Surgical treatment of tumor metastases: general considerations and results.

The prerequisite for a curative resection of metastases is their restriction to the key organs, the liver and lungs, in the sense of a limited dissemination. For long-term prognosis, the type of primary tumor as well as the radical resection of lung and liver metastases is essential. To improve the process of surgical indication and therapy of tumors, clear definitions for the terms "tumor recurrence" and "metastases" have been agreed upon. Research and clinical investigation have led to a better understanding of tumor-regulating factors, some of which are briefly described: Metastasis promoting factors include the lack of E-cadherin, which leads to a local penetration of basal membranes by tumor cells; CD44 seems to play an important role in cell-cell and cell-matrix interactions, apparently increasing the metastatic potential of tumors and reducing the long-term survival of patients. High levels of urokinase in primary tumors are also associated with a poorer prognosis, as well as plasminogen inactivator inhibitor PAI II, which plays a crucial role in tumor growth. Positive findings in bone marrow aspirates of patients with different malignancies, stained for cytokeratin 18, either are associated with higher recurrence rates in colon and breast cancer or can be correlated to the prognosis of patients with gastric cancer. Technical aspects of surgery for hepatic, pulmonary and skeletal metastases are presented and discussed with respect to curative and palliative indications.