***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 
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    ***EXAMPLES*** 
    Input: Pancreaticoduodenectomy remains the only potentially curative treatment for adenocarcinoma of the pancreas . The aim of this study was to analyze prognostic factors impacting survival after R0 pancreaticoduodenectomy for adenocarcinoma in the head of the pancreas . Between 1995 and 2002 , a  potentially curative ( R0 ) pancreaticoduodenectomy with pancreatogastrostomy for ductal adenocarcinoma in the head of the pancreas was performed in 81 patients ( 42 women and 39 men ) with a mean age of 64 years ( range 35–84 ) . Patients were identified from a prospect i ve data base and records were review ed retrospectively . Postoperative mortality was 1 % , and 40 % of patients had complications . Median survival was 18 months , and the 5-year survival was 24 % . Fifteen patients were alive at 5 years . Factors associated with poor survival in multivariate analysis were ( 1 ) two or more positive lymph nodes , ( 2 ) tumor diameter greater than 30 mm , and ( 3 ) age greater than 70 years . In patients with no or with one positive lymph node , the 5-year survival was 44 % . On the other h and , in patients with two or more positive lymph nodes , both the 3- and 5-year survival was 5 % . The main risk factor associated with poor survival after an R0 pancreaticoduodenectomy for adenocarcinoma in the head of pancreas was lymph node status : The presence of two or more positive lymph nodes was associated with decreased survival Objective : To prospect ively evaluate the survival benefit of dissection of the nerve plexus and lymphadenectomy in patients with pancreatic head cancer . Background : Despite r and omized controlled trials on the extent of surgery in pancreatic cancer , attempts have been made to perform more extended resections . Methods : A total of 244 patients were enrolled ; of these , 200 were r and omized to undergo st and ard resection or extended resection  , with the latter including the dissection of additional lymph nodes and the right half of the nerve plexus around the superior mesenteric artery and celiac axis . We evaluated 167 patients from 7 centers who fulfilled all of the required criteria . Result : Operation time was longer and estimated blood loss was higher in the extended resection group than in the st and ard resection group , but the R0 resection rate was comparable . The mean number of lymph nodes retrieved per patient was higher in the extended resection group than in the st and ard resection group ( 33.7 vs 17.3 ; P < 0.001 ) . The morbidity rate was slightly higher in the extended resection group than in the st and ard resection group . Two patients in the extended resection group died in hospital . Median survival after R0 resection was similar in the extended resection and st and ard resection groups ( 18.0 vs 19.0 months ; P = 0.239 ) regardless of lymph node metastasis . Adjuvant chemoradiation had a positive impact on overall survival . Conclusions : This study suggests that extended lymphadenectomy with dissection of the nerve plexus does not provide a significant survival benefit compared with st and ard resection in pancreatic head cancer . St and ard resection can be performed safely and efficiently , without negatively affecting oncologic efficacy or long-term survival , when compared with extended pancreaticoduodenal resection . ( NCT00679913 ) Background The value of pancreatoduodenectomy ( PD ) with extended lymphadenectomy for pancreatic cancer has been evaluated by many retrospective studies and 3 r and omized controlled trials ( RCT ) . However , the protocol s used and the results found in the 3 RCTs were diverse . Therefore , a multicenter RCT was proposed in 1998 to evaluate the primary end point of long-term survival and the secondary end points of morbidity , mortality and quality of life of patients undergoing st and ard versus extended lymphadenectomy in radical PD for pancreatic cancer . Methods From March 2000 to May 2003 , 112 patients with potentially curable pancreatic head cancer were enrolled and intraoperatively r and omized to a st and ard or extended lymphadenectomy group .  No resected patients received any adjuvant treatments . Results A hundred and one eligible patients were analyzed . Demographic and histopathological characteristics of the two groups were similar . The mean operating time , intraoperative blood loss and number of retrieved lymph nodes were greater in the extended group , but the other operative results were comparable . Conclusions Although this multicenter RCT was conducted in a strict setting , extended lymphadenectomy in radical PD did not benefit long-term survival in patients with resectable pancreatic head cancer and led to levels of morbidity , mortality and quality of life comparable to those found after st and ard lymphadenectomy Objective To evaluate , in a prospect i ve , r and omized single-institution trial , the end points of operative morbidity , operative mortality , and survival in patients undergoing st and ard versus radical ( extended ) pancreaticoduodenectomy .  Summary Background Data Numerous retrospective reports and a few prospect i ve r and omized trials have suggested that the performance of an extended lymphadenectomy in association with a pancreaticoduodenal resection may improve survival for patients with pancreatic and other periampullary adenocarcinomas . Methods Between April 1996 and June 2001 , 299 patients with periampullary adenocarcinoma were enrolled in a prospect i ve , r and omized single-institution trial . After intraoperative verification ( by frozen section ) of margin-negative resected periampullary adenocarcinoma , patients were r and omized to either a st and ard pancreaticoduodenectomy ( removing only the peripancreatic lymph nodes en bloc with the specimen ) or a radical ( extended ) pancreaticoduodenectomy ( st and ard resection plus distal gastrectomy and retroperitoneal lymphadenectomy ) . All pathology specimens were review ed , fully categorized , and staged . The postoperative morbidity , mortality , and survival data were analyzed . Results Of the 299 patients r and omized , 5 ( 1.7 % ) were subsequently excluded because their final pathology failed to reveal periampullary adenocarcinoma , leaving 294 patients for analysis ( 146 st and ard vs. 148 radical ) . The two groups were statistically similar with regard to age ( median 67 years ) and gender ( 54 % male ) . All the patients in the radical group underwent distal gastric resection , while 86 % of the patients in the st and ard group underwent pylorus preservation ( P < .0001 ) . The mean operative time in the radical group was 6.4 hours , compared to 5.9 hours in the st and ard group ( P = .002 ) . There were no significant differences between the two groups with respect to intraoperative blood loss , transfusion requirements ( median zero units ) , location of primary tumor ( 57 % pancreatic , 22 % ampullary , 17 % distal bile duct , 3 % duodenal ) , mean tumor size ( 2.6 cm ) , positive lymph node status ( 74 % ) , or positive margin status on final permanent section ( 10 % ) . The mean total number of lymph nodes resected was significantly higher in the radical group . Of the 148 patients in the radical group , only 15 % ( n = 22 ) had metastatic adenocarcinoma in the resected retroperitoneal lymph nodes , and none had retroperitoneal nodes as the only site of lymph node involvement . One patient in the radical group with negative pancreaticoduodenectomy specimen lymph nodes had a micrometastasis to one perigastric lymph node . There were six perioperative deaths ( 4 % ) in the st and ard group versus three perioperative deaths ( 2 % ) in the radical group ( P = NS ) . The overall complication rates were 29 % for the st and ard group versus 43 % for the radical group ( P = .01 ) , with patients in the radical group having significantly higher rates of early delayed gastric emptying and pancreatic fistula and a significantly longer mean postoperative stay . With a mean patient follow-up of 24 months , there were no significant differences in 1- , 3- , or 5-year and median survival when comparing the st and ard and radical groups . Conclusions Radical ( extended ) pancreaticoduodenectomy can be performed with similar mortality but some increased morbidity compared to st and ard pancreaticoduodenectomy . The data to date fail to indicate that a survival benefit is derived from the addition of a distal gastrectomy and retroperitoneal lymphadenectomy to a pylorus-preserving pancreaticoduodenectomy BACKGROUND The role of adjuvant treatment in pancreatic cancer remains uncertain . The European Study Group for Pancreatic Cancer ( ESPAC ) assessed the roles of chemoradiotherapy and chemotherapy in a r and omised study . METHODS After resection , patients were r and omly assigned to adjuvant chemoradiotherapy ( 20 Gy in ten daily fractions over 2 weeks with 500 mg/m(2 ) fluorouracil intravenously on days 1 - 3 , repeated after 2 weeks ) or chemotherapy ( intravenous fluorouracil 425 mg/m(2 ) and folinic acid 20 mg/m(2 ) daily for 5 days , monthly for 6 months ) . Clinicians could r and omise patients into a two-by-two factorial design ( observation , chemoradiotherapy alone , chemotherapy alone , or both ) or into one of the main treatment comparisons ( chemoradiotherapy versus no chemoradiotherapy or chemotherapy versus no chemotherapy ) . The primary endpoint was death , and all analyses were by intention to treat . Findings 541 eligible patients with pancreatic ductal adenocarcinoma were r and omised : 285 in the two-by-two factorial design ( 70 chemoradiotherapy , 74 chemotherapy , 72 both , 69 observation ) ; a further 68 patients were r and omly assigned chemoradiotherapy or no chemoradiotherapy and 188 chemotherapy or no chemotherapy .  Median follow-up of the 227 ( 42 % ) patients still alive was 10 months ( range 0 - 62 ) . Overall results showed no benefit for adjuvant chemoradiotherapy ( median survival 15.5 months in 175 patients with chemoradiotherapy vs 16.1 months in 178 patients without ; hazard ratio 1.18 [ 95 % CI 0.90 - 1.55 ] , p=0.24 ) . There was evidence of a survival benefit for adjuvant chemotherapy ( median survival 19.7 months in 238 patients with chemotherapy vs 14.0 months in 235 patients without ; hazard ratio 0.66 [ 0.52 - 0.83 ] , p=0.0005 ) . Interpretation This study showed no survival benefit for adjuvant chemoradiotherapy but revealed a potential benefit for adjuvant chemotherapy , justifying further r and omised controlled trials of adjuvant chemotherapy in pancreatic cancer Due to uncertainties regarding clinical ly meaningful gains from adjuvant chemotherapy after colorectal cancer surgery , several Nordic Groups in the early 1990s initiated r and omised trials to prove or reject such gains . This report gives the joint analyses after a minimum 5-year follow-up . Between October 1991 and December 1997 , 2 224 patients under 76 years of age with colorectal cancer stages II and III were r and omised to surgery alone ( n = 1 121 ) or adjuvant chemotherapy ( n = 1 103 ) which varied between trials ( 5FU/levamisole for 12 months , n = 444 ; 5FU/leucovorin for 4 - 5 months according to either a modified Mayo Clinic schedule ( n = 262 ) or the Nordic schedule ( n = 397 ) . Some centres also r and omised patients treated with 5FU/leucovorin to+/-levamisole ) . A total of 812 patients had colon cancer stage II , 708 colon cancer stage III , 323 rectal cancer stage II and 368 rectal cancer stage III . All analyses were according to intention-to-treat . No statistically significant difference in overall survival , stratified for country or region , could be found in any group of patients according to stage or site . In colon cancer stage III , an absolute difference of 7 % ( p = 0.15 ) , favouring chemotherapy , was seen . The present analyses corroborate a small but clinical ly meaningful survival gain from adjuvant chemotherapy in colon cancer stage III , but not in the other presentations BACKGROUND To compare operative morbidity , mortality , quality of life , and survival after  pancreatoduodenectomy ( PD ) versus pancreatoduodenectomy with extended lymphadenectomy ( PD/ELND ) in patients with resectable pancreatic cancer . METHODS From May 1997 to July 2003 there were 132 patients with biopsy examination-proven or suspected adenocarcinoma of the pancreatic head who agreed to participate in a single-institution , prospect i ve , r and omized trial . If resectable at operation , patients then were r and omized to st and ard PD ( 40 patients ) or PD/ELND ( 39 
    Output:
    
ConclusionS PD is associated with reduced morbidity , but equivalent long-term benefits compared to patients undergoing EPD