Malignant sarcoma of the pelvic bones

Treatment outcomes and prognostic factors vary by histopathology

Authors


Abstract

BACKGROUND:

Treatment of malignant sarcomas of the pelvis poses a challenge for local disease control and oncologic outcome. Many reports have described the dismal outcomes. Most studies are retrospective series coming out of single centers, thus biased toward patient selection and are of limited statistical power.

METHODS:

The authors used the Surveillance, Epidemiology, and End Results database to analyze 1185 pelvic sarcoma cases from 1987 to 2006. Kaplan-Meier and Cox regression were used to analyze the significance of prognostic factors. The analysis was repeated for different histopathological subtypes to determine specific prognostic factors in each case.

RESULTS:

Incidence of pelvic sarcoma in 2006 was 89 per 100,000 persons; it has significantly increased since 1973 (P < .05). The overall 5-year survival for all the patients with pelvic sarcoma was 47%, with osteosarcoma having the worst 5-year survival at 19% and patients with chordoma having the best 5-year survival at 60%. Independent prognostic factors included age, stage, grade, size of primary lesion, histopathology, and treatment-related factors. Comparing the patients only with high-grade lesions, patients with Ewing sarcoma have the best prognosis.

CONCLUSIONS:

This is an analysis of patients with pelvic sarcomas derived from a population-based registry. Survival and prognostics vary with histopathological diagnoses. Although surgical resection was associated with superior outcomes for osteosarcoma and chondrosarcoma, there was no significant difference in outcomes of patients with Ewing sarcoma treated with surgery and/or radiotherapy. Cancer 2011. © 2010 American Cancer Society.

Malignant tumors involving the pelvis pose a challenge in achieving local disease control and improving patient survival.1 Previous reports have described the significant morbidity and complications associated with surgical resection, and provide conflicting data regarding treatment outcomes and prognosis.2-16 The reasons behind such conflicting evidence are severalfold. Most of the reports emanate from a single center and thus carry a bias toward the selection of patient population and treatment modalities used.1, 13, 17, 18 Second, the small number of patients analyzed has limited the statistical power for each of the studies. Lastly, there is inconsistency in the analysis of the data, with some reports providing an analysis of outcomes and prognostic factors with respect to a particular histopathological subtype of tumor,19-29 whereas others have grouped different histopathological subtypes affecting pelvic bones as a single cohort.1, 13, 17, 18 The clinician is thus left wondering whether a uniform treatment strategy should be applied to all the patients regardless of the histopathology, as previously suggested, or each disease should be treated as a separate entity.1 An example of such a controversy is illustrated in the treatment recommendations for pelvic Ewing sarcoma, in which some authors have suggested considering radiotherapy as an alternative to surgery in pelvic Ewing sarcoma,30-34 whereas others have stressed the importance of wide excision of the primary disease for this and other sarcomas.25, 35-43

In the current study, we have made an attempt to resolve these controversies by analyzing the outcomes of all patients with sarcomas of the pelvis from 1987 to 2006 using the Surveillance, Epidemiology, and End Results (SEER) database. The data were analyzed as a single cohort and also separately with respect to different histopathological subtypes. The selection was limited to the years 1987 to 2006, because imaging such as computed tomography and magnetic resonance imaging were routinely used, permitting determination of tumor size and extent.

MATERIALS AND METHODS

The population analyzed was extracted from population-based cancer registries that participate in the National Cancer Institute (NCI)'s SEER program.44 A total of 1185 patients with a diagnosis of sarcoma and a primary disease location of pelvic bones were identified over the interval from 1987 to 2006. Sarcoma cases were identified by the designated histologic International Classification of Diseases for Oncology, Third Edition codes. Information regarding patient demographics, stage at diagnosis, size, number of primaries, cause of death, year of diagnosis, surgical and radiation treatment, and survival time until death or loss to follow-up was identified. Patients with missing data were excluded from each respective univariate and multivariate analysis.

Patient age was arbitrarily converted to a categorical variable (0-16, 17-40, 41-60, ≥60 years) for the purpose of analysis. Staging categories of local, regional, and distant disease were used according to the SEER staging system. Tumor size was converted into a categorical variable (<5, 5-10, >10) according to the American Joint Committee on Cancer recommendations and previous reports.1, 17, 20

SEER* Stat software (version 6.4.4, NCI) was used to analyze incidence rates, which were age adjusted and normalized using the 2000 US standard population. Statistical analysis was performed using the SPSS statistical package version 16.0 (SPSS Inc., Chicago, Ill). The effects of demographic, clinical, pathological, and treatment variables were tested using the log-rank test for categorical values. A multivariate analysis was carried out for determination of independent prognostic factors using the Cox proportional hazards model.

RESULTS

The demographic characteristics of the 1185 patients with sarcomas involving the pelvic bones identified in the SEER database are displayed in Table 1. The specific histopathological diagnosis was chondrosarcoma (31.3%), osteosarcoma (19%), and Ewing sarcoma (22.1%). Grade (664 patients) and size (775 patients) data were available only for a proportion of the cohort. Location was specified as pelvic bones for most of the patients (97.9%), and most of the patients (86.7%) presented with a single lesion. Incidence of pelvic sarcoma in 2006 was 89 per 100,000 persons and has shown a significant increase since 1973, with an annual percentage change of 5.39 (P < .05).

Table 1. Demographic and Clinical Characteristics for the Entire Cohort of Patients With Pelvic Sarcoma, Stratified by Different Histopathological Subtypes
CharacteristicEntire ColumnOsteosarcomaChondrosarcomaEwing SarcomaChordoma
 No.Valid % of TotalNo.Valid % of TotalNo.Valid % of TotalNo.Valid % of TotalNo.Valid % of Total
Total patients1,185100251100407100288100217100
Age, y
 0-1620016.9301271.714550.3177.8
 17-3936330.67329.11263112443.12712.4
 40-60296255823.115337.6165.66429.5
 &6032627.59035.912129.73110950.2
Sex
 Male7356213152.226966.118965.613763.1
 Female4503812047.813833.99934.48036.9
Race
 White102687.120581.735187.326692.418887.4
 Black695.92510256.272.494.2
 Other837218.4266.5155.2188.4
Ethnicity
 Hispanic16814.421184.45012.55418.9198.9
 Non-Hispanic100285.63915.635087.523181.119491.1
Stage
 Local27926.13013.714638.63914.26133.5
 Regional5134810045.718749.512746.49150
 Distant27625.88940.64511.910839.43016.5
Grade
 Low30951.72014.127477.4001152.4
 High28948.312285.98022.6711001047.6
Size
 <5 cm10514.4119.34917.124142013.8
 5-10 cm33045.15546.611740.98549.77249.7
 >10 cm29640.55244.1120426236.35336.6
Primaries
 Single103687.420882.935186.227695.818082.9
 Double12710.73815.14711.5124.23013.8
 Multiple221.95292.20073.2
Histopathology
 Osteosarcoma25121.2        
 Chondrosarcoma40734.3        
 Ewing sarcoma28824.3        
 Chordoma21718.3        
 Giant cell tumor, bone221.9        
Surgery
 Yes71758.11184830074.69835.114468.6
 No55441.91285210225.418164.96631.4
Radiation
 Yes39234.16526.26716.917362.58038.6
 No75765.918373.833083.110437.512761.4
Year of diagnosis
 1987-199637231.49035.912831.48429.26530
 1997-200681368.616164.127968.620470.815270

Patients with osteosarcoma of the pelvis constituted 19.3% of the cohort and had a mode age of >60 years (35.9%). The pediatric age group contributed the fewest numbers to patients with pelvic osteosarcoma (12%). To determine whether there is a statistically significant association between pelvic location for osteosarcoma and age, a cross table analysis was performed. Chi-square test revealed a statistically significant association between pelvic location and age >60 years (P < .001). Only 16 of these cases were diagnosed as Paget osteosarcoma. All other patients had primary osteosarcoma.

A total of 407 patients had the diagnosis of chondrosarcoma, with only 7 (1.7%) patients in the pediatric age group. Only 11.9% of patients presented with a distant stage of disease, and most of the patients with available grade information presented with low-grade lesions (77.4%). Most of these patients underwent surgical resection (74.6%), only 16.9% of patients underwent radiotherapy, and the latter did not significantly impact survival (P = .667).

Patients with Ewing sarcoma of the pelvis represented 22.1% of the cohort with a modal age group of 0 to 16 years (50.3%). Most of the patients were male (66.1%), and only 14.2% of the patients presented with local stage of disease. Surgery was performed in 35.1% of the patients, and radiotherapy was administered in 62.5% of the patients. A total of 56 (20.7%) patients underwent surgical resection as well as radiotherapy. A Kaplan-Meier curve predicting the effects of treatment on survival is shown in Figure 1B. It shows that patients undergoing surgical resection, radiation therapy, or a combination of both fared similarly and significantly better than those not receiving either therapy.

Chordoma was the histopathological diagnosis in 217 (16.7%) patients. The most common age group was >60 years (50.2%); most of the patients were male (63.1%), and 50% of all the patients presented with regional disease. Surgical resection was performed in 68.6% of the patients.

The 5-year survival of all the patients with pelvic sarcoma was 45%, for patients with osteosarcoma it was 19%, for chondrosarcoma it was 59%, for Ewing sarcoma it was 46%, and for chordoma the 5-year survival was 60%. When only high-grade tumors are considered, the 5-year survival for pelvic osteosarcoma and chondrosarcoma was 18% and 34%, respectively.

Univariate and multivariate analysis of parameters that influence survival are demonstrated in Table 2 and Table 3, respectively. Univariate analysis demonstrated a survival advantage for patients with pelvic sarcomas with age <60 years (P < .001), local stage of disease with no systemic disease involvement (P < .001), low grade (P < .001), smaller size (P < .001), single primary lesion (P < .001), histology other than osteosarcoma (P < .001), performance of surgical resection (P < .001), and nonuse of radiation therapy (P = .006). Association between nonuse of radiotherapy and improved survival may represent selection bias in patients' selection for radiotherapy for either close surgical margins or unresectable disease.

Table 2. Overall Survival According to Demographic and Clinical Characteristics for the Entire Cohort of Patients With Pelvic Sarcoma and Stratified by Different Histopathological Subtypes
CharacteristicEntire CohortOsteosarcomaChondrosarcomaEwing SarcomaChordoma
5-Year SurvivalP5-Year SurvivalP5-Year SurvivalP5-Year SurvivalP5-Year SurvivalP
  1. NA indicates not applicable.

  2. For entire cohort, age: P < .001 is true only for >60 years vs the rest; 0-16 vs 17-40 years, P = .153; 0-16 vs 41-60 years, P = .168; 17-40 vs 41-60 years, P = .935; race: P = .126 only for whites vs others; whites vs blacks, P = .148; blacks vs others, P = .982; stage: P < .001 is true for comparison between all categories; size: P < .001 is true only for <5 cm vs >10 cm; <5 cm vs 5-10 cm, P = .104; 5-10 cm vs >10 cm, P = .002; primaries: P = .007 is true only for single vs double; single vs multiple, P = .353; double vs multiple, P = .777; histopathology: P < .001 is true for osteosarcoma vs the rest; chondrosarcoma vs giant cell tumor of the bone, P = .461; chondrosarcoma vs Ewing, P = .008; chondrosarcoma vs chordoma, P = .205; Ewing vs giant cell tumor of the bone, P = .154; chordoma vs giant cell tumor of the bone, P = .395; Ewing vs chordoma, P = .067.

  3. For osteosarcoma, age: P < .001 is true only for >60 years vs the rest; 0-16 vs 17-40 years, P = .725; 0-16 vs 41-60 years, P = .160; 17-40 vs 41-60 years, P = .026; race: P = .375 only for whites vs others; whites vs blacks, P = .590; blacks vs others, P = .692; stage: P < .001 is true for comparison between all categories except local vs regional, P = .851; size: P < .096 is true only for <5 cm vs 5-10 cm; <5 cm vs >10 cm, P = .212; 5-10 cm vs >10 cm, P = .605; primaries: P < .097 is true only for single vs double; single vs multiple, P = .511; double vs multiple, P = .953.

  4. For chondrosarcoma, age: P < .001 is true only for > 60 years vs the rest, except >60 vs 0-16 years, P = .010; 0-16 vs 17-40 years, P = .654; 0-16 vs 41-60 years, P = .266; 17-40 vs 41-60 years, P = .008; race: P = .548 only for blacks vs others; whites vs blacks, P = .627; others vs whites, P = .844; stage: P < .001 is true for comparison between all categories; size: P = .067 is true for all, except <5 cm vs 5-10 cm, P = .554; primaries, P = .013 is true only for single vs double; single vs multiple, P = .545; double vs multiple, P = .765.

  5. For Ewing sarcoma, age: P = .129 is true only for 0-16 vs 17-40 years; 0-16 vs >60 years, P = .137; 0-16 vs 41-60 years, P = .965; 17-40 vs 41-60 years, P = .507; 17-40 vs >60 years, P = .362; 41-60 vs >60 years, P= 0.411; race: P = .360 only for others vs blacks; white vs others, P = .611; black vs white, P = .400; stage: P < .001 is true for comparison between all categories except local vs regional, P = .343; size, P = .018 is true only for 5-10 cm vs >10 cm; <5 cm vs 5-10 cm, P = .680; <5 cm vs >10 cm, P = .055; primaries: P = .429 is true only for single vs double. There were no patients with multiple lesions.

  6. For chordoma, age: P < .001 is true only for >60 vs 41-60 years; 0-16 vs 17-40 years, P = .512; 0-16 vs 41-60 years, P = .345; 0-16 vs >60 years, P = .057; 17-40 vs 41-60 years; P = .034; 17-40 vs >60 years, P = .044; race: P = .177 only for others vs blacks; whites vs others, P = .219; blacks vs whites, P = .990; stage: P = .001 is true for local vs distant only; local vs regional, P = .083; regional vs distant, P = .039; size: P = .003 is true only for <5 cm vs >10 cm; <5 cm vs 5-10 cm, P = .175; 5-10 cm vs >10 cm, P = .006; primaries: P = .459 is true only for single vs multiple; single vs double, P = .631; double vs multiple, P = .748.

Overall survival0.47NA0.19NA0.59NA0.46NA0.6NA
Age, y <.001 &lt.001 <.001 .129 <.001
 0-160.49 0.3 0.82 0.51 0.57 
 17-390.56 0.33 0.79 0.41 0.66 
 40-600.58 0.19 0.65 0.5 0.81 
 >600.27 0.06 0.29 NA 0.47 
Sex .608 .498 .248 .325 .378
 Male0.47 0.19 0.57 0.48 0.58 
 Female0.46 0.19 0.62 0.44 0.63 
Race .126 .375 .548 .36 .177
 White0.47 0.2 0.58 0.47 0.58 
 Black0.43 0.19 0.67 0.23 0.71 
 Other0.44 NA 0.57 0.48 0.64 
Ethnicity .906 .243 .485 .254 .505
 Hispanic0.46 0.22 0.61 0.44 0.59 
 Non-Hispanic0.47 0.19 0.58 0.47 0.59 
Stage &lt.001 <.001 <.001 <.001 .001
 Local0.68 0.38 0.73 0.7 0.68 
 Regional0.51 0.24 0.57 0.57 0.6 
 Distant0.21 0.1 0.2 0.27 0.38 
Grade <.001 .046 <.001 NA 0.545
 Low0.7 0.38 0.71 NA 0.76 
 High0.32 0.18 0.34 0.49 NA 
Size <.001 .096 .067 .018 .003
 <5 cm0.61 NA 0.69 0.55 0.78 
 5-10 cm0.57 0.2 0.69 0.59 0.66 
 >10 cm0.45 0.26 0.58 0.38 0.44 
Histopathology <.001        
 Osteosarcoma0.19         
 Chondrosarcoma0.59         
 Ewing sarcoma0.46         
 Chordoma0.6         
 Giant cell tumor, bone0.64         
Surgery <.001 <.001 <.001 .011 .064
 Yes0.6 0.32 0.71 0.55 0.64 
 No0.29 0.08 0.25 0.41 0.5 
Radiation .006 <.001 <.001 .014 .781
 Yes0.42 0.04 0.35 0.52 0.59 
 No0.49 0.25 0.64 0.37 0.6 
Year of diagnosis .351 .507 .745 .174 .413
 1987-19960.45 0.16 0.61 0.39 0.61 
 1997-20060.48 0.21 0.57 0.5 0.59 
Table 3. Multivariate Analysis for the Entire Cohort of Patients With Pelvic Sarcoma and Stratified by Different Histopathological Subtypes
CharacteristicEntire CohortOsteosarcomaChondrosarcomaEwing SarcomaChordoma
No.Hazard RatioPNo.Hazard RatioPNo.Hazard RatioPNo.Hazard RatioPNo.Hazard RatioP
  1. NA indicates not applicable.

Overall376NANA125NANA324NANA257NANA136NANA
Age, y
 0-16370.205<.001150.283.00360.164.077   60.654.473
 17-391290.254<.001420.308<.0011040.255<.001   150.497.127
 40-601340.366<.001410.474.0221240.425<.001   400.211<.001
 >6080Reference group 29Reference group 90Reference group    75Reference group 
Stage
 Local1180.31<.001170.413.0221280.258<.001380.346.001460.177<.001
 Regional1950.562.016610.441.0011660.513.0071150.449<.001740.251.002
 Distant67Reference group 49Reference group 30Reference group 105Reference group 16Reference group 
 Grade  <.001  .924  <.001      
 Low2160.328 190.964 2500.376       
 Grade164Reference group 108Reference group 74Reference group       
Size
 <5 cm570.939.828         200.36.029
 5-10 cm1580.684.036         660.579.056
 >10 cm165Reference group          50Reference group 
Primaries
 Single3370.386.029   2830.793.722      
 Double330.377.047   330.671.509      
 Multiple10Reference group    8Reference group       
Histopathology
 Osteosarcoma773.298.029            
 Chondrosarcoma2431.501.441            
 Ewing sarcoma421.075.902            
 Chordoma13Reference group             
 Giant cell tumor, bone52.906.229            
Surgery               
 Yes2910.512.004760.635.0952630.352<.001900.626.023   
 No89Reference group 51Reference group 61Reference group 168Reference group    
Radiation
 Yes861.366.139311.73.032471.112.6671630.6.005   
 No294Reference group 96Reference group 277Reference group 95Reference group    

For osteosarcoma, survival advantage was found to be associated with younger age (P < .001), localized stage (P < .001), low grade (P < .046), surgical resection (P < .001), and nonuse of radiotherapy (P < .001). For chondrosarcoma, the significant prognostic factors on univariate analysis included age <60 years (P < .001), local stage (P < .001), low grade (P < .001), absence of multiple primaries (P = .013), surgery (P < .001), and radiation (P < .001). We suspect that association of radiotherapy and poor survival is probably attributable to selection bias in selecting patients for radiotherapy.

Prognostic factors for Ewing sarcoma include local stage (P < .001), tumor size <10 cm (P < .018), surgery (P = .011), and radiotherapy (P = .014) for local control of disease. On univariate analysis, significant prognostic factors for chordoma patients included age <60 years (P < .001), local stage (P = .001), tumor size <10 cm (P = .003), and primary location pelvis not otherwise specified (P = .005).

On multivariate analysis for all patients with pelvic sarcoma, factors affecting survival independently included age, stage, grade, size of primary tumor, histopathology, and surgery. Because grade and size information was available for only a fraction of patients, 376 patients were included in the analysis. To determine the effects of this censoring, we repeated the multivariate analysis without size and stage considerations (data not shown). There was no marked change with respect to independent prognostic factors.

For osteosarcoma, independent prognostic factors as shown in Figure 2 include age (A), stage (B), and surgery (C). Independent predictors of survival for patients with pelvic chondrosarcoma are age, stage, surgery, and grade. Corresponding Kaplan-Meier curves are shown in Figure 3A-D, respectively. Factors governing survival independently among patients with Ewing sarcoma included stage, surgery, and radiotherapy (Fig 1). Survival in patients with chordoma was dictated by age, stage, and size of the primary tumor. Primary tumor size <5 cm was an independent predictor of improved survival among patients with pelvic chordoma, probably because of ease of resection.

Figure 1.

Survival for patients with pelvic Ewing sarcoma is shown with respect to (A) stage and (B) treatment modality.

Figure 2.

Survival for patients with pelvic osteosarcoma is shown with respect to (A) age, (B) stage, and (C) surgery.

Figure 3.

Survival for patients with pelvic chondrosarcoma is shown with respect to (A) age, (B) stage, (C) surgery, and (D) grade.

DISCUSSION

The current study analyzes a population-based cohort of patients with a diagnosis of malignant pelvic bone sarcoma. The SEER database compiles its data from 17 registries across the United States, and completeness is 98%.44 There is a general consensus in the literature regarding the poor outcomes among patients with a malignant sarcoma involving the pelvic bones or adjacent soft tissues.1, 13, 17, 18 A study by Mankin et al1 represents a retrospective analysis of 206 patients and reports mean 5-year survival at 51%. An earlier study by Kawai et al showed a 5-year survival of 55%17 in a cohort of 102 patients. Wirbel et al18 presented a retrospective analysis of 93 patients from 1978 to 1998 and reported a mean survival of 21.5 months for 46 patients dying of disease. The current analysis shows an overall 5-year survival of 45% in a cohort of patients from 1987 to 2006, which is lower but still comparable to survival reported in earlier studies. Mankin et al1 and Wirbel et al18 both recognized surgical margin and stage of the disease as independent predictors of survival. In addition to surgical margin and stage, Kawai et al suggested the size of primary tumor and type of surgery as independent prognostic factors.17 In contrast, Shin et al13 reported grade as the only independent prognostic factor in their cohort of 46 patients. In the current analysis, we were unable to evaluate the prognostic significance of surgical margin, because this information is not included in the SEER data set. The independent predictors of survival in the current analysis included age, stage, grade, size of the tumor, histopathology, and use of surgical treatment for pelvic sarcomas as a group. Age >50 years was also a significant factor predicting poor survival on univariate analysis in the data reported.1 Multivariate analysis was not carried out, probably because of a relatively smaller cohort, and the authors attributed the difference in survival with respect to age to other factors, such as older age and lower survival among patients with malignant fibrous histiocytoma and metastatic carcinoma. However, the current study clearly demonstrates age as an independent predictor of survival among patients with pelvic sarcomas (P < .001) (Table 3).

There has been contradictory evidence about the prognostic significance of grade versus stage for pelvic sarcomas.1, 13, 17, 18 Wirbel et al18 reported a prognostic significance for grade only if surgical stage of the tumor is excluded from the analysis. The current analysis clearly demonstrates with substantial statistical significance that both grade and stage are independent predictors of survival for pelvic sarcomas. Mankin et al1 identified variation in survival according to different histopathological diagnoses, but failed to suggest histopathology as an independent predictor of survival. In our analysis, a histopathological diagnosis of osteosarcoma was an independent predictor of poor survival. This observation is consistent with the study by Mankin et al.1

Patients with the diagnosis of osteosarcoma (251 patients) of the pelvis had the lowest 5-year survival (19%) in the cohort. Some of the larger published series report the 5-year survival ranging from 4% to 32%.22, 27, 45-48 A recent investigation by Fuchs et al20 reported a 5-year survival of 38% in a cohort of 43 patients. Only 18% of patients in the abovementioned study presented with a distant stage of disease. The difference in survival can be partially explained by a higher proportion of patients (40.6%) included in the current analysis with distant stage of disease. Mankin et al1 reported a 5-year survival rate as high as 58% in a cohort of 45 patients. The independent predictors of survival in patients with pelvic osteosarcoma in the current analysis included age, stage, and absence of radiotherapy. Stage and surgery have been widely recognized as predictors of survival in the literature for patients with pelvic osteosarcoma.20, 22, 27, 45-48 Although there is a statistical trend toward improved survival with surgical resection in multivariate analysis, we failed to identify surgical resection as an independent predictor of survival. Other prognostic factors suggested in the literature include surgical margins, response to chemotherapy, and involvement of sacrum.20, 22, 27, 45-48 Because this information is not available in the SEER database, we are unable to make a comment on the importance of these prognostic factors. An important observation with osteosarcoma of the pelvis was the absence of characteristic bimodal distribution at extreme ages. Only 12% of all the patients with pelvic osteosarcoma were in the pediatric age group, and the mode of age distribution was >60 years (35.9%, Table 1). Moreover, in this group of patients grade was not a prognostic factor. This likely reflects the overwhelming predominance of high-grade lesions in this cohort (86%).

Chondrosarcoma is the most common histopathologic diagnosis (407 patients) in the current analysis, which is consistent with previous studies.1, 13, 17, 18 The 5-year survival for patients with pelvic chondrosarcoma in the current study was 59%. This is comparable to the survival reported in some of the previous studies,1, 29 whereas others have reported a 5-year survival ranging from 72% to 92%.19, 21, 23 This difference in survival can be explained on the basis of clinical characteristics of the patients analyzed. Pring et al21 (64 patients) and Donati et al23 (124 patients) did not include any patients with distant stage of disease in their respective analysis. Only 2 of 69 patients had metastasis in the series reported by Bergh et al.19 On the contrary, 11.9% of all the chondrosarcoma patients in the current analysis presented with a distant stage of disease. In the current investigation, independent prognostic factors on multivariate analysis included age, stage, grade, and surgical resection. Grade and operability of the tumor have also been previously described as independent predictors of survival.19, 21, 23 Bergh et al19 have also suggested age as a prognostic factor for outcome. Although stage has not been implicated as a prognostic factor in previous studies, we have clearly shown that stage is an independent factor affecting survival in patients with pelvic chondrosarcoma (P < .001, Table 3).

Pelvis has been implicated as the single most common site for Ewing sarcoma.35, 49 A total of 288 (22.1%) patients with Ewing sarcoma were included in the current analysis, with a 5-year survival rate of 46%. The earlier reports on pelvic Ewing sarcoma reported survival rates only as high as 20% to 30%.32, 34 We believe that improvement in survival among patients over the past 2 decades can be attributed to improvements in multimodal therapy for Ewing sarcoma and radiological imaging. Other recent investigations, including those originating in Europe, have reported similar 5-year overall survival.33, 35, 36, 43 The independent predictors of survival in the current analysis included stage and local treatment, that is, surgery or radiotherapy. This observation has been validated by previous investigations.32-36, 43 As mentioned in the introduction section, 1 of the controversies in literature is about the efficacy of radiotherapy30-34 as compared with surgery25, 35-43 for local disease control. In the current investigation, both surgery and radiotherapy were independently associated with improved survival on multivariate analysis, without a clear advantage of 1 over the other.

Limitations of the current study include lack of any information on specific chemotherapy or any other medical therapy in the SEER database. Thus we are unable to comment directly on survival benefit conferred by the use of chemotherapy or efficacy of a particular regimen in a particular subset of patients. The database consists of patient information from tertiary treatment centers within the United States, and hence it may be reasonable to assume that appropriate chemotherapy was administered, but the data are lacking. Also, chemotherapeutic regimens and protocols in regard to various patient factors such as age are usually standardized across such facilities, facilitating an unbiased analysis. Similarly, no information regarding medical history, radiological studies, or serological workup is provided in the database, limiting our analysis regarding prognostic significance of fever, duration of symptoms, tumor volume, anemia, hypoalbuminemia, or high lactate dehydrogenase. The absence of images makes it impossible to verify the stage at diagnosis. Having acknowledged these limitations, the current article brings novel observations to the literature.

The current article clearly demonstrates that the histologic diagnosis in patients with pelvic sarcomas has a profound influence on long-term disease outcome. The comparison of different diagnoses on the basis of anatomic location as has been done in the past in the literature is not warranted. The current analysis clearly outlines the important prognostic factors for patients with pelvic sarcoma within each of the histologic diagnoses. We have outlined the specific prognostic factors and oncological outcomes for different histological subtypes of pelvic sarcoma. A novel observation is the age bias in patients with pelvic osteosarcoma. This has not been previously reported. It is only with the use of a large data set such as used in this analysis that these conclusions can be reached.

CONFLICT OF INTEREST DISCLOSURES

The authors made no disclosures.

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