Background: Mitoxantrone has been extensively used as a disease-modifying therapy for multiple sclerosis. However, estimates of the associated risk of therapy-related acute leukaemia (cancer of blood system) and cardiomyopathy (damage to heart muscles, which is well known anda reason why you can only have a finite number of treatments)-have been derived from short-term studies. This study aimed to ascertain the long-term risk of therapy-related acute leukaemia or cardiomyopathy after mitoxantrone therapy for multiple sclerosis.
Methods: Between 2002 and 2010, 50 patients were treated with mitoxantrone at a single centre using a standard protocol (12 mg/m(2) body surface area monthly for 6 months as tolerated to a maximum of 72 mg/m(2) body surface area). Follow-up haematologic and echocardiographic data were collected in March 2011.
Results: Fifteen patients (30%) were excluded from analysis either because of lack of follow-up data, death due to non-cardiac and non-haematologic causes, or cocomitant cardiovascular disease. The remaining 35 patients (70%) were followed for a median of 75 months (range: 9-103). The median cumulative mitoxantrone dose given was 72 mg/m(2) body surface area (range: 24-123). At the end of follow-up, no patients had developed therapy-related acute leukaemia. One patient suffered an asymptomatic drop in left ventricular ejection fraction from 55 to 47%.
Conclusion: This series of patients followed for up to 8.5 years suggests that the risk of either therapy-related acute leukaemia or cardiomyopathy after mitoxantrone therapy for multiple sclerosis is low when patients are treated within standard protocol.
Although this is good news that the risk of cancer and heart problems is low, the down side is that there are just too people in the study for any risk to be manifest so you can say the risk of problem is less than 1 in 50, but the risk in other studies is more like 1 in 500 in a 5 year study so there was just not enough power in the study for it to be informative