<span class="tumorshead">Glioblastoma Multiforme</span> <p>Glioblastoma multiforme accounts for 30 percent of all brain tumors and is the most common primary brain tumor in adults. The tumor presents special problems because it is not solid and cannot be removed in one clean piece. The tumor is diffuse, and individual cells tend to escape removal. As a result, the tumor often grows back near the site of the initial mass.</p>