This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
Using whole-body magnetic resonance imaging (MRI) in the initial investigation pathway is as good as standard pathways for detecting metastatic disease in adults with non-small-cell lung cancer. This NIHR-funded study also found that WB-MRI used for diagnosis and staging is quicker, cheaper and requires fewer other investigations than standard pathways.
Although patients reported that having whole-body MRI was a greater burden than standard imaging, they generally preferred whole-body MRI if it reduced staging times. In theory, it may also reduce radiation exposure, as most people would not need to have a positron-emission tomography CT scan.
Current NICE guidance recommends a sequence of investigations for staging – assessing the extent of cancer in order to plan appropriate treatment. MRI of different areas of the body is only recommended after other imaging investigations. This study suggests that whole-body MRI could have a role earlier in the pathway.
Why was this study needed?
There are about 47,200 new cases of lung cancer in the UK every year. Most of these are non-small-cell lung cancer, which spreads more slowly than small-cell lung cancer. Staging is the process of determining what ‘stage’ the cancer has reached, based on the extent of any spread.
Current staging pathways are complex, lengthy and resource-intensive as they use different techniques for various parts of the body, though most patients have a PET-CT scan. They are not yet ideal, as around 20% of people who have curative surgery relapse because of metastases that were not picked up before the operation.
Whole-body MRI is an alternative to current imaging techniques, but it was not known how accurate it is for all lung metastases. Previous research was limited to comparing whole-body MRI against one other technique only, or by looking for metastases in just one part of the body.
This study aimed to compare the diagnostic accuracy and efficiency of a whole-body MRI staging pathway with current staging pathways, including cost analysis.
What did this study do?
This diagnostic accuracy study included 187 adults diagnosed with non-small-cell lung cancer from 16 hospitals in the UK. All had stage IIIb or less according to their initial diagnostic chest CT scan, so were potentially eligible for curative treatment. Participants had whole-body MRI, as well as the standard staging investigations.
Initial treatment decisions were recorded using only standard care investigations. Next, the clinicians recorded their treatment plan just based on the whole-body MRI and any additional tests they felt necessary, arranged if not already performed. Final treatment decisions were based on all the investigations.
The opinion of an expert multidisciplinary review panel on staging, based on all initial investigations and follow-up data at 12 months, was used as the reference diagnostic standard to compare the staging recorded by both pathways.
What did it find?
- Pathways were similarly poor at correctly finding metastatic disease in people with the disease (sensitivity) which was 50% for whole-body MRI compared to 54% for standard pathways (difference ‑4%, 95% confidence interval [CI] ‑15% to 7%). This reflects how difficult it can be to detect small metastases early on.
- Both pathways were reasonably good at correctly identifying those who did not have metastases (specificity) which was 93% for whole-body MRI compared to 95% for standard pathways (difference ‑2, 95% CI ‑7% to 2%).
- Agreement with the multidisciplinary team’s final treatment decision by the consensus expert panel review at 12 months was 98% for whole-body MRI and 99% for standard pathways.
- Time taken to complete staging investigations was shorter for whole-body MRI than standard pathways: 13 days (95% CI 12 to 14 days) compared with 19 days (95% CI 17 to 21 days). This reduced staging time was important to patients.
- Mean costs per patient were £317 for whole-body MRI (95% CI £273 to £361), versus £620 for standard pathways (95% CI £574 to £666) as fewer other investigations were required.
What does current guidance say on this issue?
NICE guidance published in March 2019 says that people with known or suspected lung cancer should be offered a contrast-enhanced chest CT scan. Other techniques such as ultrasound should be considered if there is doubt. A positron-emission tomography CT should be offered before any potentially curative treatment. It says that MRI should not be routinely used to assess the stage of the primary tumour in non-small-cell lung cancer. In its recommendations for further staging, it says that the presence of metastases should be confirmed by biopsy or further imaging, for example, MRI.
What are the implications?
This study suggests that using whole-body MRI in the initial pathway has similar accuracy for diagnosis, staging and planning treatment of non-small-cell lung cancer.
As clinicians only wanted the results of the positron-emission tomography CT scan for 14% of the WB-MRI group to inform treatment decisions, this means that most people would not need to be exposed to the radiation that CT uses. Fewer investigations and faster staging would be beneficial for both patients and the NHS.
The approach of the study suggests that it reflects how imaging is carried out and interpreted in UK hospitals. Implementation may need some additional training of staff to cope with the number of people who might need whole-body MRI.
Citation and Funding
Taylor S, Mallett S, Ball S et al. Diagnostic accuracy of whole-body MRI versus standard imaging pathways for metastatic disease in newly diagnosed non-small-cell lung cancer: the prospective Streamline L trial. Lancet Respir Med. 2019;7:523-32.
This project was funded by the NIHR Health Technology Assessment Programme (project number 10/68/01).
Bibliography
Cancer Research UK. Lung cancer statistics. London: Cancer Research UK; accessed 23 July 2019.
NHS website. Lung cancer. London: Department of Health and Social Care; 2015.
NICE. Lung cancer: diagnosis and management. NG122. London: National Institute for Health and Care Excellence; 2019.
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