To evaluate the reliability of the quantitative extrapolation of the long-term effect of cancer therapies from somatic cells to germ cells, we compared the frequency of chromosome abnormalities in 303 lymphocytes from four individuals treated with radio-and/or chemotherapy 5-18 years earlier with the frequency in 422 spermatozoa from the same individuals. The mean frequency of structurally abnormal complements was much higher in germ cells than in somatic cells (P = 2.08 x 10-6). The fact that spermatogenic cells share cytoplasm is suggested as a possible factor in the increased viability of germ cells with chromosome aberrations. In addition, in spermatozoa the incidence of structural chromosome abnormalities was much higher in treated individuals than in controls (P < 0.00060), while in lymphocytes no statistically significant differences could be observed. This observation and the apparent lack of relationship between individual frequencies in the two kinds of cells suggest that the long-term effect of antitumor treatments on germ cells cannot be extrapolated from the analysis of somatic cells.
found no correlation between factors affecting chromosomal radiosensitivity in lymphocytes and stem cell spermatogonia in mammals. They concluded that only direct experiments on germ cells of higher primates and man can be used for a quantitative estimation of human genetic radiation risks arising from structural chromosome aberrations.
It is now possible to examine the chromosome constitution of human sperm by fusion of spermatozoa with zona-free hamster eggs. So far, only a few papers have been published on the chromosome aberrations in spermatozoa of men treated with radiotherapy and/or chemotherapy (Martin et al. 1986;Genesc~ et al. 1987; Jenderny and R6hrborn 1987), but there are no studies on the correlation between lymphocyte and sperm chromosome aberrations in cancer-treated individuals. To evaluate the reliability of quantitative extrapolation of the effect of cancer therapies from one cell type to another, we have analyzed the frequencies of chromosome abnormalities in spermatozoa and lymphocytes from four men 5-18 years after receiving different cancer therapies.