Does how we detect the spread of cancer need to change?
Cancers develop in an individual organ such as the lung or large bowel, and if not detected and treated, with time, can spread to other parts of the body. The technical term for this spread is metastatic disease. The presence and extent of metastatic disease is one of the main things that determines treatment; cancer that has spread often requires chemotherapy, in addition to dealing with the main tumour, by surgery for example.
How cancer is currently staged
After a patient is diagnosed with cancer, the next step is the ‘stage’ the disease to find out if it has spread, and if so where to. Radiology or medical imaging forms the bedrock of cancer staging in the NHS and various types of scans such as CT, PET and MRI are widely used. These various scans have differing abilities to detect cancer spread depending on where it is. For example, CT is very good at finding disease in the lungs but is less good at finding disease in bones, whereas MRI is very good at finding spread to the bone but may not find small areas of disease in the lungs. Patients therefore often undergo multiple different scans, which takes time (sometimes several weeks), exposes them to ionising radiation (for example from CT and PET scans), delays the start of treatment, and often adds to anxiety at a very stressful time.
Whole body MRI as an alternative?
It is now possible to scan the whole body in one go using MRI (so called whole-body MRI-WB-MRI) using scanners that are standard in the NHS. The scan takes less that an hour and potentially could act as a ‘one stop shop’ to stage cancer, allowing treatment to start sooner. There are downsides, for example the length of the scan can be difficult for some, and patients with claustrophobia may find MRI challenging due to the head and body being enclosed by the scanner; MRI scanners and more like a tube than a doughnut. Never-the-less WB-MRI has real potential to replace the current long and complex cancer staging pathways.
The Streamline Trials
The Streamline trials, funded by the NIHR Health Technology Assessment program were recently published. We compared cancer staging using WB-MRI with the standard staging pathway involving multiple scans in lung cancer (Streamline L, where 187 patients took part in the trial) and colorectal cancer (Streamline C, involving 299 patients). Patients underwent their usual standard staging scans, which were not changed by participating in the trials. Doctors reviewed the results of these standard tests and planned treatment as usual. However, in addition, patients underwent a WB-MRI scan, which was interpreted by one of a pool of NHS radiologists. Patients’ doctors first took decisions about their treatment based on the standard staging scans, without knowing the results of the WB-MRI scans. Later, the result of the WB-MRI was revealed to the treating doctors who, based on this result, stated if more tests were needed, and what their treatment would be had WB-MRI been the first staging test performed. We compared the ability of the standard and WB-MRI staging pathways to detect cancer spread, the number of tests in each pathway, the time taken to complete staging, comparative costs, treatment decisions, and patient preferences.
We found that for both cancers, the WB-MRI was just as good at finding cancer spread as the standard tests and resulted in the same treatment decisions. However, if WB-MRI had been the first test, patients would be staged quicker (by just under a week), and at less cost to the NHS (making savings on average of £69 for each patient with colorectal cancer and saving £303 for each lung cancer patient). For lung cancer patients overall, the cost of staging patients using the WB-MRI pathway was half the cost of staging patients using the standard, multiple scans. In addition, for most patients in the trial, one WB-MRI scan was enough to successfully stage their cancer: additional scans were only needed for fewer than 7% of patients with colorectal cancer, and fewer than 20% of lung cancer patients. Most patients preferred the WB-MRI pathway because it was as accurate but quicker, reduced the number of tests and did not expose them to ionising radiation.
What does this mean?
A major strength of the Streamline trials is that we tested WB-MRI exactly as it would be used in the NHS. We are very confident that if WB-MRI were more widely adopted, its performance would match our findings. Despite the challenges of undergoing a WB-MRI, a very important finding was that most patients preferred staging using WB-MRI, so we know it is acceptable. Currently access to WB-MRI is limited by the number of MRI scanners in the NHS (which are often already running flat out), and the number of radiologists who are trained in interpreting the scans. The Streamline trials suggest that the NHS should be investing in MRI scanners, and training radiologists as ultimately WB-MRI will make cancer staging quicker, cheaper and importantly, better for patients. #CMI_UCL
More information on the study is available on the NIHR Journals Library.