Fludarabine and Cyclophosphamide With or Without Rituximab in Patients With Previously Untreated Chronic B-Cell Lymphocytic Leukemia

DISEASE CHARACTERISTICS:

* Diagnosed B-cell chronic lymphocytic leukemia (CLL) defined by the National Cancer Institute (NCI) Working Group criteria
* Meets 1 of the following criteria:

  * Binet stage C disease
  * Binet stage B disease AND ≥ 1 of the following signs or symptoms\*:

    * B symptoms (night sweats, weight loss ≥ 10% within the previous 6 months, fevers \> 38°C or 100.4°F for ≥ 2 weeks without evidence of infection), or constitutional symptoms (fatigue)
    * Continuous progression (doubling of peripheral lymphocyte count within the past 6 months and absolute lymphocyte count \> 50 G/I)
    * Evidence of progressive marrow failure as manifested by the development/worsening of anemia and/or thrombocytopenia
    * Massive, progressive or painful splenomegaly or hypersplenism
    * Massive lymph nodes or lymph node clusters (\> 10 cm in longest diameter), danger of organ complications through large lymphoma (e.g., vascular compression or tracheal narrowing), or progressive lymphadenopathy
    * Occurrence of symptomatic hyperviscosity problems at leukocyte counts \> 200 G/I (symptomatic leukostasis) NOTE: \* Marked hypogammaglobulinemia or the development of a monoclonal protein in the absence of any of the above criteria for active disease is not sufficient for eligibility
* No Binet stage A disease
* No transformation to an aggressive B-cell malignancy (e.g., diffuse large cell lymphoma, Richter's syndrome, or prolymphocytic leukemia)

PATIENT CHARACTERISTICS:

* Eastern Cooperative Oncology Group (ECOG) performance status 0-1
* Cumulative Illness Rating Scale (CIRS) score \> 6
* Life expectancy \> 6 months
* Bilirubin ≤ 2 times upper limit of normal (ULN)
* Alkaline phosphatase and transaminases ≤ 2 times ULN
* Creatinine clearance ≥ 70 mL/min
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception during and for 2 months after study treatment
* No known hypersensitivity with anaphylactic reaction to humanized monoclonal antibodies or any of the study drugs
* No cerebral dysfunction that precludes chemotherapy
* No active bacterial, viral, or fungal infection
* No clinically significant autoimmune cytopenia or Coombs-positive hemolytic anemia
* No other active malignancy requiring concurrent treatment except basal cell carcinoma or tumors treated curatively by surgery
* No medical or psychological condition that would preclude study therapy
* No concurrent disease that requires prolonged (\> 1 month) therapy involving glucocorticoids

PRIOR CONCURRENT THERAPY:

* No previous treatment of CLL by chemotherapy, radiotherapy, or immunotherapy