SECONDARY CHROMOSOME CHANGES IN CHRONIC MYELOID-LEUKEMIA - RELATION TO TREATMENT

Thirty four patients with Philadelphia (Ph1) chromosome positive chronic myeloid leukemia with clonal bone marrow chromosome aberrations in addition to the Ph1, were divided into two groups: 1) 23 patients treated with busulfan only during the chronic phase, and 2) 11 patients treated with intensive chemotherapeutic schedules during the chronic phase. In all the material studied, about 85% of the patients showed at least one of three particular changes: +8, iso(17q), and/or +Ph1. The frequency of each of these three aberrations was similar in the two groups. Additional structural changes of a clonal nature were, however, seen in only 3 of the 23 patients treated with busulfan only, but were present in 5 of the 11 patients treated with intensive chemotherapy. The results indicate that intensive chemotherapy may produce new stable abnormal clones in patients with leukemia. Furthermore, chromosome 1 was involved in aberrations in all 5 patients with structural changes undergoing intensive chemotherapy, but in no patient treated with busulfan only. The 11 patients treated with intensive chemotherapy were studied in Italy, whereas 20 of the 23 patients treated with busulfan only were studied in Sweden. The possibility that the differences recorded between the two groups may be geographical in nature rather than induced by treatment cannot be excluded. © 1979.