Pre-therapeutic MRI Assessment of Early-Stage Rectal Cancer and Significant Rectal Polyps to Avoid Major Resectional Surgery

Pre-therapeutic MRI Assessment of Early-Stage Rectal Cancer and Significant Rectal Polyps to Avoid Major Resectional Surgery

When a patient is diagnosed with a rectal (bowel) polyp or cancer, radiology doctors read MRI scans to describe how deeply the cancer invades into the bowel wall (this is the 'stage' of the cancer). In this project, we will teach radiologists to find more early-stage rectal cancers. These are cancers that have only grown partially into the bowel wall. If we succeed, more patients could have these lesions removed by a local procedure that preserves the bowel and avoids the risks and complications of major surgery.

We have developed a new method for radiology doctors to read MRI scans, which is more accurate than current practice. Currently only 3/10 of early rectal cancers are found by radiologists but by using our MRI reading system, 9/10 patients can be accurately identified as having early rectal cancer. We have proven that we can teach this method to other radiology doctors whose reports help to accurately inform patients of all possible treatment options, so they can be offered the option of a local procedure.

In this initial work we will train radiology doctors in our MRI reading method in 20 hospitals. We will compare MRI reports before and after training to see if an accurate reading method improves treatments choices for patients. We will also determine whether more patients have local procedures after our training. The results of this initial work will help us to apply for national funding for a trial that we can quickly roll out to all NHS hospitals.

Many patients diagnosed with Early Rectal Cancer (ERC) are currently over-treated. Most patients with confirmed ERC will undergo an MRI, but some are not correctly identified in endoscopy and immediately removed. Of those who undergo MRI, 69% are over-staged and undergo major surgery or unnecessary radiotherapy when local excision surgery to preserve the patients rectum, and quality of life, would have been possible. <10% of patients with ERC are staged accurately and offered local excision, with the majority who are staged as ERC on MRI still undergoing major surgery, likely due to uncertainty in the staging report.

Prof Gina Brown developed a more accurate radiological staging system (PRESERVE) or ERC, whereby T2 tumours are identified and classified according to the degree of preservation of the individual layers of the rectal wall. It has been shown that PRESERVE enabled better identification of ERC suitable for local excision from the expected 30% to 89% accuracy. This improved accuracy was replicated in a further study by training a cohort of 12 radiologists. It is predicted that wider adoption of PRESERVE will result in increased organ-preserving surgery from the current rates of 10% to >50%.

Inclusion Criteria:

1. Have a rectal tumour or suspected tumour less than or equal to T3b on MRI stage or pT2 or less after excision, or 20mm or more on endoscopy with suspicion of malignancy
2. Be aged 16 years or over

Exclusion Criteria:

1. Have metastatic disease at time of initial staging
2. Have a biopsy-proven rectal malignancy which is not adenocarcinoma
3. Are contraindicated for MRI