A systematic overview of radiation therapy effects in non-Hodgkin's lymphoma.

A systematic review of radiation therapy trials in several tumour types was performed by The Swedish Council of Technology Assessment in Health Care (SBU). The procedures for evaluation of the scientific literature are described separately (Acta Oncol 2003; 42: 357-365). This synthesis of the literature on radiation therapy for non-Hodgkin's lymphoma (NHL) is based on data from seven randomized trials. Moreover, data from 17 prospective studies, 22 retrospective studies and 27 other articles were used. In total, 73 scientific articles are included, involving 13,305 patients. The results were compared with those of a similar overview from 1996 including 14,137 patients. The conclusions reached can be summarized as follows: Indolent lymphomas. Data indicate that one-third to one-half of patients with indolent lymphoma in stage I are cured by radiotherapy (follow-up more than 15 years). Addition of chemotherapy to radiotherapy does not indicate any improvement in overall outcome. Optimal radiation dose is not defined and extended field is not superior to involved field. Aggressive localized lymphomas. Data indicate that half of the patients in stage I are cured by radiotherapy alone. Although randomized and non-randomized studies favour combined modality treatment with chemotherapy followed by radiotherapy instead of radiotherapy or chemotherapy alone in localized disease, no firm conclusions can be drawn. Conflicting data have been published on the value of radiotherapy towards bulky disease and no firm conclusions can be drawn. Optimal dose for radiation alone or after chemotherapy has not been established. Total body irradiation (TBI). The value of TBI for treatment of NHL has not been proven. There is no proof that fractionated TBI in conjunction with high-dose chemotherapy is superior to chemotherapy regimens alone. Primary CNS lymphomas. Data show that radiotherapy induces a response of short duration and is associated with major neurotoxicity, especially in elderly patients. High-dose methotrexate therapy seems to lead to longer survival than radiotherapy alone. No randomized trials have been performed. There is fairly good support for primary chemotherapy including high-dose methotrexate followed by radiotherapy in patients below 60 years. To minimize the risk of neurotoxicity of combined modality treatment it has been proposed to use chemotherapy alone and delay radiotherapy for relapse, especially in patients above 60 years, or use it in chemotherapy-resistant disease. Optimal chemotherapy regimen is not defined and the role of radiotherapy remains to be determined. Head and neck lymphomas. There is some support for combined modality treatment with chemotherapy and radiotherapy for aggressive lymphomas in Waldeyer's ring with limited disease. There are sparse data supporting radiotherapy alone in localized indolent lymphomas in salivary glands. Radioimmunotherapy (RIT). Radioimmunotherapy is a new treatment modality with systemic radiation for patients with advanced NHL, where conventional external beam radiotherapy plays only a minor role. Several phase I and II studies with RIT have documented promising results. A variety of monoclonal antibodies, radionuclides and study designs with both myeloablative and non-myeloablative approach have resulted in high response rates in patients with recurrent or refractory NHL. One randomized clinical trial is published, showing superior therapy results with radiolabelled antibody compared with the corresponding unlabelled antibody.