Authors: Alice Weatherston
A study published in Neurology has revealed a potential link between the multiple sclerosis (MS) drug, termed mitoxantrone, and an increased risk of colorectal cancer.
Mitoxantrone was first developed as a chemotherapy drug, acting by suppressing the immune system. It is now utilized for aggressive forms of relapsing-remitting or progressive MS that are unresponsive to other drugs, however this use has remained in a limited capacity due to previous research highlighting an increased risk of leukemia and heart damage in patients receiving the drug.
In the current study, carried out at the University of Würzburg (Germany), researchers sought to identify whether mitoxantrone is also linked to increases in other forms of cancer not previously identified.
The full cohort of 676 patients included all German individuals with MS who had been treated with mitoxantrone in the period 1994–2007, they were then followed-up until 2010. Of these, 5.5% (37 individuals) were diagnosed with cancer following treatment with the drug. Nine developed breast cancer, seven colorectal cancer and four acute myeloid leukemia.
Leukemia rate was 10x higher and colorectal cancer rate 3x higher in individuals receiving mitoxantrone compared to the general population in Germany. All other cancer types were no more likely in MS patients taking mitoxantrone than the general population.
After investigating any other confounding factors in the study, including the cumulative amounts of mitoxantrone received and the prescription of other immunosuppressant drugs, the only factor that was significant for individuals developing cancer was a higher age when commencing mitoxantrone.
Lead author Mathias Buttmann (University of Würzburg) reinforced however that despite the risks, the use of the drug is still beneficial for some MS patients: “Despite an increased risk of acute myeloid leukemia and colorectal cancer, the overall rate of cancer was low enough to justify still using this drug for people severely affected by MS if no better treatment is available.”
Mitoxantrone is currently the only approved treatment for individuals with secondary progressive MS without relapses and is also widely available worldwide in comparison to some of the newer effective MS drugs, cementing its position in treatment regimes for the time being.
The team would now like to confirm the results of the study in a larger investigation. However, they do suggest that regular colonoscopies should be carried out on patients that have begun mitoxantrone treatment in order to identify signs of colorectal cancer early and to therefore improve chances of survival.
Source: American Academy of Neurology press release