The objective in this paper is to compare the cumulative incidence and incidence density of therapy-related acute myeloid
leukaemia in two cohorts of patients with multiple sclerosis treated with mitoxantrone, and with previously reported
data in the literature. Six new cases of acute myeloid leukaemia were observed by prospectively following two Spanish
series of 142 and 88 patients with worsening relapsing multiple sclerosis and secondary-progressive disease treated with
mitoxantrone. A literature review shows 32 further cases of acute myeloid leukaemia reported, 65.6% of which are
therapy-related acute promyelocytic leukaemia. Five cases in the cohorts fulfilled the diagnostic criteria for acute
promyelocytic leukaemia, and one patient was diagnosed with pre-B-acute lymphoblastic leukaemia. Acute myeloid
leukaemia latency after mitoxantrone discontinuation was 1 to 45 months. The accumulated incidence and incidence
density was 2.82% and 0.62%, respectively, in the Valencian cohort, and 2.27% and 0.44% in the Catalonian cohort. In the
only seven previously reported series, the accumulated incidence varied from 0.15% to 0.80%. The real incidence of
acute myeloid leukaemia after mitoxantrone therapy in the multiple sclerosis population could be higher as evidenced by
the growing number of cases reported. Haematological monitoring should continue for at least 5 years after the last dose
of mitoxantrone. These data stress the necessity of re-evaluating this ris