The purpose of this study is to test the safety of a new medicine called antibody 8H9 injected into the lining of the abdomen or peritoneum, where the tumor is. This medicine is an antibody or protein which binds to certain tumors, including DSCRT. There is a small number of DSCRT which do not bind with 8H9. If the tumor does not bind with 8H9, you might not benefit from this treatment. The investigators want to find out what effects, good and/or bad, it has.