Extra-medullary relapse of leukemia following allogeneic bone marrow transplantation

The curative effect of allogeneic bone marrow transplantation (BMT) for acu te and chronic leukemia is attributed to the intensive conditioning chemoth erapy with or without radiotherapy, as well as an immune-mediated graft ver sus leukemia (GVL) effect. A. different pattern of relapse has been observe d after allogeneic BMT for patients with leukemia. Compared with treatment using conventional chemotherapy alone, isolated extra-medullary relapse of disease appears to be seen, more commonly after allogeneic BMT. While a ful l donor's hematopoiesis may be retained, prolonged morphological remission has been observed in the recipient's bone marrow. There appears to be a pop ulation of leukemic cells with an affinity to extra-medullary tissues. The failure of the leukemic clone to repopulate the recipient's marrow suggests the presence of a more profound GVL effect in the marrow environment. The optimal treatment for extra-medullary relapse of leukemia following allogen eic BMT remains uncertain. In the case of isolated extra-medullary relapses following BMT, the leukemia may still be responsive to further treatment w ith chemotherapy and/or radiotherapy. The prognosis is poor in general, but prolonged survival has been observed in some of these patients. With the p reservation of donor's hematopoiesis in the recipient's marrow, the use of intensive chemotherapy followed by donor lymphocyte or stem cell re-infusio n is a promising option. Copyright (C) 1999 John Wiley & Sons, Ltd.