Complex hypodiploidy in acute myeloid leukaemia: a United Kingdom Cancer Cytogenetics Group study.

Forty cases of acute myeloid leukaemia with 41 hypodiploid clones were investigated in a collaborative study. Cases with -5, -7, -X or -Y either alone or in association with an established translocation were excluded. Karyotypes were reviewed in all cases and bone marrow or blood morphology was reviewed in 22 cases. Twenty-six cases were very complex (more than five abnormal chromosomes), 14 cases were complex (two to five abnormal chromosomes) and only one case was simple (one abnormal chromosome). Chromosomes 5, 7, 17 and 18 were involved in a significantly greater number of cases than expected. Only five cases had normal chromosomes 5 and 7. Chromosomes 10, X and Y were involved in significantly fewer cases than expected. Ten cases had ring chromosomes and 18 showed clonal evolution. Patients were aged between 19 and 90, median 61 years. Evidence of myelodysplasia was found on morphological review in 18/22 cases, and on clinical features in a further five cases. There was a high proportion of cases with FAB M6, 'erythroleukaemia' (9/31 cases). Only 4/16 patients treated with cytotoxic therapy achieved remission. Median survival was 2.5 months (35 patients). Survival was slightly better for patients with normal chromosomes 5 and 7, and for those with simpler karyotypes, but this was not statistically significant. This study confirms the association between hypodiploidy, complex karyotype, abnormalities of chromosomes 5 and 7 and a poor prognosis.