Current therapies for metastatic colorectal cancer only prolong life for approximately 2 years. A more innovative therapy that prolongs life significantly or even cures is needed. Bone marrow transplantation is a curative therapy for patients with leukemias and lymphomas. Tumor eradication in the case of transplantation of the patient's own marrow (autologous transplantation) is based on the intensive chemotherapy and/or radiotherapy used for conditioning. Tumor eradication in the case of transplantation using the marrow of a normal donor is based on both tumor reduction from conditioning and the immune elimination of tumor cells by T cells in the donor transplant that recognize the foreign tissue antigens expressed by the tumor cells and kill these cells. The use of bone marrow transplantation to treat tumors other than leukemia and lymphoma has been limited, and studies of transplantation of the patient's own marrow for the treatment of advanced /metastatic breast cancer have not conclusively shown benefit beyond conventional therapy.