Stage IV marginal zone B-cell lymphoma--prognostic factors and the role of rituximab: Consortium for Improving Survival of Lymphoma (CISL) study.

Stage IV marginal zone B-cell lymphomas (MZL) are detected in more than 25% of lymphoma patients. In this study, we conducted retrospective analyses of specific cases of stage IV MZL in order to assess their clinical features, as well as the treatments and prognoses of these cases. A total of 94 patients with histological diagnosis of stage IV-MZL from 17 different institutions in Korea were included. Multiple-mucosa-associated lymphoid tissue (MALT)-organs-involved MZL (M-MZL) was detected in 34 patients (36.2%). Bone-marrow-involved stage IV MZL (BM-MZL) was detected in 33 patients (35.1%). Median time to progression (TTP) was 2.4years (95% CI, 1.9-2.9). Five- and 10-year overall survival rates were 84.5% and 79.8%, respectively. Patients with lymph node involvement in stage IV MZL appeared to have worse prognoses in TTP (P=0.015). Thirty-one patients were treated with a regimen including rituximab (CTx-R[+]), and 31 with a regimen that did not include rituximab (CTx-R[-]). The CTx-R(+) group showed better responses than the CTx-R(-) group (83.9%versus 54.8%, P=0.026). However, no differences in TTP duration were detected (P=0.113). Stage IV MZL tend to follow an indolent disease course. Therefore, lymph node involvement is a more valuable prognostic factor for TTP. Rituximab appears to contribute to better responses, but not in cases of TTP.