Increased breakage of chromosome 1 in lymphocytes of patients with testicular cancer after bleomycin treatment in vitro.

Chromosome damage in vitro after bleomycin treatment during the late S and G2 phases of the cell cycle was studied in the peripheral lymphocytes of 19 untreated patients with primary testicular tumours and 22 age-matched healthy men with no excess of cancer incidence in the families. The occurrence of spontaneous chromosome aberrations was not shown to be different in the studied groups. However, in the lymphocytes treated with bleomycin, cancer patients exhibited higher numbers of break events per cell (1.06 versus 0.67, P less than 0.01) and increased frequency of cells with aberrations (55.0 versus 43.0, P less than 0.05) than control group. Aberrant cells of cancer patients had more aberrations than cells of the control sample (1.79 versus 1.53, P less than 0.01). The frequency of chromosome 1 aberrations, often encountered in cancer cells of testicular and other solid tumours, was significantly higher in lymphocytes of patients with testicular cancer (15.0 versus 8.4%, P less than 0.0001), the long arm of this chromosome being predominantly affected (12.0 versus 6.3%, P less than 0.0001). These results support the view that a genome disposed to testicular cancer is less effective in the ability to repair non-specific DNA damage in this region, more susceptible to damage, or both.