The efficacy of SRS has been established for a certain number of indications, including brain metastases, arteriovenous malformations, as an alternative to conventional surgery in cases of interventional difficulties, and in the prevention of the complications of the standard treatments in cases of meningioma and vestibular schwannoma. SRS is a promising approach in the treatment of pituitary adenomas, certain skull base tumors, and specific functional disorders.
Given the evolution of the technologies and the costs associated with SRS, the instruments that might best meet the efficacy and safety criteria are the dedicated linear accelerator and the gamma knife.
The use of an adapted linear accelerator is possible but limited in cases of lesions in very close proximity to sensitive structures, since the manipulations required to adapt the equipment in order to perform SRS can be a source of imprecision when focussing the beams. Furthermore, the need to perform quality control before each treatment lengthens the treatment time.
Presently, SRS facilities are clearly needed in Quebec. If we consider all the lesions eligible for SRS on the basis of the existing data and evaluations, more than 300 patients could benefit from SRS.
Therapeutic efficacy by instrument: Even if, in theory, the gamma knife and dedicated linear accelerator are both more suitable for the various indications for SRS, technological developments in the specific area of SRS (especially in the case of the dedicated linear accelerator) and the lack of randomized, controlled trials concerning a given indication do not permit us to conclude that either of these instruments is superior to the other from the standpoint of efficacy. However, the degree of precision offered by the gamma knife permits the treatment of lesions that are no more than 2 mm in size and which touch vital structures, such as the cranial nerves, optic chiasma and brainstem, without (theoretically) causing any injury to healthy tissues.
SRS in the Quebec context: Given the current knowledge about the clinical, economic, technical and epidemiological aspects and given the need to adequately fulfill the offer of SRS services and to adequately meet research needs, the Agency recommends that a specialized radiosurgery centre with a gamma knife be created at a university hospital. Where this specialized centre will be set up will depend on geographical and/or functional accessibility and well-established service pathways.
The institution chosen must have the necessary logistical wherewithal (structural and professional) needed to perform this type of treatment. The mandatory presence of a multidisciplinary team (neurosurgeon, neuroradiologist, radiation therapist, radiophysicist, paramedical personnel), the need to provide continuous patient management quality and the need to promote the acquisition of new professional skills clearly warrant creating the centre at a university hospital.
These conclusions are conditional upon the technological evolution of the various types of instruments and the emerging therapies (fractionated stereotactic radiotherapy) at the time when the decision to create a centre providing SRS services is made.
