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

The goal of this clinical trial is to explore the potential survival benefits of neoadjuvant chemotherapy combined with target treatments followed by radical surgery in patients with primary high-risk/grade retroperitoneal sarcoma. The main questions it aims to answer are: * Whether the 1,3-year progression-free survival time(PFS) is prolonged in the neoadjuvant therapy group, compared with the surgery-only group. * The Overall survival time in the two groups. * The safety and tolerance in the neoadjuvant therapy group. Participants will be allocated into two groups once they meet the inclusion criteria. * Surgery-only Group: Patients will directly undergo surgeries after the confirmation of diagnosis through pre-operative biopsy. * Neoadjuvant therapy group: Patients will receive the neoadjuvant chemotherapy combined with target treatment for three circles before the following sarcoma resectional surgeries.