RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. It is not yet known if giving cladribine once a day is more effective than giving cladribine once a week in patients with hairy cell leukemia.

PURPOSE: Randomized phase III trial to compare the effectiveness of cladribine given once a day to cladribine given once a week in treating patients with hairy cell leukemia.

OBJECTIVES:

• Compare the acute hematotoxicity and infection rate with daily and weekly administration of cladribine in patients with hairy cell leukemia.

OUTLINE: This is a randomized, multicenter study. Patients are randomized to one of two treatment arms.

• Arm I: Patients receive daily subcutaneous bolus injections of cladribine (2-CDA) for 5 days (standard dose).
• Arm II: Patients receive weekly subcutaneous bolus injections of 2-CDA for 5 weeks.

Patients showing complete or partial remission at evaluation on day 71 of the first treatment course do not receive any further treatment until relapse or disease progression is evident.

Patients showing minor or no response on day 71 of the first treatment course receive a subsequent course of standard dose 2-CDA.

Patients are followed every 3 months for 2 years, then every 6 months thereafter.

PROJECTED ACCRUAL: A total of 120 patients will be accrued for this study within 4 years.

DISEASE CHARACTERISTICS:

• Histologically confirmed classic form or prolymphocytic variant hairy cell leukemia (HCL)
• Newly diagnosed HCL or progressive disease after prior treatment

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• NCI 0-2

Life expectancy:

• At least 3 months

Hematopoietic:

• Not specified

Hepatic:

• Bilirubin no greater than 2.0 mg/dL

Renal:

• Creatinine no greater than 2.3 mg/dL

Other:

• HIV negative
• Not pregnant
• No other prior or concurrent malignancy except carcinoma in situ of the cervix or basal or squamous cell carcinoma of the skin

PRIOR CONCURRENT THERAPY:

• At least 4 weeks since any prior therapy and recovered

Biologic therapy:

• Not specified

Chemotherapy:

• No concurrent cytoreductive therapy
• No prior cladribine

Endocrine therapy:

• Not specified

Radiotherapy:

• Not specified

Surgery:

• Not specified