Photon Total Body Irradiation for Leukemia Transplantation Therapy: Rationale and Technique Options

Abstract

Leukemia is a classification of disease in which the two major defects are unregulated proliferation and incomplete maturation of the hemopoietic progenitors (Scheinberg, Maslak, & Weiss, 2001). Leukemia originates in the marrow, although leukemia cells may infiltrate lymph nodes, liver, spleen, and other tissues. Scheinberg et al. (2001) describe the principal clinical manifestation is the decrease of red cells and platelets as a result of the suppression of normal hemopoiesis or turnover and repopulation of blood components. In the chronic leukemias, unregulated proliferation of leukemia cells and elevated white cell count dominate. Differentiation and maturation of the leukemia cells may be largely preserved. Scheinberg further characterizes acute leukemias with unregulated proliferation also, but the maturation of the leukemia progenitors is profoundly impaired. Transplantation of blood products, in particular stem cells, has become a common treatment procedure for various types of leukemias since the early 1990’s (Scheinberg, Maslak, & Weiss, 2001). Cells void of leukemia are transplanted into the leukemia patient. The purpose of the transplant is the repopulation of the non-cancerous cells. Urbano-Ispizua et al. (2002) describes the current practice of stem cell transplantation for hematological diseases, solid tumors and immune disorders. Definitions, abbreviations and classifications described in this review are summarized here. Hemopoietic stem cell transplantation (HSCT) refers to any procedure where hemopoietic cells of any donor type and any source are given to a recipient with the intention of repopulation/replacing the hemopoietic system of the recipient in total or in part (UrbanoIspizua et al., 2002). Human Leukocyte Antigen (HLA) matching is a six point scoring system that identifies antigens and antibodies for both donor and recipient. Allogenic and autologous implants are also characterized by Urbano-Ispizua, et al (2002). Allogenic implants are procedures in which the recipient receives stem cells from a related or unrelated donor whose HLA score is identical (HLA score=6) or nearly identical (HLA score=5) to the recipient. Autologous implants refer to procedures in which the recipient receives stem cells from a collection performed while the patient is in remission or leukemiafree.