Rituximab With or Without Lenalidomide in Treating Patients With Previously Untreated Follicular Lymphoma

DISEASE CHARACTERISTICS:

* Histologically confirmed follicular lymphoma

  * Stage III or IV disease OR stage II disease not suitable for radiotherapy
  * Grades 1, 2, or 3a disease
* Previously untreated disease
* CD20-positive disease
* Patients in need of systemic therapy, meeting at least 1 of the following criteria:

  * Symptomatic enlarged lymph nodes, spleen, or other lymphoma manifestations
  * Bulky disease ≥ 6 cm in long diameter
  * Clinically significant progression over at least 6 months of any tumor lesion
  * Anemia (hemoglobin \< 100 g/L) or thrombocytopenia (platelet count \< 100 x 10\^9/L) due to lymphoma
  * Clinically significant progressive decrease in hemoglobin or platelet count due to lymphoma
  * B-symptoms, weight loss \> 10% within the past 6 months, drenching night sweats, or fever \> 38°C not due to infection
* At least one two-dimensionally measurable lesion with longest transverse diameter \> 10 mm
* Paraffin-embedded tumor tissue available
* No known CNS involvement

PATIENT CHARACTERISTICS:

* WHO performance status 0-2
* EF ≥ 50% for patients with a history of cardiac disease or older than 70 years
* Neutrophil count ≥ 1.5 x 10\^9/L
* Platelet count ≥ 100 x 10\^9/L
* Bilirubin ≤ 1.5 x upper limit of normal (ULN) (unless due to Gilbert syndrome)
* ALT ≤ 2.5 x ULN
* Alkaline phosphatase ≤ 2.5 x ULN
* Creatinine clearance ≥ 30 mL/min
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception 4 weeks prior to, during, and for 12 months after completion of study therapy
* Must be compliant and geographically proximal to allow for proper staging and follow-up
* No serious underlying medical condition, at the judgment of the investigator, which could impair the ability of the patient to participate in the trial (e.g., active autoimmune disease or uncontrolled diabetes)
* No malignancy within the past 3 years except for adequately treated carcinoma in situ of the cervix or localized nonmelanoma skin cancer
* No psychiatric disorder precluding understanding information of trial-related topics, giving informed consent, or interfering with compliance for oral drug intake
* No known hypersensitivity to trial drugs or hypersensitivity to any other components of the trial drugs
* No known HIV positivity or hepatitis C infection
* No serological evidence of current or past hepatitis B infection, unless the serological findings are clearly due to vaccination

PRIOR CONCURRENT THERAPY:

* No prior systemic therapy for this disease
* At least 3 months since prior radiotherapy
* At least 30 days since prior treatment in another clinical trial
* At least 4 weeks since prior and no concurrent corticosteroids unless administered as prophylaxis in at-risk patients for ≤ 3 days or at a dose equivalent to prednisone ≤ 15 mg/day, for indications other than lymphoma or lymphoma-related symptoms
* No concomitant drugs contraindicated for use with the trial drugs
* No other concurrent experimental drugs or anticancer therapy
* No other concurrent investigational treatments