Background: Low-dose total body irradiation (TBI) is known to be an effective treatment for low-grade non-Hodgkin’s lymphoma and chronic lymphocytic leukemia but has fallen out of favor
because of perceived side effects and the development of newer chemotherapy agents. The mechanism of action is poorly understood but may involve immunomodulation as well as direct cytotoxicity.Case Report: A 78-year-old male with relapsed Waldenstrom’s macroglobulinemia following therapy with chlorambucil underwent a five-week course of TBI. The total dose delivered was 1.5 Gy, given as 0.15 Gy twice weekly for ten sessions. During the course of therapy his CD4 cells increased from 637 (cells/mm3) to 808 partly through treatment and then declined to 654 at the completion of therapy. The CD4:CD8 ratio increased from 1.3 at the start to 1.7 at completion of therapy. His IgM levels declined from 4040 to 1640 following treatment and he became symptom-free. Other than transient thrombocytopenia, no acute or late side effects were noted.Conclusions: Although rarely used now, it is important to be aware that low-dose TBI can be an effective treatment for patients with Waldenstrom’s macroglobulinemia and similar conditions. The mechanism may partly be immune-mediated. Further investigation into the precise mechanism should be performed.

Keywords: Waldenstrom’s macroglobulinemia, total body irradiation