Context and Policy Issues
Stereotactic radiosurgery (SRS) and stereotactic radiotherapy, which deliver high doses of radiation to tumour sites, are used to stop the division of tumour cells. Three such therapies are TomoTherapy, Gamma Knife surgery (GKS), and CyberKnife surgery (CKS).
SRS refers to radiation treatment that is provided in one session. Stereotactic radiotherapy occurs over multiple sessions or days. GKS is a “framed” therapy in which the patient’s head is fixed to the treatment table and treatment is restricted to the brain, head, and neck. CKS and TomoTherapy, which are frameless, allow radiation treatment to occur in regions other than the brain, head, and neck. Before the radiation is administered, patients undergo imaging, which is generally performed using computed tomography, positron emission tomography, or magnetic resonance imaging.
Some jurisdictions are making decisions about whether to buy the Tomotherapy, GKS, or CKS systems. Evidence-informed decisions require a rigorous evaluation of the clinical effectiveness and cost-effectiveness of these therapies. This report focuses on the use of these technologies in the treatment of tumours of the lung, central nervous system, and intra-abdomen.
1. What is the comparative clinical effectiveness of TomoTherapy, Gamma Knife, and CyberKnife therapies for patients with cancer of the lung, central nervous sytem, or intra-abdomen?
2. What is the comparative cost-effectiveness of TomoTherapy, Gamma Knife, and CyberKnife therapies for patients with cancer of the lung, central nervous system, or intra-abdomen?
Published literature was obtained through a search of the Cochrane Library (Issue 2, 2009) and University of York Centre for Reviews and Dissemination databases between 2004 and May 27, 2009. The websites of health technology assessment (HTA) and related agencies were also searched, as were specialized databases such as those of the National Institute for Health and Clinical Excellence (NICE), ECRI, and EuroScan. The Google search engine was used to search the Internet. Two independent reviewers screened articles using predefined criteria.
Summary of Findings
One HTA, one randomized controlled trial (RCT), and nine cohort studies addressing the clinical effectiveness of GKS or CKS were included. Most of these studies focused on GKS and found it to be clinically effective. No clinical studies on TomoTherapy met the inclusion criteria.
The HTA, which was released by the Medical Services Advisory Committee of Australia, focused on intracranial lesions. The authors concluded that GKS was an effective and safe treatment. The authors of the RCT reported that GKS was generally well tolerated in patients with single brain metastases and had a high local tumour control rate. The patients who were treated using GKS experienced a higher percentage of distant tumour recurrences than patients undergoing surgery and whole brain radiation therapy (WBRT). Of the nine cohort studies, seven focused on GKS and concluded that GKS was clinically effective or at least similar to other standard treatments. These studies included patients with vestibular schwannoma, cavernous sinus meningiomas, metastatic brain tumours with various primary cancers, and brain metastases from ovarian cancer. An eighth cohort study compared GKS and CKS in patients with single brain metastases, and no clinically important differences in tumour control or overall survival were found. The ninth cohort study reported that CKS and conventional radiation therapy provided similar benefits in patients who had breast cancer with spine metastases.
No full economic evaluations that compared TomoTherapy, GKS, or CKS with each other were identified. One HTA evaluated the costs of GKS and CKS. One cost-effectiveness study compared GKS with WBRT, and a second compared CKS with external beam radiation therapy. No economic studies on TomoTherapy were included.
Based on a partial economic evaluation, the Medical Services Advisory Committee authors stated that GKS was more costly than linear accelerator (Linac)-based SRS. The costs per patient, based on 150 patients treated per year, were $3,757 for GKS compared with $3,549 or $960 for Linac adaptation equipment (the price was lower if the cost of the Linac unit was excluded). One cost-effectiveness study reported a payer perspective cost-utility analysis and concluded that when compared with external beam radiation therapy, CKS was a cost-effective treatment for patients with inoperable spinal metastases. A second cost-effectiveness study concluded that compared with WBRT, GKS was more cost-effective per quality-adjusted life-year for patients with multiple brain metastases.
Conclusions and Implications for Decision- or Policy-Making
For TomoTherapy, GKS, and CKS, there was a lack of evidence from RCTs. Most of the studies evaluated GKS rather than CKS, and no studies evaluated TomoTherapy. This may reflect the fact that GKS is the oldest and perhaps more widely used technology. Most of the literature on TomoTherapy, GKS, and CKS were case series reports, which were outside the scope of this report because such studies do not allow for direct comparisons of clinical or cost-effectiveness.
GKS was found to be clinically effective or to have produced similar benefits compared with other standard treatments (for example, WBRT) and conventional radiotherapy. The primary patient outcome measures in the included studies were typically tumour growth control or survival.
No cost-effectiveness analyses comparing TomoTherapy, GKS, and CKS were identified. CKS and GKS were found to be more expensive than traditional SRS. They remained cost-effective in specific situations and when compared with comparators other than TomoTherapy, GKS, or CKS. No economic studies on TomoTherapy were included.
Given the current evidence, it is not possible to reliably estimate the comparative clinical effectiveness and cost-effectiveness of TomoTherapy, GKS, and CKS.