GliomasGliomas
A variety of tumor types comprise this group of malignancies, which are derived from the supporting tissues of the brain. They include astrocytomas, which range in aggressiveness from low-grade astrocytoma to anaplastic astrocytoma to glioblastoma. Other tumors in this group include oligodendroglioma and ependymoma. A common characteristic of these tumors is a tendency towards local recurrence despite surgical removal and postoperative radiation therapy, which is currently the most effective treatment for these malignancies. All of these tumors tend to be infiltrative with less distinct borders than many other lesions treated with radiosurgery.
Radiosurgery may have a role, however, in the subset of patients whose tumors are small and relatively well localized. Radiosurgery in this situation is usually given as a "boost" treatment in conjunction with standard radiotherapy. Additionally, radiosurgery can be used for patients whose tumors recur after conventional treatment, provided the area of recurrence in small in volume and localized.
Treatment results are correlated with several factors, including patient age, performance status, tumor grade and tumor volume. Although several reports have shown improved results, the role of radiosurgery in gliomas is currently under evaluation with ongoing clinical trials.
A distinct tumor type in this group is pilocytic astrocytoma. Typically occurring in younger patients, this tumor typically is more localized than other astrocytomas and has a much better prognosis. Complete surgical removal can be curative but frequently is not possible due to tumor location deep in the brain. Radiosurgery has shown promising results in treatment of patients with these well-circumscribed lesions.
References
Larson D et al: Gamma Knife for Glioma: Selection Factors and Survival. Int. J. Rad. Onc. Biol. Phys. 36:1045-1053, 1996
Sarkaria J et al: Radiosurgery in the Initial Management of Malignant Gliomas: Survival Comparison with the RTOG Recursive Partitioning Analysis. Int. J. Rad. Onc. Biol. Phys. 32:931-941, 1995
Kondziolka D et al: Stereotactic Radiosurgery for Glial Neoplasms, in Gamma Knife Brain Surgery. Prog Neurol Surg. Basel, Karger, 1998, vol 14, pp 160-174
