radical prostatectomy ( rp ) is the standard of care among the treatment options for patients with clinically localized prostate cancer , especially in men with a life expectancy > 10 years .
a recent rp series reported the positive surgical margin ( psm ) rate to range from 11% to 38% .
psm is defined by most investigators as an extension of the tumor to the inked cut surface of the resected specimen .
a psm is more likely to occur in cases with extracapsular extension , if the prostate is not resected widely enough .
a psm can also occur in cases of organ - confined disease if resection is performed too close to the prostate , which is often referred to as a capsular incision .
a psm suggests incomplete local resection , poor cancer control , and suboptimal patient outcome .
in addition , the number and extent of the psm have been shown to be risk factors for biochemical recurrence ( bcr ) after rp .
laparoscopic radical prostatectomy ( lrp ) , and more recently robot - assisted laparoscopic radical prostatectomy ( ralrp ) , have been accepted as alternatives to open surgical methods at many institutions .
these methods have shown comparable oncological and functional outcomes in recent studies , including for psm status .
when evaluating the efficacy of rp for treating localized prostate cancer and also for considering possible adjuvant therapy , psm status is an important factor , regardless of approach .
previous data have demonstrated adverse oncologic outcomes associated with psm in patients undergoing rp , although the location of the psm and its effect on bcr - free survival of rp have rarely been examined in patients who have undergone four different types of rp . in this study
, we analyzed the location of the psm and its association with the bcr rate in patients who had undergone four different types of rp in a single center .
we retrospectively analyzed the medical records of 1,880 patients who underwent rp between september 1995 and december 2011 by five surgeons at samsung medical center , with approval from the institutional review board ( 2014 - 06 - 049 ) . among a total of 1,880 patients , 633 patients underwent radical perineal prostatectomy ( rpp ) , 309 patients underwent radical retroperitoneal prostatectomy ( rrp ) , 164 patients underwent lrp , and 774 patients underwent ralrp .
the presence of a psm , age , preoperative prostate - specific antigen ( psa ) , prostate size , follow - up length , biopsy gleason score ( gs ) , pathologic gs , clinical stage , pathologic stage , presence of nerve - sparing , and presence of bcr were recorded retrospectively .
locations of the psm were recorded in the four groups as apex , anterior , posterolateral , and base .
all rp specimens were coated with ink , sectioned at 3- to 4-mm intervals , analyzed by the same pathology department , and processed by using the stanford technique .
the surgical margin was considered positive when the tumor was found at the inked surface .
postoperative follow - up visits were typically scheduled at 3-month intervals for 1 year , biannually for the second and third years , and yearly thereafter .
bcr was defined as two consecutive psa measurements  0.2 ng / ml . rpp was performed as previously described by harris .
ralrp was performed by the transperitoneal antegrade approach with the use of the da vinci robot system ( intuitive surgical inc . ,
the choice of surgical approach was made by the patient 's physician on the basis of the patient 's preference after a discussion of benefits , risks , alternatives , and also the special conditions of each patient . in each of the surgical groups ,
unilateral or bilateral nerve preservation was considered and performed if clinically indicated by preoperative erectile function , age , and oncological parameters .
the baseline characteristics of the patients were analyzed with percentages for categorical factors or with the mean and standard deviation for continuous factors .
categorical factors were compared by using the chi - square test and fisher exact test , and continuous factors were compared by using the kruskal - wallis test .
the estimated risk of bcr according to site of psm was determined by using kaplan - meier survival analysis and was compared by use of log - rank tests . in all of the tests ,
9.4 ( sas institute inc . , cary , nc , usa ) and r ver . 3.0.3 ( r foundation for statistical computing , vienna , austria ; http://www.r-project.org/ ) .
the total number of patients was 1,880 , with 633 ( 33.7% ) undergoing rpp , 309 ( 16.4% ) undergoing rrp , 164 ( 8.7% ) undergoing lrp , and 774 ( 41.2% ) undergoing ralrp .
there were no significant differences in mean age , psa level , or prostate size according to operative group ( p=0.487 , p=0.084 , and p=0.389 , respectively ) .
the biopsy gs distribution and the clinical stage did not differ significantly by surgical type ( p=0.841 and p=0.136 , respectively ) . the pathologic gs distribution and the pathologic stage
also did not show a significant difference by surgical type ( p=0.783 and p=0.133 , respectively ) .
a psm was found in a total of 336 cases ( 17.9% ) . of these
, there were 122 cases ( 18.4% ) of rpp , 67 cases ( 21.7% ) of rrp , 28 cases ( 17.1% ) of lrp , and 119 cases ( 15.4% ) of ralrp .
the location of the psm was the apex in 136 cases ( 7.2% ) , anterior in 67 cases ( 3.5% ) , posterolateral in 139 cases ( 7.3% ) , and base in 95 cases ( 5.0% ) , and did not differ significantly by surgical type ( p=0.536 , p=0.557 , p=0.062 , and p=0.109 , respectively ) ( table 2 ) . in all patients ,
the median follow - up was 48.2 months ( interquartile range [ iqr ] , 33.4 - 64.7 months ) .
the median follow - up of each operative group was 67.7 months ( iqr , 40.7 - 90.9 months ) for rpp , 45.9 months ( iqr , 32.4 - 64.4 months ) for rrp , 41.4 months ( iqr , 27.5 - 55.8 months ) for lrp , and 43.5 months ( iqr , 32.4 - 55.5 months ) for ralrp ( p<0.001 ) .
the total number of cases of bcr was 390 ( 20.7% ) , with 181 cases ( 28.5% ) in the rpp group , 81 ( 26.2% ) in the rrp group , 24 ( 14.6% ) in the lrp group , and 104 ( 13.4% ) in the ralrp group .
cases with a psm showed a higher bcr rate than did cases with a negative surgical margin ( p=0.04 ) . in the psm group ,
the bcr rate did not differ significantly according to the location of the psm in all rp groups combined ( p=0.469 ) .
the bcr rate according to the location of the psm also did not show a significant difference in the kaplan - meier survival analysis for the four types of surgery ( p=0.694 , p=0.301 , p=0.445 , and p=0.309 for rpp , rrp , lrp , and ralrp , respectively ) ( fig .
yossepowitch et al .   demonstrated that a psm in rp specimens is an adverse outcome following rp .
pathologic tumor margin status seems to be comparable between open , laparoscopic , and robotic series overall .
however , the location of the psm and its effect on bcr - free survival of rp has rarely been examined among patients according to four different types of rp in a single center . therefore , we explored the location of the psm and its association with the bcr rate between four different types of rp .
we found that the location of the psm seemed to be unrelated to the type of rp .
in addition , the bcr rate did not differ significantly according to the location of the psm in each type of rp .
in one retrospective study , there was no significant difference in the incidence of a psm between the rpp ( 22% ) and rrp specimens ( 16% ) , and each had a 4% incidence of capsular incision .
moreover , no significant difference was found in the time to psa failure between patients who had undergone rpp with complete excision of the seminal vesicles and those who had undergone rrp .
rpp showed proven long - term cancer control of rrp with rapid convalescence and low morbidity . in a retrospective comparison of bcr
, no significant difference was found between the ralrp group and a contemporary series of rrp performed at a single center after control for clinical and pathologic features . in most series of lrp and ralrp
.   showed that regardless of surgical approach , the most common site of a psm is the prostatic apex and that insufficient removal of prostatic tissue at the apex for optimizing urethral length and avoiding incontinence can result in psms , even with tumors that do not violate the capsule pathologically ( i.e. , stage pt2 ) .
in addition , brown et al .   and khan and partin   demonstrated that comparison of surgical margin status between high - volume centers with operations performed by experienced surgeons shows a definitive advantage in achieving negative surgical margins for one surgical approach over the other .
these results differ from the results of our study , most likely due to differences in patient selection .
patient selection is the primary factor that determines the psm rate in a given series .
the experience of surgeons and the method and detail of pathologic analysis also seems influential .
although this study was retrospective and was performed at a single institution , this enabled a standardized review of all pathology specimens of the four different types of rp and strengthened our study .
this study was limited by the difference in follow - up length according to type of surgery .
the bcr rate of lrp or ralrp was relatively low compared with the bcr rate for rpp or rrp .
the median follow - up and bcr rate according to type of surgery showed statistically significant differences ( p<0.001 and p<0.001 , respectively ) ( table 1 ) .
therefore , the tendency of a higher bcr rate of rpp or rrp may come from the relatively shorter follow - up of lrp or ralrp .
oncologic outcomes with 1,000 consecutive lrps performed over a 4-year period with a median follow - up period of 12 months were reported by guillonneau et al . .
the rates were 92% for pt2a , 88% for pt2b , 77% for pt3a , and 44% for pt3b by pathologic stage .
the actuarial , 3-year , bcr - free survival was 94.5% overall , 98.2% for pt2 , and 78.7% for pt3 disease .
these two studies of lrp reported better bcr - free survival than did our study ( 89.7% ) .
this difference in bcr - free survival may be due to the shorter mean follow - up length of those studies compared with our study .
meanwhile , with regard to ralrp , badani et al .   reported a large series of 2,766 consecutive ralrps with a mean follow - up period of 22 months .
their overall actuarial 5-year , bcr - free survival was 84% overall , 84% for pt2 , and 66% for pt3 patients , which was a worse bcr - free survival than in our study ( 90.3% )
. this difference may be due to the shorter mean follow - up length of our study compared with the study of badani et al . .
because of the relatively long time period included in this study , the learning curve with surgery or progression of surgical technique may have had an effect .
especially , ralrp is a relatively newer method , so the learning curve may have influenced oncologic outcome .
each method of rp was performed by more than one surgeon , except rpp and lrp . despite this limitation ,
considering the lack of cases when performing four types of rp in a single center , this study offers a valuable comparison of the different types of rp . in summary
, the location of the psm does not seem to be related to the type of rp .
the bcr rate according to the location of the psm in each type of rp also showed no significant difference . in the end , a long - term , prospective and randomized trial with a sufficiently large number of cases from established and experienced centers of excellence is required to compare the results of lrp or ralrp with the results of rpp or rrp .
in this study , we presented the oncologic outcomes in a large contemporary cohort of patients undergoing four different types of rp .
the bcr rate also showed no significant difference according to the location of the psm in each type of rp .
 purposeto analyze the location of the positive surgical margin ( psm ) and its association with the biochemical recurrence ( bcr ) rate in cases of radical prostatectomy ( rp ) according to the type of surgery.materials and methodswe retrospectively analyzed 1,880 cases of rp . 
 baseline characteristics were analyzed . 
 locations of the psm were recorded in the four surgery groups as apex , anterior , posterolateral , and base and were analyzed by using chi - square test . 
 the association of the location of the psm with the bcr rate was analyzed by using kaplan - meier survival analysis according to the type of surgery , which included radical perineal prostatectomy ( rpp , n=633 ) , radical retroperitoneal prostatectomy ( rrp , n=309 ) , laparoscopic radical prostatectomy ( lrp , n=164 ) , and robot - assisted laparoscopic radical prostatectomy ( ralrp , n=774).resultsa psm was found in a total of 336 cases ( 18% ) : 122 cases of rpp ( 18% ) , 67 cases of rrp ( 17% ) , 29 cases of lrp ( 17% ) , and 119 cases of ralrp ( 15% ) . 
 the psm rate did not differ significantly by surgical type ( p=0.142 ) . 
 the location of the psm was the apex in 136 cases ( 7.2% ) , anterior in 67 cases ( 3.5% ) , posterolateral in 139 cases ( 7.3% ) , and base in 95 cases ( 5.0% ) , and showed no significant difference according to surgical type ( p=0.536 , p=0.557 , p=0.062 , and p=0.109 , respectively ) . 
 the bcr rate according to the location of the psm did not differ significantly for the four types of surgery ( p=0.694 , p=0.301 , p=0.445 , and p=0.309 for rpp , rrp , lrp , and ralrp , respectively).conclusionsthe location of the psm seemed to be unrelated to type of rp . 
 there was no significant correlation between the bcr rate and the location of the psm for any of the rp types . 