Fludarabine or Observation in Treating Patients With Stage 0, Stage I, or Stage II Chronic Lymphocytic Leukemia

RATIONALE: Drugs used in chemotherapy, such as fludarabine, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Sometimes, the cancer may not need treatment until it progresses. In this case, observation may be sufficient. It is not yet known whether fludarabine is more effective than observation in treating chronic lymphocytic leukemia. PURPOSE: This randomized phase III trial is studying fludarabine to see how well it works compared to observation only in treating patients with stage 0, stage I, or stage II B-cell chronic lymphocytic leukemia.