The goal of removing the tumor is to remove it completely, or to remove as much of the tumor as possible with minimal damage to healthy brain tissue around it.
During surgery, the neurosurgeon gains access to the brain by performing a craniotomy. This means the surgeon removes part of the skull to be able to see the area of the brain being treated. Once the bone flap is removed, the surgeon accesses the tumor and removes as much of it as possible, while leaving the healthy tissue unaffected. The bone flap is then replaced and the incision is closed. Sometimes a piece of the tumor (biopsy) can be sent off for evaluation by a pathologist. A biopsy can help determine if the tumor is cancerous, what type of cancer, and how aggressive it might be. Knowing these things helps determine further treatment with medications and/or radiation is necessary.
The part of the brain that controls speech is most often located within the left side (hemisphere) of the brain. If the tumor is near this area, part of the surgery can be performed while the patient is awake. The patient is put to sleep long enough for the surgeon to make the incision and gain access to the tumor. Then the patient is awakened while the surgeon works to remove the tumor. With the patient awake, the surgeon can assess what parts of the tumor can be removed without the patient losing the ability to speak.