Preparing the Patient for Transplant

Myeloablative treatment prior to transplantation will eliminate malignant tumors and suppress the immune system and prevent rejection of the transplant. The first treatments used total body irradiation and cyclophosphamide. Newer chemotherapeutic agents that are currently being used are etoposide, Ara-C, and melphalan. The specific treatment regimen depends on the disease the patient has (malignant or nonmalignant) and the type of transplant, autologous or allogeneic. Relapse is a major problem that occurs in many patients and may require a second round of treatment and transplant. New developments in chemotherapy and immunotherapy may help prevent the return of a malignant tumor or a new secondary cancer such as myelodysplasia.

Nonmyeloablative or reduced intensity conditioning is now being used for patients who might not tolerate the intensive chemotherapy and ionizing radiation from myeloablative treatment. There are two types of nonmyeloablative conditioning: (1) Reduced intensity and (2) minimally myelosuppressive. Reduced intensity conditioning does not prevent recovery of the hematopoietic system but still has a significant anti-tumor effect. Minimally myelosuppressive require pretransplant and posttransplant immunosuppression to prevent graft rejection. Graft versus host disease and infection are frequent complications of nonmyeloablative treatment. Although these patients have a slightly higher reduction in early treatment-related mortality than myeloablative patients, they are more likely to develop complications such as chronic GVHD later.