21 (6.0%) lymph node metastasis. The 5-year overall survival was 80.9% for all patients, 88.8% for IPNB with mucosal dysplasia, and 70.5% for IPNB with invasive carcinoma. According to the "Jang & Kim's modified anatomical classification," 265 (68.5%) were intrahepatic, 103 (26.6%) extrahepatic, and 16 (4.1%) diffuse type. Multivariate analysis revealed that tumor invasiveness was a unique predictor for survival analysis. (p = 0.047 [hazard ratio = 2.116, 95% confidence interval 1.010-4.433]). CONCLUSIONS: This is the first Korean multicenter study on IPNB through central pathologic and radiologic review process. Although IPNB showed good long-term prognosis, relatively aggressive features were also found in invasive carcinoma and extrahepatic/diffuse type.

Fast resist-activation dosimetry for extreme ultra-violet lithography.

Due to the rather broad band emission spectrum of the extremely hot plasma in its extreme ultra-violet (EUV) source, an EUV lithography scanner also projects out-of-band vacuum- and deep-UV (OoB V/DUV) light on the photoresist on a wafer. As this type of uncontrolled and undesirable light can activate resist chemistry, it will impair the critical dimension uniformity of the patterns, especially across the borders of the fields. Hence, OoB V/DUV quantification technology is required in the pre-production phase. For this reason, the systematic characterization of the EUV-source emission spectrum and the spatial profile of the light as projected on the wafer is indispensable to sustain stable integrated circuit production with EUV lithography. This paper introduces an in-band EUV and OoB V/DUV dosimetry method that is based on enhanced energy sensitivity by resist contrast (EESRC). This dosimetry method is applied in an EUV lithography tool to quantitatively analyze the spatial distribution the resist activation by in-band EUV and OoB V/DUV light, under several exposure conditions. This pragmatic approach can replace the current best-practice of measuring the full spectrum of an EUV light source.

Contrast Agent-Free 3D Renal Ultrafast Doppler Imaging Reveals Vascular Dysfunction in Acute and Diabetic Kidney Diseases.

To combat the irreversible decline in renal function associated with kidney disease, it is essential to establish non-invasive biomarkers for assessing renal microcirculation. However, the limited resolution and/or vascular sensitivity of existing diagnostic imaging techniques hinders the visualization of complex cortical vessels. Here, a 3D renal ultrafast Doppler (UFD) imaging system that uses a high ultrasound frequency (18 MHz) and ultrahigh frame rate (1 KHz per slice) to scan the entire volume of a rat's kidney in vivo is demonstrated. The system, which can visualize the full 3D renal vascular branching pyramid at a resolution of 167 µm without any contrast agent, is used to chronically and noninvasively monitor kidneys with acute kidney injury (AKI, 3 days) and diabetic kidney disease (DKD, 8 weeks). Multiparametric UFD analyses (e.g., vessel volume occupancy (VVO), fractional moving blood volume (FMBV), vessel number density (VND), and vessel tortuosity (VT)) describe rapid vascular rarefaction from AKI and long-term vascular degeneration from DKD, while the renal pathogeneses are validated by in vitro blood serum testing and stained histopathology. This work demonstrates the potential of 3D renal UFD to offer valuable insights into assessing kidney perfusion levels for future research in diabetes and kidney transplantation.

Cryopreserved allografts versus end-to-end anastomosis for the reconstruction of a segment-resected portomesenteric vein during advanced pancreatic cancer surgery.

BACKGROUND: Porto-mesenteric vein (PMV) infiltration of pancreatic cancer is classified as borderline resectable cancer. For en-bloc resectability, the probability of PMV resection and reconstruction is the most decisive factor. The purpose of this study was to compare and analyze PMV resection and reconstruction during pancreatic cancer surgery using end-to-end anastomosis (EA) and a cryopreserved allograft (AG) and to verify the effectiveness of reconstruction using an AG. METHODS: Between May 2012 and June 2021, 84 patients (65 underwent EA, and 19 received AG reconstruction) underwent pancreatic cancer surgery with PMV reconstruction. An AG is a cadaveric graft with a diameter of 8-12 mm and is obtained from a liver transplant donor. Patency after reconstruction, disease recurrence, overall survival, and perioperative factors were assessed. RESULTS: The median age was higher in EA patients (p = .022) and neoadjuvant therapy (p = .02) was more in AG patients. Upon histopathological examination, the R0 resection margin did not show a significant difference by reconstruction method. During a 36-month survival analysis, primary patency was significantly superior in EA patients (p = .004), and there was no significant difference in recurrence-free survival (p = .628) or overall survival (p = .638) rates. CONCLUSION: Compared with EA, AG reconstruction after PMV resection during pancreatic cancer surgery showed a lower primary patency, but there was no difference in recurrence-free or overall survival rates. Therefore, the use of AG can be a viable option for borderline resectable pancreatic cancer surgery if the patient is properly followed-up postoperatively.

Different Oncologic Outcomes According to Margin Status (High-Grade Dysplasia vs. Carcinoma) in Patients Who Underwent Hilar Resection for Mid-Bile Duct Cancer.

Margin positivity after hilar resection (HR) for bile duct cancer is commonly observed due to its longitudinal spread along the subepithelial plane; nevertheless, we cannot draw conclusions regarding the prognostic effects of margins with high-grade dysplasia (HGD) or carcinoma. We aimed to investigate the oncologic effect according to the margin status after HR, particularly between the R1 HGD and the R1 carcinoma. From 2008 to 2017, 149 patients diagnosed with mid-bile duct cancer in Samsung Medical Center, South Korea, were divided according to margin status after HR and retrospectively analyzed. Recurrence patterns were also analyzed between the groups. There were 126 patients with R0 margins, nine with R1 HGD, and 14 with R1 carcinoma. The mean age of the patients was 68.3 (±8.1); most patients were male. The mean age was higher in R1 carcinoma patients than in R1 HGD and R0 patients (p = 0.014). The R1 HGD and R1 carcinoma groups had more patients with a higher T-stage than R0 (p = 0.079). In univariate analysis, the prognostic factors affecting overall survival were age, T- and N-stage, CA19-9, and margin status. The survival rate of R0 was comparable to that of R1 HGD, but the survival rate of R0 was significantly better compared to R1 carcinoma (R0 vs. R1 HGD, p = 0.215, R0 vs. R1 carcinoma, p = 0.042, respectively). The recurrence pattern between the margin groups did not differ significantly (p = 0.604). Extended surgery should be considered for R1 carcinoma; however, in R1 HGD, extended operation may not be necessary, as it may achieve oncologic outcomes similar to R0 margins with HR.

Shear-induced volume decrease in MDCK cells.

Using a microfluidic cell volume sensor we measured the change in the cell volume of Madin-Darby Canine Kidney (MDCK) cells induced by shear stress. An increase in shear stress from 0.2 to 2.0 dyn/cm(2) resulted in a volume decrease to a steady state volume ∼ 20 - 30 % smaller than the initial resting cell volume. Independent experiments based on fluorescence quenching confirmed the volume reduction. This shear-induced cell shrinkage was irreversible on the time scale of the experiment (∼ 30 min). Treatment of 0.1 µM Hg(2+) significantly inhibited the volume decrease, suggesting that the shear-induced cell shrinkage is associated with water efflux through aquaporins. The volume decrease cannot be inhibited by 75 mM TEA, 100 µM DIDS, or 100 µM Gd(3+) suggesting that volume reduction is not directly mediated by K(+) and Cl(-)channels that typically function during regulatory volume decrease (RVD), nor is it through cationic stretch-activated ion channels (SACs). The process also appears to be Ca(2+) independent because it was insensitive to intracellular Ca(2+) level. Since cell volume is determined by the intracellular water content, we postulate that the shear induced reductions in cell volume may arise from increased intracellular hydrostatic pressure as the cell is deformed under flow, which promotes the efflux of water. The increase in internal pressure in a deformable object under the flow is supported by the finite element mechanical model.

Intraoperative Positive Pancreatic Parenchymal Resection Margin: Is It a True Indication of Completion Total Pancreatectomy after Partial Pancreatectomy for Pancreatic Ductal Adenocarcinoma?

BACKGROUND: Total pancreatectomy (TP) can be performed in cases with positive resection margin after partial pancreatectomy for pancreatic cancer. However, despite complete removal of the residual pancreatic parenchyme, it is questionable whether an actual R0 resection and favorable survival can be achieved. This study aimed to identify the R0 resection rate and postoperative outcomes, including survival, following completion TP (cTP) performed due to intraoperative positive margin. METHODS: From 1995 to 2015, 1096 patients with pancreatic ductal adenocarcinoma underwent elective pancreatectomy at the Samsung Medical Center. Among these, 25 patients underwent cTP, which was converted during partial pancreatectomy because of a positive resection margin. To compare survival after R0 resection between the cTP R0 and pancreaticoduodenectomy (PD) R0 cases, propensity score matching was conducted to balance the baseline characteristics. RESULTS: The R0 rate of cTP performed due to intraoperative positive margin was 84% (21/25). The overall 5-year survival rate (5YSR) in the 25 cTP cases was 8%. There was no difference in the 5YSR between the cTP R0 and cTP R1 groups (9.5% versus 0.0%, p = 0.963). However, the 5YSR of the cTP R0 group was significantly lower than that of the PD R0 group (9.5% versus 20.0%, p = 0.022). There was no distinct difference in postoperative complications between the cTP R0 versus cTP R1 and cTP R0 versus PD R0 groups. CONCLUSIONS: In cases with intraoperative positive pancreatic parenchymal resection margin, survival after cTP was not favorable. Careful patient selection is needed to perform cTP in such cases.

Preemptive Administration of Albumin during Pancreatectomy Does Not Reduce Postoperative Complications: A Prospective Randomized Controlled Trial.

Despite the empirical use of human albumin during pancreatectomy to replace intraoperative volume loss while preventing fluid overload and edema, its impact on postoperative outcomes remains unclear. In addition, most previous studies have focused on the effects of therapeutic albumin usage. Here, we investigated whether preemptive administration of human albumin to prevent edema during pancreatectomy could reduce the incidence of moderate postoperative complications. Adult patients undergoing pancreatectomy were assigned to either the albumin group (n = 100) or the control group (n = 100). Regardless of the preoperative albumin level, 200 mL of 20% albumin was administered to the albumin group after induction of anesthesia. The primary outcome was the incidence of moderate postoperative complications as defined by a Clavien-Dindo classification grade ≥ 2 at discharge. Intraoperative net-fluid balance, a known risk factor of postoperative complication after pancreatectomy, was lower in the albumin group than in the control group (p = 0.030), but the incidence of moderate postoperative complications was not different between the albumin and control groups (47/100 vs. 38/100, respectively; risk ratio: 1.24, 95% CI: 0.89 to 1.71; p = 0.198). Therefore, preemptive administration of human albumin to prevent fluid overload and edema during pancreatectomy is not recommended because of its lack of apparent benefit in improving postoperative outcomes.

A prognostic model to predict clinical outcomes with first-line gemcitabine-based chemotherapy in advanced pancreatic cancer.

OBJECTIVE: Our aim was to devise a prognostic model for advanced pancreatic cancer based on clinical parameters. METHODS: We retrospectively analyzed the medical records of 298 patients who received gemcitabine-based chemotherapy from January 1999 to November 2008. RESULTS: The median survival of all patients was 7 months [95% confidence interval (CI) 6.2-7.8]. Multivariate analysis revealed poor prognostic factors for overall survival such as the presence of liver metastasis [p < 0.001, hazard ratio (HR) 2.628, 95% CI 1.620-4.264], the presence of ascites or peritoneal carcinomatosis (p = 0.005, HR 1.783, 95% CI 1.194-2.661), serum C-reactive protein levels >1.2 mg/dl (p = 0.021, HR 1.568, 95% CI 1.070-2.300), and serum albumin levels <3.5 g/dl (p = 0.021, HR 1.701, 95% CI 1.085-2.667). Of 298 patients, 168 patients (56.4%) were categorized as low-risk with 0 or 1 risk factor, 80 patients (26.8%) were categorized as intermediate-risk with 2 risk factors, and 50 patients (16.8%) were categorized as high-risk with 3 or 4 risk factors. The median survival duration for the low-, intermediate-, and high-risk groups was 10.0 months (95% CI 8.7-11.3), 6.7 months (95% CI 5.7-7.7), and 4.4 months (95% CI 3.2-5.6), respectively. CONCLUSIONS: This prognostic model could help to select treatment for patients in clinical practice, and these risk-adapted treatment strategies should be further investigated in prospective studies in such patient populations.

Realistic Advantages of Early Surgical Drain Removal after Pancreatoduodenectomy: A Single-Institution Retrospective Study.

The latest guidelines from the Enhanced Recovery After Surgery (ERAS®) Society stated that early drain removal after pancreatoduodenectomy (PD) is beneficial in decreasing complications including postoperative pancreatic fistulas (POPFs). This study aimed to ascertain the actual benefits of early drain removal after PD. The data of 450 patients who underwent PD between 2018 and 2020 were retrospectively reviewed. The surgical outcomes were compared between patients whose drains were removed within 3 postoperative days (early removal group) and after 5 days (late removal group). Logistic regression analysis was performed to identify the risk factors for clinically relevant POPFs (CR-POPFs). Among the patients with drain fluid amylase < 5000 IU on the first postoperative day, the early removal group had fewer complications and shorter hospital stays than the late removal group (30.9% vs. 54.5%, p < 0.001; 9.8 vs. 12.5 days, p = 0.030, respectively). The incidences of specific complications including CR-POPFs were comparable between the two groups. Risk factor analysis showed that early drain removal did not increase CR-POPFs (p = 0.163). Although early drain removal has not been identified as apparently beneficial, this study showed that it may contribute to an early return to normal life without increasing complications.

Comparison of Oncologic Outcomes between Transduodenal Ampullectomy and Pancreatoduodenectomy in Ampulla of Vater Cancer: Korean Multicenter Study.

This study used multicenter data to compare the oncological safety of transduodenal ampullectomy (TDA) with that of pylorus-preserving pancreatoduodenectomy (PPPD) in early ampulla of Vater (AoV) cancer. Data for patients who underwent surgical resection for AoV cancer (pTis-T2 stage) from January 2000 to September 2019 were collected from 15 institutions. The clinicopathologic characteristics and survival outcomes were compared between the PPPD and TDA groups. A total of 486 patients were enrolled (PPPD, 418; TDA, 68). The oncologic behavior in the PPPD group was more aggressive than that in the TDA group at all T stages: larger tumor size (p = 0.034), advanced T stage (p < 0.001), aggressive cell differentiation (p < 0.001), and more lymphovascular invasion (p = 0.002). Five-year disease-free survival (DFS) and overall survival (OS) did not differ between the two groups when considering all T stages or only the Tis+T1 group. Among T1 patients, PPPD produced significantly better DFS (PPPD vs. TDA, 84.8% vs. 66.6%, p = 0.040) and superior OS (PPPD vs. TDA, 89.1% vs. 68.0%, p = 0.056) than TDA. Lymph node dissection (LND) in the TDA group did not affect DFS or OS (TDA + LND vs. TDA-only, DFS, p = 0.784; OS, p = 0.870). In conclusion, PPPD should be the standard procedure for early AoV cancer.

A mechanosensitive ion channel regulating cell volume.

Cells respond to a hyposmotic challenge by swelling and then returning toward the resting volume, a process known as the regulatory volume decrease or RVD. The sensors for this process have been proposed to include cationic mechanosensitive ion channels that are opened by membrane tension. We tested this hypothesis using a microfluidic device to measure cell volume and the peptide GsMTx4, a specific inhibitor of cationic mechanosensitive channels. GsMTx4 had no effect on RVD in primary rat astrocytes or Madin-Darby canine kidney (MDCK) cells but was able to completely inhibit RVD and the associated Ca(2+) uptake in normal rat kidney (NRK-49F) cells in a dose-dependent manner. Gadolinium (Gd(3+)), a nonspecific blocker of many mechanosensitive channels, inhibited RVD and Ca(2+) uptake in all three cell types, demonstrating the existence of at least two types of volume sensors. Single-channel stretch-activated currents are present in outside-out patches from NRK-49F, MDCK, and astrocytes, and they are reversibly inhibited by GsMTx4. While mechanosensitive channels are involved in volume regulation, their role for volume sensing is specialized. The NRK cells form a stable platform from which to screen drugs that affect volume regulation via mechanosensory channels and as a sensitive system to clone the channel.

Spatially resolved shear distribution in microfluidic chip for studying force transduction mechanisms in cells.

Fluid shear stress has profound effects on cell physiology. Here we present a versatile microfluidic method capable of generating variable magnitudes, gradients, and different modes of shear flow, to study sensory and force transduction mechanisms in cells. The chip allows cell culture under spatially resolved shear flow conditions as well as study of cell response to shear flow in real-time. Using this chip, we studied the effects of chronic shear stress on cellular functions of Madin-Darby Canine Kidney (MDCK), renal epithelial cells. We show that shear stress causes reorganization of actin cytoskeleton, which suppresses flow-induced Ca(2+) response.

An overview of recent strategies in pathogen sensing.

Pathogenic bacteria are one of the major concerns in food industries and water treatment facilities because of their rapid growth and deleterious effects on human health. The development of fast and accurate detection and identification systems for bacterial strains has long been an important issue to researchers. Although confirmative for the identification of bacteria, conventional methods require time-consuming process involving either the test of characteristic metabolites or cellular reproductive cycles. In this paper, we review recent sensing strategies based on micro- and nano-fabrication technology. These technologies allow for a great improvement of detection limit, therefore, reduce the time required for sample preparation. The paper will be focused on newly developed nano- and micro-scaled biosensors, novel sensing modalities utilizing microfluidic lab-on-a-chip, and array technology for the detection of pathogenic bacteria.

Contribution of aquaporins to cellular water transport observed by a microfluidic cell volume sensor.

Here we demonstrate that an impedance-based microfluidic cell volume sensor can be used to study the roles of aquaporin (AQP) in cellular water permeability and screen AQP-specific drugs. Human embryonic kidney (HEK-293) cells were transiently transfected with AQP3- or AQP4-encoding genes to express AQPs in plasma membranes. The swelling of cells in response to hypotonic stimulation was traced in real time using the sensor. Two time constants were obtained by fitting the swelling curves with a two-exponential function, a fast time constant associated with osmotic water permeability of AQP-expressing cells and a slow phase time constant associated mainly with water diffusion through lipid bilayers in the nontransfected cells. The AQP-expressing cells showed at least 10x faster osmotic water transport than control cells. Using the volume sensor, we examined the effects of Hg (2+) and Ni (2+) on the water transport via AQPs. Hg (2+) inhibited the water flux in AQP3-expressing cells irreversibly, while Ni (2+) blocked the AQP3 channels reversibly. Neither of the two ions blocked the AQP4 channels. The microfluidic volume sensor can sense changes in cell volume in real time, which enables perfusion of various reagents sequentially. It provides a convenient tool for studying the effect of reagents on the function and regulation mechanism of AQPs.

Dynamic effects of Hg2+-induced changes in cell volume.

Using a microfluidic volume sensor, we studied the dynamic effects of Hg2+ on hypotonic stress-induced volume changes in CHO cells. A hypotonic challenge to control cells caused them to swell but did not evoke a significant regulatory volume decrease (RVD). Treatment with 100 muM HgCl2 caused a substantial increase in the steady-state volume following osmotic stress. Continuous hypotonic challenge following a single 10-min exposure to HgCl2 produced a biphasic volume increase with a steady-state volume 100% larger than control cells. Repeated hypotonic challenges to cells exposed once to Hg2+ resulted in a sequential approach to the same steady-state volume. Stimulation after reaching steady state caused a reduction in peak cell volume. Repeated stimulation was different than continuous stimulation resulting in a more rapid approach to steady state. Substituting extracellular Na+ with impermeant NMDG+ in the hypotonic solution produced a rapid RVD-like volume decrease and eliminated the Hg2+-induced excess swelling. The volume decrease in the presence of Hg2+ was inhibited by tetraethylammonium and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid disodium, blockers of K+ and Cl(-) channels, respectively, suggesting that part of the Hg2+ effect was increasing NaCl influx over KCl efflux. The presence of multiple phases of steady-state volume and their sensitivity to the stimulation history suggests that factors beyond solute fluxes, such as modification of mechanical stress within the cytoskeleton also plays a role in the response to hypotonic stress.

Clinical outcomes of hepatic resection and radiofrequency ablation in patients with solitary colorectal liver metastasis.

BACKGROUND: The role of the radiofrequency ablation (RFA) in treatment of solitary liver metastasis has not been established yet. Both hepatic resection (HR) and RFA have been used increasingly in the treatment of colorectal liver metastases. STUDY: A systemic review was performed to determine the impact of treatment modality of solitary liver metastasis on recurrence patterns, disease-free survival, and overall survival (OS) rates. RESULTS: Solitary liver metastases were treated by HR in 116 patients (75.8%) and 37 patients (24.2%) were treated with RFA. Prognostic factors, recurrence rate, recurrence patterns, and survival rates were analyzed. The cumulative 3-year and 5-year local recurrence free survival rates were markedly higher in the HR group (88.0% and 84.6%) as compared with those in the RFA group [53.3% and 42.6%, respectively (P

Treatment outcomes of hepatic and pulmonary metastases from colorectal carcinoma.

BACKGROUND AND AIM: The resection of synchronous or metachronous pulmonary and liver metastasis is an aggressive treatment option for patients with stage IV colorectal cancer and has been shown to yield acceptable long-term survival. We reviewed our experience with colorectal cancer patients with both liver and lung resections to determine the efficacy of surgical resections. METHODS: We performed a single institution, retrospective analysis of all patients who underwent surgical hepatic and pulmonary resection for metastatic colorectal cancer between 1995 and 2004. RESULTS: A total of 32 patients underwent resection of both hepatic and pulmonary metastases secondary to colorectal cancer. The 5-year overall survival from initial operation was 60.8%. The disease-free interval was 44.3 months (95% confidence interval: 24.7 and 63.8, respectively). Neither the number of pulmonary lesions nor the time interval between the primary surgery and the metastasectomy had a significant impact on survival (P = 0.134). CONCLUSION: An aggressive surgical treatment of selected colorectal cancer patients with lung and liver metastases resulted in prolonged survival. The 5-year survival rate of 60.8% with no perioperative mortality was observed in our study.

Risk factor stratification after simultaneous liver and colorectal resection for synchronous colorectal metastasis.

BACKGROUND/AIM: This study was conducted to devise a prognostic model for patients undergoing simultaneous liver and colorectal resection. MATERIALS AND METHODS: A retrospective analysis was performed on 138 colorectal patients who underwent simultaneous liver and colorectal resection between September 1994 and September 2005. The primary endpoint of the study was overall survival. Three patients with positive liver resection margin were excluded from the analysis. RESULTS: At multivariate level, poor prognostic factors were liver resection margin < or =5 mm (P = 0.047; relative risk, 1.684; 95% CI = 1.010-2.809), CEA greater than 5 ng/ml (P = <0.001; relative risk, 2.507; 95% CI = 1.499-4.194), number of liver metastasis > 1 (P = <0.042; relative risk, 1.687; 95% CI = 1.020-2.789), and lymph node > or = 4 (P = <0.012; relative risk, 1.968; 95% CI = 1.158-3.347). The risk stratification grouping of the 135 patients was performed according to the following criteria: low risk group, 0-1 factor; intermediate risk group, 2 factors; high-risk group, 3-4 factors. Of 135 patients, 86 patients (63.0%) were categorized as low-risk group, 36 patients (26.6%) as intermediate risk group, and 14 patients (10.4%) as high-risk group. Median survival times for low, intermediate, high-risk groups were 68.0, 43.6 (95% CI, 24.7-62.4), and 23.5 months (95% CI, 9.4-31.5), respectively. The high-risk group demonstrated an approximately threefold (relative risk, 3.1; 95% CI, 1.6-6.0) increased risk of death. CONCLUSIONS: A simple risk factor stratification system was proposed to evaluate the chances of cure of patients after simultaneous resection of liver metastases and primary colorectal carcinoma. The risk factor stratification showed three groups with distinct survival. The risk stratification may help to predict patient survival after simultaneous liver and colorectal resection. This system needs further prospective validation.