Centroblastic-centrocytic non-Hodgkin's lymphoma stage I-III: patterns of failure following radiotherapy

To investigate the patterns of failure and survival after involved-field or more extensive radiotherapy for centroblastic-centrocytic non-Hodgkin's lymphoma (NHL) as well as the impact of radiotherapy dose on local control.

47 patients with Stage I-III centroblastic-centrocytic NHL were treated with involved-field (IF) extended-field radiotherapy (EF-RT) or total lymphatic irradiation (TLI). The involved regions received 25.5-50 Gy, non-involved regions were treated with a dose of 26 Gy in most cases.

In Stage I/II, the majority of relapses (64%) were nodal and were located adjacent or distant to the former radiation portals. 79% of relapses occurred after IF-RT, 21% after EF-RT or TLI. 5-year overall survival (OAS) after EF-RT/TLI and IF-RT for Stages I/II was 85% and 83%, respectively (n.s.); relapse free survival (RFS) was 73% and 61%, respectively (n.s.). A tendency for better overall survival was found for patients who relapsed at one or two sites (5-year overall survival 100%) compared to patients with three or more relapse sites (5-year overall survival 0%). For Stage III overall survival was 72%, freedom from progression (FFP) was 27% at 5 years. We found a dose-effect correlation for local control with a relapse rate of 31% after 26-34 Gy and 4% after application of 36 Gy; no relapses occurred after doses of 40 Gy or more.

In involved lymph node regions a relatively small number of relapses was observed after application of a minimal dose of 36 Gy. In Stages I/II most relapses were located outside the radiation portals, yet EF-RT was not superior to IF-RT in terms of overall survival and relapse free survival. Prospective randomized trials are necessary to prove a potentially favorable effect of more extended radiotherapy portals (TLI or TNI [total nodal irradiation]) and to evaluate the optimal radiotherapy dose.