Acute leukaemia with t(4;11) in patients previously exposed to carcinogens.

We report three cases of acute leukaemia with t(4;11) (q21;q23), one of them of undifferentiated and the other two of lymphoid phenotype, occurring after adjuvant radiochemotherapy for breast cancer (two cases) or occupational exposure to radiation (one case). Although the myeloid phenotype and characteristic chromosomal anomalies usually observed in secondary leukaemia were lacking, our observations raise the possibility of causal relationship between exposure to carcinogens and the occurrence of a leukaemia with t(4;11).