**5. Effectiveness of TBI for various leukemias**

Leukemia is a broad classification for several types of this disease. This variety of leukemias differs based on pathological examination of cell definition. Bredeson et al. (2002) provide a summary and results of clinical trials including TBI. Patients with acute myeloid leukemia (AML) have shown to be fairly responsive to stem cell transplants with TBI preparation. Results of randomized studies comparing TBI containing regimens with total chemotherapy preparatory regimens indicate a 75% actuarial survival with TBI compared to 51% without. Relapse rates are lower with the TBI regimens as well. 14% relapsed within 2 years with TBI while 34% relapsed under chemotherapy regimens.

Bredeson et al. (2002) reports acute lymphoblastic leukemia (ALL) results show significant improvement with TBI regimens. 52% disease-free survival rates are reported when TBI is utilized as compared to 37% with chemotherapy alone. The percentage relapse is nearly identical from both types of regimens. Studies of treatments for chronic myeloid leukemia patients show fairly high yet identical disease-free survival rates. Nearly 80% survival rates were reported for both protocols. Relapse rates were indistinguishably different.
