DISEASE CHARACTERISTICS: Histologically diagnosed indolent non-Hodgkin's lymphoma (NHL) of 1 of the following types: Diffuse small lymphocytic cell Follicular small cleaved cell Follicular mixed small and large cleaved cell Mantle cell lymphoma/leukemia (intermediate differentiated lymphoma) Preferentially treated on protocol NCCTG-958053 when available Monocytoid B-cell Mucosa-associated lymphoid tissue (MALT) Lymphoplasmacytic lymphoma (Waldenstrom's macroglobulinemia) Histology documented by lymph node (or other mass) or bone marrow biopsy within 6 months prior to entry Relapsed after cytotoxic chemotherapy regimens At least 1 measurable lesion by palpation, chest x-ray, CT, or MRI, e.g.: Lymph node at least 1.5 x 1.5 cm by palpation Spleen at least 3 cm below left costal margin The following exclude: CNS involvement by positive CSF cytology or CT/MRI B- or T-cell chronic lymphocytic leukemia Hairy cell leukemia Mycosis fungoides Aggressive lymphoma