Acute leukaemia after immunosuppressive therapy.

Three cases of acute myeloid leukaemia developing after treatment of renal disease with cyclophosphamide have been studied. None of the cases was complicated by additional treatment with irradiation or other cytotoxic agents, or by a pre-existing malignancy. Marrow aplasia as a cause of the leukaemia was ruled out. It is suggested that the immunosuppressive action of cyclophosphamide could predispose to the development of malignancy in two ways: malignant clones of cells could emerge and multiply or oncogenic viruses could invade the cells or escape from immunological control and cause induction and development of malignancy.