***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: Surgery is the st and ard treatment for patients with resectable esophageal carcinoma , but the long term prognosis of these patients is unsatisfactory . Some r and omized trials of preoperative chemotherapy suggest that the prognosis of patients who respond may be improved AIMS This prospect i ve study was design ed to determine the utility of 18F-labelled deoxyglucose ( FDG ) in positron emission tomography ( PET ) ( FDG-PET ) for assessing the response to neoadjuvant chemoradiation therapy ( CRT ) in locally advanced oesophageal tumours . PATIENTS AND METHODS Thirty-six patients with locally advanced oesophageal cancer ( clinical T4 stage ) without organ metastases , underwent FDG-PET before and 1 month after CRT . Patients were classified as major responders by serial FDG-PET when the post-CRT PET demonstrated a strong reduction of FDG uptake at the primary tumour site ( > 80 % reduction of tumour-to-liver uptake ratio ) without any abnormal FDG uptake elsewhere in the body . PET response was compared with histology obtained during post-induction transthoracic oesophagectomy . RESULTS A strong correlation was found between the extent of lymph node ( LN ) involvement as shown by the pre-CRT PET and the major response rate ( P = 0.001 ) : such response occurred in nine of 11 N0M0 patients ( 82 % ) , in three of nine N(1 - 2)M0 patients ( 33 % ) and in two of 16 patients ( 13 % ) with distant lymphatic spread . Such a correlation was not found for computed tomography or endoscopic ultrasonography . The sensitivity of serial FDG-PET for a major CRT response was 10 of 14 ( 71 % ) , its specificity 18 of 22 ( 82 % ) . The concordance between the response assessment by PET and histopathology was 78 % . The median survival time after CRT of PET major responders compared with PET non-major responders was 16.3 months and 6.4 months , respectively . The metabolic response as measured by serial FDG-PET is a stronger prognostic factor for overall survival ( P = 0.002 ) than the extent of LN involvement seen on the pretreatment FDG-PET ( P = 0.087 ) . CONCLUSIONS These data indicate that CRT response as assessed by serial FDG-PET is strongly correlated with pathological response and survival PURPOSE Whole-body 18F-fluorodeoxyglucose ( [18F]FDG ) positron emission tomography ( PET ) imaging before and after induction therapy was prospect ively evaluated in patients with esophageal cancer to determine whether changes in PET images could measure response to therapy . PATIENTS AND METHODS Between April 1997 and April 1999 , 39 patients ( 34 men and five women ; median age , 59 years ; range , 36 to 76 years ) with esophageal cancer were prospect ively enrolled in a single-institution clinical trial of staging , including PET , induction therapy , restaging including PET , and esophagectomy .  All patients undergoing esophagectomy after induction therapy ( n = 17 ) were followed either to recurrence , to death , or through a disease-free interval of at least 24 months . RESULTS PET after st and ard staging studies and before therapy imaged undetected sites of metastatic disease in six patients ( 15 % ) . Restaging ( including PET ) after induction therapy did not identify any patients with disease progression or any patients with loco-regionally unresectable disease at exploration . The median decrease in the st and ardized uptake value ( SUV ) during induction therapy was 59 % . After R0 esophagectomy , the 2-year disease-free and overall survival was 38 % and 63 % , respectively , among patients who had a less than 60 % decrease in SUV , and 67 % and 89 % , respectively , among patients who had a greater than 60 % decrease in SUV ( P = .055 and P = .088 , respectively ) . CONCLUSION Compared with conventional imaging , PET detects additional sites of metastatic disease at initial evaluation . After induction therapy , PET did not add to the estimation of loco-regional resectability and did not detect new distant metastases . However , changes in [18F]FDG PET may predict disease-free and overall survival after induction therapy and resection in patients with esophageal cancer . Further evaluation in larger trials is warranted Purpose The purpose of this study was to evaluate the impact of FDG-PET following chemoradiotherapy ( CRT ) on treatment planning and survival in patients with oesophageal cancer ( OC ) . Methods Fifty-three consecutive OC patients had a post-treatment PET scan to evaluate tumour response to CRT prior to possible surgery . Baseline pre-CRT PET was performed in 33 patients . Prospect ively recorded post-CRT management plans were compared with post-PET treatment . High impact was defined as a change in treatment intent or modality . Survival was analysed using the Kaplan-Meier product limit method and Cox proportional hazards regression model . Results After completion of CRT , 23/53 patients ( 43 % ) achieved complete metabolic response ( CMR ) , as compared with only four ( 8 % ) with complete response on computed tomography .  High PET impact was observed in 19 patients ( 36 % ) . CMR was strongly predictive of survival ( p<0.008 ) on multivariate analysis . CMR patients in whom resection was not performed had comparable survival to those ( CMR and non-CMR ) who underwent resection . Conclusion The use of post-treatment FDG-PET for assessment of tumour response after CRT changed the clinical management of more than one-third of OC patients .  CMR status as assessed by PET powerfully stratified prognosis . Even in the absence of a baseline study , normalisation of uptake at all sites of known tumoral involvement carries a good medium-term prognosis BACKGROUND Patients with esophageal cancer who receive neoadjuvant chemoradiotherapy  are restaged with computed tomography ( CT ) , endoscopic ultrasound with fine needle aspiration ( EUS-FNA ) , and integrated positron emission computed tomography ( FDG-PET/CT ) , and the results affect treatment . METHODS This is a prospect i ve trial on a consecutive series of patients who had initial chest , abdomen , and pelvis CT scan ; EUS-FNA ; and fluoro-2-deoxy- d -glucose (FDG)-integrated PET/CT ; neoadjuvant chemoradiotherapy ; repeat staging tests ; pathologic staging ; and , if appropriate ,  resection with lymphadenectomy .  The primary objective was to assess the accuracy of these 3 tests in restaging patients after  neoadjuvant therapy .  RESULTS There were 48 patients ( 41 men ) , and 41 underwent Ivor Lewis esophagogastrectomy with lymphadenectomy .  The accuracy of each test for distinguishing pathologic T4 from T1 to T3 disease is 76 % , 80 % , and 80 % for CT scan , EUS-FNA and FDG-PET/CT , respectively . The accuracy for nodal disease was 78 % , 78 % , and 93 % for CT scan , EUS-FNA and FDG-PET/CT , respectively ( P = .04 ) . FDG-PET/CT correctly identified M1b disease in 4 patients , falsely suggested it in 4 patients , and missed it in 2 patients , whereas for CT , it was 3 , 3 , and 3 patients . Fifteen ( 31 % ) patients were complete responders , and FDG-PET/CT accurately predicted complete response in 89 % compared with 67 % for EUS-FNA ( P = .045 ) and 71 % for CT ( P = .05 ) . CONCLUSIONS FDG-PET/CT is more accurate than EUS-FNA and CT scan for predicting nodal status and complete responders after neoadjuvant therapy in patients with esophageal cancer .  FDG-PET/CT and CT alone provide targets for biopsy , but results are often falsely positive OBJECTIVE The objective was to identify whether repeat positron emission tomography scan after neoadjuvant chemoradiotherapy in patients with esophageal cancer predicted a complete response . METHODS A retrospective study using a prospect i ve data base was performed . Patients had esophageal cancer and underwent neoadjuvant chemoradiotherapy , an initial and repeat positron emission tomography , endoscopic ultrasound with fine-needle aspiration ( at the same institution ) , and Ivor Lewis esophagogastrectomy with lymph node resection .  RESULTS There were 221 patients who underwent Ivor Lewis , 86 of whom had their initial and repeat positron emission tomography scans performed at the same center . Of these , 37 patients ( 43 % ) were complete responders . The median maximum st and ardized uptake value of esophageal cancer decreased by 72 % in the 37 patients who were complete responders , by 58 % in the 31 patients who were partial responders , and by 37 % in the 18 patients who had a minimal pathologic response . When the maximum st and ardized uptake value decreased by more than 64 % , the patient was likely to be a complete responder ( P = .003 , area under the curve = 0.75 ) . CONCLUSION When initial and repeat positron emission tomography scans are performed at the same center at least 30 days after the completion of preoperative chemoradiotherapy , the percent change in the maximum st and ardized uptake value is a predictor of the response to chemoradiotherapy by a patient with esophageal cancer . When the maximum st and ardized uptake value decreases by 64 % or more , it is likely that the patient is a complete responder . These data may help guide neoadjuvant therapy and identify patients for a future r and omized study that compares observation with surgical resection in patients with esophageal cancer who appear to be complete responders Objective : To evaluate the utility of 18F-FDG-PET in predicting response to concomitant chemoradiation in locally-advanced esophageal cancer . Summary Background Data : Approximately 25 % of esophageal cancer patients experience a  pathologic complete response ( pCR ) to preoperative chemoradiation therapy .  Computed tomography , endoscopy , and endoscopic ultrasound are unable to identify patients experiencing a pCR . Growing evidence supports the use of 18F-FDG-PET in the staging of esophageal cancer in its ability to detect occult metastatic and lymph nodal disease . The identification of patients with a pCR to chemoradiation could potentially spare those patients the morbidity associated with a resection . Methods : Eligibility criteria included T3-T4N0M0 or T1-T4N1M0 esophageal cancer . Patients underwent an initial 18F-FDG-PET before treatment and then repeated 4 to 6 weeks after chemoradiation , prior to the esophagectomy . Chemoradiation consisted of : cisplatinum , 5-fluorouracil , and radiation to a median dose of 50.4 Gy . Pathologic response was determined from a systematic review of the esophagectomy specimens . Results : Sixty-four patients have completed therapy to date . Response was as follows : pCR 27 % , pathologic residual microscopic ( pCRmicro ) 14.5 % , partial response 19 % , and stable or progressive disease 39.5 % . A pretreatment st and ardized uptake value ( SUVmax1hour ) ≥15 was associated with an observed 77.8 % significant response ( pCR + pCRmicro ) compared with 24.2 % for patients with a pretreatment SUVmax1hour < 15 ( P = 0.005 ) . Significant response was observed in 71.4 % of patients with a decrease in SUVmax1hour ≥10 compared with 33.3 % when the SUVmax1hour decreased < 10 ( P = 0.004 ) . Conclusions : Pretreatment and posttreatment 18F-FDG-PET can be useful for predicting significant response to chemoradiation in esophageal cancer . These data should be considered in evaluation of patients for esophagectomy after chemoradiation PURPOSE To assess the efficacy of 18Fluorodeoxyglucose-positron emission tomography ( FDG-PET ) for predicting a pathologic response in locally advanced esophageal cancer after neoadjuvant chemoradiotherapy . METHODS AND MATERIAL S All enrolled patients were treated with neoadjuvant chemoradiotherapy followed by esophagectomy and underwent two FDG-PET scans , before and after neoadjuvant chemoradiotherapy . We compared the results of the preoperative FDG-PET scans with the pathologic results . RESULTS From July 2001 to July 2004 , 32 patients ( 29 men and 3 women ) were enrolled in this study .  Pathologic complete response ( pCR ) in the esophagus was achieved in 21 of 32 patients ( 66 % ) . The sensitivity , specificity , positive predictive value ( PPV ) , and negative predictive value ( NPV ) in the primary tumors of the preoperative FDG-PET were 27 % , 95 % , 75 % , and 71 % , respectively . In regional lymph 
    Output:
    
Studies performed outside of the United States and studies of higher method ologic quality yielded significantly higher overall accuracy .