7592 Background: Several studies have shown that the addition of rituximab (R) to CHOP (cyclophosphamide, doxorubicin, vincristine, prednisona), or shortening the interval between cycles of chemotherapy to two weeks, improves survival of patients with DLBCL. These studies prompted our group (GOTEL) to evaluate in a prospective study, the feasibility and efficacy of R-CHOP-14 in patients (pts) with DLBCL. Methods: Patients (younger than 70 years) with stage II bulky, III or IV DLBCL, and no significant co-morbidities were included in the study. R was administered on day 1 before chemotherapy. R-CHOP was recycled every 14 days. No antimicrobial prophylaxis was administered. All pts received filgrastim (5 μg/kg) from day +3 to +10. Pts received 6 cycles if CR was achieved after 3 cycles; those in PR, and those pts with bone marrow disease at diagnosis, received 8 cycles. Involved field radiation therapy was permitted for pts with stage II bulky disease. Results: From May 2002 to august 2004, 77 pts were included. Median age was 54 years (range, 15–70); 55 patients were younger than 60 years. According to the age adjusted International Prognostic Index (aaIPI), 13 pts (17%) had low risk disease, 27 pts (35%) low-intermediate risk, 29 pts (38%) high-intermediate risk, and 8 pts (10%) high risk disease. Grade 3–4 toxicity occurred as follow: neutropenia in 15 pts (19%), anaemia in 7 pts (9%), thrombocytopenia in 4 pts (5%), mucositis in 4 pts (5%) and peripheral neurotoxicity in 4 pts (5%). Ten pts were hospitalized (febrile neutropenia: 8 cases, one case of gastric perforation and one pulmonary embolism). After therapy, 61 pts (79%) achieved a CR/CRu (C.I. 95%: 57%-90%) and 14 pts (18%) a PR. 2 pts (3%) had refractory disease. With a median follow-up of 20 months, progression-free and overall survival at 24 months were 68% and 87%, respectively. Conclusions: Administration of R-CHOP-14 (with filgrastim support) is feasible and effective in patients younger than 70 years. [Table: see text]