20 Gy Versus 30 Gy: Will it Make a Difference?

Abstract

In the current issue of the Journal, Kelsey et al., report on a phase 2 trial evaluating the use of a lower than conventional dose (20 Gy) as consolidation therapy for patients with bulky or nonbulky stage I to IV diffuse large B-cell lymphoma (DLBCL) or mediastinal large B-cell lymphoma (MLBCL) who have achieved a complete response to 4 or more cycles of conventional chemoimmunotherapy. The conventional dose in this setting has been 30 to 36 Gy. The primary endpoint was freedom from local recurrence. With a median follow-up of 4þ years, only 1 patient developed disease progression within the radiation field. The local control rate was 98%, which is similar to reported outcomes in previous combined-modality therapy experience for DLBCL. Radiation therapy is the most effective single agent for the treatment of lymphoma. The continued challenge we have as radiation oncologists is to provide this therapy safely. We can accomplish that with reduction in field size and the use of advanced radiation therapy techniques such as intensity modulated radiation therapy/volumetric modulated arc therapy or proton therapy, as well as maneuvers such as deep inspiration breath hold. But perhaps the simplest approach is to reduce the radiation dose. Several trials in lymphoma have tested this possibility and confirmed the efficacy of lower doses in specific situations, including the German Hodgkin StudyGroupHD10 trial and theBritishNational Lymphoma Investigation/National Cancer Research Institute trial. For DLBCL, the British National Lymphoma Investigation/National Cancer Research Institute trial tested 30 Gy versus 40 to 45 Gy for a variety of scenarios for patients with DLBCL and concluded there was no difference. In large trials from the German non-Hodgkin lymphoma study group, a dose of 36 Gy was often used for patients with