Inclusion Criteria:

- Patients must have histologically or cytologically confirmed diagnosis of CD20+
diffuse large B cell lymphoma (LBCL) of any stage, including subtypes mediastinal
large B cell, centroblastic, immunoblastic, T cell rich B cell and anaplastic B cell
lymphoma

- Patients must have received no prior anti-lymphoma therapy.

- Age >18 years.

- Patients must have a treatment plan to include R/CHOP or R/CHOP followed by
radiotherapy.

- Ability to understand and the willingness to sign a written informed consent
document.

Exclusion Criteria:

- Patients who have known HIV infection.

- Patients who are, in the opinion of their treating oncologist, unable to undergo
R/CHOP chemotherapy.