Cyberknife New Hope for Brain Tumours. Intracranial Stereotactic Radiosurgery (SRS)
Posted Mar 11 2010 3:24am
Benign and Primary Tumours
The most common intracranial lesions are metastases and malignant (e.g., astrocytomas) or benign (e.g., meningiomas, acoustic neuromas) primary tumours. Primary benign brain tumours and malignancies are much less common than brain metastases. Stereotactic radiosurgery has become an accepted treatment option for patients with meningiomas, vestibular schwannomas and pituitary adenomas.
Each year, thousands of patients worldwide undergo radiosurgery for these benign tumour types. In many ways, patients with benign tumours are ideal candidates for radiosurgery. Primarily, unlike malignant gliomas, these tumours rarely invade the adjacent tissue and therefore highly focused and precise treatments such as stereotactic radiosurgery can be used to completely treat the entire tumour. Secondly, benign tumours are typically well visualized by magnetic resonance imaging (MRI). This permits a clear delineation between the tumour and nearby structures so unnecessary radiation exposure to healthy tissue can be minimized. Lastly, radiosurgery of benign tumours makes good use of the radiobiologic principles.
For benign tumours, both the target and the adjacent nervous system act as late responding tissues due to their slow rate of proliferation. Consequently, dose fractionation adds little theoretical benefit compared to conformal, single fraction radiation delivery. SRS is especially attractive to patients with malignant brain tumours because of its minimally invasive nature and the fact that no recovery period is required after the procedure is completed.