This study is designed to determine if an antibody (CC49) which has been labeled with the radionuclide 131-I and injected into a vein, will bind primarily to tumors but not to normal tissues, allowing detection of these tumors by scanning and a therapeutic delivery of radiation. This radiolabeled antibody, 131I-CC49, is an investigational agent. The amount of radiatioactivity bound to the antibody is larger than that used for diagnostic scanning in hopes that therapeutic doses of radiation can be selectively delivered to the tumor sites. The 131I- antibody will be injected once, as a one treatment course. Interferon, an agent to stimulate cells to express the substance that the CC49 antibody reacts with, with be given before and after the antibody.