Chromosome studies in patients with acute nonlymphocytic or acute lymphocytic leukemia submitted to bone marrow transplantation--results of a European cooperative study.

The chromosomal data of 58 acute nonlymphocytic leukemia (ANLL) patients and of 32 acute lymphocytic leukemia (ALL) patients submitted to bone marrow transplantation and collected from nine institutions are reported. Chromosomal studies were available at diagnosis in 19 cases with ANLL: seven had a partially or completely abnormal pattern. Forty-one patients had a chromosome study before bone marrow transplantation and all had a normal pattern. Thirteen patients with ALL were studied at diagnosis: five had a partially or completely abnormal karyotype. Of 20 cases analyzed before bone marrow transplantation, only one has maintained the abnormal pattern of diagnosis in part of the cells. Karyotypes were available in nine ANLL patients relapsed after bone marrow transplantations. Two showed the same clonal abnormalities seen at diagnosis; in three other cases the leukemic clone of relapse carried an additional chromosome abnormality with respect to the pattern at diagnosis and four more cases presented at relapse complex abnormalities; two of them had a cytogenetically normal pattern at diagnosis. In four of ten relapsed ALL cases chromosomes analyses were available. A relapse in donor cells and a hyperdiploid pattern were observed in two cases, respectively, while a normal, recipient pattern was documented in the other two cases. Serial chromosome studies performed in acute leukemia patients after bone marrow transplantation may allow the detection of different chromosomal patterns of relapse. In those cases who relapsed with a cell clone cytogenetically different from the pattern at diagnosis, a direct role played by the conditioning treatment in the pathogenesis of the relapsing disease may be hypothesized.