A compound for use as a therapeutic or diagnostic radiopharmaceutical includes a group capable of complexing a medically useful metal attached to a moiety which is capable of binding to a gastrin releasing peptide receptor. A method for treating a subject having a neoplastic disease includes administering to the subject an effective amount of a radiopharmaceutical having a metal chelated with a chelating group attached to a moiety capable of binding to a gastrin releasing peptide receptor expressed on tumor cells with subsequent internalization inside of the cell. A method of forming a therapeutic or diagnostic compound includes reacting a metal synthon with a chelating group covalently linked with a moiety capable of binding a gastrin releasing peptide receptor.
 The research carried out in connection with this invention was supported in part by a grant from the Department of Energy (DOE), grant number DE-FG02-89ER60875, a grant from the U.S. Department of Veterans Affairs Medical Research Division and the Department of Radiology MU-C2-02691. The Government has certain rights in the invention.