Like other brain tumors, mixed gliomas are graded on a scale of one to four based upon how quickly they are expected to grow: grade I tumors tend to grow slower, while grade IV spread very quickly. Generally speaking, mixed gliomas that are grade I or II are considered benign, meaning they are relatively slow growing, are less likely to return if completely removed, are unlikely to spread to other parts of the brain or spinal cord, and may be treated only with surgery, instead of with radiation therapy and/or chemotherapy as well. Grade III or IV tumors, on the other hand, are relatively fast growing, likely to come back after surgery (even if they’re completely removed), likely to spread to other parts of the brain and spinal cord, and will likely be treated with radiation therapy and chemotherapy in addition to surgery. These mixed gliomas, especially grade IV tumors, are much more difficult to cure.
It is worth noting that these delineations aren’t always black and white when it comes to brain tumors, including mixed gliomas. In some cases, radiation therapy and chemotherapy are used on benign brain tumors, and even slow-growing brain tumors can be life threatening if they’re located in a particularly sensitive part of the brain.