Extended field and total central lymphatic radiotherapy in the treatment of early stage lymph node centroblastic-centrocytic lymphomas : Results of a prospective multicenter study

BACKGROUND. A prospective multicenter trial was performed to evaluate survival, patterns of relapse, and toxicity for clinically staged patients with lymph node centroblastic-centrocytic (cb/cc) lymphomas in Stages I-IIIA after large extended field irradiation (EFI) or total central lymphatic irradiation (TCLI). METHODS. Between January 1986 and August 1993, 117 adults with clinical Stage I-IIIA lymph node cb/cc lymphoma (Kiel classification) were recruited. Patients in Stages I or II with mediastinal, hilar, periaortic, iliac, or mesenteric involvement and in Stage IIIA received TCLI, whereas patients with more peripherally located cb/cc lymphomas were treated with EFI. TCLI and EFI were administered to a total dose of 26 gray (Gy) with 2 Gy per daily fraction, with the exception of the whole abdomen, which was irradiated to a total dose of 25.5 Gy with 1.5 Gy per fraction. A boost of 10 Gy with 2 Gy per fraction was administered to enlarged and involved lymph nodes at the start of radiotherapy. RESULTS. Sixty, 40, and 17 patients had Stage I, II, and limited IIIA disease (no bulk and less than 6 involved lymph node regions), respectively. Overall survival was 86% at 5 and 7 years; median follow-up was 68 months. The probabilities of relapse at any site, recurrences in lymph nodes, and in-field lymph node recurrences after TCLI were 17% in Stage 56%, 43%, and 40% in Stage II, respectively; and 44%, 35%, and 35% in Stage IIIA, respectively. The risk of disseminated extralymphatic relapses was 9% at 7 years. The most important adverse prognostic factor for in-field lymph node recurrences was a deviation of >20% from the assigned total radiation dose. After EFI, patients in Stage I had a significantly lower risk of recurrences in adjuvant irradiated lymph node regions than in unirradiated lymph node regions. Acute toxicity of EFI and TCLI was moderate. CONCLUSIONS. In-field lymph node recurrences remained the main risk after TCLI, and a deviation of >20% from the assigned radiation dose was the major risk factor for in-field recurrences. From these data, a total dose of 40-44 Gy in conventional fractionation for the treatment of macroscopic cb/cc lymphomas and 30 Gy for the treatment of subclinical disease is recommended. A randomized study comparing TCLI with EFI is now being organized by this group.