***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    Input: OBJECTIVE To evaluate the effect of extensive lymphadenectomy on survival in patients with gastric cancer . DESIGN Retrospective analysis SETTING University Hospital , Norway . SUBJECTS 183 patients with stomach cancer resected for cure during the time period 1980 - 90 . INTERVENTIONS 78 patients had an R1- and 105 patients and R2 resection . 124 patients were treated by total gastrectomy  , 5 by proximal-- and 54 by distal resection . MAIN OUTCOME MEASURES Morbidity , mortality and long term survival . RESULTS The morbidity was 33 % ( 60/183 ) , of which 39 ( 21 % ) were general complications ( pneumonia , thrombosis , or cardiovascular disease ) . 14 patients died postoperatively ( 8 % ) . By logistic regression analysis we found that splenectomy was the only variable associated with both morbidity and immediate postoperative mortality . Five year survival was 39 % for patients who had undergone curative resections , 30 % for patients who had had an R1 resection , and 47 % for those who had had an R2 resection . By multivariate analysis ( Cox ) we found that N-classification ( TNM ) , tumour diameter of less than 45 mm , type of lymph node dissection ( R2 ) and operation period ( after 1984 ) correlated with improved survival . CONCLUSION Extensive lymph node dissection improves survival without increasing morbidity or postoperative mortality BACKGROUND In Japan the surgical approach to treatment of potentially curable gastric cancer , including extended lymphadenectomy , seems in retrospective surveys to give better results than the less radical procedures favoured in Western countries . There has , however , been no evidence from r and omised trials that extended lymphadenectomy ( D2 gastric resection ) confers a survival advantage . This question was addressed in a trial involving thirty-two surgeons in Europe . METHODS In a prospect i ve r and omised controlled trial , D1 resection ( level 1 lymphadenectomy ) was compared with D2 resection ( levels 1 and 2 lymphadenectomy ) . Central r and omisation ( 200 patients in each arm ) followed a staging laparotomy . FINDINGS The D2 group had greater postoperative hospital mortality ( 13 % vs 6.5 % ; p=0.04 [ 95 % Cl 9 - 18 % for D2 , 4 - 11 % for D1 ] and higher overall postoperative morbidity ( 46 % vs 28 % ; p<0.001 ) ; their postoperative stay was also longer . The excess postoperative morbidity and mortality in the D2 group was accounted for by distal pancreaticosplenectomy and splenectomy . In the whole group ( 400 patients ) , survival beyond three years was 30 % in patients whose gastrectomy included en-bloc pancreatico-splenic resection versus 50 % in the remainder . INTERPRETATION D2 gastric resections are followed by higher morbidity and mortality than D1 resections . These disadvantages are consequent upon additional pancreatectomies and distal splenectomies , and in long-term follow-up the higher mortality when the pancreas and spleen are resected may prove to nullify any survival benefit from D2 procedures A r and omized clinical trial was performed to compare  D1 and D2 gastrectomy in specialized Western centres . This paper reports short‐term results The contention that the R2 radical gastrectomy for localized and potentially curable gastric carcinoma may be superior to gastrectomy without lymphadenectomy ( R1 ) was assessed by r and omized trial . Five years after commencement 403 patients have been evaluated at surgery and only 43 ( 11 per cent ) found eligible ( S0–2 , P0 , H0 , N0–1 ) , 22 of whom underwent R1 and 21 R2 gastrectomy .  Seven patients had final histological stages in excess of the protocol . The R2 group had a longer operating time ( P<0.005 ) , a greater blood transfusion requirement ( P<0.005 ) , a longer hospital stay ( 0.05>P>0.025 ) and required reoperation in four cases . There were no postoperative deaths . Four patients have died from the disease in the R1 group and five in the R2 group , there being no difference in the probability of survival at a median follow‐up of 3.1 years . The small proportion of patients suitable for radical R2 surgery , the high associated morbidity and the fact that survival advantage has yet to be proven in trial suggest that this procedure should not yet be performed outside of controlled clinical trials Background : Studies have shown that the survival of patients with gastric adenocarcinoma is related to the number of regional lymph nodes with metastases . The probability of identifying node-positive cancers increases with the number of lymph nodes resected and examined . It has been recommended that at least 15 lymph nodes be removed and examined for adequate staging . Prospect i ve r and omized studies have shown the lymph node yield is much greater with the D2 resection than the D1 . This study evaluated the relative contribution of both the number of resected lymph nodes and the extent of gastric resection  ( D1/D2 ) on the outcome of patients with proximal gastric cancer . Methods : The medical records of 114 patients with adenocarcinoma of the proximal stomach , who underwent a curative gastric resection , were review ed . Patients were stratified into four groups , i.e. , two groups , D1/D1.5 and D2/D2.5 , based on the extent of resection , and two groups based on the number of lymph nodes removed , fewer than 15 lymph nodes and 15 or more lymph nodes . Survival was determined by the method of Kaplan-Meier and differences compared by the log-rank test . Multivariate analysis was performed by using the Cox model . Results : The number of resected lymph nodes had no effect on the survival of the group as a whole . A significant improvement in survival was noted for patients with a D2 or greater resection . The median survival of patients with 15 or more lymph nodes resected improved from 25 months to 42 months when treated with an extended resection , ( D2 or D2.5 ) . Resection of 15 or more lymph nodes alone , or combined with an extended resection , result ed in a statistically significant improvement in survival for patients in American Joint Committee on Cancer Staging ( AJCC ) stage II . Conclusions : Both resection of 15 or more lymph nodes and extended lymphadenectomy contributed to the survival advantage observed in patients with AJCC stage II gastric cancer . The D2 gastric resection prolonged the median survival time and improved the 5-year survival rate for patients with 15 or more resected lymph nodes BACKGROUND A multicenter , r and omized , clinical trial was initiated to evaluate the possible benefits of extended D2 ( D2 + ) lymphadenectomy after potentially curative resection of gastric cancer . METHODS St and ard D2 lymphadenectomy was defined according to the Japanese Gastric Cancer Association classification . D2 + lymph node dissection additionally included the removal of para-aortic nodes . RESULTS Of 781 patients screened , 275 were r and omized to st and ard D2 ( n = 141 ) or extended D2 + ( n = 134 ) lymphadenectomy . The overall morbidity rates were comparable in D2 ( 27.7 % ; 95 % confidence interval [ CI ] , 20.3 - 35.1 ) and D2 + ( 21.6 % ; 95 % CI , 13.7 - 29.5 ) groups ( P = .248 ) . Pre-existing cardiac disease , splenectomy , and excessive blood loss were identified as risk factors for overall and nonsurgical complications . Postoperative mortality rates were 4.9 % ( 95 % CI , 1.4 - 8.5 ) and 2.2 % ( 95 % CI , 0 - 4.7 ) , respectively ( P = .376 ) . CONCLUSIONS The interim safety analysis failed to show any significant difference with regard to the extent of lymph node dissection . The surgical outcome was not different between the 2 surgeries PURPOSE In the tumor-node-metastasis ( TNM ) staging system , no recommendations are provided on what lymph node retrieval technique is to be used to determine lymph node status , which leads to variability in nodal status assessment and TNM staging . PATIENT AND METHODS Lymph node retrieval was quantitated using data from 237 curatively resected gastric cancer patients , from a prospect i ve , r and omized trial that compared the Western resection with limited  ( D1 ) and the  Japanese resection with extended lymphadenectomy ( D2 ) , and compared data from the literature . Moreover , the efficacy of different lymph node retrieval techniques was determined . RESULTS The mean yield of lymph nodes was 15 in D1 and 30 in D2 , which is similar to results from German investigators , but substantially lower than results from Japanese investigators ( 60 in D2 ) . Use of a fat-clearance technique significantly increased ( P = .01 ) nodal yields compared with conventional retrieval . Significantly higher yields ( P < .001 ) were obtained by a Japanese surgeon using conventional retrieval directly postoperatively . Experience of surgicopathologic teams with processing resection specimens did not influence nodal yields . Further analysis showed that reference values for nodal yields per anatomically defined station as reported in the literature were contradicted by our results and indicated the ambiguity of such st and ards . CONCLUSION Despite some anatomical variability in the distribution of lymph nodes , advice on the number of nodes to examine per N level , feasible in all patients , should be incorporated into the TNM classification to st and ardize nodal status assessment . Based on our findings , we advocate retrieval of nodes immediately postoperatively by the surgeon PURPOSE Radical gastrectomy with regional lymphadenectomy is the only curative treatment option for gastric cancer . The extent of lymphadenectomy , however , is controversial . The two European r and omized trials only reported an increase in operative morbidity and mortality , but failed to show survival benefit , in the D2 lymphadenectomy group . We conducted a r and omized controlled trial to compare the Japanese st and ard D2 and D2 + para-aortic nodal dissection . PATIENTS AND METHODS Only experienced surgeons in both procedures from 24 Japanese institutions participated in the study . Patients with potentially curable gastric adenocarcinoma ( T2-subserosa , T3 , or T4 ) who were surgically fit were intraoperatively r and omized .  Postoperative morbidity and hospital mortality were recorded prospect ively in a fixed format and were compared between the two groups in this study . RESULTS A total of 523 patients were r and omized between July 1995 and April 2001 .  Postoperative complications were reported in 24.5 % of all patients . Although the morbidity for the extended surgery group ( 28.1 % ) was slightly higher than the st and ard group ( 20.9 % ) , there was no difference in the incidence of four major complications ( anastomotic leak , pancreatic fistula , abdominal abscess , pneumonia ) between the two groups . Hospital mortality was reported at 0.80 % : one patient in each group died of operative complications , while one from each group died of rapid progressive cancer while inpatient . CONCLUSION Specialized surgeons could safely perform gastrectomy with D2 lymphadenectomy in patients with low operative risks . Para-aortic lymphadenectomy could be added without increasing major surgical complications in this setting It is still unclear whether D2 lymphadenectomy improves the survival of patients with gastric cancer and should therefore be performed routinely or selectively . The aim of this multicentre r and omized trial was to compare D2 and D1 lymphadenectomy in the treatment of gastric cancer BACKGROUND Gastrectomy with D2 lymphadenectomy is the st and ard treatment for curable gastric cancer in eastern Asia . Whether the addition of para-aortic nodal dissection ( P AND ) to D2 lymphadenectomy for stage T2 , T3 , or T4 tumors improves survival is controversial . We conducted a r and omized , controlled trial at 24 hospitals in Japan to compare D2 lymphadenectomy alone with D2 lymphadenectomy plus P AND in patients undergoing gastrectomy for curable gastric cancer . METHODS Between July 1995 and April 2001 , 523 patients with curable stage T2b , T3 , or T4 gastric cancer were r and omly assigned during surgery to  D2 lymphadenectomy alone ( 263 patients ) or to D2 lymphadenectomy plus P AND ( 260 patients ) . We did not permit any adjuvant therapy before the recurrence of cancer . The primary end point was overall survival . RESULTS The rates of surgery-related complications among patients assigned to D2 lymphadenectomy alone and those assigned to D2 lymphadenectomy plus P AND were 20.9 % and 28.1 % , respectively ( P=0.07 ) . There were no significant differences between the two groups in the frequencies of anastomotic leakage , pancreatic fistula , abdominal abscess , pneumonia , or death from any cause within 30 days after surgery ( the rate of death was 0.8 % in each group ) . The median operation time was 63 minutes longer and the median blood loss was 230 ml greater in the 
    Output:
    
D2 lymphadenectomy can improve DSS in patients with resectable carcinoma of the stomach , although the increased incidence of postoperative mortality reduces its therapeutic benefit