***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Summary AIM : The aim of our study was to evaluate the accuracy of preoperative TNM staging with endoscopic ultrasound ( EUS ) in gastric cancer patients in comparison with the pathohistological stage of the resected specimen , and to determine the possible implication s of EUS for individualized treatment of gastric cancer patients at our institution . PATIENTS AND METHODS : The study included 82 patients operated for resectable gastric cancer between January 1st 2001 and July 1st 2003 at the Maribor Teaching Hospital Department of Abdominal and General Surgery . The EUS stage was assessed preoperatively at the Endoscopical Unit , and the pathohistological stage in the resected specimen was determined postoperatively at the Department of Pathologic Morphology according to recommended st and ards . RESULTS : Comparison of EUS and pathohistological assessment s revealed accuracy of EUS staging for locoregional tumor infiltration ( category T ) in 68 % of patients . The accuracy of EUS staging was 68 % for T1 , 69 % for T2 , 69 % for T3 and 60 % for T4 . Lymph nodes ( category N ) were correctly staged with EUS in 57 % of cases . The EUS stage was correct for lymph nodes with no metastases ( N− ) in 40 % of cases , and for lymph nodes with metastases ( N+ ) in 90 % . There was no significant difference in accuracy of EUS staging with regard to tumor site ( P = 0.768 ) or tumor size ( P = 0.766 ) . CONCLUSIONS : According to our results the accuracy of EUS staging matched pathohistological staging with regard to tumor infiltration and lymph node stage in 68 % and 57 % of cases respectively . Underestimation of the final T2 and T3 stages as T1 stage by EUS presents a problem regarding the consistency of EUS examination at our institution , particularly with respect to individual treatment for early gastric cancer . The present uncertainty in EUS stage reliability makes it necessary to have a strategy of radical resection with D2 lymphadenectomy in patients within EUS stages T1–T3 , with additional CT examinations in more advanced EUS stages in order to visualize the circumstances of tumor growth . Nevertheless , EUS provides an opportunity for the surgeon to gain more insight into the loco-regional circumstances of the gastric tumor process . For development of individual modes of treatment based on EUS staging , a more reliable assessment of EUS stage is m and atory BACKGROUND / AIMS Endoscopic ultrasonography is expected to be useful for invasion depth staging of early gastric cancer . A prospect i ve blind study of the staging characteristics of endoscopy and endoscopic ultrasonography for early gastric cancer was performed . METHODS Findings of endoscopy and endoscopic ultrasonography using a 20 MHz thin ultrasound probe were independently review ed and the results of 52 early gastric cancer lesions analysed . RESULTS The overall accuracy rates in invasion depth staging of early gastric cancer were 63 % for endoscopy and 71 % for endoscopic ultrasonography . No statistically significant differences were observed in overall accuracy .  Endoscopic ultrasonography tended to overstage , and lesions that were classified as mucosal cancer by endoscopic ultrasonography were very likely ( 95 % ) to be limited to the mucosa on histological examination . All 16 lesions staged as mucosal cancer independently but coincidentally by both methods were histologically limited to the mucosa . CONCLUSIONS Endoscopic ultrasonography is expected to compensate for the understaging of lesions with submucosal invasion that are endoscopically staged as mucosal cancer BACKGROUND AND STUDY AIMS This study aim ed to compare the diagnostic accuracy of endoscopic ultrasonography ( EUS ) with that of conventional endoscopy for staging depth of invasion ( T staging ) in early gastric cancer . PATIENTS AND METHODS A total of 955 patients with suspected early gastric cancer were prospect ively registered .  EUS staging was carried out prospect ively by a single endoscopist using either miniprobe or radial EUS depending on the endoscopic appearance of the tumor . Conventional endoscopy staging was performed retrospectively by consensus between two endoscopists who were blinded to the EUS staging . Conventional endoscopy staging was conducted on the basis of endoscopic features such as surface nodularity and fold convergence . Patients underwent either surgical ( n = 586 ) or endoscopic resection ( n = 369 ) with curative intent . The staging accuracy of each test was compared with the pathological staging of the resected specimen . RESULTS The presence of a T1 m tumor was histologically confirmed in 644 cases ( 67.4 % ) and that of a T1sm tumor in 311 cases ( 32.6 % ) . The overall accuracy of EUS staging was 67.4 % ( 644 / 955 ) and that of  conventional endoscopy staging was 73.7 % ( 704 / 955 ) ( P < 0.001 ) . The accuracy of miniprobe EUS  was significantly higher than that of radial EUS ( 79.5 % vs. 59.6 % , P < 0.001 ) , but did not differ significantly from that of conventional endoscopy ( 79.0 % ) . CONCLUSIONS EUS does not substantially impact on pretreatment T staging of patients with early gastric cancer compared with conventional endoscopy . Therefore , EUS may not be necessary routinely , and conventional endoscopy may be sufficient for determining the optimal therapeutic strategy , especially in relation to endoscopic resection for early gastric cancer Background Endoscopic ultrasonography ( EUS ) is an integrated part of the pretherapeutic evaluation program for patients with upper gastrointestinal ( GI ) tract cancer . Whether the clinical impact of EUS differs between surgeons from different countries is unknown . The same applies to the potential clinical influence of EUS misinterpretations . The aim of this study was to evaluate the interobserver agreement on predefined treatment strategies between surgeons from four different countries , with and without EUS , and to evaluate the clinical consequences of EUS misinterpretations . Methods One hundred patients with upper GI tract cancer were r and omly selected from all upper GI tract cancer patients treated at Odense University Hospital between 1997 and 2000 . Based on patient records and EUS data base results , a case story was created with and without the EUS result for each patient . Four surgeons were asked to select the relevant treatment strategy in each case , at first without knowledge of the EUS and thereafter with the EUS result available . Interobserver agreement and impact of EUS misinterpretations were evaluated using the actual final treatment of each patient as reference . Results Three of four or all four surgeons agreed on the same treatment strategy for nearly 60 % of the patients with and without the EUS results . Treatment decisions were changed in 34 % based on the EUS results , and the majority of these changes were toward nonsurgical and palliative treatments ( 85 % ) . Interobserver agreement was relatively low , but overall EUS increased kappa values from 0.16 ( “ poor ” ) to 0.33 ( “ fair ” ) , thus indicating increased overall agreement after the EUS results were available . EUS conclusion regarding stage or resectability was wrong in 17 % of the cases , but only one serious event would have been the clinical result of EUS misinterpretations . Conclusion Despite being used in different ways by different surgeons , EUS did change patient management in one third of the cases . The impact of  EUS misinterpretations seemed very low , and this study confirmed one of the strongest clinical possibilities of EUS , i.e. , the ability to detect nonresectable cases . EUS is an important imaging modality for oncosurgeons from different countries Background Early gastric cancer ( EGC ) with undifferentiated histology has not been generally accepted as an indication for endoscopic treatment . This study was design ed to evaluate the outcomes and clinicopathological factors associated with the complete resection of undifferentiated EGC using endoscopic submucosal dissection ( ESD ) . Methods A retrospective analysis of prospect ively collected data was performed on consecutive patients who underwent ESD .  Among the 456 EGCs treated using ESD at the Seoul National University Hospital , Seoul , Korea , between April 2005 and June 2008 , 60 lesions ( 13.2 % ) were diagnosed as undifferentiated gastric cancer ( poorly differentiated adenocarcinoma or signet ring cell carcinoma ) . Results En bloc resection was performed in all lesions without significant complications . The size discrepancy between the pretreatment endoscopy and the resected specimen was significantly higher in undifferentiated EGCs than differentiated EGCs ( p = 0.002 ) . The complete resection rate was significantly lower for undifferentiated EGC ( 55 % ) cases than differentiated EGC cases ( 84.1 % ; p < 0.001 ) . Independent risk factors for incomplete resection of undifferentiated EGC included tumor size > 20 mm , submucosal invasion , and presence of ulceration . During a mean observation time of 16 months , no recurrence developed in any of the patients with undifferentiated EGCs thought to be completely resected by ESD . Conclusions ESD might be considered an alternative treatment modality in carefully selected cases of undifferentiated EGC Conventional imaging studies are often not sensitive enough to allow accurate preoperative staging of intra-abdominal tumour spread .  Laparoscopy and laparoscopic ultrasound appear to be suitable to improve staging of gastrointestinal tumors . Within a 10-month period 40 patients with upper GI tract cancer underwent laparoscopy  for intra-abdominal staging . Additionally laparoscopic ultrasound was performed on 20 of these patients using a flexible echo-endoscope equipped with a curved array transducer ( 5/7.5 MHz ) . By laparoscopy additional information compared to conventional staging was obtained in 16 patients ( 40 % ) . Laparoscopy revealed peritoneal carcinomatosis and liver metastases in seven and four patients , respectively . M1-lymph nodes were detected in four patients . Laparoscopic ultrasound was able to image otherwise inaccessible regions of the abdominal cavity and induced a change of staging in seven of 20 patients in whom laparoscopy was uneventful . Ultrasound also proved to be valuable for localization of M1-lymph nodes . In summary , combination of laparoscopy and laparoscopic ultrasound  improved staging in 23 of 40 patients ( 57 % ) . Consequently surgery was ab and oned in 16 patients due to incurable or non-resectable disease , while down-staging occurred in seven patients , who subsequently underwent resection . Laparoscopy is capable of improving staging of intra-abdominal malignancy by detection and subsequent biopsy of small lesions . Laparoscopic ultrasound can replace the lack of tactile sensitivity in laparoscopy , thus enabling the detection of non-superficial lesions Background : Local and multimodal therapeutic strategies for tumours of the oesophagus and gastric cardia , require precise preoperative staging . Endosonography is considered the most accurate staging method , while computed tomography ( CT ) has limitations especially in the evaluation of local infiltration . Macroscopic endoscopic evaluation was reported to be accurate in selected series , but no study has yet compared all three staging modalities . Methods : One hundred and seventeen unselected patients with tumours of the oesophagus and gastric cardia were prospect ively staged first by the endoscopic macroscopic appearance and then by endosonography .  All patients had preoperative CT scans , however , only the 36 patients receiving the scans at our institution were included in the study . The preoperative staging results were then compared to postoperative histology which was available as the gold st and ard in all included patients . Kappa statistics were used to exclude chance agreement of the clinical staging results with the pathohistological findings . Differences between the result ing ĸ values for the different staging modalities were analysed with a jack-knife test . Results : Endoscopic macroscopic staging and endosonography  ( accuracy 67 and 69 % , weighted ĸ 0.78 and 0.84 ) were significantly more accurate than CT ( accuracy 33 % , weighted ĸ 0.44 ) for determination of the T category ( p = 0.006 and p = 0.001 ) . After exclusion of tumours of the cardia ( n = 33 ) , the accuracy  of macroscopic and endosonographic staging  ( accuracy 72 and 75 % , weighted ĸ 0.86 and 0.88 ) increased and remained more accurate than CT ( accuracy 50 % , weighted ĸ 0.62 ) . The main pitfall in our series in staging the T category was the overestimation of T2 tumours in the cardia as T3 or even as T4 tumours due to the inability to visualise the serosa . The accuracy of predicting lymph node metastasis was 68 % for macroscopic endoscopic , 79 % for endosonographic , and 67 % for CT staging . Only endosonographic staging was significantly different from chance agreement with histology ( weighted ĸ = 0.56 ) . Endosonographic staging was significantly more accurate than endoscopic macroscopic and CT staging ( p = 0.03 ) . Conclusions : Endosonography is the most accurate staging modality for overall preoperative staging of oesophageal and cardial tumours . Endoscopic macroscopic staging allows a reasonably accurate assessment of the T category BACKGROUND AND STUDY 
    Output:
    
Overall , as demonstrated also by the Bayesian nomograms , which enable readers to calculate post-test probabilities for any target condition prevalence , the EUS accuracy can be considered clinical ly useful to guide physicians in the locoregional staging of people with gastric cancer .
Moreover , we must emphasize that the analysis of positive and negative likelihood values revealed that EUS diagnostic performance can not be considered optimal either for disease confirmation or for exclusion , especially for the ability of EUS to distinguish T1a ( mucosal ) versus T1b ( submucosal ) cancers and positive versus negative lymph node status .
By analyzing the data from the largest series ever considered , we found that the diagnostic accuracy of EUS might be considered clinical ly useful to guide physicians in the locoregional staging of people with gastric carcinoma .
Moreover , physicians should be warned that  EUS performance is lower in diagnosing superficial tumors ( T1a versus T1b ) and lymph node status ( positive versus negative ) .