Imaging team of the year

Mercury II: Low rectal cancer

Better imaging of rectal cancers using magnetic resonance imaging (MRI) scans to locate and map the tumour site more accurately have led to improved outcomes for patients, with a reduced risk of long term damage. “When we started, people were wanting to do very big operations and irradiating all the patients,” says Gina Brown, professor at the Royal Marsden Hospital in London, who was chief investigator of the Mercury trial into the use of MRI for staging rectal cancer. “It’s a very radical operation, fine if you need it but some patients don’t, and the side effects can ruin your life.”

Changing this started with the study, funded by the Pelican Cancer Foundation, which aimed to validate an MRI classification system for cancers in the lowest third of the rectum, where outcomes were worse. “MRI produces exquisite detailed pictures,” Brown says, “enabling the surgeon to operate more precisely.” Incomplete removal of the tumour, typically around 30%, was reduced to 9%, even lower in some patients whose MRI scans showed that in their cases sphincter-preserving surgery without preoperative radiotherapy was possible.

The technique has been disseminated nationally through training backed by the Department of Health. A national registry has been set up and is expected to show a lowering in the permanent colostomy rates as a result of the more selective …