colorectal cancer ( crc ) is the fourth leading cause of cancer - specific mortality worldwide , with 610,000 related deaths each year1 . crc is the fourth most common form of cancer in the united states2 and the third leading cause of cancer - related death in the western world3 . laparoscopic resection for crc was first described in 19914 and has since been widely applied by surgeons to treat patients with crc . several articles have reported the short - term advantages of laparoscopic colorectal surgery ( lcrs ) over conventional open colorectal surgery ( ocrs ) and have concluded that laparoscopic surgery causes less pain , results in better pulmonary function , shorter duration of postoperative ileus , less fatigue , and a better quality of life5 - 7 . however , the value of laparoscopic colorectal surgery has remained controversial because the long - term outcomes have not been clarified . the long - term results of colorectal surgery , such as tumor recurrence rate , disease - free survival rate , and mortality rate , have been gradually published8 - 10 . several randomized control trials ( rcts ) that compare lcrs with ocrs have been conducted8 - 30 . therefore , we conducted a meta - analysis of the data from these rcts and compared the outcomes of lcrs and ocrs by considering several factors listed below . in addition , we selected the rcts for which the follow - up period was at least 3 years to evaluate the long - term outcomes of lcrs . to identify papers relevant to our study we searched through the major medical databases such as medline , embase , science citation index , and cochrane controlled trial register for studies published between january 1990 and may 2011 . the following search terms were used :  laparoscopy ,   laparoscopy - assisted ,   surgery ,   colorectal cancer ,  and all related articles . furthermore , we limited our literature search to those studies that involved a follow - up period of 3 or more years to examine the long - term outcomes of lcrs . we treated studies that are part of a series or studies described by the same author as a single study . most appropriate data of a series of studies were used for this meta - analysis . ) extracted data from each article by using a structured sheet and entered the data into a database . because this analysis was performed by the principle of intention - to - treat31 , all patients converted from the laparoscopic group to the conventional open surgery group remained in the laparoscopic group for analysis . for the short - term analysis , we collected data on the duration of the operation , estimated blood loss , number of patients requiring transfusion , number of harvested lymph nodes , time required for resumption of oral intake , duration of hospital stay , length of operation wound , complications , and perioperative mortality . for the long - term analysis , we used data on the rate of tumor recurrence , disease - free survival rate , and mortality . if necessary weighted mean differences ( wmds ) and odds ratios ( ors ) were used for the analysis of continuous and dichotomous variables , respectively . random - effects models were used to identify heterogeneity between the studies32 and the degree of heterogeneity was assessed using the 2 test . the confidence interval ( ci ) was established at 95% and p values of less than 0.05 were considered to indicate statistical significance . statistical analyses were performed using the review manager ( revman ) software version 5.0.25 provided by the cochrane collaboration , copenhagen , denmark . weighted mean differences ( wmds ) and odds ratios ( ors ) were used for the analysis of continuous and dichotomous variables , respectively . random - effects models were used to identify heterogeneity between the studies32 and the degree of heterogeneity was assessed using the 2 test . the confidence interval ( ci ) was established at 95% and p values of less than 0.05 were considered to indicate statistical significance . statistical analyses were performed using the review manager ( revman ) software version 5.0.25 provided by the cochrane collaboration , copenhagen , denmark . we identified 12 papers reporting rcts that compared lcrs and ocrs for colorectal cancer8 - 24 . our meta - analysis included 4458 patients with colorectal cancer ; of these , 2375 had undergone lcrs , and 2083 , ocrs . the results of the short- and long - term are shown in fig . 1 and fig the outcomes of lcrs and ocrs in the short- and long - term are reported below . the operative duration for lcrs was significantly longer than for ocrs , i.e. , by 39.32 min ( wmd = 39.32 ; 95% ci = 30.72 - 47.91 ; p < 0.00001 ) . eleven of the 12 rcts included data on operative duration , and the 11 rcts indicated that the duration of operations using lcrs was significantly longer than that of operations using ocrs . blood loss in patients who underwent lcrs was significantly lesser than patients in those who underwent ocrs , by an average volume of 133.05 ml ( wmd = -133.05 ; 95% ci = -201.30 to -64.81 ; p = 0.0001 ) . we found no significant differences between patients who underwent lcrs and those that had ocrs for the number of transfused patients or the number of dissected lymph nodes . patients in the lcrs group resumed oral intake on an average of 1.08 days sooner than did patients in the ocrs group , and the difference was significant ( wmd = -1.08 ; 95% ci = -1.36 to -0.80 ; p < 0.00001 ) . the duration of hospital stay was significantly shorter by an average of 2.80 days for patients in the lcrs group than for those in the ocrs group ( wmd = -2.80 ; 95% ci = -4.78 to -0.81 ; p = 0.006 ) . the average length of the wound caused by each operation was significantly shorter by 10.97 cm in the lcrs group than in the ocrs group ( wmd = -10.97 ; 95% ci = -14.37 to -7.57 ; p < 0.00001 ) . differences in overall perioperative complications and anastomotic leakage between the lcrs group and the ocrs group were insignificant for treatment of the colorectal cancer . we also found no significant differences in perioperative mortality between the surgery groups when we pooled data for treatment of the colorectal cancer . the rate of wound - site recurrence for patients in the lcrs group was significantly higher than for those in the ocrs group in our analysis of the pooled data for crc treatment ( or = 2.87 ; 95% ci = 1.08 - 7.68 ; p = 0.04 ) . restricting wound - recurrence to isolated abdominal - wall recurrences , in the absence of recurrent disease elsewhere , our analysis of the local and distant metastasis recurrence between the lcrs group and the ocrs group for treatment of the colorectal cancer indicated no significant difference . there was also no significant difference between the surgery groups for the overall recurrence of tumors . we found no significant differences in the 3- and 5-year disease - free survival rates between patients who underwent lcrs and those who underwent ocrs . there was no significant difference between the lcrs and ocrs groups for cancer - related mortality for treatment of the colorectal cancer . likewise , there was no significant difference in overall mortality between the lcrs and ocrs groups . in the short - term period , significant heterogeneity was detected between studies with respect to the following 4 factors : intraoperative blood loss , duration of hospital stay , length of operation wound , and overall complications . in the long - term period the operative duration for lcrs was significantly longer than for ocrs , i.e. , by 39.32 min ( wmd = 39.32 ; 95% ci = 30.72 - 47.91 ; p < 0.00001 ) . eleven of the 12 rcts included data on operative duration , and the 11 rcts indicated that the duration of operations using lcrs was significantly longer than that of operations using ocrs . blood loss in patients who underwent lcrs was significantly lesser than patients in those who underwent ocrs , by an average volume of 133.05 ml ( wmd = -133.05 ; 95% ci = -201.30 to -64.81 ; p = 0.0001 ) . we found no significant differences between patients who underwent lcrs and those that had ocrs for the number of transfused patients or the number of dissected lymph nodes . patients in the lcrs group resumed oral intake on an average of 1.08 days sooner than did patients in the ocrs group , and the difference was significant ( wmd = -1.08 ; 95% ci = -1.36 to -0.80 ; p < 0.00001 ) . the duration of hospital stay was significantly shorter by an average of 2.80 days for patients in the lcrs group than for those in the ocrs group ( wmd = -2.80 ; 95% ci = -4.78 to -0.81 ; p = 0.006 ) . the average length of the wound caused by each operation was significantly shorter by 10.97 cm in the lcrs group than in the ocrs group ( wmd = -10.97 ; 95% ci = -14.37 to -7.57 ; p < 0.00001 ) . differences in overall perioperative complications and anastomotic leakage between the lcrs group and the ocrs group were insignificant for treatment of the colorectal cancer . we also found no significant differences in perioperative mortality between the surgery groups when we pooled data for treatment of the colorectal cancer . the rate of wound - site recurrence for patients in the lcrs group was significantly higher than for those in the ocrs group in our analysis of the pooled data for crc treatment ( or = 2.87 ; 95% ci = 1.08 - 7.68 ; p = 0.04 ) . restricting wound - recurrence to isolated abdominal - wall recurrences , in the absence of recurrent disease elsewhere , the differences between the groups was insignificant ( p = 0.09 ) . our analysis of the local and distant metastasis recurrence between the lcrs group and the ocrs group for treatment of the colorectal cancer indicated no significant difference . there was also no significant difference between the surgery groups for the overall recurrence of tumors . we found no significant differences in the 3- and 5-year disease - free survival rates between patients who underwent lcrs and those who underwent ocrs . there was no significant difference between the lcrs and ocrs groups for cancer - related mortality for treatment of the colorectal cancer . likewise , there was no significant difference in overall mortality between the lcrs and ocrs groups . in the short - term period , significant heterogeneity was detected between studies with respect to the following 4 factors : intraoperative blood loss , duration of hospital stay , length of operation wound , and overall complications . in the long - term period previous articles showed that laparoscopic surgery for crc is associated with low morbidity , less pain , fast recovery , and short hospital stay , compared to conventional open surgery in the short - term5 - 7 . recent articles reporting rcts have shown that long - term oncological results for lcrs are comparable to those for ocrs33 . therefore , we examined the oncological results of lcrs and compared to those of ocrs in short- and long - term periods by a meta - analysis of 12 rcts . in the short - term period , this meta - analysis showed that lcrs has a significantly long operative time but significantly reduces the intraoperative blood loss compared with ocrs . potential explanations for the abovementioned results are meticulous dissection facilitated by instruments for laparoscopic surgery and videoscopic magnification34 . we also found that there was no significant difference in the number of patients requiring blood transfusions between the lcrs and ocrs groups . the lack of difference in the number of harvested lymph nodes between the 2 groups may suggest that the quality of the operative techniques is the same . patients who underwent lcrs resumed oral intake significantly earlier and had significantly shorter hospital stays than did patients who underwent ocrs ; this finding suggests that lcrs leads to faster recovery . the safety and feasibility of lcrs is similar to that of ocrs as shown by insignificant differences in the overall perioperative complications , anastomotic leakage , and perioperative mortality between the surgery groups . in the long - term period , this study showed that there is no significant difference in the overall recurrence , local recurrence , or distant recurrence of metastases between the lcrs and ocrs groups . the rate of wound - site recurrence for the lcrs group was significantly higher than that for the ocrs group . in 7 of the 9 studies that reported data on wound - site recurrence , the rates of wound - site recurrence for lcrs were similar to the rates for ocrs . in the clasicc trial , the number of extraction - site recurrences was higher than that of trocar - site recurrences in the lcrs group . therefore , the authors emphasize the need for adequate wound protection during specimen extraction13 . in the color trial , the number of trocar - site recurrences was higher than that of extraction - site recurrences in the lcrs group . in this meta - analysis the differences of wound - site recurrence between the groups was insignificant , restricting wound - recurrence to isolated abdominal - wall recurrences , in the absence of recurrent disease elsewhere . reported that port - site metastasis may be a part of the systemic disease rather than an unfortunate sequelae of the learning curve for laparoscopic surgery35 . we found no significant difference between the lcrs and ocrs groups for overall mortality , 3- and 5-year disease - free survival rate and cancer - related mortality . these results suggest that the long - term oncological results of lcrs are similar to those of ocrs . reported that lcrs significantly prolongs cancer - related survival in treatment of colon cancer10 , but our meta - analysis of the pooled data did not show this difference . quality of life ( qol ) after laparoscopic surgery is improved in the early postoperative period compared with qol after open surgery . in the long - term period , however , qol after lcrs is similar to qol after ocrs9 , 36 . from the cosmetic viewpoint , lcrs is superior to ocrs because the length of operation wound was significantly shorter in lcrs than in ocrs . significant heterogeneity was observed between the 12 rcts for intraoperative blood loss , duration of hospital stay , length of operation wound , overall complications in the short - term period , and overall mortality in the long - term period . this heterogeneity may be attributable to variation in the skills of the surgeons and the condition of the tumor . in conclusion , this meta - analysis showed that lcrs has the benefits of reducing intraoperative blood loss , earlier resumption of oral intake , and shorter duration of hospital stay in short - term and seems to be similar in the long - term oncological outcomes , comparing to ocrs .