Gemtuzumab Ozogamicin With or Without Chemotherapy in Treating Older Patients With Acute Myeloid Leukemia

RATIONALE: Monoclonal antibodies such as gemtuzumab ozogamicin can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. Drugs used in chemotherapy uses different ways to stop cancer cells from dividing so they stop growing or die. Combining gemtuzumab ozogamicin with chemotherapy may kill more cancer cells. PURPOSE: Phase II trial to study the effectiveness of gemtuzumab ozogamicin with or without chemotherapy in treating older patients who have acute myeloid leukemia.