***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: Objectives : The aim of this prospect i ve registry-based population study was to investigate the efficacy of extralevator abdominoperineal excision ( ELAPE ) regarding local recurrence rates within 3 years after surgery . Background : Local recurrence of rectal cancer is more common after abdominoperineal excision ( APE ) than after anterior resection . Extralevator abdominoperineal excision was introduced to address this problem . No large-scale studies with long-term oncological outcomes have been published . Methods : All Swedish patients operated on with an APE and registered in the Swedish ColoRectal Cancer Registry 2007 to 2009 were included ( n = 1397 ) and analyzed with emphasis on the perineal part of the operation . Local recurrence at 3 years was collected from the registry . Results : The local recurrence rates at 3 years [ median follow-up , 3.43 years ( APE , 3.37 years ; ELAPE , 3.41 years ; not stated : 3.43 years ) ] were significantly higher for ELAPE compared with APE ( relative risk , 4.91 ) . Perioperative perforation was also associated with an increased risk of local recurrence ( relative risk , 3.62 ) . There was no difference in 3-year overall survival between APE and ELAPE . In the subgroup of patients with very low tumors ( ⩽4 cm from the anal verge ) , no significant difference in the local recurrence rate could be observed . Conclusions : Extralevator abdominoperineal excision results in a significantly increased 3-year local recurrence rate as compared with st and ard APE . Intraoperative perforation seems to be an important risk factor for local recurrence . In addition to significantly increased 3-year local recurrence rates , the significantly increased incidence of wound complications leads to the conclusion that ELAPE should only be considered in selected patients at risk of intraoperative perforation PURPOSE Despite the major improvements that have been made due to total mesorectal excision ( TME ) , low rectal cancer still remains a challenge . METHODS By investigating a prospect i ve r and omized rectal cancer trial in which surgeons had undergone training in  TME  the factors responsible for the poor outcome were determined and a new method for assessing the quality of surgery was tested . RESULTS Survival differed greatly between abdominoperineal resection ( APR ) and anterior resection ( AR ; 38.5 % v 57.6 % , P = .008 ) . Low rectal carcinomas have a higher frequency of circumferential margin involvement ( 26.5 % v 12.6 % , P < .001 ) . More positive margins were present in the patients operated with APR ( 30.4 % ) compared to AR ( 10.7 % , P = .002 ) . Furthermore , more perforations were present in these specimens ( 13.7 % v 2.5 % , P < .001 ) . The plane of resection lies within the sphincteric muscle , the submucosa or lumen in more than 1/3 of the APR cases , and in the remainder lay on the sphincteric muscles . CONCLUSION We systematic ally described and investigated the pathologic properties of low rectal cancer in general , and APR in particular , in a prospect i ve r and omized trial including surgeons who had been trained in TME . The poor prognosis of the patients with an APR  is ascribed to the resection plane of the operation leading to a high frequency of margin involvement by tumor and perforation with this current surgical technique . The clinical results of this operation could be greatly improved by adopting different surgical techniques and possibly greater use of radiochemotherapy Summary Background Local recurrence rates in operable rectal cancer are improved by radiotherapy ( with or without chemotherapy ) and surgical techniques such as total mesorectal excision . However , the contributions of surgery and radiotherapy to outcomes are unclear . We assessed the effect of the involvement of the circumferential resection margin and the plane of surgery achieved . Methods In this prospect i ve study , the plane of surgery achieved and the involvement of the circumferential resection margin were assessed by local pathologists , using a st and ard pathological protocol in 1156 patients with operable rectal cancer from the CR07 and NCIC-CTG CO16 trial , which compared short-course ( 5 days ) preoperative radiotherapy and selective postoperative chemoradiotherapy , between March , 1998 , and August , 2005 . All analyses were by intention to treat . This trial is registered , number IS RCT N 28785842 . Findings 128 patients ( 11 % ) had involvement of the circumferential resection margin , and the plane of surgery achieved was classified as good ( mesorectal ) in 604 ( 52 % ) , intermediate ( intramesorectal ) in 398 ( 34 % ) , and poor ( muscularis propria plane ) in 154 ( 13 % ) . We found that both a negative circumferential resection margin and a superior plane of surgery achieved were associated with low local recurrence rates . Hazard ratio ( HR ) was 0·32 ( 95 % CI 0·16–0·63 , p=0·0011 ) with 3-year local recurrence rates of 6 % ( 5–8 % ) and 17 % ( 10–26 % ) for patients who were negative and positive for circumferential resection margin , respectively . For plane of surgery achieved , HRs for mesorectal and intramesorectal groups compared with the muscularis propria group were 0·32 ( 0·16–0·64 ) and 0·48 ( 0·25–0·93 ) , respectively . At 3 years , the estimated local recurrence rates were 4 % ( 3–6 % ) for mesorectal , 7 % ( 5–11 % ) for intramesorectal , and 13 % ( 8–21 % ) for muscularis propria groups . The benefit of short-course preoperative radiotherapy did not differ in the three plane of surgery groups ( p=0·30 for trend ) . Patients in the short-course preoperative radiotherapy group who had a resection in the mesorectal plane had a 3-year local recurrence rate of only 1 % . Interpretation In rectal cancer , the plane of surgery achieved is an important prognostic factor for local recurrence .  Short-course preoperative radiotherapy reduced the rate of local recurrence for all three plane of surgery groups , almost abolishing local recurrence in short-course preoperative radiotherapy patients who had a resection in the mesorectal plane . The plane of surgery achieved should therefore be assessed and reported routinely . Funding Medical Research Council ( UK ) and the National Cancer Institute of Canada Purpose Local recurrences are more common after abdominoperineal excision ( APE ) than after anterior resection of rectal cancer . Extralevator APE was introduced to address this problem . This prospect i ve registry-based population study aims to investigate the efficacy of extralevator APE ( ELAPE ) in improving short-term oncological outcome . Methods All Swedish patients operated with any kind of abdominoperineal excision and registered in the Swedish Rectal Cancer Registry 2007–2009 were included ( n = 1,397 ) and analyzed with emphasis on the perineal part of the operation . Short-term perioperative and oncological results were collected from the registry . Results Extralevator APE did not result in fewer intraoperative perforations or involved circumferential resection margins as compared to st and ard APE for the entire group . Intraoperative perforations were significantly fewer for patients with low tumours ( ≤4 cm ) ( ELAPE : n = 28/386 versus APE : n = 9/58 ) ( p = 0.043 ) and for early ( T0–T2 ) T-stages ( ELAPE : n = 3/172 versus APE : n = 6/75 ) ( p = 0.025 ) . There were significantly more post-operative wound infections for ELAPE than for APE ( n = 106 ( 20.4 % ) versus n = 25 ( 12.0 % ) , p = 0.011 ) . Conclusions The short-term results indicate that selective use of extralevator APE can be warranted , for example , for subgroups with low tumours . In conclusion , selective use of the extralevator APE is advocated as not all patients seem to benefit from the technique , and there are significantly more short-term complications after extralevator APE Background The extralevator abdominoperineal excision ( ELAPE ) has been proposed as oncologically superior to st and ard abdominoperineal excision ( SAPE ) . However , little is known regarding comparative margins achieved in ELAPE and SAPE . The purpose of this study was to compare patterns of tissue removal between these two groups that can aid patient selection . Methods Twenty APE specimens , comprising 10 SAPEs and 10 ELAPEs , were selected r and omly from a single UK centre . Transverse slices of pathological specimens were matched to corresponding axial MRI images obtained from conventional pelvic MRI imaging . Measurements from the muscularis propria to the resection margin [ muscularis to margin ( MTM ) distance ] were recorded by height ( from anal verge ) and quadrant for each surgical group . MTM distances achieved on histopathological assessment were also compared to MRI assessed distances necessary to achieve a clear CRM . Results ELAPE specimens had a greater mean MTM distance than for SAPE ( 7.75 vs. 5.61 mm , p = 0.02 ) . ELAPE had significantly greater MTM distances in lateral and posterior quadrants ( p < 0.05 ) than SAPE at 30–49 mm . There was no significant difference in mean anterior distances ( 1.57 vs. 1.16 mm , p = 0.507 ) with the smallest difference at a height of 60–69 mm . Two ( 2 % ) of pathological MTM distances within ELAPE group failed to achieve the minimum MRI assessed distance compared with 30 ( 23 % ) in the SAPE group , which had higher CRM positivity . Conclusions ELAPE appears to confer oncological benefit over SAPE but with notable exceptions , including tumours located above and below the puborectalis sling and anteriorly at the level of prostate where exenteration may be more appropriate OBJECTIVE To evaluate the oncological results and possible benefits associated with extralevatory abdominoperineal excision ( ELAPE ) when compared with conventional abdominoperineal excision ( APE ) . BACKGROUND ELAPE was introduced in 2007 with the purpose of reducing the rate of positive resection margins after resection of low rectal cancers . Preliminary studies have shown promising results . No large-scale or nationwide data have been presented . METHODS Data base study based on data from the Danish Colorectal Cancer Group 's prospect i ve data base . Data on all ELAPEs and APEs performed in Denmark in the period January 1 , 2009 , through August 2012 were retrieved and evaluated for differences in demography , tumor characteristics , and oncological results . Uni- and multivariate logistic regression analyses were performed to identify risk factors for resection with a positive circumferential resection margin ( CRM+ ) . RESULTS A total of 554 patients were included , 301(54 % ) were operated by ELAPE ; 253(46 % ) by APE . Sixty-three percent were men , median ( interquartile range ) age was 69 ( 61 - 76 years ) years , and tumors removed had predominantly T-stages T2 and T3 ( 32 % and 45 % , respectively ) . Overall , CRM+ was found in 13 % of patients . When divided according to type of procedure , we found no significant differences in demography and tumor T- and N-stages . Resections with a CRM+ were more common after ELAPE ( 16 % vs 7 % ; P = 0.006 ) . After uni- and multivariate logistic regression analyses , surgery by ELAPE remained a risk factor for a CRM+ [ odds ratio , 2.59 ( 95 % confidence interval , 1.31 - 5.12 ) ; P = 0.006 ) . CONCLUSIONS In this nationwide study , resection of low rectal cancers by ELAPE did not improve short-term oncological results , when compared with conventional APE BACKGROUND : There is debate whether performing the perineal part of the abdominoperineal resection in a prone position in comparison with a lithotomy position optimizes circumferential resection margins and , subsequently , cancer outcomes . OBJECTIVE : The aim of this study was to compare outcomes of patients undergoing abdominoperineal in a prone vs a lithotomy position .  DESIGN : A single-center , prospect ively maintained colorectal cancer data base was queried for patients with stages I to III rectal cancer undergoing abdominoperineal resection in a prone vs a lithotomy position from 1997 to 2007 . Patients were compared with respect to demographics , tumor and treatment characteristics , perioperative morbidity , and oncologic outcomes . Oncologic outcomes were adjusted for age , ASA class , tumor stage , and use of adjuvant treatments . & khgr;2 , Fisher exact probability test , Wilcoxon rank-sum test , Kaplan-Meier estimates , log-rank sum test , and Cox regression models were used for the analysis . P < .05 was considered significant . RESULTS : The query returned 168 patients ( 81 prone and 87 lithotomy ) , with a median age of 63 ( interquartile range , 52–74 ) years and a median follow-up of 42 ( interquartile range , 23–69 ) months . Prone and lithotomy patients were not statistically different regarding demographics , tumor stage , rates of R0 resection 
    Output:
    
The ELAPE was associated with a significantly lower intraoperative perforation rate .
There were no differences regarding the circumferential margin involvement , R0 resections , and local recurrence rate .
There was less blood loss in ELAPE patients .
The ELAPE significantly lowered the intraoperative perforation rate , with no benefits regarding circumferential resection margin involvement and local recurrence rate