Introduction

Initial reports have described rectal endoscopic knife-assisted full-thickness resection (kFTR) as a novel technique for achieving R0 resection in deeply invasive or technically challenging rectal lesions, avoiding the significant morbidity and mortality of rectal surgery.^1,2​​​​ We aimed to evaluate the feasibility, safety, and technical outcomes of rectal kFTR.

Aims & Methods

In this retrospective international study, we included consecutive patients who underwent rectal kFTR at 15 centres across 4 continents between April 2017 and April 2025. We included patients with adenocarcinoma suspected of deep submucosal invasion, severe fibrosis, or subepithelial lesions were included. Primary outcomes were technical success, en-bloc and R0 resection rates and adverse events. Secondary outcomes included rectal preservation, length of hospital stay, and recurrence. Risk factors for adverse events were evaluated using univariate and multivariate logistic regression.

Results

A total of 94 patients (mean age 65 years [IQR 58-73]; 56.4% male; 79.8% ASA I/II) underwent rectal kFTR. Median lesion size was 35 mm [IQR 25-50]. kFTR was performed for suspected deep invasion (57; 60.6%), severe fibrosis (31; 33%), and subepithelial lesions (6; 6.4%). Of lesions included, 59 (62.8%) were in the distal rectum, and 13 (13.8%) were anterior.

Technical success was achieved in 92 procedures (97.9%). Mean procedure time was 135 minutes (IQR 100-180). Antibiotics were administered in 83 procedures (88.3%) for a median of 5 days (IQR 5-5). Median hospital stay was 1 day (IQR 1 - 3). Overall, 19 adverse events occurred in 15/94 (16%) patients: 12 (63.1%) mild, 6 (31.6%) moderate, and 1 (5.3%) severe per ASGE lexicon. Delayed bleeding occurred in 4 (4.3%) patients, and post-procedural pain in 7 patients (7.4%). Surgery was required in one case for a recto-vaginal fistula. Increasing lesion size was the only risk factor independently associated with a higher risk of adverse events (OR 1.05, 95% CI 1.02–1.09, p = 0.003).

En-bloc and R0 resections were achieved in 91/94 (96.8%) and 74 (78.7%) procedures, respectively. Rectal preservation was achieved in 68 patients (72.3%) while, 25 (26.6%) underwent completion surgery for non-curative cancer resections, with no residual tumor in the surgical specimen in 11/25 cases (44%).

Among 59 patients with adenocarcinoma and available follow-up (median 12 months (IQR 6 - 23.5)), 3 (5.1%) experienced loco-regional recurrences, 1 (1.7%) had distant metastasis from a pT2 adenocarcinoma with surgery after kFTR, and 1 died of non-cancer-related causes.

Conclusion

kFTR appeared to be a feasible and safe technique for excising deeply invasive adenocarcinomas and complex fibrotic or subepithelial rectal lesions in expert centres. The high rate of R0 resections enabled accurate histopathological risk stratification, supporting individualised post-procedural management and rectal preservation in most patients. Rectal kFTR may serve as an alternative to device-assisted endoscopic full-thickness resection and local surgical excision, potentially avoiding radical surgery in highly selected patients. Further prospective research is needed to confirm these findings.

References

1. Argenziano ME*, Sorge A*, Poortmans PJ, Montori M, Balducci D, Hoorens A, Maroni L, Tate DJ, Knife-Assisted Full-Thickness Resection Guided by Pocket Detection Method for Detection and Complete Excision of Deeply Invasive Rectal Cancer, VideoGIE (2024), doi: https://doi.org/10.1016/j.vgie.2024.11.004.
2. Argenziano, M.E.*, Sorge, A.*, Hoorens, A., Montori, M., Poortmans, P.J., Smeets, S., Tornai, T., Debels, L.K., Desomer, L. and Tate, D.J. (2025), Knife-assisted full-thickness resection guided by the pocket-detection method for posterior deeply invasive rectal cancer: A novel endoscopic approach (with video). DEN Open, 5: e70116. https://doi.org/10.1002/deo2.70116