Chromosomal aberrations in lymphocytes of patients treated with melphalan.

Chromosome lesions detected in lymphocytes from 14 patients previously treated with melphalan, a bifunctional alkylating agent, have been analyzed on R-banded preparations. In comparison to controls, there was no significant increase of chromatid-type lesions, but chromosome-type lesions were quite frequent, affecting 21.5% of metaphases, on the average. Reciprocal translocations represent 54%, unbalanced translocations 15%, deletions 19% and inversions 6% of all rearrangements. Most of these would not have been detected without the use of chromosome banding. The distributions of affected chromosomes and chromosome bands were not random. Almost all imbalances resulting from rearrangements lead to losses but not to gains. The distribution of the abnormal chromosomes has been compared to that observed in controls and in in vitro experiments, and to the characteristic pattern of malignant cells from patients affected by secondary acute leukemia (ANLL).