soft tissue sarcomas ( stss ) are a heterogeneous group of solid tumors that arise from embryonic mesenchymal cells and that have distinct clinical and pathological features . microscopically , arcinosarcomas are biphasic tumors comprising an intimate admixture of carcinomatous and sarcomatous components with an abrupt or gradual transition from one to the other . stss of the genitourinary ( gu ) tract are relatively rare , accounting for only 2.1% of all stss and 1% to 2% of all malignant gu tumors [ 1 - 3 ] . because of the rarity of urological stss , clinical data are limited and prognosis is often considered unpredictable . recently , several groups have reported their long - term experiences with gu stss and have investigated prognosis and prognostic factors [ 4 - 6 ] . although the consensus is that total surgical resection provides the patient the best chance for cure , there is no universal agreement concerning prognostic factors for gu stss . several analyses of prognostic factors influencing the overall survival ( os ) of patients with gu stss have revealed that tumor stage , grade , size , and anatomic site are important for patient survival . to the best of our knowledge , no prior study has investigated clinical outcomes and prognostic factors of gu stss in a korean patient population . in this study , we investigated prognostic factors of gu stss on the basis of 28 years of experience with these tumors at a single center in korea . between january 1982 and july 2009 , 48 patients who were histologically diagnosed with a gu sts at our institute were included in this study . sarcomas of the gu tract that originated from the kidney , ureter , bladder , prostate , paratesticular region , and retroperitoneum were included . sarcomas that originated from female genital organs such as the uterus , ovary , vulva , or vagina were excluded from this study . demographic and clinical data were retrieved by reviewing patients ' charts , clinical data , operative notes , radiological reports , and pathological reports . the variables analyzed were patient age , sex , tumor histology , tumor size , primary organ , metastasis at diagnosis , and status of surgical resection . tumors were divided into two groups on the basis of size : one group comprised tumors smaller than 5 cm , and the other comprised tumors larger than 5 cm . local recurrence or metastasis was defined as the first recurrence of disease at the primary tumor site or distant site detected by a radiographic modality , such as computed tomography . univariate analysis of variables to determine prognostic factors was performed by using the log rank test . the results of the cox model analysis are reported as hazard ratios and 95% confidence intervals . the kaplan - meier estimate of the survival curve was used to summarize the data , whereas differences between patient groups were assessed by the log rank test . between january 1982 and july 2009 , 48 patients who were histologically diagnosed with a gu sts at our institute were included in this study . sarcomas of the gu tract that originated from the kidney , ureter , bladder , prostate , paratesticular region , and retroperitoneum were included . sarcomas that originated from female genital organs such as the uterus , ovary , vulva , or vagina were excluded from this study . demographic and clinical data were retrieved by reviewing patients ' charts , clinical data , operative notes , radiological reports , and pathological reports . the variables analyzed were patient age , sex , tumor histology , tumor size , primary organ , metastasis at diagnosis , and status of surgical resection . tumors were divided into two groups on the basis of size : one group comprised tumors smaller than 5 cm , and the other comprised tumors larger than 5 cm . local recurrence or metastasis was defined as the first recurrence of disease at the primary tumor site or distant site detected by a radiographic modality , such as computed tomography . univariate analysis of variables to determine prognostic factors was performed by using the log rank test . the results of the cox model analysis are reported as hazard ratios and 95% confidence intervals . the kaplan - meier estimate of the survival curve was used to summarize the data , whereas differences between patient groups were assessed by the log rank test . during the study period , 48 patients with gu stss were treated at our institution . the mean age at diagnosis was 47.1 years ( range , 3 to 80 years ) . the mean follow - up duration was 43.6 months ( range , 6 to 167 months ) . the most common site was the retroperitoneum ( n=16 , 33.3% ) followed by the kidney ( n=12 , 25% ) , prostate ( n=10 , 20.8% ) , bladder ( n=7 , 14.5% ) , ureter ( n=1 , 2% ) , and paratesticular region ( n=1 , 2% ) . the mean tumor size was 9.5 cm ( range , 2.2 to 24 cm ) and 43 patients ( 89.5% ) had tumors larger than 5 cm . the histological subtypes of sarcoma were as follows : leiomyosarcoma ( 24 , 50% ) , rhabdomyosarcoma ( 9 , 18.7% ) , and liposarcoma ( 4 , 8% ) . of the 48 patients , 33 ( 68.7% ) underwent surgical resection and 15 ( 31.2% ) were treated by chemotherapy , radiotherapy , or both . at the time of analysis , 20 patients ( 41.6% ) had died of their sts , 2 patients ( 4.1% ) had died of unrelated causes , and 26 patients ( 54.1% ) were alive . the 5-year estimated survival rate of patients with a retroperitoneal sarcoma was 82% , while that of patients with a bladder sarcoma was 73% . the 5-year estimated survival rate for patients who presented with prostate sarcoma was 44% , while that for patients who presented with renal sarcoma was 39% . there were no significant differences in survival according to age ( p=0.79 ) , gender ( p=0.84 ) , tumor size ( p=0.59 ) , or histological subtype ( p=0.69 ) according to the univariate analysis ( table 2 ) . however , a significant difference in survival according to metastasis at diagnosis was observed ( fig . 2 ) . patients who underwent surgical resection also showed significantly better overall survival ( fig . patients with retroperitoneal sarcomas had more favorable survival outcomes than did patients with bladder , kidney , or prostate sarcomas ( fig . these three factors ( metastasis , surgical resection , and primary organ ) were also significantly associated with improved overall survival in the multivariate analysis ( table 2 ) . during the study period , 48 patients with gu stss were treated at our institution . the mean age at diagnosis was 47.1 years ( range , 3 to 80 years ) . the mean follow - up duration was 43.6 months ( range , 6 to 167 months ) . the most common site was the retroperitoneum ( n=16 , 33.3% ) followed by the kidney ( n=12 , 25% ) , prostate ( n=10 , 20.8% ) , bladder ( n=7 , 14.5% ) , ureter ( n=1 , 2% ) , and paratesticular region ( n=1 , 2% ) . the mean tumor size was 9.5 cm ( range , 2.2 to 24 cm ) and 43 patients ( 89.5% ) had tumors larger than 5 cm . the histological subtypes of sarcoma were as follows : leiomyosarcoma ( 24 , 50% ) , rhabdomyosarcoma ( 9 , 18.7% ) , and liposarcoma ( 4 , 8% ) . of the 48 patients , 33 ( 68.7% ) underwent surgical resection and 15 ( 31.2% ) were treated by chemotherapy , radiotherapy , or both . at the time of analysis , 20 patients ( 41.6% ) had died of their sts , 2 patients ( 4.1% ) had died of unrelated causes , and 26 patients ( 54.1% ) were alive . the 5-year estimated survival rate of patients with a retroperitoneal sarcoma was 82% , while that of patients with a bladder sarcoma was 73% . the 5-year estimated survival rate for patients who presented with prostate sarcoma was 44% , while that for patients who presented with renal sarcoma was 39% . there were no significant differences in survival according to age ( p=0.79 ) , gender ( p=0.84 ) , tumor size ( p=0.59 ) , or histological subtype ( p=0.69 ) according to the univariate analysis ( table 2 ) . however , a significant difference in survival according to metastasis at diagnosis was observed ( fig . 2 ) . patients who underwent surgical resection also showed significantly better overall survival ( fig . patients with retroperitoneal sarcomas had more favorable survival outcomes than did patients with bladder , kidney , or prostate sarcomas ( fig . these three factors ( metastasis , surgical resection , and primary organ ) were also significantly associated with improved overall survival in the multivariate analysis ( table 2 ) . less than 5% of stss arise in the gu tract and only 15% of stss arise within the retroperitoneum . the rarity of gu sts is a major obstacle to clinical   research ; contemporary data in the medical literature are limited . mondaini et al reviewed sarcomas of different histological types in a multicenter study involving eight different hospitals in tuscany , italy . the mskcc group reported two consecutive series , one including 43 patients treated between 1982 and 1989 and another including 131 patients treated between 1977 and 2003 . the latter study was an extension of the former study with a prolonged follow - up . owing to the rareness of stss , and therefore the absence of randomized controlled trials , no standard treatment options for this disease exist . this multimodal approach has replaced amputation as the primary surgical treatment of choice . in the present study the mean tumor size of 9.5 cm found in the present study is slightly smaller than that reported previously [ 9 - 11 ] . the 5-year os was 51.4% , similar to the results of previous studies that reported 5-year os rates of 50% . dotan et al reported that the presence of metastasis and rhabdomyosarcoma were unfavorable prognostic variables . in our study , the presence of metastasis at diagnosis was associated with survival in both univariate and multivariate analyses . lewis et al reported that the presence of unresectable disease and incomplete surgical resection were the most significant factors predictive of disease - specific death . in a study by van dalen et al of 143 patients treated in the netherlands , complete tumor resection was correlated with better overall survival in the multivariate analysis . however , dotan et al reported that complete resection was not a significant factor predictive of disease - specific survival in univariate and multivariate analysis in 102 patients with primary tumors only . these results suggest that any type of surgical resection can provide the best chance of survival in patients presenting with primary disease or with primary and metastatic disease . consistent with this , we found that the absence of surgical resection was an unfavorable prognostic variable for overall survival . therefore , we suggest that surgical resection may contribute to a favorable prognosis in patients with urological stss . the prognosis of retroperitoneal stss has been reported to be more favorable than that of the other gu stss . disease prognosis was the worst for stss of the kidney , whereas the prognosis was better for retroperitoneum , bladder , and prostate sarcomas , as reported previously . according to a previous study , the size of stss is an important prognostic variable , in contrast with our findings . this discrepancy may be because stss arising from the retroperitoneum can attain a large size owing to the flexibility of the retroperitoneum . however , retroperitoneal stss showed a better prognosis than bladder , prostate , and renal stss in our study . the histological subtype of the gu stss was not a prognostic factor for disease - specific survival in either the univariate or the multivariate analysis ; in other words , we did not observe an association between histological subtype and disease - specific survival . surgical resection , metastasis at diagnosis , and the primary organ were significant predictors of prognosis . the data presented in this study contribute to our understanding of urological stss and may help in the development of an optimal therapeutic strategy to treat stss .