a properly performed lymphadenectomy helps detect occult nodal metastases in 25% of the patients undergoing rc . currently , extended radical lymphadenectomy is strongly recommended for all patients undergoing rc for the treatment of bladder cancer , because of more accurate staging and improved postoperative survival . moreover , recent reports have shown that the resection of a large number of lns is associated with a survival advantage among patients with ln - positive disease . however , morbidity increases if large numbers of lns are resected . most bladder cancer patients who are required to undergo rc are evaluated before the procedure by cystoscopy and computed tomography . establishing a correlation between tumor location and the direction of ln metastatic spread is useful knowledge for surgeons performing rc with lymphadenectomy . the aim of this study was to determine the number and location of the tumors in the bladder and to determine the correlation between these factors and ln metastasis . we retrospectively reviewed the records of patients who underwent surgery for bladder cancer ( pathological n1 or higher ) at ilsan hospital ( department of urology , national health insurance corporation ilsan hospital , goyang , korea ) between 1 january 2000 and 31 august 2010 . to ensure consistency , the same investigator reviewed all of the charts to extract data on demographics , admission and operation , and pathological conditions . a total of 78 cases of patients who had undergone rc with extended lymphadenectomy were identified from the database . we excluded 42 patients without ln metastasis or any other organ metastasis ( m1 ) . the location of the cancer within the bladder was classified as right or left ( defined by a vertical line between the ureteral orifices ) , front or posterior ( defined by a horizontal cross line between the ureteral orifices ) , or whole ( defined as the presence of an invading mass in more than two zones ) bladder . additionally , the ln metastasis pattern was classified as right , left , or bilateral in reference to the aorta . statistical analyses were performed by using spss ver . 12.0 ( spss inc . , chicago , il , usa ) . continuous variables were expressed as medians ( ranges ) and were compared by using an independent t - test . correlations between the location of the bladder tumor and the site of ln metastasis were determined by using the chi - square test . survival was compared by using the log - rank test and kaplan - meier analysis . we retrospectively reviewed the records of patients who underwent surgery for bladder cancer ( pathological n1 or higher ) at ilsan hospital ( department of urology , national health insurance corporation ilsan hospital , goyang , korea ) between 1 january 2000 and 31 august 2010 . to ensure consistency , the same investigator reviewed all of the charts to extract data on demographics , admission and operation , and pathological conditions . a total of 78 cases of patients who had undergone rc with extended lymphadenectomy were identified from the database . we excluded 42 patients without ln metastasis or any other organ metastasis ( m1 ) . the location of the cancer within the bladder was classified as right or left ( defined by a vertical line between the ureteral orifices ) , front or posterior ( defined by a horizontal cross line between the ureteral orifices ) , or whole ( defined as the presence of an invading mass in more than two zones ) bladder . additionally , the ln metastasis pattern was classified as right , left , or bilateral in reference to the aorta . statistical analyses were performed by using spss ver . 12.0 ( spss inc . , chicago , il , usa ) . continuous variables were expressed as medians ( ranges ) and were compared by using an independent t - test . correlations between the location of the bladder tumor and the site of ln metastasis were determined by using the chi - square test . survival was compared by using the log - rank test and kaplan - meier analysis . the patients included 30 men and 6 women with an average age of 66 years ( range , 48 to 79 years ) . there were 3 ( 8.3% ) , 15 ( 41.7% ) , 11 ( 30.6% ) , and 7 ( 19.4% ) pathologic pt1 , pt2 , pt3 , and pt4 cases , respectively . the mean number of resected lns was 10.4 ( range , 4 to 29 ) , and the mean number of pathologically positive lns was 1.8 ( range , 1 to 11 ) . as shown in table 1 , we observed 28 and 8 patients with pathologic pn1 and pn2 , respectively . we observed 16 patients ( 44.4% ) with bladder cancer on the right side ( group 1 ) , 16 patients ( 44.4% ) with bladder cancer on the left side ( group 2 ) , 2 patients ( 5.6% ) with posterior bladder cancer ( group 3 ) , and 2 patients ( 5.6% ) with whole bladder cancer ( group 4 ) . in group 1 , 14 patients ( 87.5% ) had right - sided ipsilateral positive lns , and 2 patients ( 12.5% ) had left - sided contralateral positive lns ( 12.5% ) . in group 2 , 4 patients ( 25% ) had right - sided contralateral positive lns , and 12 patients ( 75% ) had left - sided ipsilateral positive lns . in group 3 , two patients ( 100% ) had right - sided posterior positive lns . in group 4 , two patients ( 100% ) had positive lns on both sides ( table 2 ) . we found a significant correlation between the location of the tumor and the site of ln metastasis ( chi - square test , p<0.001 ) . ipsilateral metastasis was found in 26 cases , contralateral metastasis in 6 cases , and no ln metastasis in 42 cases . kaplan - meier survival analysis showed that the 5 year median survival rate of patients with ipsilateral metastasis was 37% , with contralateral metastasis was 18% , and without ln metastasis was 61% ( p<0.001 ) ( fig . , the presence of ipsilateral or contralateral metastasis predicts poor survival in patients with bladder cancer . most bladder cancer patients experience lymphatic metastasis in the course of disease progression . nonetheless , many studies have shown that patients with ln - positive disease can achieve long - term survival by extended radical lymphadenectomies despite initial poor prognosis . those same studies have shown that a positive ln status is found in 23% of all bladder cancer patients . furthermore , data from those analyses highlight that patients with ln - positive disease have a mean 5 year recurrence - free survival rate of 30% ( range , 20.9 to 35% ) . the relationship between the location of the primary tumor and the direction of metastatic spread has not been fully investigated . interestingly , however , a recent study has suggested a close correlation between the histologic characteristics of the primary tumor and the metastatic pattern . to the best of our knowledge , this was the first study to analyze the correlation between tumor location in the bladder and pattern of ln metastasis relative to survival rates . the 5 year survival rate of the ipsilateral ln - positive group was 37% , whereas that of the contralateral ln - positive group was 18% . this result indicates that patients with contralateral ln metastasis might have a poorer prognosis than those with ipsilateral ln metastasis . of the 32 patients with a lateralized bladder tumor , 6 ( 19% ) had lns in the contralateral side . these data suggest that bilateral nodal dissection in patients with invasive bladder cancer does not necessarily occur . in fact , invasive bladder cancer usually spreads around the circumference of the bladder in a large percentage of cases . on the other hand , wishnow et al . analyzed patients in whom the primary bladder tumor was localized clearly to one side of the bladder , and they observed unsuspected metastasis only in patients with ipsilateral ln cancer . on the basis of these findings , we advocate a restricted pelvic lymphadenectomy for patients in whom gross examination shows no evidence of nodal metastasis during rc . in our study , we found a significant correlation between the location of the bladder tumor and ln positivity . however , we are reluctant to not infer that there is no evidence of nodal metastasis on the contralateral side in patients with bladder cancer . in fact , our data indicate that lymphadenectomies must be performed bilaterally , even if the primary cancer is limited to the right or left hemisphere of the bladder wall , because even contralateral nodal metastases may eventually occur . the risk of contralateral metastases is only slightly lower than that of ipsilateral metastases . in agreement with our claim , previous retrospective studies have shown a survival benefit for patients undergoing bilateral extended radical lymphadenectomies [ 6 - 8 ] . notwithstanding the possible advantages , all of the participating urological surgeons unanimously agreed that an extended radical lymphadenectomy takes up to 60 minutes longer than does a lymphadenectomy that cranially ends at the level of the iliac arteries and therefore , knowledge of the exact location of the tumor would be useful for surgeons performing rcs and lymphadenectomies . although the group with ln metastasis on the contralateral side had a poorer prognosis than did those with ln metastasis on the ipsilateral side , tumor grade was also a valid prognostic factor . when the latter is taken into account , the distance of the ln from the tumor itself may not be an independent prognostic factor . the current study had some limitations : the surgeon may have been biased toward the presence of ipsilateral ln metastases , the sample population was small , a single operator was not used , and a single chemotherapy protocol was not performed . the site of ln metastasis was significantly correlated with the location of the bladder tumor . moreover , survival was significantly affected in patients with ipsilateral and contralateral ln - positive bladder cancer .
purposeresection of a large number of lymph nodes ( lns ) increases survival in patients with ln - positive disease ; however , morbidity also increases . here , 
 we investigated the correlation between tumor location and ln metastasis in bladder cancer.materials and methodsthirty - six patients with pathological n1 or higher bladder cancer , who underwent radical cystectomy with extended lymphadenectomy , were reviewed retrospectively . 
 the tumor location was classified as right , left , front , posterior , or whole bladder . 
 the ln metastasis pattern was classified as right , left , or bilateral . 
 the correlation between tumor location and ln metastasis was determined by chi - square test . 
 survival rates were compared by kaplan - meier analysis.resultsthe numbers of patients with a tumor on the right ( group 1 ) , left ( group 2 ) , posterior ( group 3 ) , or whole ( group 4 ) bladder were 16 ( 44.4% ) , 16 ( 44.4% ) , 2 ( 5.6% ) , and 2 ( 5.6% ) , respectively . in group 1 , 14 patients ( 87.5% ) had right - sided ipsilateral lns , and 2 patients ( 12.5% ) had left - sided contralateral lns . in group 2 , 4 patients ( 25% ) had right - sided contralateral lns , and 12 patients ( 75% ) had left - sided ipsilateral lns . in group 3 , both patients ( 100% ) had right - sided posterior lns . in group 4 , 
 both patients ( 100% ) had positive lns on both sides . 
 tumor location and ln metastasis were significantly correlated ( p<0.05 ) . moreover , 
 the survival rate was significantly higher in patients with no ln metastasis than in patients with ipsilateral or contralateral ln - positive bladder cancer.conclusionsthe location of the bladder tumor and direction of metastatic spread were significantly correlated . 
 mandatory bilateral lymphadenectomy during radical cystectomy should be questioned .