Increased Attenuation of Intestinal Contents at CT Indicates Bowel Necrosis in Closed-Loop Small Bowel Obstruction.

Background Preoperative recognition of irreversible bowel necrosis is important, as it provides valuable guidance for surgical strategy selection but also may inform perioperative risk assessment and communication. Few studies have focused on the association between CT signs and bowel necrosis. Purpose To assess the diagnostic accuracy of CT signs to predict bowel necrosis in patients with closed-loop small bowel obstruction (CL-SBO). Materials and Methods This retrospective single-center study included patients who were surgically confirmed to have CL-SBO caused by adhesion or internal hernia between January 2016 and May 2022. Necrosis was determined based on surgical exploration and postoperative pathologic examination. Two radiologists independently reviewed CT signs by both subjective visual assessment and objective measurement. Disagreements were resolved in consensus with a third gastrointestinal radiologist. Univariable and multivariable analyses were used to assess the association between CT signs and bowel necrosis, and Cohen κ was used to assess interobserver agreement. Sensitivity and specificity were calculated for each CT sign. Results This study included 145 patients: 61 (42.1%) in the necrotic group (median age, 62 years [IQR, 51-71.5 years]; 37 [60.7%] women) and 84 (57.9%) in the nonnecrotic group (median age, 61.5 years [IQR, 51-68.8 years]; 51 [60.7%] women). Univariable analysis and multivariable analysis showed that increased attenuation of intestinal contents and increased attenuation of intestinal wall were independent predictors for bowel necrosis (odds ratio = 45.3 and 15.1; P = .001 and P < .001, respectively). Increased attenuation of intestinal contents and increased attenuation of intestinal wall had similar sensitivity (64% and 67%, respectively) and specificity (99% and 92%, respectively) for predicting bowel necrosis. However, interobserver agreement was better for assessing the contents than the wall (κ = 0.84 and 0.59, respectively). Conclusion Increased attenuation of intestinal contents was a highly specific CT sign with good reproducibility to predict bowel necrosis in CL-SBO. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Taourel and Zins in this issue.

[Study on therapeutic mechanism of Rehmanniae Radix Praeparata- Corni Fructus in sequelae of ischemic stroke based on network pharmacology technology].

In ischemic stroke sequela phase, Rehmanniae Radix Praeparata-Corni Fructus drug pair has the effect in protecting damaged neurons, but its mechanism has not been clear. In this study, network pharmacology was used to predict the mechanism of Rehmanniae Radix Praeparata-Corni Fructus in the treatment of ischemic stroke sequela. Through database search and literature retrie-val, 40 active ingredients of Rehmanniae Radix Praeparata and Corni Fructus were obtained, and their targets were obtained through STITCH and TCMSP databases. The targets of ischemic stroke sequela were obtained through OMIM,GAD,TTD and DrugBank databases. By screening the intersections of active ingredients targets and stroke treatment targets, 21 potential targets were obtained. The DAVID database was used for GO enrichment analysis and KEGG pathway analysis of potential targets. GO enrichment analysis showed that Rehmanniae Radix Praeparata-Corni Fructus were mainly involved in regulation of blood pressure, negative regulation of extrinsic apoptotic signaling and positive regulation of angiogenesis. KEGG pathway analysis showed that Rehmanniae Radix Praeparata-Corni Fructus could inhibit inflammatory response and apoptosis signaling pathway by regulating HIF-VEGFA signaling pathway in neural stem cell proliferation, TNF signaling pathway and NF-kappaB signaling pathway. Molecular docking technique was used to verify that Rehmanniae Radix Praeparata-Corni Fructus component has a good binding activity with potential targets. The results showed that in ischemic stroke sequela phase, Rehmanniae Radix Praeparata-Corni Fructus drug pair could play an important role in recovering neural function, promoting the proliferation of neural stem cells, angiogenesis, preventing neural cells apoptosis and regulating inflammatory factors.

Epidermoid cyst in intrapancreatic accessory spleen: A systematic review.

BACKGROUND/OBJECTIVES: Due to its rarity, epidermoid cyst in intrapancreatic accessory spleen (ECIPAS) is still a diagnostic dilemma during clinical practice. The aim of this review was to summarize the epidemiologic features and management of ECIPAS. METHODS: MEDLINE and EMBASE were searched for English articles reporting on ECIPAS up to April 30th, 2018 following the methodology suggested by the PRISMA guidelines. Categorical variables were reported as frequency and percentage. Continuous variables were reported as median (range). RESULTS: A total of 56 patients from 47 full articles were included for the final data synthesis. More than half of the ECIPASs (59%) were found incidentally. The female/male ratio was 1.33. ECIPAS is typically a single mono-/multi-lobular cystic lesions in the pancreatic tail with thickened cystic wall or various amount of solid component which had identical density/signal to the spleen on imaging examinations. The cyst is filled with serous or non-serous fluid. Recognition of the surrounding ectopic splenic tissue is the key point to diagnose ECIPAS. However, no preoperative examination was able to make a definite diagnosis. Almost all the patients (96%) received surgical treatment, due to the suspicion of pancreatic malignant or potentially malignant cystic tumor, especially mucinous cystic neoplasm (MCN). CONCLUSIONS: Although seldom encountered, ECIPAS should be considered as a differential diagnosis for pancreatic cystic lesions, especially when solid component was detected. As a benign disease, unnecessary surgery should be avoided. Because it is difficult to make a definite diagnosis preoperatively by one single examination, multiple modalities may be required.

High nuclear Survivin expression as a poor prognostic marker in pancreatic ductal adenocarcinoma.

BACKGROUND: Survivin, one of the key regulators of mitosis and apoptosis, has long been well recognized to play important biological roles in many neoplasms, including pancreatic ductal adenocarcinoma (PDAC). However, its prognostic value in PDAC remains controversial. PATIENTS AND METHODS: Nuclear expression of Survivin was detected, using tissue microarray-based immunohistochemistry, in paired-tumor and nontumor samples from 306 patients with radically resected PDAC. The staining H scores were further correlated with clinicopathologic features and disease-specific survival (DSS). RESULTS: Nuclear Survivin expression was much higher in tumor than in nontumor tissues (P < 0.001). No significant association between tumoral Survivin expression and clinicopathologic variables was found. For prognosis, high Survivin expression was associated with shortened DSS in all eligible patients and four subgroups, that is, male and nondiabetic patients as well as those with head-located and G1-2 tumors, shown by univariate analyses. In addition, a statistically marginal significance was revealed in eight subgroups. For the entire cohort and two subgroups, nuclear Survivin expression was also multivariate identified as an independent predictor for DSS. For patients with G1-2 tumors, it was the single prognostic marker. CONCLUSION: Our data suggest an association between high nuclear Survivin expression and poor prognosis in PDAC. However, further confirmation might be necessary.

Intrapancreatic accessory spleen: a diagnostic dilemma.

BACKGROUND: As intrapancreatic accessory spleen (IPAS) is rarely encountered during clinical practice, the aim of this review was to summarize the epidemiologic features, the diagnosis and treatment of IPAS. METHODS: MEDLINE and EMBASE were searched for articles reporting on IPAS. Categorical variables were reported as frequency and percentage. Continuous variables were reported as median (range). RESULTS: A total of 105 patients were included, of which 73% were detected incidentally. The male/female ratio was 1.23. The size of IPAS in patients who had previously undergone splenectomy was larger than that of patients without prior splenectomy (2.5 cm vs 1.5 cm; p = 0.020). No preoperative examination was able to make a definite diagnosis for all IPASs. More than half of the patients (55%) received surgical treatment, most of which (87%) were suspected as pancreatic neuroendocrine tumors (p-net) preoperatively. CONCLUSIONS: Although rare, IPAS should be considered in the differential of patients with suspected incidental p-net, especially if there has been a past history of splenectomy. Preoperative diagnosis is important as unnecessary surgery can be avoided. As it is difficult to make a definite diagnosis of IPAS by one single examination, multiple techniques may be required.

Surgeons' knowledge regarding the diagnosis and management of pancreatic cancer in China: a cross-sectional study.

BACKGROUND: Pancreatic cancer is rare but highly malignant. Studies have shown that surgeons' knowledge closely links to the correct diagnosis and treatment outcomes of pancreatic cancer. The purpose of this study was to survey current surgeons' knowledge regarding pancreatic cancer. METHODS: A cross-sectional study was conducted among 705 surgeons who attended the 2011 China Surgical Week's meeting in Beijing. A questionnaire regarding the risk factors, clinical manifestations, diagnosis, and treatment of pancreatic cancer was used. Surgeons' answers were analyzed and compared among different regions, levels of hospital, and professional ranks. RESULTS: Most surgeons had a correct knowledge toward the risk factors, diagnosis, and management of pancreatic cancer. However, several knowledge gaps were identified. They include "The association between type 2 diabetes and pancreatic cancer", "The most common histologic type of pancreatic neoplasm", "the typical clinical symptoms of pancreatic cancer", "The accuracy of ultrasound in screening pancreatic cancer", "Enhanced CT in the diagnosis of pancreatic cancer", and "Which is more superior between MRI and CT in the diagnosis of pancreatic cancer". We also found that overall surgeons' responses did not depend on their geographic locations, but on hospital levels and professional ranks. Surgeons working at level three hospitals had better knowledge than others in certain areas and resident surgeons had fewer correct answers in some areas. CONCLUSIONS: Although most surgeons have a good knowledge in most areas related to the diagnosis and treatment of pancreatic cancer in China, certain knowledge gaps exist, particularly among trainees and those from low level hospitals. Continuing medical education programs to improve these knowledge gaps should be implemented.

Misdiagnosis of a Drain-site Hernia Containing Fallopian Tube Fimbria on 18F-FDG PET/CT.

In a 55-year-old woman with sigmoid colon cancer, a subcutaneous mass in the left lower abdomen was incidentally found and gradually enlarged. For further diagnosis and staging, an 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography scan was performed, which revealed a subcutaneous mass in the left lower abdomen with mild uptake of 18F-FDG, suggesting the possibility of metastasis. However, post-surgery and pathological confirmation, this mass was diagnosed as a drain-site hernia containing fallopian tube fimbria, which is extremely rare but should be considered in the differential diagnosis of subcutaneous mass in the lower abdomen.

Prediction of bowel necrosis by reduced bowel wall enhancement in closed-loop small bowel obstruction: Quantitative methods.

PURPOSE: To assess diagnostic performance and reproducibility of reduced bowel wall enhancement evaluated by quantitative methods using CT to identify bowel necrosis among closed-loop small bowel obstruction (CL-SBO) patients. METHODS: This retrospective single-center study included patients who diagnosed with CL-SBO caused by adhesion or internal hernia during January 2016 and May 2022. Patients were divided into necrotic group (n = 41) and non-necrotic group (n = 67) according to surgical exploration and postoperative pathology. Two doctors independently measured the attenuation of bowel wall and consensus was reached through panel discussion with a third gastrointestinal radiologist. Reduced bowel wall enhancement was assessed by four quantitative methods. Univariate analyses were used to evaluate the association between each method and bowel necrosis, and kappa/intraclass correlation coefficient values were used to assess interobserver agreement. Diagnostic performance parameters were calculated for each method. RESULTS: Reduced bowel wall enhancement in arterial phase (OR 8.98, P < 0.0001), reduced bowel wall enhancement in portal phase (OR 16.84, P < 0.001), adjusted reduced bowel wall enhancement in arterial phase (OR 29.48, P < 0.001), adjusted reduced bowel wall enhancement in portal phase (OR 145.69, P < 0.001) were significantly associated with bowel necrosis. Adjusted reduced bowel wall enhancement in portal phase had the best diagnostic performance (AUC: 0.92; Youden index: 0.84; specificity: 94.03 %) and interobserver agreement (kappa value of 0.59-0.73) to predict bowel necrosis. CONCLUSION: When assessing reduced bowel enhancement to predict bowel necrosis among CL-SBO patients, using unenhanced CT images and proximal dilated loop as standard references in portal phase is the most accurate quantitative method among those tested.

Should Positive Cytology Revealed by Intraoperative Lavage Preclude Radical Resection in Resectable Pancreatic Cancer?: A Systemic Review and Meta-analysis.

OBJECTIVES: The aims of this review were to determine whether positive peritoneal lavage cytology (CY+) precludes radical resection in pancreatic cancer and to propose prospections for future studies. METHODS: MEDLINE, Embase, and Cochrane Central were searched for related articles. Dichotomous variables and survival outcomes were analyzed with the estimation of odds ratio and hazards ratio (HR), respectively. RESULTS: A total of 4905 patients were included, of which 7.8% were CY+. Positive peritoneal lavage cytology was correlated with poor overall survival (univariate survival analysis [HR, 2.35; P < 0.00001]; multivariate analysis [HR, 1.62; P < 0.00001]), poor recurrence-free survival (univariate survival analysis [HR, 2.50; P < 0.00001]; multivariate analysis [HR, 1.84; P < 0.00001]), and higher initial peritoneal recurrence rate (odds ratio, 5.49; P < 0.00001). CONCLUSIONS: Although CY+ predicts poor prognosis and a higher risk of peritoneal metastasis after curative resection, it is not sufficient to preclude curative resection based on the current evidence, and high-quality trials should be conducted to assess the prognostic impact of operation among resectable CY+ patients. In addition, more sensitive and accurate methods to detect peritoneal exfoliated tumor cells and more effective comprehensive treatment for resectable CY+ pancreatic cancer patients are clearly warranted.

[Studies on the interaction of rhein with bovine serum albumin by spectroscopic and voltammetric methods].

The interaction between rhein and bovine serum albumin(BSA) was studied by UV-Visible, fluorescence spectroscopy and circular dichroism in conjunction with electrochemical method. The results indicated that rhein has a powerful ability to quench the albumin's fluorescence in a static mode. The binding constants(KA) and binding site numbers (n) obtained at different temperatures were 3.67 x 10(5), 0.99 (298 K) and 2.60 x 10(4), 0.83 (309 K) respectively. According to the thermodynamic parameters the main sorts of binding force of rhein-BSA was fixed as electrostatic. The distance between donor and acceptor in rhein-BSA was 3.28 nm based on the Förster energy transfer theory. Results of the circular dichroism and synchronous fluorescence show that the binding can cause conformation change of BSA.

Air in the biliary duct as an indicator of Type V Mirizzi syndrome: a case report.

Mirizzi syndrome, known as extrinsic bile compression syndrome (EBCS), is difficult to diagnose without surgery. To the best of our knowledge, our case shows that air in the biliary duct may indicate Type V Mirizzi syndrome. A 48-year-old Chinese male, complaining of anorexia with weight loss and jaundice, showed decreased bilirubin for two months after being diagnosed with gallbladder stones. Upon re-examination of the CT, evidence of air in the biliary duct was discovered. Type V EBCS was finally diagnosed during surgery. The patient underwent cholecystectomy, cholecystocolic fistula excision, and Roux-en-Y choledochojejunostomy. The postoperative course was uneventful. Mirizzi's syndrome is a condition which is difficult to diagnose and treat. Air in the biliary duct can be a sign of Type V Mirizzi syndrome, which aids in diagnosis of Type V EBCS before surgery. Cholecystectomy, fistula excision and biliary-enteric anastomosis with Roux-en-Y loop appear to be the most appropriate surgical interventions for the condition.

Preservation or Ligation of Splenic Vessels During Spleen-Preserving Distal Pancreatectomy: A Meta-Analysis.

Purpose/aim: Spleen preservation distal pancreatectomy (SPDP) can be achieved by either splenic vessel preservation distal pancreatectomy (SVP-DP) or Warshaw technique (WT). Although studies comparing SVP-DP with WT have been reported, controversies exist. The aim of our study is to assess and compare the safety and feasibility of SVP-DP and WT. Materials and methods: Two authors searched the online database independently till April 30, 2017. Data extraction and quality assessment were performed independently by two authors. Short- and long-term outcomes of WT and SVP-DP were evaluated. Subgroup analysis was performed on laparoscopic surgery. Odds ratios (OR) with 95% confidence interval (CI) and mean difference (MD) with 95% CI were estimated. Results: A total of 664 patients from 11 retrospective cohort studies were included. Meta-analysis showed the WT group had a significantly higher incidence of splenic infarction (OR = 0.12; 95% CI: 0.07-0.20; p < 0.00001) and gastric/epigastric varices (OR = 0.11; 95% CI: 0.05-0.24; p < 0.00001). And more patients suffering from splenic infarction from WT group needed further splenectomy (OR = 0.13; 95% CI: 0.02-0.84; p = 0.03). While there was no difference between the two procedures in terms of pancreatic fistula (OR = 0.55; 95% CI: 0.25-1.19; p = 0.13), overall morbidity (OR = 0.87; 95% CI: 0.59-1.30; p = 0.50) and hospital stay (MD = -0.45; 95% CI: -1.73-0.82; p = 0.49). Conclusions: Due to relatively higher risk of postoperative splenic infarction, gastric/epigastric varices and Clavien-Dindo III-V complications, WT is not as safe as SVP-DP. However, well-conducted randomized clinical trials are still needed due to the limitations of current studies.

Research progress on circularRNAs in pancreatic cancer: emerging but promising.

There is currently no diagnostic modality for early-stage pancreatic cancer. Given that adjuvant therapies require further development, the overall survival of pancreatic cancer remains unsatisfactory. Circular RNAs (circRNAs) are a class of noncoding RNAs that play an important role in the progression of many diseases including cancer. CircRNAs mainly bind to microRNAs as microRNA sponges to restore the expression of targeted genes and regulate tumor invasion, metastasis, proliferation, and apoptosis. CircRNAs also play roles in the diagnosis and targeted therapy of tumors. Studies on the mechanisms of action of circRNAs in pancreatic cancer are still in their infancy, but it is anticipated that this field will gradually advance. In this review, we provide a brief introduction to circRNAs from four perspectives: biogenesis, functions, and mechanisms of action, tumor therapy with circRNAs, and circRNAs' roles in pancreatic cancer.

Clinicopathological and prognostic significance of MKK4 and MKK7 in resectable pancreatic ductal adenocarcinoma.

Mitogen-activated protein kinase kinase 4 (MKK4) and mitogen-activated protein kinase kinase 7 (MKK7) were shown to regulate biological behavior in many malignancies. In pancreatic ductal adenocarcinoma (PDAC), it remains controversial whether MKK4 and MKK7 have pro-oncogenic or tumor-suppressive activities. Furthermore, their clinicopathological and prognostic implications are unknown. In the present study, we detected MKK4 and MKK7 expressions in the nucleus and cytoplasm of resected PDAC tissues from 321 patients by tissue microarray-based immunohistochemistry. Cytoplasmic MKK4 and MKK7 expressions were significantly downregulated, whereas nuclear MKK4 expression was significantly upregulated in tumor tissues compared with nontumor tissues. Tumor cytoplasmic MKK4 and MKK7 expressions were significantly negatively associated with histologic grade. Cytoplasmic MKK4 expression was also negatively correlated with CA19-9 level. By univariate analysis, high cytoplasmic MKK4 expression was significantly associated with longer cancer-specific survival (hazard ratio [HR], 0.705; 95% confidence interval, 0.510-0.974), with a similar trend observed for MKK7 expression. High MKK4 and MKK7 messenger RNA expressions were significantly associated with longer overall survival in The Cancer Genome Atlas database. Although MKK4 expression was not significant in a multivariate Cox regression analysis, combination of MKK4/MKK7 and pN stage was identified as an independent prognostic indicator and had the lowest HR (HR, 0.308; 95% confidence interval, 0.126-0.752). Furthermore, combined analysis of MKK4 and MKK7 greatly increased the prognostic predictive power. In addition, downregulation of MKK4 or MKK7 increased proliferation of pancreatic cancer cells in vitro. In conclusion, high MKK4 expression and its combination with high MKK7 expression both predicted favorable prognosis in resectable PDAC.

WT1 associated protein promotes metastasis and chemo-resistance to gemcitabine by stabilizing Fak mRNA in pancreatic cancer.

WT1 associated protein (WTAP), playing an important role in several malignancies owing to its complex function in transcriptional and post-transcriptional regulation, is an independent prognostic indicator for pancreatic cancer (PC). However, its specific role and underlying mechanism in PC remain unclear. In the present study, we found that WTAP could promote migration/invasion and suppress chemo-sensitivity to gemcitabine in PC. Further mechanical investigation revealed that WTAP could bind to and stabilize Fak mRNA which in turn activated the Fak-PI3K-AKT and Fak-Src-GRB2-Erk1/2 signaling pathways. In addition, GSK2256098, a specific Fak inhibitor, could reverse WTAP-mediated chemo-resistance to gemcitabine and metastasis in PC. Taken together, Fak inhibitor might be a promising therapeutic option for PC patients with WTAP overexpression.

Pancreatic carcinosarcoma mimics malignant intraductal papillary mucinous neoplasm: A rare case report and literature review.

RATIONALE: Carcinosarcoma, an extremely rare pancreatic primary tumor, is characterized by coexistence of both carcinomatous and sarcomatous components. Due to its rarity, the clinical manifestation and imaging features have not been recognized. An accurate diagnostic method has not been available and a widely accepted guidelines instructing treatment has not been established. PATIENT CONCERNS: We present an uncommon case of pancreatic carcinosarcoma (PCS) which has been preoperatively diagnosed as pancreatic malignant intraductal papillary mucinous neoplasm. A radical resection, including total pancreatectomy (TP) and splenectomy, was performed. DIAGNOSIS: The diagnosis of PCS was confirmed by postoperative pathology. INTERVENTIONS: A radical resection, including TP and splenectomy, was performed. The patient was followed up by abdominal contrast-enhanced computed tomography scan and blood tumor marker examination. OUTCOMES: The patient is still alive and self-sufficient 7 months after the surgery. No evidence of tumor recurrence is found during follow-up. LESSONS: Although, until recently, there are no widely accepted guidelines instructing treatment for PCS, a radical resection is still a possible way. All the pancreatic neoplastic patients with high surgical risk should be transferred to a specialized high-volume pancreatic center to get precise preoperative evaluation, fine operation technique, and careful postoperative management.

WT1-associated protein is a novel prognostic factor in pancreatic ductal adenocarcinoma.

Although Wilms tumor 1 (WT1)-associated protein (WTAP) was initially found to be a specific WT1-binding protein, it has increasingly attracted attention because of its oncogenic role in various types of malignancies, including cholangiocarcinoma, glioblastoma and acute myeloid leukemia. However, the clinical impact of WTAP on pancreatic ductal adenocarcinoma (PDAC) is still unknown. A total of 145 patients who underwent surgical treatment from 2004 to 2008 were enrolled in the present study. The cytoplasmic and nuclear expression of WTAP in tumor and adjacent normal tissues was examined by immunohistochemical analysis in order to investigate the relationship between WTAP and the clinicopathological factors and prognosis of patients with PDAC. The nuclear and cytoplasmic expression of WTAP in tumor tissues was significantly higher compared with non-tumor tissues (P<0.001). High expression of WTAP in the nucleus was significantly associated with gender (P=0.010) and tumor stage (P=0.020), while high expression of WTAP in the cytoplasm was significantly associated with gender (P=0.018), histological grade (P=0.047) and perineural invasion (P=0.028). In addition, a univariate analysis revealed that high nuclear expression of WTAP in tumor tissues was significantly associated with poor overall survival (P<0.001), as well as several clinicopathological variables, including gender and N stage. In a multivariate Cox regression analysis, nuclear WTAP expression was identified as an independent prognostic indicator for PDAC (relative risk, 1.855; 95% confidence interval, 1.033-3.333; P=0.039). The results of the present study indicated that high nuclear expression of WTAP is a valuable molecular biomarker of a poor prognosis among patients with PDAC.

[The genotypic profiles of Candida albicans isolates from patients with oral lichen planus].

OBJECTIVE: The aim of this study was to investigate the genotypic profiles of Candida albicans isolates from erosive oral lichen planus (OLP) and non-erosive OLP. METHODS: A total of 112 isolates obtained from healthy control (26), erosive OLP (62) and non-erosive OLP (24) were screened for genotypic profiles by using the randomly amplified polymorphic DNA (RAPD) assay. RESULTS: RAPD analyses with some random primer reavealed 4 different genotypes among all isolates, and there was significant difference in genotypic constitution between every two groups. Statistically, B and D were the major types in healthy group; A and C were the major types in erosive OLP; A and D were the major types in non-erosive OLP. CONCLUSION: Some Candida albicans isolates with special genotypic profiles may contribute to the development and progression of OLP.

[Role of ataxia telangiectasis mutated in the oncogenesis of oral squamous cell carcinoma].

OBJECTIVE: To investigate the role of ataxia telangiectasis mutated (ATM) gene in the oncogenesis and progression of oral squamous cell carcinoma (OSCC). METHODS: A total of 61 formalin-fixed and paraffin-embedded samples were obtained from patients with hyperkeratosis, oral leukoplakia, OSCC and normal healthy controls. The expression of ATM protein in all of the samples was investigated by streptavidin-peroxidase immunohistochemistry assay. PCR was also performed to detect the loss of heterozygosity (LOH) in D11s2179 of ATM gene. The correlations between ATM and the clinical and histopathological characteristics were also investigated. RESULTS: The results indicated that the ATM expression was increased in oral premalignant lesions (P<0.05). For OSCC, 68.8% samples showed normal or increased ATM expression, while 31.3% had decreased or absent ATM expression. Significant differences were found between the group of decreased or absent ATM expression and that of normal or increased expression over the histopathological grade and lymph node metastasis state. PCR results displayed that none of the samples from oral premalignant lesions showed abnormal changes, while 3 of the OSCC (9.38%) showed loss of heterozygosity (LOH) and 2 (6.25%) with microsatellite instability (MSI). Those 3 samples of LOH showed absent ATM expression. CONCLUSION: These findings indicated that the over expression of ATM may contribute to prevent carcinogenesis of OSCC. ATM inactivation may be one of the genetic alterations of the molecular progression of OSCC.