Advice
Clinical and technical evidence
Clinical and technical evidence
A literature search was carried out for this briefing in line with the interim process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting mibs@nice.org.uk.
Published evidence
Five studies are summarised in this briefing, with a reported total of 259 patients. Table 1 summarises the clinical evidence as well as its strengths and limitations.
Overall assessment of the evidence
The evidence for AlignRT is limited to small studies and retrospective analyses of patient records. This quantity and quality of evidence is typical for this clinical area because intracranial tumours of all types are relatively rare.
There is a degree of overlap between the patient cohorts reported in some of the studies, so the total number of patients in these studies is not clear. All of the studies were completed in the US and the generalisability of these studies to NHS practice is not clear.
The evidence shows that AlignRT can accurately position a patient for radiosurgery at a similar level of accuracy to existing methods such CT- and frame-based methods.
Table 1 summarises the clinical evidence as well as its strengths and limitations.
Table 1 Summary of selected studies
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Study size, design and location |
Retrospective review of 163 patient records over 5.5 years (490 intracranial lesions) in the US. The 134 patients (82%) with follow-up imaging data available had 378 lesions and 39 post-operative cavities. |
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Intervention and comparator(s) |
SIG-RS using Align RT alone to treat brain metastases (n=90) compared with surgery before SIG-RS (43); SIG-RS before WBRT (30); WBRT before SIG-RS (4). These data were compared with historical studies. |
|
Key outcomes |
The actuarial 12‑month local control of the malignancy was 79% (71% to 86%) and the actuarial 12‑month survival was 56% (95% CI 49% to 63%). This compares with previous frame-based and frameless studies reporting 12‑month local control rates of 71% to 89% and 76% to 80% respectively, and survival rates of 33% to 37% and 40% to 44% respectively. |
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Strengths and limitations |
Retrospective audit of patient notes with no comparator group; high overall mortality (73% dead at analysis; longest follow-up 45.1 months); this is in line with other similar studies in this area. This cohort overlaps with that reported by Pan et al. 2012. |
|
Study size, design and location |
Observational prospective study of 44 consecutive patients (115 intracranial metastases) in the US. |
|
Intervention and comparator |
SIG-RS to treat brain metastases (using AlignRT) compared with conventional frame-based or frameless stereotactic radiosurgery. |
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Key outcomes |
The patients who received SIG-RS (AlignRT) alone (n=22) had similar clinical outcomes to those having conventional frame-based or frameless stereotactic radiosurgery. |
|
Strengths and limitations |
Small study with high overall mortality, which is typical for this patient group (70% dead at analysis; longest follow-up 21.6 months; median 6 months). The patients in this study were also included in the cohort reported by Pham et al. (2014). |
|
Study size, design and location |
Observational study of 23 patients positioned using AlignRT without frames or masks. Positioning was confirmed using CBCT. |
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Intervention and comparator(s) |
AlignRT and CBCT. |
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Key outcomes |
Patient movement between the 2 methods of set-up and the time taken to complete the AlignRT procedure. The average movement after initial set-up with surface imaging was 1.85 mm in the anterior-posterior direction and <1.0 mm in the lateral and superior-inferior directions. Surface imaging with AlignRT took an average of 14 minutes out of the average total set-up time of 26 minutes including CBCT. |
|
Strengths and limitations |
A small study examining the feasibility of using AlignRT to position patients. Final positioning was confirmed by CBCT and not the AlignRT device; the latter was used during treatment. |
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Study size, design and location |
Comparative observational study including 15 patients and using a phantom head model to assess patient positioning accuracy. |
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Intervention and comparator(s) |
AlignRT versus conventional frame-based SRS using CBCT. |
|
Key outcomes |
The accuracy of AlignRT in 1D motion detection was 0.1±0.1 mm using the head phantom. Head movement for SRS patients using a frame was <1.0 mm (0.3±0.2) and <1.0° (0.2±0.2) for 98% of the duration of treatment (1 patient had head rotation <1.5°). Similar movement was observed for AlignRT (0.3±0.2 mm and 0.2°±0.1°) and for 98% of the treatment time, the motion magnitude was <1.1 mm and <1.0°. |
|
Strengths and limitations |
This study was based on a small number of patients – only 4 patients in the frameless- (AlignRT) SRS group compared with 11 in the control framed-SRS group. Data gathered from phantom models may not reflect use in human studies. |
|
Study size, design and location |
Retrospective observational study on 15 patients in the US. |
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Intervention and comparator(s) |
All positions were monitored using AlignRT during treatment. |
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Key outcomes |
The 15 patients were treated for 62 metastases and followed up for an average of 7.1 months (1.1 to 24.3) or until death (11 patients). Treatment-related toxicity was below grade 3. |
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Strengths and limitations |
This study was based on a small number of patients (15) and had no comparator group. It shows that the use of AlignRT in routine radiosurgery may provide similar outcomes to conventional radiosurgery. |
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Abbreviations: CBCT, cone beam CT; CI, confidence interval; SIG-RS, surface imaging-guided radiosurgery; SRS, stereotactic radiosurgery; WBRT, whole-brain radiation therapy. |
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