Background
Phase II trial (CARTS). 55 patients with T2-T3 low rectal cancer (within 10 cm from anal verge) who received preoperative CRT (chemoradiation with capecitabine) followed by transanal endoscopic microsurgery (TEM). Evaluated organ preservation via TEM in patients achieving good response after CRT.
Interventions and follow up
Arm A: CRT: 50 Gy/25 fx + capecitabine 825 mg/m² BID → TEM local excision (full-thickness) at 8 weeks post-CRT
Primary endpoint: Radical surgery-free rate at 1 year
mFollow up: 12 months (primary)
Primary endpoint: Radical surgery-free rate at 1 year
mFollow up: 12 months (primary)
Results
Radical surgery-free rate at 1 yr: 72% (T2), 52% (T3)
pCR rate: 35% (T2), 12% (T3)
1-yr local recurrence: 6% (all patients)
Salvage APR required: 28% (T2), 48% (T3)
pCR rate: 35% (T2), 12% (T3)
1-yr local recurrence: 6% (all patients)
Salvage APR required: 28% (T2), 48% (T3)
Adverse events
Main adverse events: Grade ≥3 acute CRT toxicity: 11%. TEM wound dehiscence: 25%. Bladder/bowel dysfunction data not mature at primary report.
Conclusions
Preoperative CRT followed by TEM achieves organ preservation in 72% of T2 and 52% of T3 rectal cancers at 1 year. However, significant salvage surgery rates — especially in T3 — indicate TEM after CRT is not appropriate for locally advanced disease. T2N0 tumors with good clinical response are the optimal candidates for this approach.
Key Limitations
Key Limitations: Small single-arm phase 2 study. High wound dehiscence rate (25%) with TEM. T3 tumors required salvage surgery in ~50% — organ preservation was marginal. Short follow-up at primary endpoint; true local recurrence rates require longer follow-up. Not designed as watch-and-wait study — all patients underwent TEM regardless of response quality. Modern watch-and-wait (IWWD, Renehan) avoids even TEM in cCR patients.
Clinical Context
CARTS defined the role of TEM as an organ-preserving option for T2 rectal cancer with good CRT response. Current practice increasingly favors watch-and-wait for clinical complete responders (IWWD data: 20–30% regrowth rate, but salvageable with radical surgery in most cases) over mandatory local excision (TEM) for all patients.
References
References: Stijns RCH et al, JAMA Surg 2019 (CARTS)