Neoadjuvant Chemotherapy Combined With Targeted Treatment in High-risk Retroperitoneal Sarcoma

Inclusion Criteria: * Histologically proven primary high-risk Retroperitoneal sarcoma(RPS) (Including Dedifferentiated liposarcoma (DDLPS), leiomyosarcoma(LMS), Undifferentiated pleomorphic sarcoma(UPS), Solitary fibrous tumor(SFT)). * Primary localized RPS without histories of surgical resection, chemo- or radio-therapy, targeted therapy. Patients who underwent laparotomy with biopsy only will also be considered as primary cases. * Without histories of second malignant tumors. * In DDLPS * Diagnosis should be confirmed based on MDM2(Mouse double minute 2 homolog) and CDK4(Cyclin-dependent kinase 4) expression on IHC (immunohistochemistry), while MDM2 amplification in the Fish test is highly recommended. * All grade 2-3 DDLPS can be included. * In LMS * All grades of LMS can be included. * Tumor size ≥10cm * In UPS or SFT * All grades of UPS can be included. * High-risk SFT with a score ≥6 in 'Risk stratification of SFT for development of metastasis' introduced in The 5th edition of the WHO(World Health Organization) Soft tissue sarcoma classification. * Sarcoma without protruding across the diaphragm * Possibility of R0/R1 resection evaluated through preoperative MDT(multi-disciplinary team) discussion * No multi-organ or system dysfunction/failure or patients with slight dysfunction of organ/system could be easily recovered * Tolerable of chemotherapy and surgery through MDT evaluation and tests. * American Society of Anesthesiologist (ASA) ≤3 * Fully unders…