The MERCURY trial, which validated MRI staging for rectal cancer, established that MRI can predict which of the following with high accuracy BEFORE surgery?
- A Likelihood of achieving a negative CRM, guiding patient selection for preoperative (chemo)radiotherapy ✓
- B Presence of synchronous liver metastases invisible on CT
- C Microsatellite instability status of the tumour
- D Response to FOLFOX chemotherapy at 6 weeks
Correct answer: A. Likelihood of achieving a negative CRM, guiding patient selection for preoperative (chemo)radiotherapy
Explanation
The MERCURY study (MRI and Rectal Cancer European Equivalence) demonstrated that high-resolution pelvic MRI can accurately predict the pathological CRM, T stage, and extramural vascular invasion before surgery. This allows selection of patients likely to have a positive CRM (who should receive preoperative chemoradiotherapy to downstage) versus those with predicted negative CRM (who may proceed directly to surgery). MSI status and chemotherapy response prediction are not roles of MRI. CT-PET or liver-specific MRI is used for occult hepatic metastases.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.