Inclusion Criteria:

- All patients must have previously untreated stage III, IV, or bulky stage II diffuse
large B-cell non-Hodgkin's lymphoma which is positive for CD20

- Adequate sections from the original diagnostic specimen must be available for
submission for review; an adequate biopsy requires sufficient tissue to establish the
architecture and a REAL or WHO histologic subtype with certainty; thus, core
biopsies, especially multiple core biopsies MAY be adequate; whereas, needle
aspirations or cytologies are not adequate

- Patients may also be registered to SWOG-8947 and SWOG-8819

- Patients must have an age-adjusted International Prognostic Index score of 0 or 1

- All patients must have bidimensionally measurable disease documented within 28 days
prior to registration; patients with non-measurable disease in addition to measurable
disease must have all non-measurable disease assessed within 42 days prior to
registration

- Patients must have a unilateral bone marrow aspirate and biopsy performed within 42
days prior to registration

- Patients must have a CT scan of the chest and abdomen/pelvis performed within 28 days
prior to registration

- Patients must not have clinical evidence of central nervous system involvement by
lymphoma; any laboratory or radiographic tests performed to assess CNS involvement
must be negative within 42 days of registration

- Patients must not have a previous diagnosis of indolent lymphoma (histologic
transformation are ineligible); as patients with nodal diffuse large ell lymphoma may
have bone marrow involvement with small lymphocytes, such patients are eligible

- Patients must not have received prior chemotherapy, radiation, or antibody therapy
for lymphoma

- All patients must have a Zubrod performance status of 0-2

- Serum LDH must be measured within 28 days prior to registration

- Patients must have a cardiac ejection fraction >= 45% by MUGA scan or an ECHO with no
significant abnormalities within 42 days prior to registration

- Patients known to be HIV positive, or who have a history of solid organ
transplantation are ineligible as the biology and natural history of HIV associated,
or post transplant lymphomas are very different than that of de novo diffuse large
cell lymphomas; patients at high risk of hepatitis B virus infection should be
screened before initiation of rituximab

- Patients requiring continuing supplemental oxygen therapy are ineligible

- No other prior malignancy is allowed except for the following: adequately treated
basal cell or squamous cell skin cancer, in situ cervical cancer, adequately treated
stage I or II cancer from which the patient is currently in complete remission, or
any other cancer from which the patient has been disease-free for 5 years

- Pregnant or nursing women may not participate due to the potential for congenital
abnormalities, and of harm to nursing infants due to this treatment regimen; women or
men of reproductive potential may no participate unless they have agreed to use an
effective contraceptive method

- If day 28 or 42 falls on a weekend or holiday, the limit may be extended to the next
working day

- In calculating days of tests and measurements, the day a test or measurement is
done is considered day 0; therefore, if a test is done on a Monday, the Monday 4
weeks later would be considered day 28; this allows for efficient patient
scheduling without exceeding the guidelines

- All patients must be informed of the investigational nature of this study and must
sign and give written informed consent in accordance with institutional and federal
guidelines

- At the time of patient registration, the treating institution's name and ID number
must be provided to the Data Operations Center in Seattle in order to ensure that the
current (within 365 days) date of institutional review board approval for this study
has been entered into the data base