Everolimus in Treating Older Patients With Mantle Cell Lymphoma Previously Treated With First-Line or Second-Line Chemotherapy

DISEASE CHARACTERISTICS: * Diagnosis of mantle cell lymphoma * Stable disease after first- or second-line chemotherapy * No uncontrolled cerebral or leptomeningeal disease PATIENT CHARACTERISTICS: * WHO performance status 0-2 * Life expectancy ≥ 3 months * Age ≥ 60 years or patients ≥ 40 and \< 60 years who are not suitable for high-dose chemotherapy followed by autologous stem cell transplantation or allogeneic stem cell transplantation * ANC ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 * Hemoglobin \> 9 g/dL * Serum creatinine ≤ 1.5 times upper limit of normal (ULN) * SGPT and SGOT ≤ 3 times ULN * Bilirubin ≤ 1.5 times ULN * No other malignancies within the past 3 years except treated cervical carcinoma or basal cell cancer * No other serious or non-controlled illnesses (e.g., diabetes mellitus, uncontrolled hypertension, serious infections, serious malnutrition, unstable angina pectoris, weak heart, myocardial infarction within the past 6 months, chronic liver illness, active ulceration in the gastrointestinal tract, psychiatric illness) * No known HIV infection * No gastrointestinal disturbances that could influence the absorption of everolimus and cause short-intestine syndrome (e.g., atrophic gastritis) * No coagulation or bleeding diatheses * Not pregnant or nursing * Fertile patients must use effective contraception * Patients must have complied with their previous drug prescription PRIOR CONCURRENT THERAPY: * See Disease Characteristics * See Patient Characteristics * Recovered from all prior therapy * At least 2 weeks since prior surgery, radiotherapy, or systemic antitumor therapy * More than 4 weeks since prior experimental medication * No chronic therapy with systemic steroids or other immunosuppressants except rituximab * No prior organ transplantation * No therapy with vitamin K antagonist, except low-dose coumarin * No prior mTOR inhibitors