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.

OBJECTIVES:

• Identify prognostic factors that predict a short survival in patients with stage 0-II B-cell chronic lymphocytic leukemia treated with fludarabine or observation only.

OUTLINE: This is a randomized study. Patients are stratified according to risk (high risk vs low risk). Patients in the low-risk group undergo observation only. Patients in the high-risk group are randomized to 1 of 2 treatment arms.

• Arm I: Patients receive fludarabine.
• Arm II: Patients undergo observation only.

PROJECTED ACCRUAL: A total of 880 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Confirmed diagnosis of B-cell chronic lymphocytic leukemia

  • Rai stage 0-II (Binet stage A) disease

• Meets 1 of the following criteria:

  • High-risk disease, as defined by the following:

    • Serum thymidine kinase level > 7.0 U/L
    • Elevated β2-microglobulin level
    • Presence of non-nodular bone marrow infiltration
    • Short lymphocyte doubling time

  • Low-risk disease

    • Meets none of the criteria (as listed above) for high-risk disease

PATIENT CHARACTERISTICS:

Performance status

• Not specified

Life expectancy

• More than 6 months

Hematopoietic

• No autoimmune hemolytic anemia
• No thrombocytopenia

Hepatic

• Not specified

Renal

• Not specified

Other

• No severe organ dysfunction
• No other prior or concurrent malignancy

PRIOR CONCURRENT THERAPY:

Chemotherapy

• No prior chemotherapy
• No other concurrent chemotherapy