Medical Physics Seminar – Monday, February 20, 2012
Total marrow irradiation: an emerging area of interdisciplinary and translational research for hematological malignancies
Susanta K Hui, PH.D., DABR (guest of Dr. Bhudatt Paliwal)
Assosiate Professor, Therapeutic Radiology and Masonic Cancer Center, University of Minnesota, MN
For many decades radiation has been used for cancer treatment with limited success. In recent years treatment has been improved by (i) more accurate and complete identification of the target, (ii) increasing the precision of tumor localization, and (iii) conformal radiation dose delivery. Although external beam therapy is advancing with image guided conformal therapy, total body irradiation for hematological malignancies has remained empirical and essentially unchanged over the past 25 years. Total body irradiation (TBI) provides immunosuppression and eradicates radiosensitive malignant cells as a part of the pre-conditioning regimen for hematopoietic stem cell transplantation (HCT). Many side effects of HCT are either directly or indirectly related to current TBI treatment regimens. Because of the associated toxicity of standard TBI, the therapeutic dose is limited and dose escalation has not been feasible. The outlook for high-risk patients with hematological malignancies requiring HCT using standard TBI is poor due to both a high rate of treatment related mortality (TRM) and a low probability for disease free survival (DFS). In summary, disease recurrence is the major cause of treatment failure.
The solution to this problem mandates the development of novel treatment approaches. We are developing novel multi-modality image-guided adaptive and highly conformal total marrow irradiation for selective radiations of desired target for entire body to reduce dose to all critical organs as shown in the adjacent figure. While these developments gave us the foundation for targeted dose escalation to improve clinical outcomes that more effectively eradicate disease, while having minimal impact on regimen related toxicity and TRM. We acknowledged that further technological developments and scientific understanding are necessary for moving this multidisciplinary translational research to successful clinical trial. We will illustrate this with examples from our recent research and clinical studies on Total Marrow Irradiation.