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.