CyberKnife® radiosurgery new hope for brain tumours

The most common intracranialWithin the skull. lesions are metastasesSecondary tumours’ that result from the spread of a malignant tumour to other parts of the body. and malignantDescribes a tumour resulting from uncontrolled cell division that can invade other tissues and may spread to distant parts of the body. (e.g., astrocytomas) or benignNot dangerous, usually applied to a tumour that is not malignant. (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 pituitaryA gland deep in the brain that produces several hormones controlling the production of other hormones throughout the body adenomas.

Each year, thousands of patients worldwide undergo radiosurgery for these benign tumourAn abnormal swelling that is not cancerous; in other words, it does not invade local tissues or spread to distant parts of the body. types. In many ways, patients with benign tumours are ideal candidates for radiosurgery. Primarily, unlike malignant gliomas, these tumours rarely invade the adjacent tissueA group of cells with a similar structure and a specialised function. 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 visualised by magnetic resonance imagingA technique for imaging the body that uses electromagnetic waves and a strong magnetic field. (MRIAn abbreviation for magnetic resonance imaging, a technique for imaging the body that uses electromagnetic waves and a strong magnetic field.). This permits a clear delineation between the tumour and nearby structures so unnecessary radiationEnergy in the form of waves or particles, including radio waves, X-rays and gamma rays. 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 systemThe network of nerves, which are bundles of nerve fibres carrying information in the form of electrical impulses. 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.