***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: Prospect i ve assessment of lymph node status , based on the findings of computed tomography , external ultrasonography and palpation , was compared with clinical results in 179 patients who underwent oesophagectomy with systematic node dissection .  Preoperative findings for each node group were classified into four grade s : involvement not suspected ( − ) ; possible involvement ( ± ) ; probable involvement ( + ) ; and definite involvement ( + + ) . When only ( + + ) or ( + ) assessment was categorized as positive , the specificity was more than 94 per cent , although the sensitivity was less than 40 per cent . The preoperative assessment correlated significantly with the incidence of node involvement ( P < 0·02 ) , the degree of lymphatic invasion ( P < 0·0001 ) and outcome after operation . For patients with all nodes assessed as ( − ) , the 5‐year survival rate was 70 per cent , compared with 26 per cent for those with nodes assessed as ( + ) , P = 0·001 . Preoperative assessment provided useful information on nodal status PURPOSE To evaluate the value of external ultrasonography ( US ) of the neck in current dedicated preoperative staging of patients with cancer of the esophagus and gastroesophageal junction ( GEJ ) . MATERIAL S AND METHODS We analyzed 180 consecutive patients ( 154 men , 26 women , and mean age 63 ( 38 - 84 ) years ) without palpable cervical lymphadenopathy , treated between January 2001 and March 2006 . Suspicious lesions were confirmed by cytological examination . All first 125 consecutive patients ( group A ) were staged by st and ard endoscopic ultrasonography ( EUS ) , multidetector computed tomography ( md-CT ) , positron emission tomography with (18)F-fluorodeoxyglucose ( FDG-PET ) and external US . The other 55 patients ( group B ) were prospect ively staged according to a revised protocol consisting of routine EUS and md-CT , while PET was only performed in subjects with T3-T4 and /or N1 disease and external US solely on indication . RESULTS Cervical metastases were found in seven patients from group A ( 6 % ) and in five from group B ( 9 % ) . Twenty percent ( 4/20 ) of the tumors above the carina and 5 % ( 8/160 ) of the distal tumors presented with cervical metastases . All were diagnosed as T3 and T4 tumors on EUS . Eleven of these metastases were detected by external US and nine on md-CT . All nodal metastases were detected by the combination of PET and md-CT . No cervical metastases were missed by the diagnostic algorithm in group B. CONCLUSION In present staging procedures for esophageal cancer , routine external US seems to have no additional value in detecting cervical metastases . It is still indicated to obtain cytological proof of suspected cervical lesions BACKGROUND AND OBJECTIVE A range of fixed-effect and r and om-effects meta-analytic methods are available to obtain summary estimates of measures of diagnostic test accuracy . The hierarchical summary receiver operating characteristic ( HSROC ) model proposed by Rutter and Gatsonis in 2001 represents a general framework for the meta- analysis of diagnostic test studies that allows different parameters to be defined as a fixed effect or r and om effects within the same model . The Bayesian method used for fitting the model is complex , however , and the model is not widely used . The objective of this report is to show how the model may be fitted using the SAS procedure NLMIXED and to compare the results to the fully Bayesian analysis using an example . METHODS The HSROC model , its assumptions , and its interpretation are described . The advantages of this model over the usual summary ROC ( SROC ) regression model are outlined . A complex example is used to compare the estimated SROC curves , expected operating points , and confidence intervals using the alternative approaches to fitting the model . RESULTS The empirical Bayes estimates obtained using NLMIXED agree closely with those obtained using the fully Bayesian analysis . CONCLUSION This alternative and more straightforward method for fitting the HSROC model makes the model more accessible to meta-analysts Objective To determine the prevalence of occult cervical nodal metastases in patients with squamous cell cancer and adenocarcinoma of the esophagus , and to determine the impact of esophagectomy with three-field lymph node dissection on survival and recurrence rates . Summary Background Data Although esophagectomy with three-field lymph node dissection is commonly practice d in Japan , its role in the surgical management of esophageal cancer in the United States , especially in patients with esophageal adenocarcinoma , is essentially unknown . Methods This is a prospect i ve observational study of esophagectomy with three-field lymphadenectomy .  Eighty patients underwent resection between August 1994 and April 2001 . Clinicopathological information and follow-up data were collected on all patients until death or June 2001 . Results Hospital mortality and morbidity rates were 5 % and 46 % , respectively . Metastases to the recurrent laryngeal and /or deep cervical nodes occurred in 36 % of patients irrespective of cell type ( adenocarcinoma 37 % , squamous 34 % ) or location within the esophagus ( lower third 32 % , middle third 60 % ) . Overall 5-year and disease-free survival rates were 51 % and 46 % , respectively . Sixty-nine percent presented with nodal metastases . The 5-year survival rate for node-negative patients was 88 % ; that for those with nodal metastases was 33 % . The 5-year survival rate in patients with positive cervical nodes was 25 % ( squamous 40 % , adenocarcinoma 15 % ) . Conclusions Esophagectomy with three-field lymph node dissection can be performed with a low mortality and reasonable morbidity . Unsuspected metastases to the recurrent laryngeal and /or cervical nodes are present in 36 % of patients regardless of cell type or location within the esophagus . Thirty percent of patients were upstaged , mainly from stage III to stage IV . An overall 5-year survival rate of 51 % suggests a true survival benefit beyond that achieved solely on the basis of stage migration BACKGROUND AND OBJECTIVES Both ultrasound ( US ) and computed tomography ( CT ) can be used to detect supraclavicular lymph node metastases . Aim was to compare US , US plus fine-needle aspiration ( US-FNA ) , CT , US + CT , and US-FNA + CT for the detection of these metastases in esophageal or gastric cardia cancer patients . METHODS Between 1994 and 2004 , 567 patients underwent US and CT for esophageal or gastric cardia cancer staging . Gold st and ard was postoperative detection of lymph nodes in the resected specimen , FNA , or a radiological result with follow-up . RESULTS Sensitivities of US ( 75 % ) , US-FNA ( 72 % ) , US + CT ( 80 % ) , and US-FNA + CT ( 79 % ) were higher than sensitivity of CT alone ( 25 % ) ( P < 0.001 ) . Specificities were high for US-FNA ( 100 % ) , CT ( 99 % ) , and US-FNA + CT ( 99 % ) , whereas those of US alone ( 91 % ) and US + CT ( 91 % ) were lower ( P < 0.001 ) . In 4/65 ( 6 % ) patients with true-positive malignant lymph nodes , CT was positive with US and /or US-FNA being negative . However , in 36/65 ( 55 % ) patients , US and /or US-FNA were positive with CT being negative . CONCLUSION US-FNA seems the preferred diagnostic modality for the detection of supraclavicular lymph node metastases in patients with esophageal or gastric cardia cancer .  Sensitivity of metastases detection only slightly improves if US-FNA is combined with CT . A prospect i ve , comparative study is however needed BACKGROUND AND OBJECTIVE Publication bias and other sample size effects are issues for meta-analyses of test accuracy , as for r and omized trials . We investigate limitations of st and ard funnel plots and tests when applied to meta-analyses of test accuracy and look for improved methods . METHODS Type I and type II error rates for existing and alternative tests of sample size effects were estimated and compared in simulated meta-analyses of test accuracy . RESULTS Type I error rates for the Begg , Egger , and Macaskill tests are inflated for typical diagnostic odds ratios ( DOR ) , when disease prevalence differs from 50 % and when thresholds favor sensitivity over specificity or vice versa . Regression and correlation tests based on functions of effective sample size are valid , if occasionally conservative , tests for sample size effects . Empirical evidence suggests that they have adequate power to be useful tests . When DORs are heterogeneous , however , all tests of funnel plot asymmetry have low power . CONCLUSION Existing tests that use st and ard errors of odds ratios are likely to be seriously misleading if applied to meta-analyses of test accuracy . The effective sample size funnel plot and associated regression test of asymmetry should be used to detect publication bias and other sample size related effects BACKGROUND Exact clinical staging before treatment of esophageal cancer has become increasingly important in the evaluation and comparison of the results of different treatment modalities , including surgery , chemotherapy , and radiotherapy . METHODS The accuracy of preoperative tumor staging by using an esophagography , esophagoscopy , percutaneous and endoscopic ultrasonography , and computed tomography was assessed in 224 patients with resectable esophageal cancer . The results of tumor staging by these tests were compared prospect ively with the pathologic stage of the esophagectomy specimens with respect to the T and N categories defined by the International Union Against Cancer TNM classification . RESULTS For the T category , the overall accuracy was 80 % . For the N category , overall accuracy was 72 % , with a sensitivity of 78 % , a specificity of 60 % , and a positive predictive value of 78 % . Overall , the accuracy of stage grouping was 56 % . CONCLUSIONS Either the T or N categories can be predicted reliably by clinical staging techniques . However , the preoperative stage grouping might not be valid in resectable , localized esophageal cancer Objective To determine the impact of radical node dissection on the recurrence patterns and survival rates of patients with carcinoma of the esophagus . Summary Background Data The role of esophagectomy with radical lymphadenectomy in the treatment of esophageal cancer is controversial . Most centers favor a limited operation with no attempt at nodal clearance . However , disease recurrence and patient survival rates remain dismal with or without preoperative therapy . The authors postulate that a more radical node dissection would reduce local failure rates and enhance survival . Methods One hundred eleven patients with esophageal cancer underwent en bloc esophagectomy with radical lymph node dissection between 1988 and 1998 . In 90 % of patients the procedure was applied nonselectively and without any preoperative therapy . Patients were prospect ively followed up for recurrence patterns and survival . Results The 5-year survival rate including noncancer deaths was 40 % . The 5-year survival rates for patients with stage 1 , 2A , 2B , 3 , and 4 disease were 78 % , 72 % , 0 % , 39 % , and 27 % , respectively . Forty percent of patients had node-negative disease ( 5-year survival rate , 75 % ) , and 60 % had nodal metastases ( 5-year survival rate , 26 % ) . Recurrence occurred in 39 % of patients and was local in only 8 % . Conclusions Radical esophagectomy results in superior overall and stage-specific 5-year survival rates . Extensive node dissection has a positive impact on survival rates , particularly in patients with nodal metastases AIM This study evaluates the use of neck ultrasound in staging squamous oesophageal carcinoma . MATERIAL S AND METHODS A prospect i ve analysis of the clinical , neck ultrasound ( US ) and thoraco-abdominal computed tomography ( CT ) findings in 121 patients with squamous oesophageal carcinoma at presentation was performed . The relationship between malignant neck nodes , mediastinal and abdominal adenopathy , location and size of the primary tumour was analysed . RESULTS Ten of 121 patients ( 8 % ) had clinical ly palpable neck nodes which were deemed malignant in six ( 5 % ) following US and fine-needle aspiration for cytology . Of those 111 patients with no palpable neck nodes , 31 ( 28 % ) had malignant nodes shown on US . The more cephalad the location of the primary tumour , the higher the frequency of malignant neck nodes which were found in 80 % , 52 % , 29 % and 9 % of cervical , upper thoracic , mid-thoracic and lower thoracic oesophageal tumours , respectively . Eleven ( 29 % ) of the 38 patients with malignant neck nodes shown on US had no CT evidence of additional adenopathy in the mediastinum or upper abdomen . Neck US altered TNM staging in 22/121 ( 18 % ) patients at presentation . CONCLUSION Neck US frequently detects clinical ly impalpable metastatic nodes leading to altered TNM staging in patients with squamous oesophageal 
    Output:
    
Our analysis shows that ultrasonography may be an effective and reliable approach to detect cervical lymph node metastasis in esophageal cancer .