# MERCURY

Source: https://onco.cc/trials/mercury/  
OnCo record `mercury` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The study that proved a scan can tell, before any surgery, whether the surgeon will get all of a rectal cancer out, which is why every rectal cancer in the NHS now gets an MRI first.

## Summary

MERCURY tested whether high-resolution magnetic resonance imaging could predict the circumferential resection margin, the single strongest predictor of local recurrence after rectal cancer surgery. Of 408 patients, 354 (87 percent) had a clear margin at histopathology. Where the scan predicted a clear margin it was right in 327 of 349 cases (94 percent), and specificity for a clear margin was 92 percent. High-resolution scans were technically satisfactory in 93 percent, and the technique reproduced across centres. That reproducibility is what made MRI staging a national standard: it lets the multidisciplinary team decide before the operation who needs radiotherapy first, which is the decision CR07 and STAR-TREC then refined.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-24
- Also known as: Magnetic Resonance Imaging and Rectal Cancer European Equivalence Study
- Tags: uk; rectal; staging; mri
- Phase: observational
- Setting: Prospective observational study of high-resolution preoperative magnetic resonance imaging against the histopathology of the resected specimen, in 408 consecutive patients with rectal cancer treated by colorectal multidisciplinary teams in 11 units in four European countries between January 2002 and October 2003
- Sponsor: MERCURY Study Group
- Enrolled: 408
- Result: Magnetic resonance imaging predicted a clear circumferential resection margin correctly in 327 of 349 patients (94 percent), with 92 percent specificity, reproducibly across 11 units.

## Sources

- BMJ 2006: https://europepmc.org/article/MED/16984925

## Connected records

- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Rectal cancer](https://onco.cc/cancers/rectal-cancer/)
- fronts: [Imaging](https://onco.cc/fronts/imaging/), [Surgery & Interventional](https://onco.cc/fronts/surgery/)
- technologies: [MRI](https://onco.cc/technologies/mri/)
- institutions: [The Royal Marsden](https://onco.cc/institutions/royal-marsden/)

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JSON: https://onco.cc/api/v1/entities/mercury.json