The protocol intends to explore the biology which may underlie recurrences of retroperitoneal liposarcoma. Surgery remains the only curative intent intervention for this disease. Often, tumors recur in locations within the retroperitoneum remote from the original primary tumor. This study hypothesizes that normal appearing retroperitoneal fat actually harbors underlying genetic changes which predispose to development of future liposarcoma. To accomplish this goal, retroperitoneal fat is sampled from quadrants within and remote from the primary tumor and is subsequently subjected to genetic analyses looking for such predisposing factors.

Inclusion Criteria:

• Adult patients (age ≥18 years).
• Histologically confirmed retroperitoneal liposarcoma via preoperative biopsy, or cross-sectional imaging suspicious for liposarcoma with planned surgical resection
• Will be undergoing surgical resection for treatment of primary or recurrent disease
• Have provided informed consent to participate in this study

Exclusion Criteria:

• Prior surgical anatomy which makes sampling of remote areas of the retroperitoneum technically impossible or clinically undesirable for safety reasons

Adult patients (age 18 years or older) with retroperitoneal tumors suspicious for liposarcoma.