Is it common to have more than one brain tumor at a time?

It is not common to have more than one brain tumor at a time. The vast majority of people who have a brain tumor only have one. However, there are some cases in which people can have multiple brain tumors. This is more likely to occur in people who have certain genetic conditions, such as neurofibromatosis type 1 (NF1) or tuberous sclerosis complex (TSC). Additionally, people who have been exposed to certain environmental toxins, such as radiation, are also at an increased risk of developing multiple brain tumors.