A method for treating a brain tumor includes providing a surgical instrument having an inner member and an outer member. The outer member has a distal region forming a cutting window. The inner member is rotatably received within the outer member, and has a cutting tip that is exposed at the window. The cutting tip and the distal region of the outer member combine to define a cutting implement. An opening is created through the patient's skull to provide access to a brain tumor target site. The cutting implement is delivered through the opening to the target site. The cutting tip is placed into contact with the tumor and operated to cut the tumor. The target site is selectively aspirated to remove cut tumor tissue.