Acute non‐lymphocytic leukemia and acute myeloproliferative syndrome following radiation therapy for non‐hodgkin's lymphoma and chronic lymphocytic leukemia. Cytogenetic studies

Seven cases of acute nonlymphocytic leukemia (ANLL) and one of malignant myeloproliferative syndrome were identified from a pool of 189 cases of non‐Hodgkin's lymphoma (NHL) and CLL treated primarily with extensive radiotherapy at the Clinical Center, the National Institutes of Health. Four patients also received chemotherapy, two for only short periods. The median time interval from the diagnosis of the primary malignancy to the development of leukemia was 61 months (range 33 to 98 months) and the median survival after the diagnosis of leukemia was two months (0 to 9 months). All eight patients were cytogenetically abnormal and serial chromosome studies revealed that hypodiploidy was the most commonly observed chromosomal abnormality. Abnormalities of chromosome #7 were seen in all five patients analyzed by the chromosome banding technique; four of them had monosomy 7. The next most frequently involved chromosome was #5. The complexity, extensive nature, and long duration of the cytogenetic abnormalities prior to the diagnosis of leukemia in these patients may be characteristic of secondary leukemia in radiation‐treated lymphoma and the presence of such anomalies may predict leukemic transformation.