OBJECTIVES: I. Determine the safety of serial intradermal or subcutaneous vaccinations of HER-2 derived p369-377 peptide incorporated into polylactide-co-glycolide (PLG) microspheres with adjuvant sargramostim (GM-CSF) in patients with stage III or IV HER-2 expressing cancers. II. Determine whether cytotoxic T lymphocytes (CTL) specific for the HER-2 protein can be elicited in patients with HLA-A2 by immunization with this regimen. III. Determine which route of immunization, intradermal or subcutaneous, is more effective in generating HER-2 specific CTL in these patients on this regimen. IV. Determine the extent to which escalated dose of PLG peptide affects the immune response in these patients on this regimen.