Multiple Sclerosis Drug May Increase Cancer Risk

Patients taking mitoxantrone for multiple sclerosis found to have higher rates of breast and colorectal cancers and leukemia.

A recent study found the drug mitoxantrone, which treats multiple sclerosis (MS), may increase the risk for colorectal and other types of cancer.

Mitoxantrone treats aggressive types of relapsing-remitting or progressive MS that is resistant to other MS drugs. The use of this drug has been linked to heart damage and leukemia.

The current study, published in Neurology, evaluated the drug to see if there is a risk for other forms of cancer.

Researchers gathered data on 676 patients taking mitoxantrone for MS from 1997 to 2007 and followed them until 2010.

Researchers found that 37 patients (5.5%) were diagnosed with cancer after taking the drug. Of those patients diagnosed, 9 had breast cancer, 7 had colorectal cancer, and 4 had acute myeloid leukemia, which is already associated with the drug.

In German patients taking mitoxantrone, the rate of leukemia was 10 times higher than the general population, and the rate of colorectal cancer was 3 times higher.

Patients taking the drug were more likely to develop breast cancer and other types of cancer than the general population.

Researchers also studied whether the dosage amount and if other immunosuppressant drugs had an effect on cancer development. They found that the older the patient was when starting the drug, the higher the risk of cancer, according to the study.

"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," concluded study author Mathias Buttmann, MD. "Mitoxantrone is the only approved treatment for people with secondary progressive MS without relapses and should be considered in people where the disease is evolving quickly. Also, many of the new and highly effective MS drugs are not available to people in a number of countries for economic reasons, so mitoxantrone is being used for people with very active relapsing forms of the disease."