Introduction

Advances in transanal resection techniques have led to the increased use of surgical and endoscopic local excision (LE) as a diagnostic and potentially organ-sparing approach for early-stage (cT1-2N0) rectal cancer (RC). Current international guidelines recommend completion total mesorectal excision (TME) following LE for surgically fit patients with pT2 RC due to the 20-30% overall risk of lymph node metastasis (LNM). However, the risk of LNM is known to vary according to the presence of histological risk factors. Therefore, omitting completion TME in selected patients with pT2 RC may constitute an oncologically safe alternative, provided there are no additional high-risk histological features other than muscularis propria invasion. The aim of this study was to determine the rate of LNM in patients with pT2 RC without additional histological risk factors.

Aims & Methods

Data from two large Dutch multicentre registries were analysed to evaluate the rate of LNM in patients with pT2 RC who underwent surgery between 2012 and 2020. In accordance with the clinical selection criteria for LE, only patients without suspected LNM on baseline imaging (cN0) were included in the study. Patients who received (neo)adjuvant (chemo)radiotherapy were excluded. Treatment strategies included primary TME, surgical LE followed by completion TME, or surgical LE followed by active surveillance with MRI for at least 24 months. Histological risk factors available in both registries were lymphovascular invasion (LVI) and poor tumour differentiation (PD). Definitive LNM status was determined by histology after TME. Patients on active surveillance after LE were classified as LNM-negative if there was no evidence of LNM (cN0) on MRI during a minimum surveillance period of 24 months. The primary study outcome was the rate of LNM in pT2 RC patients without LVI and PD. Secondary outcomes included the association between the two histological risk factors and the rate of LNM using univariable and multivariable analyses adjusted for age and sex.

Results

A total of 334 patients with pT2 RC met the inclusion criteria (mean age 69 years, 64% male). The majority of patients (262/334, 78%) underwent primary TME, while initial surgical LE was performed in 72/334 (22%). Within the LE group, subsequent TME surgery was performed in 59/72 (82%) patients, either as completion surgery (n=51) or as salvage surgery during the follow-up period (n=8). The remaining 13/72 (18%) patients underwent active surveillance for at least 24 months without suspicion of LNM on MRI during a median follow-up of 42 months (IQR 32-55). The overall rate of LNM in the cohort was 17% (55/334). In the 266/334 (80%) patients without LVI and PD, the rate of LNM was 13% (34/266). The presence of either LVI alone or PD alone resulted in LNM rates of 31% (18/58) and 14% (1/7), respectively. When both LVI and PD were present, LNM occurred in 2 out of 3 cases. In our study, only LVI was identified as an independent predictor of LNM in multivariable analysis (p<0.001; OR = 3.1, 95% CI 1.6-5.9).

Conclusion

In this large retrospective surgical cohort of patients with pT2 RC, the absence of LVI and PD was associated with a 13% risk of LNM. However, more detailed histological reassessment including risk factors such as tumour budding and perineural invasion may identify a subgroup of pT2 RC with an even lower risk of LNM. This may allow the omission of completion TME.

Introduction

In colorectal epithelial neoplasms, lesions classified as type 2B according to the Japan Narrow Band Imaging (NBI) Expert Team classification (JNET), which are characterized by irregular microsurface or microvascular patterns, are often difficult to diagnose accurately using NBI magnifying endoscopy (ME) alone. Therefore, supplementary pit pattern diagnosis using crystal violet (CV)-stained ME (CV-ME) is recommended. However, CV is potentially carcinogenic, and CV-ME is relatively complex and time-consuming. Acetic acid (AA)-enhanced NBI ME (ANBI-ME) has been proposed as a simpler and safer alternative. Based on our previous study identifying 4.5% AA as the optimal concentration[1], this study prospectively evaluated the diagnostic utility of 4.5% ANBI-ME as a substitute for CV-ME (UMIN registration number: 00045621).

Aims & Methods

From October 2021 to March 2024, colorectal lesions classified as JNET type 2B or 3 during colonoscopy were prospectively enrolled until 300 cases were included. Each lesion underwent ANBI-ME with 4.5% AA, followed by CV-ME. The area of suspected deepest invasion was selected, and one representative image from ANBI-ME and one from CV-ME were independently assessed by two expert endoscopists blinded to histopathology. Intermethod and interobserver agreement were evaluated using Cohen’s weighted kappa. Diagnostic accuracy for each modality was calculated using the individual and consensus diagnoses of the two experts (McNemar’s test). AA whitening duration (AD), representing a reversible mucosal reaction, was measured during ANBI-ME and analyzed by histological depth (low-grade dysplasia [LGD], high-grade dysplasia [HGD], superficial submucosal invasive carcinoma [SMs], and deep submucosal invasive carcinoma [SMd]) using Kaplan–Meier analysis and the log-rank test.

Results

After excluding four unresected lesions, 296 lesions were analyzed. Median lesion size was 18 mm. Locations included the cecum (30), ascending colon (47), transverse colon (69), descending colon (13), sigmoid colon (73), and rectum (64); 122 lesions were elevated and 174 flat. Histological diagnosis included 77 LGD, 145 HGD, 18 SMs, and 56 SMd. Good agreement was observed between modalities (κ = 0.65 and 0.62) and between observers (κ = 0.78 for ANBI-ME, κ = 0.66 for CV-ME). Consensus was reached in 216 ANBI-ME and 192 CV-ME cases. Diagnostic accuracy was significantly higher with ANBI-ME than CV-ME for both observers (81% vs. 76%, p = 0.028; 75% vs. 69%, p = 0.025). Among consensus cases, ANBI-ME also showed higher accuracy (66% vs. 57%, p < 0.01). Median AD (in seconds) was 52 for LGD, 80 for HGD, 132 for SMs, and 107 for SMd, with a significantly shorter duration observed in LGD (p < 0.001).

Conclusion

ANBI-ME demonstrated diagnostic performance equivalent to or superior to CV-ME for colorectal lesions classified as JNET type 2B or 3. In addition, AA whitening duration (AD) may complement the assessment of histological depth of invasion.

References

[1]. Shimizu T, Yamagata T, Kanno Y, et al. A single-center pilot study on the efficacy and safety of acetic acid-enhanced magnifying endoscopy with narrow-band imaging for diagnosis of colorectal epithelial neoplasms. Gastrointest Endosc. 2025;101(2):416-424.

Introduction

Third-space endoscopy (TSE) is standard for treating neoplastic and motility disorders but is limited by intra-procedural bleeding. Vessel pre-sealing using electrocautery in an underwater setting may mitigate this, improving procedural safety and efficiency.

Aims & Methods

We conducted a randomized controlled trial (NCT05804266) comparing underwater (saline immersion) vs conventional CO₂-based coagulation during TSE procedures (ESD and POEM). Patients were randomized 1:1. The same electrosurgical settings (SWIFT COAG E3, 89 W for POEM and SWIFT COAG E4, 124 W for ESD) and instruments (VIO 3 and HybridKnife T-type, Erbe Elektromedizin GmbH, Tübingen, Germany) were used across arms. In the underwater group, vessels ≥1.2 mm were coagulated under saline immersion to enable pre-sealing; smaller vessels were treated conventionally. In the control group, all vessels were treated under CO₂, with vessel isolation when needed. Primary endpoint was the rate of intra-procedural bleeding requiring further hemostatic treatment (knife tip, coagulation forceps) of pre-sealed vessels. Secondary outcomes included other adverse events (ie delayed bleeding).

Results

Among 70 patients (37 underwater, 33 CO₂, no significant demographic difference including history of antiplatelet/anticoagulant therapy, discontinued in all patients on therapy), intra-procedural bleeding requiring hemostasis of pre-sealed vessels occurred in 12/37 (32.4%) underwater group vs 25/33 (75.8%) control (RR 0.43(0.26-0.71); NNT 2.3; P<0.01). In the underwater group, no patient required coagulation forceps; all bleedings were managed with the knife. In contrast, 9/33 (27.3%) control patients required forceps (RR: 0.05 (0.00-0.78); NNT 3.76 P<0.01). One intra-procedural perforation and two post-procedural adverse events (delayed bleeding and fever) occurred in the control group; none in the underwater arm (n.s). No mortality occurred.

Conclusion

Underwater (saline immersion) vessel pre-sealing significantly reduces the risk of intraprocedural bleeding and consequently the need of hemostatic devices, suggesting a safer, cost-effective alternative to conventional coagulation in TSE.