Colorectal cancer and non small cell lung cancer (NSCLC) are leading causes of cancer-related deaths. In both diseases, accurate staging is vital for optimal outcomes, particularly for the identification of metastases. Current staging pathways, such as those recommended by the UK’s National Institute for Health and Care Excellence (NICE) rely on several individual high technology imaging modalities such as CT, PET-CT, and MRI, which differ in their diagnostic accuracies across individual organs. For colorectal cancer, the guidance on staging pathways includes CT of the chest abdomen and pelvis, supplemented by pelvic MRI for local staging of rectal cancer. It is also not unusual for patients to undergo PET CT and/or liver MRI if disease spread is suspected. Staging pathways in lung cancer are even more complex, with CT, PET-CT, MRI, US and endobronchial/ percutaneous biopsy all recommended at various points during staging.
Since modern MRI scanners can image the entire body within 1 h, a multi-centric UK- based group of researchers hypothesized that whole-body MRI (WB-MRI) — which typically scans from the head to mid-thigh — is a potentially more accurate and safer alternative to standard multimodality staging pathways.
The group set up two large prospective, multicentre trials, one for colorectal cancer and one for NSCLC. They involved nearly 500 patients across 16 hospitals in the UK. The results of these trials have now been published (Taylor SA 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. May 9, 2019. Doi: /10.1016/S2213-2600(19)30090-6; Taylor SA et al Diagnostic accuracy of whole-body MRI versus standard imaging pathways for metastatic disease in newly diagnosed colorectal cancer: the prospective Streamline C trial, Lancet Gastroenterol Hepatol. May 9, 2019 doi. 10.1016/S2468-1253(19)30056-1).
The findings show that WB-MRI scans reduced the average time needed to determine the size of tumors and how much they had spread, by five days for colorectal cancer patients and six days for lung cancer patients. The treatments decided upon were similar, since results from MRI were as accurate as those of standard investigations, but the costs per patient were reduced by nearly a quarter in the case of colorectal cancer and were almost halved for lung cancer. More research is needed to determine how this affects outcomes for patients.
The authors are aware that despite their accuracy and efficiency, that MRI scanners are not as widely available as other imaging technologies and are in high demand. “Our results, obtained in a real-world NHS setting, suggest that WBMRI could be more suitable for routine clinical practice than the multiple imaging techniques recommended under current guidelines,” says lead author Professor Stuart Taylor from UCL, UK. “While demand on NHS MRI scanners is currently high, adopting WB-MRI more widely could actually save rather than increase costs, as well as reducing the time before a patient’s treatment can begin.”
For the first time, the two new trials compare the diagnostic accuracy and efficiency of WB-MRI with the standard NHS pathways, which use a range of imaging techniques for assessing colorectal and lung cancers. The standard imaging tests were undertaken as usual and the usual multi-disciplinary panel made a first treatment decision based on their results. Once this decision had been recorded, they considered images and reports from WB-MRI. The panel were then able to say whether their first treatment decision would have been different based on WB-MRI result. Patients were also followed up after 12 months to evaluate the accuracy of WB MRI compared with standard tests.
Sensitivity and specificity of diagnosis for WB MRI did not differ from those obtained by the standard tests for both cancers. The use of WB MRI reduced the time it took to complete diagnostic tests, from an average of 13 days to an average of 8 days in the colorectal cancer trial and from 19 days to 13 days in the lung cancer trial. Costs were reduced from an average of £285 to £216 in the colorectal cancer trial and from an average of £620 to £317 in the lung cancer trial.
In the colorectal cancer trial, agreement with the final multi-disciplinary panel treatment decision based on standard investigations and WB-MRI was high (95% and 96%, respectively), as were results for the lung cancer trial (99% for standard investigations, and 98% for WB MRI).
The authors note that waiting times might not be representative of other UK hospitals or of hospitals in other countries. A further limitation of the lung cancer trial is that sensitivity in detecting the spread of cancers – including the development of secondary tumors and the spread to lymph nodes – was low using both current standard imaging techniques and whole body MRI.
Writing in a linked Comment, Professor Andreas Schreyer from Brandenburg Medical School, Germany, said of the colorectal cancer trial: “MRI has faced considerable backlash within the medical community due to relatively high costs and the high demand. This is why it is particularly important to think “outside the box” and look out for new medical pathways and paradigms and not to be driven by prejudices. Such new pathways, e.g. the use of WB-MRI which are often thought of as more expensive and complex at first sight, can eventually change clinical pathways while being more time- and cost-efficient..”