Trial Information

A Randomized Trial of Robotic Compared to Fixed Gantry Radiosurgery for Brain Metastases

Radiosurgery can be performed using multiple Co-60 sources, a modified traditional
gantry-based linear accelerator, or a robotic linear accelerator. Each technique has its own
advantages and disadvantages. Co-60 radiosurgery has very precise target localization by
using a rigid immobilization device. The requirement for rigid immobilization limits its
treatments to the head and neck. Robotic radiosurgery permits precise radiation to be
delivered without the requirement for rigid immobilization. Robotic radiosurgery uses
real-time imagining, allowing it to track the cancer or internal structures as they move
during treatment. Another advantage is that it can deliver many small beams of radiation
(as many as 200) in a limited time period and can treat lesions anywhere in the body. A
traditional gantry-based linear accelerator normally requires some form of immobilization
and requires more time for multiple isocentre set up but can provide both radiosurgery and
conventional treatments.

Brain metastases occur in up to 50% of patients with cancer. It has been reported up to 65%
of patients with brain metastases will present with one to three lesions. This represents
18,000 patients in Ontario each year who would be eligible for radiosurgery as part of their
management. Randomized trials have demonstrated improved palliation and overall survival
when radiosurgery is added to conventional whole brain radiation therapy (WBRT). As a result
the treatment of brain metastases currently represents the largest resource use for
radiosurgery. During the commissioning and initial use of the first robotic radiosurgery
device in Ontario (CyberKnife) the investigators became aware of its potential advantages
for the treatment of brain metastases. Treatment planning time and on treatment time with
robotic radiosurgery appeared to be better than with a traditional linear accelerator and
patients appeared to be more comfortable with the minimal/ non-invasive immobilization
required. Surprisingly, there were very little direct comparisons of robotic radiosurgery
with other techniques in the literature and only one prospective randomized trial comparing
two different approaches to delivering Co-60 radiosurgery was identified. Given the
increasing importance of radiosurgery and the resource implications for radiation treatment
programs in Ontario, this study is proposed to conduct a direct comparison of robotic to
traditional linear accelerator radiosurgery for brain metastases. The primary outcome will
be treatment planning and delivery time and an important secondary outcome is patient
comfort. Treatment planning time will include immobilization preparation, CT simulation,
image fusion, radiation planning and treatment plan quality assurance. Treatment delivery
time will include patient set up, target localization and treatment delivery. The Juravinski
Cancer Centre (JCC) and McMaster University are uniquely posed to perform this comparison
with access to both robotic and linear accelerator radiosurgery techniques as well as
research methodology expertise in clinical trials technology assessment, and health services
research.