Comparison of the long-term outcomes between proximal and distal IgG4-related sclerosing cholangitis: A multicenter cohort study.

BACKGROUND AND AIMS: Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is considered a biliary manifestation of IgG4-related diseases. However, there has been a controversy on the clinical outcomes according to the location of the involved bile duct. We therefore compared the clinical outcomes and long-term prognosis of IgG4-SC with proximal bile duct involvement (proximal IgG4-SC) and IgG4-SC with distal bile duct involvement (distal IgG4-SC). METHODS: We reviewed the data of patients with IgG4-SC that were prospectively collected at 10 tertiary centers between March 2002 and October 2020. Clinical manifestations, outcomes, association with autoimmune pancreatitis (AIP), steroid-responsiveness, and relapse of IgG4-SC were evaluated. RESULTS: A total of 148 patients (proximal IgG4-SC, n = 59; distal IgG4-SC, n = 89) were analyzed. The median age was 65 years (IQR, 56.25-71), and 86% were male. The two groups were similar in terms of jaundice at initial presentation (51% vs 65%; P = 0.082) and presence of elevated serum IgG4 (66% vs 70%; P = 0.649). The two groups showed significant differences in terms of steroid-responsiveness (91% vs 100%; P = 0.008), association with AIP (75% vs 99%; P = 0.001), and occurrence of liver cirrhosis (9% vs 1%; P = 0.034). During a median follow-up of 64 months (IQR, 21.9-84.7), the cumulative relapse-free survival was significantly different between the two groups (67% vs 79% at 5 years; P = 0.035). CONCLUSIONS: Relapse of IgG4-SC frequently occurred during follow-up. Proximal IgG4-SC and distal IgG4-SC had different long-term outcomes in terms of steroid-responsiveness, occurrence of liver cirrhosis, and recurrence. It may be advantageous to determine the therapeutic and follow-up strategies according to the location of bile duct involvement.

Efficacy and safety of intragastric balloon for obesity in Korea.

BACKGROUND/AIMS: Intragastric balloon (IGB) is the only available endoscopic bariatric and metabolic therapy in Korea. End-ball (Endalis) has the longest history of clinical use among the IGBs available in Korea. However, little clinical data on this system have been reported. In this study, we aimed to evaluate the efficacy and safety of End-ball in Korea. METHODS: We performed a retrospective cohort study of patients who underwent IGB insertion (End-ball) from 2013 to 2019. Demographic and anthropometric data were collected. The efficacy and safety of IGB treatment were analyzed. RESULTS: In total, 80 patients were included. Mean age was 33.7 years and 83.8% were female. Initial body mass index was 34.48±4.69 kg/m2. Body mass index reduction was 3.72±2.63 kg/m2 at the time of IGB removal. Percent of total body weight loss (%TBWL) was 10.76%±6.76%. Percentage excess body weight loss was 43.67%±27.59%. Most adverse events were minor, and 71.4% of participants showed nausea, vomiting, or abdominal pain. CONCLUSION: IGB treatment showed good efficacy and safety profile in Korean patients with obesity. In terms of %TBWL and percentage excess body weight loss, the efficacy was similar to that in the Western population.

Gastroesophageal Reflux Disease Increases Susceptibility to Nontuberculous Mycobacterial Pulmonary Disease.

BACKGROUND: Gastroesophageal reflux disease (GERD) is a common comorbidity of nontuberculous mycobacteria (NTM) pulmonary disease (PD). Although GERD is associated with more symptoms and severe disease in patients with NTM PD, whether GERD is associated with an increased risk of NTM PD developing is unknown. RESEARCH QUESTION: Does GERD influence the development of NTM PD? Are there any factors associated with an increased risk of NTM PD among patients with GERD? What is the impact of NTM PD on the health-care use of patients with GERD? STUDY DESIGN AND METHODS: Data from the Korean National Health Insurance Service National Sample Cohort between 2002 and 2015 were used. The incidence and risk of NTM PD were compared between patients with GERD (GERD cohort; n = 17,424) and patients matched for age, sex, type of insurance, and Charlson Comorbidity Index (matched cohort; n = 69,696). Using the GERD cohort, the factors associated with incident NTM PD also were evaluated. RESULTS: During a median follow-up duration of 5.1 years, the age- and sex-adjusted incidence of NTM PD was significantly higher in the GERD cohort (34.8 per 100,000 person-years [PY]) than in the matched cohort (10.5 per 100,000 PY; P < .001), with a subdistribution hazard ratio (HR) of 3.36 (95% CI, 2.10-5.37). Regarding risk factors associated with NTM PD, age of 60 years or older (adjusted HR, 3.57; 95% CI, 1.58-8.07) and bronchiectasis (adjusted HR, 18.69; 95% CI, 6.68-52.28) were associated with an increased risk of incident NTM PD in the GERD cohort. Compared with patients with GERD who did not demonstrate NTM PD, those with NTM PD showed higher all-cause (13,321 PY vs 5,932 PY; P = .049) and respiratory disease-related (5,403 vs 801; P = .011) ED visits or hospitalizations. INTERPRETATION: GERD is associated with an increased incidence of NTM PD. Older age and bronchiectasis are risk factors for NTM PD in patients with GERD. NTM PD in patients with GERD is associated with increased health-care use.

Clinical outcomes of endoscopic papillectomy of ampullary adenoma: A multi-center study.

BACKGROUND: Ampullary adenoma is a rare premalignant lesion, but its incidence is increasing. Endoscopic papillectomy has become the first treatment of choice for ampullary adenomas due to its safety and effectiveness, thereby replacing surgical resection. However, recurrence rates and adverse events after endoscopic papillectomy were reported in up to 30% of cases. AIM: To review the long-term outcomes of endoscopic papillectomy and investigate the factors that affect these outcomes. METHODS: We retrospectively analyzed the data of patients who underwent endoscopic papillectomy for ampullary adenoma at five tertiary hospitals between 2013 and 2020. We evaluated clinical outcomes and their risk factors. The definitions of outcomes were as follow: (1) curative resection: complete endoscopic resection without recurrence; (2) endoscopic success: treatment of ampullary adenoma with endoscopy without surgical intervention; (3) early recurrence: reconfirmed adenoma at the first endoscopic surveillance; and (4) late recurrence: reconfirmed adenoma after the first endoscopic surveillance. RESULTS: A total of 106 patients were included for analysis. Of the included patients, 81 (76.4%) underwent curative resection, 99 (93.4%) had endoscopic success, showing that most patients with non-curative resection were successfully managed with endoscopy. Sixteen patients (15.1%) had piecemeal resection, 22 patients (20.8%) had shown positive/uncertain resection margin, 11 patients (16.1%) had an early recurrence, 13 patients (10.4%) had a late recurrence, and 6 patients (5.7%) had a re-recurrence. In multivariate analysis, a positive/uncertain margin [Odds ratio (OR) = 4.023, P = 0.048] and piecemeal resection (OR = 6.610, P = 0.005) were significant risk factors for early and late recurrence, respectively. Piecemeal resection was also a significant risk factor for non-curative resection (OR = 5.424, P = 0.007). Twenty-six patients experienced adverse events (24.5%). CONCLUSION: Endoscopic papillectomy is a safe and effective treatment for ampullary adenomas. Careful selection and follow-up of patients is mandatory, particularly in cases with positive/uncertain margin and piecemeal resection.

Healthcare Utilization and Medical Cost of Gastrointestinal Reflux Disease in Non-tuberculous Mycobacterial Pulmonary Disease: A Population-Based Study, South Korea, 2009-2017.

Gastroesophageal reflux disease (GERD) is a common non-respiratory comorbidity in patients with non-tuberculous mycobacterial pulmonary disease (NTM-PD). However, little is known about the association between GERD and healthcare utilization and medical costs of NTM-PD. Thus, we evaluated this association using the Health Insurance Review and Assessment Service National Patient Sample. NTM-PD patients with GERD had significantly higher healthcare use and spent a higher total on medical costs (5,098 vs. 2,675 USD/person/year) than those without GERD (P <0.001 for all). Therefore, an appropriate management of GERD in NTM-PD patients can be an important factor to reduce the disease burden.

Low insertion of cystic duct increases risk for common bile duct stone recurrence.

BACKGROUND: Common bile duct (CBD) stone is one of the most frequent biliary diseases. Recurrence after the complete removal of CBD stones is high, and we aim to evaluate the rate and risk factors for symptomatic recurrence of CBD stones after endoscopic retrograde cholangiopancreatography (ERCP). METHODS: We, retrospectively, reviewed the database of patients who underwent ERCP for CBD stones and subsequent cholecystectomy between January 2015 and December 2017 at a tertiary hospital. The recurrence of symptomatic CBD stones was defined as the presence of a CBD stone with related symptoms at least 6 months after the ERCP procedure. The primary outcomes were recurrence of symptomatic CBD stones and its risk factors. RESULTS: Among the 362 enrolled patients, 60 experienced a symptomatic recurrence of CBD stones between 6 months and 5 years after the procedure. The mean duration of follow-up was 32.3 ± 8.1 months. The patients with recurrences were older and had a longer follow-up duration. Low insertion of the cystic duct (HR = 2.893, p = 0.016), distal CBD angulation (HR = 1.015, p = 0.034), maximum CBD diameter (HR = 1.070, p = 0.012), number of ERCP sessions at first admission (HR = 1.558, p = 0.032), and cannulation time (HR = 1.030, p = 0.008) were the independent risk factors for symptomatic recurrent CBD stones. CONCLUSIONS: Patients with risk factors, especially those with low cystic duct insertion, are more prone to symptomatic recurrent CBD stones and should be followed more carefully.

Prognosis and Clinical Characteristics of Patients with Pancreatic Ductal Adenocarcinoma Diagnosed by Endoscopic Ultrasonography but Indeterminate on Computed Tomography.

Background/Aims: Endoscopic ultrasonography (EUS) provides high-resolution images and is superior to computed tomography (CT) scan in diagnosing small pancreatic ductal adenocarcinoma (PDAC). As a result, the use of EUS for early detection of PDAC has attracted attention. This study aimed to identify the clinical and radiological characteristics of patients with PDAC diagnosed by EUS but not found on CT scan. Methods: The medical records of patients diagnosed with PDAC at 12 tertiary referral centers in Korea from January 2003 to April 2019 were reviewed. This study included patients with pancreatic masses not clearly observed on CT scan but identified on EUS. The clinical characteristics and radiological features of the patients were analyzed, and survival analysis was performed. Results: A total of 83 patients were enrolled. The most common abnormal CT findings other than a definite mass was pancreatic duct dilatation, which was identified in 61 patients (73.5%). All but four patients underwent surgery. The final pathologic stages were as follows: IA (n=31, 39.2%), IB (n=8, 10.1%), IIA (n=20, 25.3%), IIB (n=17, 21.5%), III (n=2, 2.5%), and IV (n=1, 1.4%). The 5-year survival rate of these patients was 50.6% (95% confidence interval, 38.8% to 66.7%). Elevated liver function testing and R1 resection emerged as significant predictors of mortality in the multivariable Cox regression analysis. Conclusions: This multicenter study demonstrated favorable long-term prognosis in patients with PDAC diagnosed by EUS but indeterminate on CT scan. EUS should be considered for patients with suspected PDAC but indeterminate on CT scan.

Effect of histological examination on the diagnosis of pancreatic mass using endoscopic ultrasound fine-needle aspiration.

BACKGROUND: Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a well-established method for the diagnosis of solid pancreatic lesions. However, the diagnostic yield of EUS-FNA for pancreatic lesions varies at around 70-90%. Samples from EUS-FNA consist of cells and tissues that can be analyzed separately, and the results can be combined for a final diagnosis. OBJECTIVES: To investigate the effect of cytological and histological analysis of EUS-FNA samples on the final diagnosis, and identify factors that may affect the accuracy of the cytological, histological, and overall analysis. MATERIAL AND METHODS: A single-center prospective observational study was conducted at a tertiary university hospital from July 2018 to June 2019. Patients who underwent EUS-FNA for pancreatic solid lesions with a 22-gauge EUS-FNA needle were included in our study. Liquid-based cytological analysis of the specimen and histological analysis of the whitish core were performed, and factors that affected the diagnostic accuracy of each analysis were evaluated. RESULTS: In 63 EUS-FNA samples, the overall diagnostic accuracy was 87.3%, which was significantly higher than the cytological accuracy of 73.8% (p = 0.031) and the histological accuracy of 69.8% (p = 0.001). Factors that affected the results differed in each group: 1) cytological analysis: size, location, and approach method; 2) histological analysis: specimen weight; and 3) overall analysis: size, location, and approach method. CONCLUSIONS: Histologic evaluation of core material obtained from EUS-FNA improved diagnostic accuracy, and factors that affected each result were analyzed. Further studies with prospective randomized trials are recommended to support our data.

Rates and Risk Factors for Interval Gastric Cancers at Screening Gastroscopy.

BACKGROUNDS/AIMS: Interval gastric cancers (GCs) can be encountered during screening gastroscopy. This study investigated the rate of interval GCs and their risk factors. MATERIALS AND METHODS: We retrospectively investigated subjects who underwent screening gastroscopy from 2005 to 2017 in a university hospital and were diagnosed with GC. Subjects were grouped based on their endoscopic images and descriptive results into interval GC and initially diagnosed GC groups. Interval GCs were defined when endoscopic results within the previous 3 years were negative for GC. The clinico-pathological characteristics of the groups and risk factors for interval GCs were evaluated. RESULTS: Of 54 724 subjects who underwent screening gastroscopy, 234 were diagnosed with GC, of which 43 were interval GCs. The rate of interval GCs was 18.4% (43/234, mean age 61.6 years). Interval GCs were smaller than initially diagnosed GCs (1.6 vs 1.9 cm, P = .011). They were located in the low-to-mid-body in 44.2%, antrum in 48.8%, and high body and cardia in 7%. Their observation time was shorter (248.74 vs 410.64 sec, P = .032). In multivariate analysis, they were associated with short observation time (odds ratio [OR] 0.99, 95% CI 0.994-0.998, P < .001) and location in the low-to-mid-body (OR 2.12, 95% CI 1.071-4.181, P = .031), although differentiation, ulcerated type, metaplasia, Helicobacter pylori infection, and endoscopists' experience were not associated with interval GCs. CONCLUSIONS: The rate of interval GCs was significant during screening gastroscopy. They might be reduced by increasing observation time, focusing on smaller lesions, and observing the low-to-mid-body of the stomach more carefully.

Immunotherapy for pancreatic cancer.

Pancreatic cancer, a highly lethal cancer, has the lowest 5-year survival rate for several reasons, including its tendency for the late diagnosis, a lack of serologic markers for screening, aggressive local invasion, its early metastatic dissemination, and its resistance to chemotherapy/radiotherapy. Pancreatic cancer evades immunologic elimination by a variety of mechanisms, including induction of an immunosuppressive microenvironment. Cancer-associated fibroblasts interact with inhibitory immune cells, such as tumor-associated macrophages and regulatory T cells, to form an inflammatory shell-like desmoplastic stroma around tumor cells. Immunotherapy has the potential to mobilize the immune system to eliminate cancer cells. Nevertheless, although immunotherapy has shown brilliant results across a wide range of malignancies, only anti-programmed cell death 1 antibodies have been approved for use in patients with pancreatic cancer who test positive for microsatellite instability or mismatch repair deficiency. Some patients treated with immunotherapy who show progression based on conventional response criteria may prove to have a durable response later. Continuation of immune-based treatment beyond disease progression can be chosen if the patient is clinically stable. Immunotherapeutic approaches for pancreatic cancer treatment deserve further exploration, given the plethora of combination trials with other immunotherapeutic agents, targeted therapy, stroma-modulating agents, chemotherapy, and multi-way combination therapies.

Prevalence and clinical characteristics of antibiotics associated drug induced liver injury.

BACKGROUND: The use of antibiotics increases recently. Accordingly, the incidence of antibiotics associated with drug induced liver injury (DILI) also increases. The purpose of this study is to evaluate the proportion and the clinical characteristics of antibiotic associated with DILI. METHODS: This study is a retrospective study of analyzed adult patients who were referred to the department of hepatology for the elevation of liver function tests and the frequency of elevated liver enzyme of patients with prescribed antibiotics during the same period at outpatient setting as a validation set. RESULTS: Antibiotics associated with DILI (64.0%) are the most common reason agent among consulting to hepatology department. Rheumatoid arthritis related drugs (11.0%), health supplements (5.0%), herbal medicines (4.0%), anti-viral drugs, anti-inflammatory analgesics/acetaminophen and lipid-lowering agents (3.0%) were next common causative drug for DILI in inpatients setting (training set). The frequency of antibiotics associated with DILI was high in order of flomoxef, cetrazole, ceftriaxone, vancomycin, piperacillin/tazobactam and amoxicillin/clavulanate. In the same period, 32% of the patients who prescribed flomoxef showed elevated liver enzyme levels above the upper normal limit. The prevalence of flomoxef induced DILI (>3 folds of ALT) was 13% and liver enzyme levels were five times higher than upper normal limits in 5% of flomoxef groups. Hypertension or diabetes was the risk factor of flomoxef associated with DILI. CONCLUSIONS: The Prevalence of antibiotics associated with DILI was 2-14%. Co-morbidity with diabetes and hypertension was the risk factor of flomoxef associated with DILI.

Is There Pathological Uniformity between the Periphery and Center of a Gastrointestinal Stromal Tumor?

BACKGROUND: Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors and have some malignant potential. Mitotic count is important for predicting the malignant potential of GISTs. Proper treatment of GISTs requires accurate pathological diagnosis. In general, endoscopic ultrasound-guided fine-needle aspiration and deep biopsy are used for pathological diagnosis of GIST before making decisions about surgery. This study sought to evaluate the pathological uniformity of gastric GISTs for mitotic index of the center and periphery of the GIST. METHODS: We retrospectively reviewed the data of 37 gastric GIST patients who underwent wedge resection at Hanyang University Hospital. We used Armed Forces Institute of Pathology criteria to classify gastric GISTs. To determine the pathological uniformity of gastric GISTs, we compared GIST risk stratification between the center and periphery of GISTs. RESULTS: The mean size of GISTs was 3.56 ± 2.10 cm. Three lesions were located in the antrum, 11 in the fundus, 9 in the cardia, and 14 in the body. The mean age of patients was 58.65 ± 9.44 years; 18 patients were male and 19 were female. Thirty-five patients (94.6%) showed the same level of risk stratification between the center and periphery of gastric GISTs, while two patients (5.4%) presented different levels of risk between the two sites. No significant difference in mitotic count was observed between the two sites (kappa value = 0.863; p = 0.001). CONCLUSIONS: Mitotic index category (either more than five mitoses per high-power field or five or fewer mitoses per high-power field) of GISTs showed good concurrence between the center and periphery.

Diagnostic Performance of Serum Asialo α1-Acid Glycoprotein Levels to Predict Liver Cirrhosis.

Background/Aims: To date, studies on various noninvasive techniques have been suggested to evaluate the degree of liver fibrosis. We aimed to investigate the diagnostic performance of serum asialo α1-acid glycoprotein (AsAGP) in the diagnosis of liver cirrhosis compared with chronic hepatitis for clinically useful result. Methods: We conducted a case-control study of 96 patients with chronic liver disease. Chronic hepatitis was defined as the presence of chronic liver disease on ultrasonography, with a liver stiffness of less than 5.0 kPa as shown on magnetic resonance elastography (MRE). Liver cirrhosis was defined as liver stiffness of more than 5.0 kPa on MRE. The serum AsAGP concentration was compared between the two groups. Results: Serum AsAGP levels were significantly higher in patients with cirrhosis than in those with chronic hepatitis (1.83 µg/mL vs 1.42 µg/mL, p<0.001). Additionally, when comparing patients in each cirrhotic group (Child-Pugh grades A, B, and C) to those with chronic hepatitis, AsAGP levels were significantly higher in all the cirrhotic groups (p<0.05, p<0.01, p<0.001, respectively). The sensitivity and specificity of AsAGP for detecting cirrhosis were 79.2% and 64.6%, respectively, and the area under the curve value was 0.733. The best diagnostic cutoff to predict cirrhosis was 1.4 µg/mL. AsAGP and bilirubin were found to be independent risk factors for the prediction of cirrhosis in the logistic regression analysis. Conclusions: Serum AsAGP showed an acceptable diagnostic performance in predicting liver cirrhosis.

Gastro-oesophageal reflux disease increases healthcare use and medical costs in patients with bronchiectasis: a Korean nationwide population-based study.

BACKGROUND: Gastro-oesophageal reflux disease (GORD) is not only a common aetiology but also accompanying comorbidity of non-cystic fibrosis bronchiectasis (bronchiectasis). However, the association between GORD and the disease burden of bronchiectasis has not been well evaluated. Our study aimed to evaluate whether GORD is associated with increased healthcare use and medical costs in patients with bronchiectasis. METHODS: We analyzed the data from 44,119 patients with bronchiectasis using a large representative Korean population-based claim database between 2009 and 2017. We compared the healthcare use [outpatient department (OPD) visits and emergency room (ER) visits/hospitalizations] and medical costs in patients with bronchiectasis according to the presence or absence of GORD. RESULTS: The prevalence of GORD in patients with bronchiectasis tended to increase during the study period, especially in the 50s and older population. GORD was associated with increased use of all investigated healthcare resources in patients with bronchiectasis. Healthcare use including OPD visits (mean 47.6/person/year versus 30.0/person/year), ER visits/hospitalizations (mean 1.7/person/year versus 1.1/person/year), and medical costs (mean 3564.5 Euro/person/year versus 2198.7 Euro/person/year) were significantly higher in bronchiectasis patients with GORD than in those without GORD (p < 0.001 for all). In multivariable analysis, bronchiectasis patients with GORD showed 1.44-fold (95% confidence interval = 1.37-1.50) and 1.26-fold (95% confidence interval = 1.19-1.33) increased all-cause and respiratory-related ER visits/hospitalizations relative to those without GORD, respectively. After adjusting for potential confounders, the estimated total medical costs (mean 4337.3 versus 3397.4 Euro/person/year) and respiratory disease-related medical costs (mean 920.7 versus 720.2 Euro/person/year) were significantly higher in bronchiectasis patients with GORD than in those without GORD (p < 0.001 for both). CONCLUSION: In patients with bronchiectasis, GORD was associated with increased healthcare use and medical costs. Strategies to reduce the disease burden associated with GORD are needed in patients with bronchiectasis.

Malignant potential of small pancreatic neuroendocrine neoplasm and its risk factors: A multicenter nationwide study.

BACKGROUND: Pancreatic neuroendocrine neoplasms (PNENs) show heterogeneous biological behavior, and most small PNENs show indolent features. Consequently, selected cases can be considered for observation only, according to the National Comprehensive Cancer Network guideline, however, supporting clinical evidence is lacking. We investigated the clinical course of small PNENs and their risk factors for malignant potential. METHODS: A total of 158 patients with small pathologically confirmed PNENs ≤2 cm in initial imaging were retrospectively enrolled from 14 institutions. The primary outcome was any metastasis or recurrence event during follow-up. RESULTS: The median age was 57 years (range, 22-82 years), and 86 patients (54%) were female. The median tumor size at initial diagnosis was 13 mm (range, 7-20 mm). PNENs were pathologically confirmed by surgery in 137 patients and by EUS-guided fine needle aspiration biopsy (EUS-FNAB) in 21 patients. Eight patients underwent EUS-FNAB followed by surgical resection. The results of WHO grade were available in 150 patients, and revealed 123 grade 1, 25 grade 2, and 2 neuroendocrine carcinomas. A total of 145 patients (92%) underwent surgical resection, and three patients had regional lymph node metastasis. During the entire follow-up of median 45.6 months, 11 metastases or recurrences (7%) occurred. WHO grade 2 (HR 13.97, 95% CI 2.60-75.03, p = 0.002) was the only predictive factor for malignant potential in multivariable analysis. CONCLUSIONS: WHO grade is responsible for the malignant potential of small PNENs ≤2 cm. Thus, EUS-FNAB could be recommended in order to provide early treatment strategies of small PNENs.

Correlation between Three-Dimensional Volume and Malignant Potential of Gastrointestinal Stromal Tumors (GISTs).

BACKGROUND AND PURPOSE: Gastrointestinal stromal tumors (GISTs) are rare diseases of the gastrointestinal tract but they are the most common gastrointestinal tumors of mesenchymal origin. Since most GISTs have malignant potential, their probability of malignant progression must be evaluated. This study was conducted to examine the correlation between three-dimensional GIST volume measured by CT and malignant potential. MATERIALS AND METHODS: A retrospective study was performed on 70 patients diagnosed with GIST after surgical resection in Hanyang University Seoul Hospital from 2012 to 2017. Linear regression analysis was used to establish which between the length of the long axis of GISTs, originally considered a predictor of malignancy, and their volume was a more accurate predictor of malignancy. Tumor dimensions were measured by CT. RESULTS: Data were analyzed using the chi-square test or Student's t-test and logistic regression. Of the GISTs, 53 (75.71%) were in the stomach, 3 (4.29%) in the small intestine, and 14 (20.0%) in the large intestine. The mean age of the malignant GIST group was significantly higher than that of the benign GIST group (p = 0.032), their tumor long axes were significantly greater (p = 0.073), their tumor volumes were significantly larger (p = 0.001), and the frequency of tumor necrosis was higher (p = 0.001). In multivariate analysis, malignant GIST was associated with location in organs other than the stomach (OR 7.846, 95% CI 1.293-47.624, p = 0.025), longer axis (OR 1.037, 95% CI 1.011-1.065, p = 0.006), larger volume (OR 1.003, 95% CI 1.000-1.006, p = 0.029), and necrosis (OR 12.222, 95% CI 1.945-76.794, p = 0.008). The mean age of the recurrent GIST group was higher than that of the non-recurrent group (p = 0.045), their tumor long axes were significantly longer (p = 0.005), and their volumes were greater, but this last difference was not significant (p = 0.072). CONCLUSIONS: Tumor volume can be considered an additional risk factor in assessing the malignant potential of GISTs and tends to increase in recurrent GISTs.