Image-guided stereotactic radiosurgery (SRS) can be an effective and feasible approach for treating up to three spinal metastases, according to an international team of researchers reporting on the results of a recently concluded phase II RTOG 0631 clinical trial.
Samuel Ryu, head of neuro- and spinal oncology at the Henry Ford Health System in Detroit, USA, and principal investigator for the trial, presented the results at the 2011 Annual Meeting of the American Society for Radiation Oncology (ASTRO) in Miami, USA.
The goals of the phase II trial were to study the emerging technique of spine radiosurgery within the cooperative group setting, and to demonstrate the technical feasibility of treating spinal metastases with image-guided stereotactic radiosurgery.
“The message we get from the results of the phase II trial is that spine radiosurgery—despite its complexity—can be carried out successfully in the community hospital setting,” said Ryu.
Forty six patients were enrolled at 16 institutions between August 2009 and March 2011. Each patient received a single SRS treatment of 16 Gray units (a measure of radiation dose) after their treatment plans were rapid-reviewed by the principle investigator to ensure that they met previously-agreed-upon standards for quality of tumor coverage and compliance with normal tissue dose constraints and delivery of image-guided radiosurgery treatment.
Rapid review results showed that the treatment plans were optimal and acceptable in 100% of the patients. Spinal cord dose constraints were optimal for all patients (i.e. less than 10% of the spinal cord received 10 Gy of dose). Image-guidance treatment compliance was optimal in 20 patients (91%) and acceptable in two (9%) with pre-set parameters calling for less than 2-3 millimetres of difference between the target position at the time of treatment planning and the target position at the end of treatment.
According to the study protocol, previous clinical experience with stereotactic radiosurgery for spinal metastasis has shown it to be effective for pain control and improvement of neurological function in patients with epidural compression (Ryu 2003; Gertzen 2005; Degen 2005; Ryu 2004).
“As the technology for stereotactic radiosurgery becomes more widely available, we felt it was critical to study the emerging technique of spine radiosurgery in a phase II trial within a national cooperative group,” Ryu said. “On the basis of the phase II results we are proceeding with a planned RTOG 0631 phase III study, comparing the effectiveness of SRS with conventional external beam radiotherapy, in terms of pain relief and quality of life outcomes in 240 patients with spine metastasis.”