| BackgroundPrimary retroperitoneal soft tissue sarcoma(PRSTS)is the common type of retroperitoneal tumors,and its origin is complex.Primary retroperitoneal liposarcoma(PRPLS)accounts for 40% as the most common histotype of retroperitoneal soft tissue sarcoma.PRPLS often originates from adipose tissues surrounding the kidney.On account of the lack of typical clinical symptoms,a large size of tumor due to the extension of retroperitoneal space,and the tumor invasion of adjacent organs,it is very difficult to diagnose in early stage.Surgical operation is the most effective therapeutic method,but the local recurrence rate of tumor is extremely high following operation.Furthermore,it is not clear whether adjuvant chemotherapy or radiotherapy could treat this disease.And the prognosis is poor.There were few researches on PRSTS and PRPLS at home and abroad,and they were not comprehensive and systematic.Thus,the diagnosis and treatment are extremely in need of being solved in clinical.ObjectiveThis study analyzed the clinicopathological features of PRSTS and PRPLS retrospectively,and explored and summarized the factors which related to the disease-specific survival of patients with PRPLS.MethodOur research had collected 298 patients diagnosed pathologically as PRSTS and 67 patients as PRPLS following surgery from the Southwest Hospital of The Third Military Medical University between January 2005 and March 2015.The endpoint of follow-up was October 2015.The follow-up was performed through letter,via outpatient re-examination,or telephone correspondence.The endpoint was October 2015.The gender,age at presentation,main clinical symptoms,the position of tumor,the treatments and pathological subtype were statisticsed and analyzed in PRSTS patients.The samples of PRPLS were dyed by HE and handled by S-P method of immunohistochemistry.Immunohistochemical results of Ki-67,Vimentin and S-100 were recorded,and the relationship of between Ki-67 expression index and prognosis of PRPLS patients was analyzed.For PRPLS patients,the pathological subtype,histological grade,surgerical methods,tumor burden,age at presentation,gender,first recrudescent time following surgery and follow-up time of primary tumor were statisticsed and analyzed contrastively to obtain factors related to prognosis and recurrence,and therapeutic effects.SPSS 18.0 software(SPSS,Inc.,Chicago,IL,USA)was used for statistical analysis.Survival plots were performed using Kaplan–Meier method.Univariate survival analysis was performed using log-rank statistics and multivariate analysis was accomplished with the Cox proportional hazards regression model.The ?2 test or nonparametric test was used to examine correlation analysis.P < 0.05 was regarded as statistically significant.ResultUp to March 2015,there were 298 patients diagnosed clinicopathologically as PRSTS following operation by our hospital,including 141 patients were males and 157 were females.And the age ranged from 15 years to 78 years,with 52-year median age.The primary clinical symptoms were abdominal mass with abdominal girth increasing,ventosity and stomachache,emaciation and poor appetite,space-occupying lesion in kidney and so on.Location of tumors in left upper abdomen,right upper abdomen,hypogastrium and pelvic cavity were 64,71,106 and 57 respectively.Celiac or pelvic organs of 161 patients were invaded by tumors and blood vessels of 51 patients were invaded by tumors.174 patients received primary tumor complete resection and the remaining 124 patients received palliative operation.All 298 PRSTS patients included 67 liposarcoma patients,47 leiomyosarcoma patients,50 malignant fibrous histiotoma patients,25 fibrosarcoma patients,13 rhabdomyosarcoma patients and 96 other rare pathological subtype patients.65 PRPLS patients were followed up,including 35 males and 30 females,and age ranged from 16 years to 77 years old.Their median survival time was 38.1 months and total survival rate was 58.5%.51 patients who underwent tumor complete resection included 27 males and 24 females.Their median survival time was 43.3 months and total survival rate was 64.7%.25 patients(49%)were diagnosed as the well-differentiated pathological subtype,8(15.7%)were myxoid/round cell subtype,8(15.7%)were pleomorphic/mixed-type subtype,and 10(19.6%)were dedifferentiated subtype.Thus,18(35.3%)were high-grade and the remaining 33(64.7%)were low-grade.32 patients received contiguous organ resection,and 15 was determined microscopically positive margins after surgery.22 patients suffered from first local recurrence following surgery,and the median recurrent time was 29.3 months.14 patients received palliative surgery or biopsy.The median survival time was 19.4 months and the total survival rate was 35.7%.Immunohistochemical results revealed that in all 65 tumor samples,Ki-67 was expressed in 64 patients,while 62 and 23 patients were Vimentin-positive and S-100-positive respectively.Ki-67 and Vimentin were more sensitive markers than S-100 for PRPLS diagnosis.Ki-67 expression was mainly examined in high-grade tumors,videlicet dedifferentiated,pleomorphic or mixed-type PRPLS.On the contrary,S-100 was predominantly expressed in well-differentiated PRPLS.Moreover,there is a negative correlation between Ki-67 expression index and prognosis of PRPLS patients.Survival analysis detected that factors which influenced prognosis of PRPLS patients were pathological subtype of primary tumor(?2=19.467,P <0.01),histological grade(?2=19.053,P < 0.01),tumor burden(?2=6.826,P < 0.05),complete resection(?2=15.471,P <0.01),contiguous organ resection(?2=7.130,P <0.01).Factors related to local recurrence were pathological subtype(?2=14.995,P <0.01)and histological grade(?2=14.810,P <0.01).Positive gross margins(?2=15.471,P <0.01)significantly did influence disease-specific survival,but microscopically margins(P >0.05)did not.Multivariate analysis revealed that pathological subtype,histological grade and contiguous organ resection were the independent factors of prognosis,while histological grade was an independent factor of recurrence.Age at presentation and gender of patients were neither associated with prognosis nor recurrence.Correlation analysis showed postoperative recurrence(P <0.01)influenced prognosis strongly.Histological grade(P >0.05)was not associated with the tumor burden,but was with invasion of adjacent organs(P <0.01).In addition,the tumor burden was not correlated to tumor invasion of adjacent organs(P >0.05)or recurrence(P >0.05).Conclusion1.PRSTS used to appear from 40 years to 60 years with no difference in gender.Tumor mainly occurred in hypogastrium and it usually made adjacent organs and blood vessels in invasion.The complete resectable rate of primary tumor was not high.Liposarcoma,malignant fibrous histiotoma and leiomyosarcoma were common pathological subtypes in PRSTS.2.PRPLS is the most common type in PRSTS.Surgical operation is the most effective therapeutic method for PRPLS.3.Ki-67 and Vimentin are more sensitive than S-100 for diagnosis of PRPLS.The relationship of between Ki-67 expression index and the prognosis of PRPLS patients was negative correlation.4.The independent markers of prognosis were pathological subtype,histological grade and contiguous organ resection.5.Histological grade was an independent marker of local recurrence.6.Microscopically positive margins did not influence disease-specific survival,but positive gross margins significantly did.7.The most common and predominant cause of death of PRPLS is local recurrence following surgery. |
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