Original article
Clinical endoscopy
Diagnostic performance of Japan NBI Expert Team classification for differentiation among noninvasive, superficially invasive, and deeply invasive colorectal neoplasia

https://doi.org/10.1016/j.gie.2017.02.018Get rights and content

Backgrounds and Aims

The Japan NBI Expert Team (JNET) classification is the first universal narrow-band imaging magnifying endoscopic classification of colorectal tumors. Considering each type in this classification, the diagnostic ability of Type 2B is the weakest. Generally, clinical behavior is believed to be different in each gross type of colorectal tumor. We evaluated the differences in the diagnostic performance of JNET classification for each gross type (polypoid and superficial) and examined whether the diagnostic performance of Type 2B could be improved by subtyping.

Methods

We analyzed 2933 consecutive cases of colorectal lesions, including 136 hyperplastic polyps/sessile serrated polyps, 1926 low-grade dysplasias (LGDs), 571 high-grade dysplasias (HGDs), and 300 submucosal (SM) carcinomas. We classified lesions as polypoid and superficial type and compared the diagnostic performance of the classification system in each type. Additionally, we subtyped Type 2B into 2B-low and 2B-high based on the level of irregularity in surface and vessel patterns, and we evaluated the relationship between the subtypes and histology, as analyzed separately for polypoid and superficial types. We also estimated interobserver and intraobserver variability.

Results

The diagnostic performance of JNET classification did not differ significantly between polypoid and superficial lesions. Ninety-nine percent of Type 2B-low lesions were LGDs, HGDs, or superficial submucosal invasive (SM-s) carcinomas. In contrast, 60% of Type 2B-high lesions were deep submucosal invasive (SM-d) carcinomas. The results were not different between each gross type. Interobserver and intraobserver agreements for Type 2B subtyping were good, with kappa values of .743 and .786, respectively.

Conclusions

Type 2B subtyping may be useful for identifying lesions that are appropriate for endoscopic resection. JNET classification and Type 2B sub classification are useful criteria, regardless of gross type.

Section snippets

Methods

This study included 2933 consecutive cases of colorectal lesions that had been endoscopically or surgically resected. A total of 1901 patients were enrolled; 1351 patients (71.1%) had 1 lesion, 314 patients (16.5%) had 2 lesions, 132 patients (6.9%) had 3 lesions, and 104 patients (5.5%) had 4 or more lesions. All lesions were assumed to be independent observations for the purpose of statistical analysis. Each case was examined by NBI magnifying observation at the Department of Endoscopy of

Relationships between the JNET classification and histologic findings for each gross type

The results of NBI magnifying endoscopic diagnoses for all 2933 lesions using the JNET classification are shown in Table 1. According to the Paris classification, 2114 of the 2933 lesions were categorized as polypoid lesions (0-Is and 0-Ip) and the remaining 819 as superficial lesions (0-IIa, 0-IIb, and 0-IIc).

The 2114 polypoid-type lesions consisted of 57 HP/SSP lesions, 1435 LGD lesions, 431 HGD lesions, 50 SM-s carcinoma lesions, and 141 SM-d carcinoma lesions (Table 2). Histologically, 98%

Discussion

In general, there is a consensus in Japan that LGD, HGD, and SM-s carcinoma are considered to be appropriate for endoscopic resection.32, 33 Additionally, SM-d carcinoma should be surgically resected because of the possibility of lymph node metastasis. As a principle, en bloc resection is essential for carcinoma to obtain a precise histologic diagnosis.33, 34 Detailed histologic information can only be acquired from a complete specimen, and having this information enables us to make decisions

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    DISCLOSURE: All authors disclosed no financial relationships relevant to this publication. Research support for this study was provided to Shinji Tanaka by a Grant-in-Aid from the Japan Agency for Medical Research and Development, AMED (15ck0106102h0102).

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