RATIONALE: Monoclonal antibodies, such as rituximab, can block cancer growth in different
ways. Some block the ability of cancer cells to grow and spread. Others find cancer cells and
help kill them or carry cancer-killing substances to them. Drugs used in chemotherapy, such
as cyclophosphamide, vincristine sulfate, prednisone, and liposome-encapsulated doxorubicin
citrate, work in different ways to stop the growth of cancer cells, either by killing the
cells or by stopping them from dividing. It is not yet known whether rituximab and
combination chemotherapy are more effective when given together with or without
liposome-encapsulated doxorubicin citrate in treating older patients with diffuse large
B-cell non-Hodgkin lymphoma.
PURPOSE: This randomized phase II trial is studying the side effects of giving rituximab
together with cyclophosphamide, vincristine sulfate, and prednisone with or without
liposome-encapsulated doxorubicin citrate and to see how well it works in treating older
patients with stage II, stage III, or stage IV diffuse large B-cell non-Hodgkin lymphoma.