onc brain

Lower GI

1 study across 1 date

2026-05-18

OPERA Trial (5-year rectal preservation)

OPERA post-hoc: W14 DRE+rectoscopy reliably identifies cCR; 5-yr organ preservation 75% vs 83% (Arm A vs B, p=0.24).

W14 good response: Arm B 88% vs Arm A 65% (p=0.004). 5-yr OP: 75% (A) vs 83% (B), p=0.24; cCR 81% vs nCR 77%.
W14 good response: Arm B 88% vs Arm A 65% (p=0.004). 5-yr OP: 75% (A) vs 83% (B), p=0.24; cCR 81% vs nCR 77%.
  • 🔍 Post-hoc analysis of OPERA trial; N=141 with CTRE at W14 (122/141, 87%)
  • 🔍 W14 assessment: DRE + rectoscopy (±MRI); defined CR, near-CR (nCR), partial response (PR)
  • 📊 W14 good response (cCR+nCR): 76%; PR: 24%
  • 📊 Good response by arm: Arm B 88% vs Arm A 65% (p=0.004)
  • 📊 MRI TRG1-2 concordance in W14 CR pts: 98% (80/82)
  • 📊 5-yr organ preservation rates
    • By arm: 75% (Arm A) vs 83% (Arm B), p=0.24
    • By response depth: cCR 81% vs nCR 77% (similar)
  • ⚠️ Post-hoc analysis; W14 response classification not prespecified as primary decision gate in original OPERA design
  • ⚠️ nCR likely reflects radiation side effects (mucosal change), not residual tumor; authors caution against using nCR to justify radical surgery
  • 🔗 Original OPERA trial compared standard vs contact X-ray boost; this analysis cuts across both arms to validate timing of response assessment
  • ❓ Whether W14 CTRE alone (without W24 MRI) is sufficient to safely defer W24 reassessment in nCR pts
📚 Sources · 🐦 1 tweet