***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: PURPOSE A prospect i ve study of preoperative tumor-node-metastasis staging of patients with esophageal cancer ( EC ) was design ed to compare the accuracy of 18-F-fluoro-deoxy-D-glucose ( FDG ) positron emission tomography ( PET ) with conventional noninvasive modalities . PATIENTS AND METHODS Seventy-four patients with carcinomas of the esophagus ( n = 43 ) or gastroesophageal junction ( n = 31 ) were studied . All patients underwent attenuation-corrected FDG-PET imaging , a spiral computed tomography ( CT ) scan , and an endoscopic ultrasound ( EUS ) . RESULTS FDG-PET demonstrated increased activity in the primary tumor in 70 of 74 patients ( sensitivity : 95 % ) . False-negative PET images were found in four patients with T1 lesions . Thirty-four patients ( 46 % ) had stage IV disease . FDG-PET had a higher accuracy for diagnosing stage IV disease compared with the combination of CT and EUS ( 82 % v 64 % , respectively ; P : = .004 ) . FDG-PET had additional diagnostic value in 16 ( 22 % ) of 74 patients by upstaging 11 ( 15 % ) and downstaging five ( 7 % ) patients . Thirty-nine ( 53 % ) of the 74 patients underwent a 2- or 3-field lymphadenectomy in conjunction with primary curative esophagectomy . In these patients , tumoral involvement was found in 21 local and 35 regional or distant lymph nodes ( LN ) . For local LN , the sensitivity of FDG-PET was lower than EUS ( 33 % v 81 % , respectively ; P : = .027 ) , but the specificity may have been higher ( 89 % v 67 % , respectively ; P : = not significant [ NS ] ) . For the assessment of regional and distant LN involvement , compared with the combined use of CT and EUS , FDG-PET had a higher specificity ( 90 % v 98 % , respectively ; P : = . 025 ) and a similar sensitivity ( 46 % v 43 % , respectively ; P : = NS ) . CONCLUSION PET significantly improves the detection of stage IV disease in EC compared with the conventional staging modalities . PET improves diagnostic specificity for LN staging UNLABELLED We investigated whether the st and ardized uptake value ( SUV ) of the primary tumor , the tumor length measured on a PET image , the number of (18)F-FDG PET-positive nodes , and the PET stage were independent prognostic predictors over other clinical variables in patients with esophageal squamous cell carcinoma who were undergoing curative surgery . METHODS Sixty-nine patients with newly diagnosed esophageal squamous cell carcinoma who underwent preoperative (18)F-FDG PET and curative esophagectomy were included . The events for survival analysis were defined as recurrence or metastasis and cancer-related death . The disease-free and overall survival rates of each variable were estimated by the Kaplan-Meier method . The Cox proportional hazards model was used to evaluate independent prognostic variables for multivariate survival analysis . RESULTS Using univariate survival analysis , the presence of adjuvant therapy , pathologic stage , number of CT-positive nodes ( 0 , 1 , > or = 2 ) , tumor length on PET ( cutoff : 3 cm , 5 cm ) , number of PET-positive nodes ( 0 , 1 , 2 , > or = 3 ) , and PET stage ( N0 M0 , N1 M0 , M1 ) were significant prognostic predictors for disease-free survival . However , only the number of PET-positive nodes was an independent significant prognostic predictor for disease-free survival in multivariate analysis ( hazard ratio = 1.87 , P < 0.001 ) . In univariate survival analysis , the sex , presence of adjuvant therapy , clinical and pathologic stages , number of CT-positive nodes , maximum SUV of the primary tumor ( cutoff : 6.3 , 13.7 ) , tumor length on PET , number of PET-positive nodes , and PET stage were significant prognostic predictors for overall survival . In contrast , the clinical stage ( hazard ratio = 0.53 , P < 0.05 ) , pathologic stage ( hazard ratio = 3.14 , P < 0.005 ) , tumor length by PET ( hazard ratio = 2.74 , P = 0.01 ) , and number of PET-positive nodes ( hazard ratio = 1.71 , P < 0.05 ) were independent significant prognostic predictors for overall survival in multivariate analysis . CONCLUSION In addition to the pathologic stage , (18)F-FDG PET provides noninvasively independent prognostic information using the number of positive lymph nodes and the tumor length on the PET image in preoperative esophageal squamous cell carcinoma . A revised TNM classification system for esophageal carcinoma may consider tumor length and the number of positive lymph nodes as important prognostic factors AIMS This study reports mode , timing and predictive factors of recurrence after  curative surgery for cardia cancer . METHODS A prospect i ve study in a series of 92 curatively ( R0 ) resected patients from 1988 to 2002 . RESULTS The 5-year recurrence rate was 71 % . Lymph node involvement was the only predictor of recurrence . No patients with more than 6 metastatic nodes were free from relapse 2 years after surgery . Locoregional , peritoneal and haematogenous relapses showed a similar median recurrence time ( 12 , 10 and 12 months , respectively ) , 80 % occurred within 24 months . CONCLUSIONS Few patients can be cured by surgery , lymph nodal involvement is the only predictor of recurrence Purpose To evaluate the clinical impact of FDG-PET in staging oesophageal cancer and whether this information improves prognostic stratification . Methods Impact was based on comparison of a prospect ively recorded pre-PET plan with post-PET treatment in 68 consecutive patients undergoing primary staging .  Survival was analysed using the Kaplan-Meier product limit method and the Cox proportional hazards regression model . Results FDG-PET findings impacted on the management of 27/68 patients ( 40 % ) : in 12 therapy was changed from curative to palliative and in three from palliative to curative , while in 12 other patients there was a change in the treatment modality or delivery but not in the treatment intent . The median survival was 21 months , with post-PET stage and treatment intent both strongly associated with survival ( p<0.001 ) . Conventional stage was not able to clearly stratify this population . Conclusion The use of FDG-PET for primary staging of oesophageal cancer changed the clinical management of more than one-third of patients and provided superior prognostic stratification compared with conventional investigations PURPOSE To determine the impact of 18-F-fluoro-deoxy-D-glucose positron emission tomography ( FDG-PET ) in the staging and prognosis of patients with locally advanced esophageal cancer ( LAEC ) . METHODS AND MATERIAL S Between January 2000 and October 2004 , all patients with LAEC evaluated in the Department of Radiation Oncology were considered for enrollment into a Phase II trial of  preoperative chemoradiation . Entry required a staging whole-body FDG-PET scan . RESULTS One hundred ten consecutive patients were evaluated ; 38 were ineligible for reasons including treatment elsewhere , prior malignancy , or refusal of treatment . After conventional staging ( clinical examination , endoscopic ultrasound , and chest/abdominal computerized tomography ) , 33 patients were ineligible because of metastatic disease or poor performance status . Of the remaining 39 patients , 23 were confirmed to have LAEC after FDG-PET staging and were treated in the Phase II trial ( Cohort I ) . Sixteen patients , however , had FDG-PET findings consistent with occult metastatic disease and were deemed ineligible for the trial but were treated with curative intent ( Cohort II ) . The 2-year survival rate for the 23 patients in Cohort I was 64 % , compared with 17 % ( p=0.003 ) for patients in Cohort II ( FDG-PET positive ) . CONCLUSIONS More than one-third of patients determined to have LAEC with conventional staging were upstaged with the use of FDG-PET . Despite comparable therapy , upstaging with FDG-PET predicts poor 2-year survival BACKGROUND The stage of esophageal cancer is currently determined by the anatomic TNM classification system as opposed to information about tumor biology . METHODS A retrospective review was made of a prospect i ve electronic data base . Patients had esophageal cancer , dedicated positron emission tomography ( PET ) using F-18-fluorodeoxyglucose ( FDG-PET ) and maximum st and ardized uptake value ( maxSUV ) measured . Biopsies were obtained from suspicious nodal and systemic locations , and when indicated , resection with complete lymphadenectomy was performed . RESULTS There were 89 patients ( 53 men ) . The median maxSUV for patients with high grade dysplasia , stage I , IIa , IIb , III , and IVa esophageal cancer was 1.7 , 2.9 , 8.9 , 7.7 , 9.5 , and 12 , respectively . Multivariate analysis showed patients with a high maxSUV were more likely to have poorly differentiated tumors ( risk ratio 1.89 , p = 0.032 ) and advanced stage ( risk ratio 2.6 , p < 0.001 ) . The maxSUV correlated better ( r(2 ) = 0.85 ) than the current TNM staging system for survival ( r(2 ) = 0.68 ) . Receiving operator characteristics curve demonstrated a maxSUV of 6.6 to be the optimal cut-off point . The 4-year survival of patients with a maxSUV of 6.6 or less was 89 % , whereas it was only 31 % for those patients with values greater than 6.6 ( p < 0.001 ) . CONCLUSIONS The maxSUV of an esophageal cancer on dedicated FDG-PET scan is an independent predictor of stage , tumor characteristics , and survival . It predicts survival better than the current TNM staging system . This information may help guide treatment strategies 
    Output:
    
SUV measured in patients with esophageal cancer , reflecting the metabolic activity of tumor and malignancy , could serve as a prognostic factor .
Considering that the FDG-PET can add important information of metabolism in detection and staging to conventional imaging modality , we anticipate that SUV could be used in patients with esophageal carcinoma