Endoscopic submucosal dissection and JNET classification for colorectal neoplasia: A North American academic center experience

Objectives

Endoscopic submucosal dissection (ESD) enables minimally invasive resection of superficial gastrointestinal neoplasms en bloc regardless of size. The Japan narrow band imaging expert team (JNET) classification utilizes optical magnification and narrow band imaging (NBI) to predict pathology. In North America, ESD is far from ubiquitous, and regional outcomes are not widely described. To date there are no North American studies describing the application and yield of the JNET classification as applied in the practice of ESD.

Methods

A retrospective, single-center, cohort analysis was performed on a prospectively maintained database of ESD procedures. Between July 2016 and February 2023, all consecutive patients treated with ESD for colorectal lesions were identified and stratified by lesion location, JNET, NBI International Colorectal Endoscopic, lateral spreading tumors, and Paris classifications. Univariate analysis was used for clinicopathological data. p < 0.05 was considered statistically significant.

Results

A total of 112 patients were identified. One lesion, a lipoma, was excluded. Overall, 49.5% (55/111) of lesions were colonic and 50.5% (56/111) rectal. Most lesions were lateral spreading tumors (60.4%, 67/111). Overall, 96.4% (107/111) ESDs were successfully completed, 98.1% (105/107) en bloc, and 87.9% (94/107) R0. Adverse events occurred in 1.8% (2/111) of procedures. The median diameter was 4.0 cm and resected in a median time of 62.0 min. Overall, 70.1% (47/67) lesions were upstaged from pre-ESD biopsy. JNET 2B showed 80.2% (95% CI 71.5-87.1) accuracy for high-grade dysplasia or sm1. All JNET type 3 were ≥sm2 (p < 0.001).

Conclusions

ESD permits safe and effective resection of superficial colorectal neoplasms. JNET classification was more accurate than pre-resection biopsy at predicting histology in this series.

Hyperplastic polyp-like adenoma: a subtype of colonic adenoma with a proliferative zone confined to the lower two-thirds of the crypt

BACKGROUND

The proliferative zone of colonic adenomas is confined to the upper third of the crypt or is scattered along its entire axis. In contrast, there are unusual adenomas with proliferative zones confined to the lower two-thirds of the crypt. We investigated the frequency and endoscopic features of adenomas with lower proliferative zones.

METHODS

We retrospectively reviewed consecutive patients who underwent colonoscopies between September 2022 and March 2023 at the Toyoshima Endoscopy Clinic. Colorectal polyps were endoscopically assessed using the Japan Narrow-Band Imaging Expert Team (JNET) classification. All resected polyps were histologically examined, and the proliferative zone locations were assessed in the adenomas.

RESULTS

The frequency of adenomas with a lower proliferative zone was 1.8% (44/2420) in adenomas. Among these adenomas, JNET type 1 incidence was 43.2% (19/44), which was significantly higher than that in adenomas with a normal proliferative zone. Adenomas with a lower proliferative zone were diminutive (mean size: 2.5 mm) and prone to develop in the proximal colon.

CONCLUSION

Colonic adenomas with proliferative zones confined to the lower two-thirds of the crypt often appear as diminutive, hyperplastic polyps.

[Risk factors analysis and prediction model construction of submucosal deep infiltration of early colorectal tumor]

Objective: To investigate the risk factors for the development of deep infiltration in early colorectal tumors (ECT) and to construct a prediction model to predict the development of deep infiltration in patients with ECT. Methods: The clinicopathological data of ECT patients who underwent endoscopic treatment or surgical treatment at the Cancer Hospital, Chinese Academy of Medical Sciences from August 2010 to December 2020 were retrospectively analyzed. The independent risk factors were analyzed by multifactorial regression analysis, and the prediction models were constructed and validated by nomogram. Results: Among the 717 ECT patients, 590 patients were divided in the within superficial infiltration 1 (SM1) group (infiltration depth within SM1) and 127 patients in the exceeding SM1 group (infiltration depth more than SM1). There were no statistically significant differences in gender, age, and lesion location between the two groups (P>0.05). The statistically significant differences were observed in tumor morphological staging, preoperative endoscopic assessment performance, vascular tumor emboli and nerve infiltration, and degree of tumor differentiation (P<0.05). Multivariate regression analysis showed that only erosion or rupture (OR=4.028, 95% CI: 1.468, 11.050, P=0.007), localized depression (OR=3.105, 95% CI: 1.584, 6.088, P=0.001), infiltrative JNET staging (OR=5.622, 95% CI: 3.029, 10.434, P<0.001), and infiltrative Pit pattern (OR=2.722, 95% CI: 1.347, 5.702, P=0.006) were independent risk factors for the development of deep submucosal infiltration in ECT. Nomogram was constructed with the included independent risk factors, and the nomogram was well distinguished and calibrated in predicting the occurrence of deep submucosal infiltration in ECT, with a C-index and area under the curve of 0.920 (95% CI: 0.811, 0.929). Conclusion: The nomogram prediction model constructed based on only erosion or rupture, local depression, infiltrative JNET typing, and infiltrative Pit pattern has a good predictive efficacy in the occurrence of deep submucosal infiltration in ECT.

Objective validity of the Japan Narrow-Band Imaging Expert Team classification system for the differential diagnosis of colorectal polyps

BACKGROUND AND AIM

The Japan Narrow-Band Imaging (NBI) Expert Team (JNET) classification is a recently proposed NBI magnifying endoscopy-based classification system for colorectal tumors. Although the usefulness of this system has been reported by JNET experts, its objective validity remains unclear. We tested its validity and usefulness for the diagnosis of colorectal polyps by including colonoscopy experts and non-experts as test participants.

METHODS

Forty NBI images of polyps of various JNET types were shown to 22 doctors (11 experts and 11 non-gastrointestinal [GI] trainees) who had not examined the patients. The doctors diagnosed the polyps based solely on the surface and vessel patterns in the magnified images and the JNET classification system. Concordance rates of their diagnoses with the pathological findings of the polyps were determined, and the results for experts and non-GI trainees were compared.

RESULTS

Both for colonoscopy experts and non-GI trainees, the JNET classification system was particularly useful for classifying polyps as benign or malignant. Although the accuracy rates for classifying polyps into each JNET type varied among colonoscopy experts, those who were familiar with the JNET classification system were able to diagnose polyps with approximately 90% accuracy. Common mistakes were attributable to misunderstandings of the wording in the JNET classification chart and lack of proper training.

CONCLUSION

The JNET classification system is a practical approach for the diagnosis of colorectal polyps. Training is required even for experienced colonoscopists to adopt the system properly. Common pitfalls must be shared among colonoscopists to improve the accuracy of the diagnosis.