RETROPERITONEAL SARCOMA - Etiology and pathogenesis

Retroperitoneal sarcoma

1. RETROPERITONEAL SARCOMA Team S4

2. INTRODUCTION Most retroperitoneal tumors are MALIGNANT ,and about one third are SOFT TISSUE SARCOMA Retroperitoneal Sarcoma represents about 10-15% of all soft tissue sarcoma The most frequent retroperitoneal sarcoma subtypes are LIPOSARCOMA(45%),LEIOMYOSARCOMA, UNDIFFERENTIATED PLEOMORPHIC SARCOMA(MFH) The average age of presentation is 54 years ;M=F Distribution The differential diagnosis of retroperitoneal sarcoma are PRIMARY GERM CELL TUMORS ,LYMPHOMA,AND METASTATIC TESTICULAR TUMORS In most series,the overall survival of patients presenting with retroperitoneal sarcoma is 33% - 39%

3. CLINICAL PRESENTATION Presentation of retroperitoneal sarcoma is variable, depending on the size and location of the tumor Usually present as large masses : 70% are larger than 10 cm at diagnosis Symptomatic tumors may presents with abdominal pain,weight loss,early satiety,nausea,vomitting,back or flank pain,paraesthesia and weakness Some tumors are asymptomatic until they grow large enough to compress or invade nearby structures Evaluation of nodal enlargement and testicular evaluation in men are important and symptoms related to lymphoma should be ruled out

4. INVESTIGATION CT and MRI plays a crucial role in evaluation of retroperitoneal sarcoma Contrast enhanced CT of abdomen and pelvis used to define the extent of the tumor and it's relationship to adjacent structures CT imaging of chest to rule out metastasis (11% of patients presents with synchronous metastasis) Angiography or Magnetic resonance arteriography /venography also used to delineate vascular anatomy when involvement of critical vascular structures is suspected CT guided core needle biopsy for tissue diagnosis Other laboratory investigation includes beta-HCG ,Alpha fetoprotien and Lactate dehydrogenase to rule out other retroperitoneal tumors

5. MANAGEMENT Complete Surgical resection(R0 resection) is the most effective treatment for primary and recurrent retroperitoneal sarcoma Enbloc resection often involves removal contiguous structures such as Colon,Kidney,Pancreas,Psoas muscle,small bowel,inferior vena cava and aorta The ability to perform a Complete Surgical Resection at the time of initial presentation is the most important prognostic factor for survival The usual reasons for unresectability are extensive vascular involvement or presence of multiple peritoneal implants Patients with complete gross resection have a median survival of 103 months compared with 18 months for patient with incomplete resection

6. ADJUVANT THERAPY RADIATION THERAPY Because of high rates of local recurrence ; radiation therapy has been proposed for treating microscopic residual disease as an adjunct to surgical resection For high risk patients ;defined as those with large,high grade tumors or recurrent low grade tumors ; Preoperative radiation therapy to a total dose of 50Gy followed by surgical resection is considered Post operative radiotherapy only advisable if the tumor bed is clearly away from dose limiting structures There is no role for adjuvant chemotherapy as they failed to show any survival benefits in retroperitoneal sarcoma Even with optimal chemotherapy and radiotherapy,the median survival of patients with unresectable disease is 10 months

7. FOLLOW UP Retroperitoneal sarcoma recur more often than extremity and trunk sarcoma Retroperitoneal leiomyosarcoma in addition to recurring locally in tumorbed and metastazing to lungs;spreads to Liver Retroperitoneal sarcoma also recur diffusely throughout the peritoneal cavity (sarcomatosis) Palliative resection often be the only meaningful option in patients who develop recurrence ;re resection of recurrent disease is of limited value resulting in 17% of 3 year disease free survival Patients whose recurrence grows less than 0.9 cm/ month benefitted from complete resection of the recurrence ,whereas recurrent tumor growth of more than 0.9cm / month associated with poor outcome

8. For patients with Metastatic Retroperitoneal Sarcoma STS tumors tends to spread hematogenously to Lungs (most common),liver and also to bones TUMOR GRADE is the most important predictor of metastasis Isolated pulmonary metastasis should be resected whenever feasible There are few effective chemotherapeutic options Single or combination therapy with anthracyclines can be used as first line therapy Gemcitabine and docetaxel is second line regimen Patients who undergo complete resection should undergo active surveillance as the risk of local recurrence and distant metastasis after 5 years is 23% and 21% respectively

9. OTHER HISTOLOGIC SUBTYPES DERMATOFIBROSARCOMA PROTUBERANS ANGIOSARCOMA DESMOID TUMORS MALIGNANT PERIPHERAL NERVE SHEATH TUMORS RHABDOMYOSARCOMA EWING’S SARCOMA SYNOVIAL SARCOMA CHONDROSARCOMA KAPOSI’S SARCOMA EPITHELIOID SARCOMA MALIGNANT HEMANGIOPERICYTOMA CLEAR CELL SARCOMA ALVEOLAR SOFT PART SARCOMA

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