[Retroperitoneal sarcomas: 1. Natural history and preoperative evaluation]

The disease is usually disseminated via the blood stream. These large tumors displace adjacent organs and are usually close to vital structures. High rate of local or peritoneal recurrence may be explained by resection problems. Local recurrence is the most frequent cause of patient death. No adjuvant treatment has proved to be beneficial on survival. Diffusion of the disease is usually hematogenous. Hepatic and pulmonary metastases are the most common, while lymph node invasion is very rare. This account for no systematic lymph node dissection in these tumors. Preoperative biopsy through a retroperitoneal route under CT scan vision is advised, before operation. NMR and CT scan are the best tools to assess extension of tumor through anatomical structures. Quality of surgical resection is the main factor which determine prognosis in term of local or peritoneal recurrence risk. This risk is best evaluated by pathological examination which must determine whether the specimen is or not complete.