MAGE -A1, MAGE- A3, and NY-ESO-1 are antigens that can be found with significant frequency on neuroblastoma, rhabdomyosarcoma, and osteogenic sarcoma, three relatively common solid tumors that in some cases can be associated with a high risk for relapse. In this study each subject will be screened for the presence of these antigens, and an individualized vaccine will be developed and administered using the subject's own dendritic cells (DC).