Residual disease after chemotherapy in aggressive malignant lymphoma: the role of radiotherapy.

Residual disease in patients with diffuse large B-cell lymphoma after intensive chemotherapy remains a problem. Radiotherapy has been used in some retrospective studies without definitive conclusions. We report the first controlled clinical trial to define the role of radiotherapy in this setting of patients. One hundred and sixty-six patients with diagnosis of diffuse large B-cell lymphoma, high- or high-intermediate clinical risk, with residual disease (defined as tumor mass < 5 cm) were randomly assigned to received radiotherapy at the involved field, with 30 Gy delivered in 20 sessions or no radiation (control group). Median follow-up was 135 mo; patients who received radiotherapy have an better outcome. Actuarial curves at 10 yr showed that progressive-free disease was 86% and overall survival was 89%; those were statistical significant when compared to patients who did no received radiotherapy: 32% and 58% respectively, (p < 0.001). Toxicity was mild and well tolerated. We concluded that presence of residual mass after chemotherapy in patients with aggressive malignant lymphoma has a worse prognosis, and salvage radiotherapy improves outcome with mild toxicity. We feel that radiotherapy will be considered as necessary treatment in this special group of patients.