A Montreal neurosurgeon says a commonly used drug to treat brain cancer patients is overused and actually impedes the patient’s immune response. Dexamethasone, also known as Decadron, is widely prescribed to reduce swelling during brain surgery. Dr. Charles Couturier, a neurosurgeon-scientist at the Montreal Neurological Institute, was part of an international team of scientists that looked at certain cells in brain tumours that suppress the immune system. They found that patients who were given the drug had significantly higher immune suppression than those who did not take the drug. “It reduces the inflammation to a point where it becomes overly immunosuppressive and prevents immunotherapy from working properly,” Dr. Couturier told CTV News. “But not only that, it does it in an irreversible way,” he added. “So what we found is that patients that are even given a single dose before their surgery, which is extremely common, we give it so that the pressure and the swelling gets reduced temporarily during the surgery so that we don’t have to fight against the swelling when we operate on these patients. And even that single dose is enough to have a lasting impact on the immune environment.” Couturier hopes the findings will spur conversations between patients and their doctors about whether they will really benefit from taking the drug. He said his team and other scientists are already trying to come up with an alternative way to reduce brain swelling during surgery. Couturier and his team’s research was featured in the journal Nature. “Programs, Origins, and Immunomodulatory Functions of Myeloid Cells in Gliomas” was published on Feb. 26.