This study is for people with a type of cancer called sarcoma. The sarcoma is in the belly area, known as retroperitoneal space. The study is looking at whether giving chemotherapy before surgery helps people live longer without the disease coming back. Chemotherapy uses strong medicine to kill cancer cells. This study is for people with two specific sarcoma types: **DDLPS (Dedifferentiated Liposarcoma)** and **LMS (Leiomyosarcoma)**. Participants will be placed in one of two groups: one group will have surgery only, while the other group will get chemotherapy followed by surgery.

Here are three key points to think about:

• The study involves large surgery and possibly chemotherapy, which has side effects.
• Participants need to visit for chemotherapy and check-ups, lasting several weeks.
• Eligible participants will be at least 18 years old with high-risk sarcoma and need to give consent.

Before joining, participants should talk to their doctors about the possible benefits and risks, such as side effects from chemotherapy and surgery recovery.