***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: BACKGROUND Minimally invasive , laparoscopically assisted surgery was first considered in 1990 for patients undergoing colectomy for cancer . Concern that this approach would compromise survival by failing to achieve a proper oncologic resection or adequate staging or by altering patterns of recurrence ( based on frequent reports of tumor recurrences within surgical wounds ) prompted a controlled trial evaluation . METHODS We conducted a noninferiority trial at 48 institutions and r and omly assigned 872 patients with adenocarcinoma of the colon to undergo open or laparoscopically assisted colectomy performed by credentialed surgeons . The median follow-up was 4.4 years . The primary end point was the time to tumor recurrence . RESULTS At three years , the rates of recurrence were similar in the two groups--16 percent among patients in the group that underwent laparoscopically assisted surgery and 18 percent among patients in the open-colectomy group ( two-sided P=0.32 ; hazard ratio for recurrence , 0.86 ; 95 percent confidence interval , 0.63 to 1.17 ) . Recurrence rates in surgical wounds were less than 1 percent in both groups ( P=0.50 ) . The overall survival rate at three years was also very similar in the two groups ( 86 percent in the laparoscopic-surgery group and 85 percent in the open-colectomy group ; P=0.51 ; hazard ratio for death in the laparoscopic-surgery group , 0.91 ; 95 percent confidence interval , 0.68 to 1.21 ) , with no significant difference between groups in the time to recurrence or overall survival for patients with any stage of cancer . Perioperative recovery was faster in the laparoscopic-surgery group than in the open-colectomy group , as reflected by a shorter median hospital stay ( five days vs. six days , P<0.001 ) and briefer use of parenteral narcotics ( three days vs. four days , P<0.001 ) and oral analgesics ( one day vs. two days , P=0.02 ) . The rates of intraoperative complications , 30-day postoperative mortality , complications at discharge and 60 days , hospital readmission , and reoperation were very similar between groups . CONCLUSIONS In this multi-institutional study , the rates of recurrent cancer were similar after laparoscopically assisted colectomy and open colectomy , suggesting that the laparoscopic approach is an acceptable alternative to open surgery for colon cancer 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 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 Purpose This study was to ascertain whether a robot-assisted ( RA ) approach to APR might facilitate a cylindrical APR by enabling a deeper pelvic dissection during an abdominal approach , concurrently comparing the feasibility and short-term oncologic outcomes . Methods Forty-eight consecutive patients with lower rectal cancer who had undergone curative APR ( 21 RA vs. 27 open ) were prospect ively enrolled . The short-term operative outcomes and oncologic feasibility were evaluated and compared . A levator muscle excision was performed concomitantly with the abdominal procedure in the RA group and with the perineal procedure in the open group . Results No patients in the RA group experienced intraoperative perforation or required conversion to open APR . Overall , a cylindrical APR was performed in 72 % of patients , and subtotal excision of the levator muscle , i.e. , either one or both sides of the puborectalis and pubococcygeus muscles , was more likely in the RA group ( P = 0.019 ) . A positive CRM was exclusively identified in four open APR patients . The mean number of retrieved lymph nodes was greater in the RA group ( 20 vs. 16 , P = 0.035 ) . There was no difference in perineal morbidity between the two groups ( P = 0.445 ) . Conclusions The RA approach facilitates an efficient excision in the pelvic region than open APR during the abdominal procedure . The RA approach also demonstrated a trend toward improved oncologic outcomes with equivalent postoperative morbidities than with the open approach BACKGROUND : Extralevator abdominoperineal excision for distal rectal cancers involves cylindrical excision of the mesorectum with wide division of the levator ani muscles . Although this technique has been shown to decrease local cancer recurrence and improve survival , it leaves the patient with a considerable pelvic floor defect that may require reconstruction . OBJECTIVE : We developed an innovative technique of robotic extralevator abdominoperineal excision combined with robotic harvest of the rectus abdominis muscle flap for immediate reconstruction of the pelvic floor defect . DESIGN : This was a retrospective review pilot study . SETTING : This study was conducted at a tertiary care cancer center . PATIENTS : Three patients who underwent robotic extralevator abdominoperineal excision with robotic rectus abdominis flap harvest for distal rectal adenocarcinoma were included . MAIN OUTCOMES MEASURES : Intraoperative and postoperative outcomes included operative time , intraoperative complications , length of hospital stay , wound complications , incidence of perineal hernia , persistent pain , and functional limitations . RESULTS : Three patients underwent this procedure . The median operative time was 522 minutes with median hospital stay of 6 days . One patient experienced perineal wound complication requiring limited incision and drainage followed by complete healing of the wound by secondary intention . The other 2 patients did not experience any wound complications . Longest follow-up was 16 months . None of the patients developed perineal hernias during this time period . LIMITATIONS : The small sample size and retrospective nature were limitations . CONCLUSIONS : This technique confers multiple advantages including improved visualization and dexterity within the pelvis and accurate wide margins at the pelvic floor . An incisionless robotic flap harvest with preservation of the anterior rectus sheath obviates the risk of ventral hernia while providing robust tissue closure of the radiated abdominoperineal excision wound . This technique may result in faster postoperative recovery , decreased morbidity , improved functional outcomes and cosmesis . Further studies are needed to prospect ively analyze this approach ( Supplemental Digital Content 1 , video abstract , http://links.lww.com/DCR/A188 ) BACKGROUND : Recent studies have shown that extralevator abdominoperineal resection has the potential for reduced circumferential resection margin involvement , intraoperative bowl perforation , and local recurrence rates ; however , it has been suggested that extended resection may be associated with increased morbidity because of the formation of a larger perineal defect . OBJECTIVE : This study was undertaken to demonstrate the feasibility and complications of extralevator abdominoperineal resection for locally advanced low rectal cancer in China . DESIGN : This was a prospect i ve cohort study . SETTING : The study was conducted at 7 university hospitals throughout China . PATIENTS : A total of 102 patients underwent this procedure for primary locally advanced low rectal cancer between August 2008 and October 2011 . MAIN OUTCOME MEASURES : The main outcome measures comprised circumferential resection margin involvement , intraoperative perforation , postoperative complications , and local recurrence . RESULTS : The most common complications included sexual dysfunction ( 40.5 % ) , perineal complications ( 23.5 % ) , urinary retention ( 18.6 % ) , and chronic perineal pain ( 13.7 % ) . Chronic perineal pain was associated with coccygectomy ( p < 0.001 ) , and the pain gradually eased over time . Reconstruction of the pelvic floor with biological mesh was associated with a lower rate of perineal dehiscence ( p = 0.006 ) and overall perineal wound complications ( p = 0.02 ) in comparison with primary closure . A positive circumferential margin was demonstrated in 6 ( 5.9 % ) patients , and intraoperative perforations occurred in 4 ( 3.9 % ) patients . All circumferential margin involvements and intraoperative perforations were located anteriorly . The local recurrence was 4.9 % at a median follow-up of 44 months ( range , 18–68 months ) . LIMITATIONS : This was a nonr and omized , uncontrolled study . CONCLUSIONS : Extralevator abdominoperineal resection performed in the prone position for low rectal cancer is a relatively safe approach with acceptable circumferential resection margin involvement , intraoperative perforations , and local recurrences . Reconstruction of the pelvic floor with biological mesh might lower the rate of perineal wound complications ( see Video , Supplemental Digital Content 1 , http://links.lww.com/DCR/A161 ) 
    Output:
    
Conclusions Transabdominal division of the levators during APER is feasible and reproducible , with acceptable perioperative and good early oncological outcomes .