Relapse is the recurrence of the original disease and occurs more often in autologous transplants than in allogeneic transplants. The cause for relapse can be the result of inadequate chemotherapy or radiation therapy prior to transplant. Another cause can be the incomplete removal of malignant cells by purging. Other factors that can lead to a relapse are the degree of matching (allografts), immunosuppression, and whether the patient develops graft versus host disease.
