The Pelican MERCURY Team
Miss Amy Lord, Consultant Colorectal Surgeon Basingstoke Hospital and Pelican Research & Education Consultant
Prof Brendan Moran, Consultant Colorectal Surgeon, Basingstoke Hospital
Prof Gina Brown, Consultant Radiologist, Imperial College London
Ms Daphne Robertson, Chief Executive, Pelican Cancer Foundation
PELICAN CANCER FOUNDATION, BASINGSTOKE: – DEVELOPING AND SUPPORTING MERCURY 3 TO ENHANCE PRECISION SURGERY FOR PATIENTS WITH RECTAL CANCER BY ACCURATE RADIOLOGICAL IMAGING.
Background / Introduction
Bowel cancer, also known as colorectal cancer, is one of the most common cancers in the world. Pelican Cancer Foundation was formed and developed to promote precision surgery and over the past 20 years the Charity has been at the forefront in surgery for rectal cancer and in training and education.
Precision surgery cures most patients with colorectal cancer, if diagnosed early, and some patients when the bowel cancer has spread to the liver, the lungs or to the peritoneum, which is the lining of the abdominal cavity.
Basingstoke surgeons are pioneers in surgery for colon and rectal cancer surgery in addition to highly specialised surgery for liver metastases and peritoneal metastases.
Some patients, particularly patients with cancer of the lower part of the bowel, may benefit from radiotherapy or chemotherapy before surgery, but there are serious side-effects, such as long-term poor bowel function and increased need for a permanent stoma bag.
In this context, selection of the right treatments for each individual patient is crucial and Pelican is a leader in surgical treatment and educational initiatives to improve individualised patient care.
The traditional form of staging is pathology (examining the tumour under a microscope after it has been removed) but staging before surgery (using X-Ray techniques or Radiology) is becoming increasingly important to plan treatment.
For patients with rectal cancer, planning treatment has been revolutionized by precision radiology in the form of ultrasound, CT (computerized tomography) and MRI (Magnetic Resonance Imaging).
These radiology techniques are categorized as “Imaging” a term which means “seeing” what is going on inside. Imaging allows “cancer staging” meaning it is possible to “see” how large tumours are, whether a tumour involves a nearby organ, such as the bladder, and whether the cancer has spread to other organs such as the liver or the lungs.
Pelican has helped develop, fund and deliver two world class studies entitled MERCURY 1 and MERCURY 2. MERCURY stands for “Magnetic Resonance Imaging and Rectal Cancer European Equivalence” as these studies involved training radiologists from a number of European countries in a new method of staging using MRI scans. The pre-operative scans can predict not only what would be found under the microscope after surgery, but also risks of a patient developing a recurrence of their cancer after surgery.
The original MERCURY studies went on to change the way pre-operative imaging for rectal cancer staging was carried out worldwide. This meant that with accurate MRI scans, many patients could be spared additional treatments before surgery by identifying those who could be cured with surgery alone.
The studies found that tumour close to the surgical margins (which risks cancer cells being left behind) results in recurrence of the tumour and these patients should have radiotherapy and/or chemotherapy before surgery or alternatively a more extensive surgical operation.
The Future – MERCURY 3
Pelican is currently working with Prof Gina Brown, Prof Brendan Moran and Miss Amy Lord to develop and deliver MERCURY 3 which is a futuristic study, further refining the use of MRI to stage cancers in patients with rectal cancer.
This study will involve national and international collaborators, multicentre patient research and educational initiatives for radiologists, surgeons and other professionals. MERCURY 3 will be initially in the UK and Ireland, prior to global extension, to improve staging, surgical precision and maximise outcomes for patients with rectal cancer.
Currently staging is based on a system called TNM (which stands for Tumour, Nodes, Metastases) and shows how deeply the tumour invades into the bowel wall (T), whether there are any lymph nodes or glands involved (N) and whether the tumour has spread (metastasized) elsewhere in the body (M)).
This 100-year-old staging system was designed for pathology rather than for radiology staging but the terminology has been extrapolated over the years to try to predict the stage by clinical examination and radiology in order to plan treatment. Unlike pathology, it is difficult to tell whether lymph glands are involved on MRI (the accuracy is only around 50%) and this therefore affects how well MRI can predict prognosis using the TNM system.
More recently, research by Prof Brown and colleagues has shown that MRI can show tumour invading the veins (called extramural vascular invasion or EMVI) or forming nodules along veins (called tumour deposits, or TD). This has led to them developing a new MRI based staging system called MRI-TDV . MRI-TDV incorporates the results of the previous MERCURY and MERCURY 2 studies and accounts for tumour and tumour deposits close to the surgical margins, which is not included in the current TNM system.
The team have already shown that MRI-TDV staging was able to predict prognosis better than MRI-TNM (Lord et al, Lancet Oncology 2021). The results suggested that there may be a tendency to over-treat around one third of patients with radiotherapy when using MRI-TNM staging, meaning they would have all of the side effects of treatment (such as poor bowel function) but no benefit in terms of cancer cure and survival.
This has major implications for both patients’ quality of life and the use of NHS resources when giving unnecessary, potentially harmful, treatment. The main criticism of the study was a concern that only expert radiologists, in centres such as Basingstoke and St Marks (the two hospitals where the study was based), would be able to do this.
Building on experience from the previous MERCURY studies, the key aim of MERCURY 3 will be to train radiologists and multidisciplinary teams (MDTs) at multiple sites, to use MRI-TDV. The aim is to prove that MRI-TDV can be reliably reported by all radiologists and confirm that it predicts prognosis better than MRI-TNM in a larger scale study involving multiple hospitals.
A key part of this study will be determining how to communicate the risks and benefits of different treatment options to patients based on the information from the study. This information will help them to make informed decisions.
Pelican is providing funding to directly involve patients in this process from the beginning and ensure their voices are heard. Pelican will also play a key role in future training of radiologists and other MDT members through a national training programme aiming to improve rectal cancer staging and decision-making based on the results of MERCURY 3.