The purpose of this study is to determine whether a specific subtype of lymphoma responds optimally to treatment with rituximab and chemotherapy.

Treatment with rituximab and chemotherapy (R-CHOP)is the accepted treatment for young patients with diffuse large B cell Non-Hodgkin's Lymphoma. However not every patient benefits with this expensive therapy. Recent data suggest that patients with BCL-6 negative lymphoma are more sensitive to Rituximab therapy. It is also known that patients with high-intermediate and high IPI risk does not benefit form standard three weekly CHOP chemotherapy.

In this study we intend to define a subgroup of patients in whom this therapy will be of maximum benefit.

We will prospectively treat a group of patients with the following characteristics:

< 60 years old low and low intermediate IPI risk BCL-6 negative B-cell NHL Treatment regimen: R-CHOP (standard dosis) for 8 cycles

Inclusion Criteria:

• Diagnosis of Large B cell Non-Hodgkin Lymphoma CD20+
• BCL-6 negative
• Age < 61 years old
• ECOG 2 or less
• IPI low, low intermediate
• Stage II, III or IV
• Signed Informed Consent

Exclusion Criteria:

• Stage I
• Previous treatment
• Lymphomatous central nervous system involvement
• Heart disease
• Kidney failure (serum creatinine > 2 mg/dl)
• HIV +
• Viral Hepatitis
• Pregnancy