Gliomatosis cerebri: a review.

OPINION STATEMENT: Gliomatosis cerebri (GC) is an intriguing disease for several reasons. First, it is difficult to draw the border between GC and diffuse gliomas. In this regard, GC could represent the most invasive form of diffuse gliomas. Second, both in terms of histologic grading and clinical course, GC is a heterogeneous disease, ranging from rapidly evolving to slowly and somewhat indolent forms. Because of the extensive spread of the disease, surgery-outside a biopsy for diagnosis-is rarely indicated in gliomatosis cerebri. Therapeutic options include radiotherapy, generally involving the whole brain, and chemotherapy with temozolomide or nitrosoureas. Because of the rarity of the disease, no trial comparing these two modalities has been undertaken so far. Decision is, therefore, based on small retrospective noncomparative studies and expert opinions. On one hand, there is a rationale to postpone the whole brain radiotherapy because of late neurotoxicity, but on the other hand, there is also the risk that an aggressive disease evolves to intracranial hypertension making the radiotherapy hazardous or even impossible. As a consequence, the patient would lose the opportunity to receive a potentially effective treatment. In this decision, the evaluation of histologic data together with clinical and radiologic features, performance status, and molecular profile may be of help. Because radiotherapy usually involves large volumes of the brain, chemotherapy is generally preferred up front in patients with a slowly evolving disease. Conversely, in patients with rapidly (ie, over few weeks) evolving disease with neurologic deficits or when histologic features of glioblastoma are evident, whole brain radiotherapy (45 Gy with 1.8 Gy fractions), alone or associated with concomitant temozolomide, is often preferred. The value of advanced of magnetic resonance imaging and positron emission tomography techniques to predict outcome and monitoring the treatment still remains to be defined.