Doctors at Memorial Sloan-Kettering Cancer Center and at other institutions study normal and cancer cells. To study these cells we need to have human tissue, body fluids, and blood. You will be having or have had a procedure to remove tissue. We would like to use some of this tissue. We will use it for laboratory studies on the causes, prevention, diagnosis and treatment of sarcoma, gastrointestinal or other intra-abdominal cancers. We will only use extra tissue left over after all needed testing has been done. We would also like to study components of your immune blood cells and blood serum (the liquid portion of your blood). In some patients we will take a blood sample before the tissue or body fluid is removed, usually at the same time that other routine pre-procedure blood tests are drawn. If we need more blood, it will be drawn when you are seeing your doctor anyway. We will not draw more than 50cc (4-5 tablespoons) at any one time. With your permission, we may also send a small portion of the blood to a repository at the National Cancer Institute. This sample will be used to identify special proteins in the blood that may be useful for diagnosing cancer. Information about your treatment and your response to treatment may be linked to the tissue specimens obtained. This information may be important for the research studies that will be done on your tissue and blood specimens. All of this information will be kept in strictest confidence; we will use it only for biomedical research. Your name will not be used in any report.