Chromosome aberrations induced by etoposide (VP-16) are not random

The clastogenic effect of etoposide, an anti-cancer chemotherapeutic drug, was investigated in vitro on lymphocytes of 5 healthy donors. The analysis of the first division metaphases arising after mutagenesis in G1 phase shows that chromosome-type aberrations are much more frequent than chromatid-type lesions. The distribution in relation to chromosome lengths of the 439 breakpoints that were accurately identified is not random: chromosomes 1, 11 and 17 are most frequently involved, while chromosomes 4, 5 and X are seldom affected. This non-random distribution may be related to chromosome structure, since R-band-rich chromosomes are significantly more affected than G-band-rich chromosomes.