***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: Objective To identify factors that have contributed to reduced rates of death and complications after esophageal resection in a 17-year period at a tertiary referral center . Summary Background Data There has been an evolving refinement in surgical technique and perioperative management of patients undergoing esophageal resection at Queen Mary Hospital during the past two decades . As of the end of 1998 , there had been no hospital deaths among the last 105 consecutive resections performed for esophageal squamous cancer . Methods The results of esophageal resection for squamous cell carcinoma were analyzed using a prospect i ve esophageal data base . A longitudinal study was performed to compare and analyze rates of death and complications for three consecutive time periods . Results The study group comprised 710 patients who underwent one-stage esophageal resection between 1982 and 1998 . A transthoracic esophagectomy was the preferred approach in 590 patients ( 83 % ) . The overall hospital death rate was 11 % . The leading causes of hospital death were pulmonary complications ( 45.5 % ) and progression of malignant disease ( 21.5 % ) ; anastomotic leakage accounted for 9 % of deaths . During the study period , the hospital death rate decreased from 16 % to 3.2 % , and the incidence of postoperative respiratory failure decreased from 15.5 % to 6.5 % . Perioperative factors that correlated with the decreased death rate over time were the increased postoperative use of  epidural analgesia  and  bronchoscopy  ( for clearance of pulmonary secretions ) , a decrease in history of smoking , and a decrease in surgical blood loss of more than 1,000 mL. Conclusions In this series of predominantly transthoracic esophagectomies , there has been a decline in the hospital death rate to less than 5 % . These results are largely attributable to factors aim ed at reducing postoperative pulmonary complications Background We clarified the incidence of adenocarcinoma of the esophagogastric junction ( AEG ) at a Japanese high-volume cancer center and its clinicopathological features between the Siewert subtypes . Methods Patients with AEG were selected from a prospect i ve data base of gastric and esophageal tumors established by Kanagawa Cancer Center . The Siewert subtypes were determined retrospectively by examining pathological pictures of the resected specimens and by evaluating the pathology and endoscopy findings . Results From January 1986 to December 2005 , 147 ( 4.0 % ) patients were determined to have AEG ; 2,794 ( 75.8 % ) were diagnosed to be true gastric cancer , whereas 745 ( 20.2 % ) were true esophageal cancer . Of these 147 patients with AEG , 5 ( 3.4 % ) were classified as type I , 82 ( 55.8 % ) as type II , and 60 ( 40.8 % ) as type III tumors . The depth of tumor invasion was deeper and the nodal metastases were more frequent in type III compared with type II . The risk factors for nodal metastases included the depth and size of the tumor , but not the Siewert subtypes itself . Mediastinal nodal metastases were strongly influenced by a thoracotomy and the extent of the dissection . The pathological grade was higher in type III than in type II . Although the 5-year survival rate was significantly higher in type II than in type III tumors , the survival difference disappeared when the patients were restricted to an R0 resection , even though type III patients demonstrated a more advanced stage . Conclusions The proportions of AEG were strikingly different between Japan and western countries . Although each Siewert subtype had some different characteristics , nodal metastases were determined by both the tumor progression and the extent of the nodal dissection . An R0 resection was a key for the survival in AEG Purpose : To investigate the importance of lymph node yield ( LNY ) and the ratio of afflicted lymph nodes in esophageal carcinoma patients . Patients and Methods : Between 1992 and 2004 , 368 patients with esophageal carcinoma underwent surgery .  Esophagectomy with curative intent was performed in 255 patients .  Subtotal esophagectomy was performed either by thoracoabdominal ( 104 patients , 40.8 % ) or by transhiatal approach ( 151 patients , 59.2 % ) . Results : According to the LNY , patients were grouped into 3 groups . Twenty-six patients had ≤5 , 96 had 6 to 18 , and 113 had ≥19 dissected lymph nodes . In patients with nodal involvement ( pN1 ) , no significant overall survival differences were identified when stratifying subgroups according to the LNY . However , LNY had striking prognostic relevance in pN0 patients . The median overall survival was 23 ( ≤5 LN ) , 36 ( 6–18 LN ) , and 88 months ( ≥19 ) . Even for patients with tripled LNY than the proposed minimum by the International Union Against Cancer ( UICC ) ( 18 LN ) , the rate of patients with detected lymph node metastases was only 46 % , compared with 61 % for patients with a LNY of ≥19 ( P = 0.002 ) . In pN1 patients classified according to the ratio of afflicted lymph nodes , median overall survival was 27 months in patients with a ratio < 11 % , compared with 15 and 13 months in patients with a ratio of 11 % to 33 % and > 33 % , respectively ( P < 0.001 ) . Multivariate Cox regression modeling identified ratio as the strongest independent prognostic factor for overall survival in pN1 and the LNY in pN0 patients . Conclusions : The minimal regional LNY of 6 lymph nodes as recommended by the UICC for esophageal carcinoma is far too low to appropriately stage the disease . The LNY and the ratio should be reflected in the next version of the UICC classification OBJECTIVE To study survival , morbidity , and ability to swallow , after  oesophagectomy for cancer of the oesophagus and cardia . DESIGN Prospect i ve open study . SETTING University hospital , Norway . SUBJECTS 83 patients , 38 with squamous cell carcinoma and 45 with adenocarcinoma of the oesophagus and cardia . INTERVENTIONS Transhiatal ( n = 51 ) and transthoracic ( n = 32 ) oesophagectomy . Oesophageal replacement was by either stomach ( n = 80 ) or colon ( n = 3 ) . Cervical anastomosis was used in all but 2 . MAIN OUTCOME MEASURES Early and late morbidity and mortality , length of stay in intensive care unit and in hospital , and survival analysis . RESULTS 30 Day and in hospital mortality were 0 and 4 % for transhiatal , and 6 % and 9 % for transthoracic , oesophagectomy . Complications included recurrent nerve palsy ( n = 7 ) , anastomotic leaks ( n = 5 ) , and chylothorax ( n = 4 ) . 17 Patients ( 22 % ) needed dilatations for stenosis of the anastomosis , and 71 ( 85 % ) of the patients left hospital within four weeks of operation . Survival analysis showed a 5 year survival rate of 33 % for patients with adenocarcinoma operated on for cure and a 2 year survival of 28 % for patients with squamous cell carcinoma . CONCLUSIONS Oesophagectomy for cure is worthwhile as some patients are cured and most of the remainder have prolonged relief of their dysphagia . Palliative resections should not be done in patients with distant metastases or invasion of adjacent organs by the tumour because of long stay in hospital , appreciable morbidity , and short life expectancy Objective : “ Rediscovered ” in 1976 , transhiatal esophagectomy ( THE ) has been applicable in most situations requiring esophageal resection and reconstruction . The objective of this study was to review the authors ’ 30-year experience with THE and changing trends in its use . Methods : Using the authors ’ prospect i ve Esophagectomy Data base , this single institution experience with THE was analyzed retrospectively . Results : Two thous and and seven THEs were performed—1063 ( previously reported ) between 1976 and 1998 ( group I ) and 944 from 1998 to 2006 ( group II ) , 24 % for benign disease , 76 % , cancer . THE was possible in 98 % . Stomach was the esophageal substitute in 97 % . Comparing outcomes between group I and group II , statistically significant differences ( P < 0.001 ) were observed in hospital mortality ( 4 % vs. 1 % ) ; adenocarcinoma histology ( 69 % vs. 86 % ) ; use of neoadjuvant chemoradiation ( 28 % vs. 52 % ) ; mean blood loss ( 677 vs. 368 mL ) ; anastomotic leak ( 14 % vs. 9 % ) ; and discharge within 10 days ( 52 % vs. 78 % ) . Major complications remain infrequent : wound infection/dehiscence , 3 % , atelectasis/pneumonia , 2 % , intrathoracic hemorrhage , recurrent laryngeal nerve paralysis , chylothorax , and tracheal laceration , < 1 % each . Late functional results have been good or excellent in 73 % . Aggressive preoperative conditioning , avoiding the ICU , improved pain management , and early ambulation reduce length of stay , with 50 % in group II discharged within 1 week . Conclusion : THE refinements have reduced the historic morbidity and mortality of esophageal resection . This largest reported THE experience reinforces the value of consistent technique and a clinical pathway in managing these high acuity esophageal patients Objective : Using Worldwide Esophageal Cancer Collaboration data , we sought to ( 1 ) characterize the relationship between survival and extent of lymphadenectomy  , and ( 2 ) from this , define optimum lymphadenectomy . Summary Background Data : What constitutes optimum lymphadenectomy to maximize survival is controversial because of variable goals , analytic methodology , and generalizability of the underpinning data . Methods : A total of 4627 patients who had esophagectomy alone for esophageal cancer were identified from the Worldwide Esophageal Cancer Collaboration data base .  Patient-specific risk-adjusted survival was estimated using r and om survival forests . Risk-adjusted 5-year survival was averaged for each number of lymph nodes resected and its relation to cancer characteristics explored . Optimum number of nodes that should be resected to maximize 5-year survival was determined by r and om forest multivariable regression . Results : For pN0M0 moderately and poorly differentiated cancers , and all node-positive ( pN+ ) cancers , 5-year survival improved with increasing extent of lymphadenectomy . In pN0M0 cancers , no optimum lymphadenectomy was defined for pTis ; optimum lymphadenectomy was 10 to 12 nodes for pT1 , 15 to 22 for pT2 , and 31 to 42 for pT3/T4 , depending on histopathologic cell type . In pN+M0 cancers and 1 to 6 nodes positive , optimum lymphadenectomy was 10 for pT1 , 15 for pT2 , and 29 to 50 for pT3/T4 . Conclusions : Greater extent of lymphadenectomy was associated with increased survival for all patients with esophageal cancer except at the extremes ( TisN0M0 and ≥7 regional lymph nodes positive for cancer ) and well-differentiated pN0M0 cancer . Maximum 5-year survival is modulated by T classification : resecting 10 nodes for pT1 , 20 for pT2 , and ≥30 for pT3/T4 is recommended CONTEXT Hospitals that treat a relatively high volume of patients for selected surgical oncology procedures report lower surgical in-hospital mortality rates than hospitals with a low volume of the procedures , but the reports do not take into account length of stay or adjust for case mix . OBJECTIVE To determine whether hospital volume was inversely associated with 30-day operative mortality , after adjusting for case mix . DESIGN AND SETTING Retrospective cohort study using the Surveillance , Epidemiology , and End Results (SEER)-Medicare linked data base in which the hypothesis was prospect ively specified . Surgeons determined in advance the surgical oncology procedures for which the experience of treating a larger volume of patients was most likely to lead to the knowledge or technical expertise that might offset surgical fatalities . PATIENTS All 5013 patients in the SEER registry aged 65 years or older at cancer diagnosis who underwent pancreatectomy , esophagectomy , pneumonectomy , liver resection , or pelvic exenteration , using incident cancers of the pancreas , esophagus , lung , colon , and rectum , and various genitourinary cancers diagnosed between 1984 and 1993 . MAIN OUTCOME MEASURE Thirty-day mortality in relation to procedure volume , adjusted for comorbidity , patient age , and cancer stage . RESULTS Higher volume was linked with lower mortality for pancreatectomy ( P=.004 ) , esophagectomy ( P<.001 ) , liver resection ( P=.04 ) , and pelvic exenteration 
    Output:
    
There was no difference in blood loss .
Analysis of 5-year survival showed no significant difference between the groups and was subject to significant heterogeneity .
This meta- analysis of studies comparing transthoracic with transhiatal esophagectomy for cancer demonstrates no difference in 5-year survival , however lymphadenectomy and reported surgical quality was suboptimal in both groups and the transthoracic group had significantly more advanced cancer .