A 55-year-old man has a 4 cm rectal adenocarcinoma at 7 cm from the anal verge on rigid sigmoidoscopy, staged as cT3N1M0. According to MERCURY trial-based principles, the MRI report shows the circumferential resection margin (CRM) involvement is predicted. What is the preferred neoadjuvant strategy?

• A Short-course radiotherapy (5 × 5 Gy) with immediate surgery
• B Long-course chemoradiotherapy (45-50.4 Gy with concurrent capecitabine) followed by surgery after 8-12 weeks ✓
• C Total neoadjuvant therapy (TNT) with induction chemotherapy followed by chemoradiotherapy
• D Surgery first with post-operative adjuvant chemoradiotherapy

Explanation

The MERCURY trial established MRI-based CRM prediction as the key imaging tool for rectal cancer management. When MRI predicts a threatened or involved CRM (tumor within 1 mm of the mesorectal fascia), long-course chemoradiotherapy (45-50.4 Gy with concurrent capecitabine or 5-FU) followed by delayed surgery after 8-12 weeks is the standard approach to downstage the tumor and achieve R0 resection. This converts a predicted R1 resection into an R0 by shrinking the tumor away from the CRM. Short-course radiotherapy with immediate surgery is used for resectable cT3 with clear CRM, while TNT is gaining traction especially for cT4 or high-risk cases.

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.