Diagnostic performance of conventional endoscopy in the identification of submucosal invasion by early gastric cancer: the “non-extension sign” as a simple diagnostic marker

Abstract

Background and aim The ability to differentiate between mucosal (M) or microinvasive submucosal (SM1: depth of less than 500 lm) and invasive submucosal (SM2: depth of 500 lm or more) cancer is paramount when choosing the method of treatment for early gastric cancer (EGC). The ''non-extension sign'' relates to a localized increase in thickness and rigidity due to massive submucosal invasion by a cancer. The present study sought to assess the ability of conventional endoscopy (CE) to correctly identify SM2 cancer using only the non-extension sign. Methods This is a retrospective study based on a prospectively collected database. EGCs had been diagnosed according to invasion depth as M-SM1 or SM2. In terms of the endoscopic diagnostic criterion, lesions positive for the non-extension sign were classified as SM2 cancers, while those negative for the non-extension sign were classified as M-SM1 cancers. Histopathological findings were used as the gold standard. Results We examined a total of 863 lesions from 704 patients, comprising 104 true-positive, 733 true-negative, 9 false-positive, and 17 false-negative lesions. This yielded a sensitivity of 92.0 % (95 % confidence interval (CI), 87.0-97.0 %), a specificity of 97.7 % (95 % CI, 96.7-98.8 %), a positive predictive value of 85.9 % (95 % CI, 79.7-92.1 %), a negative predictive value of 98.8 % (95 % CI, 98.0-99.6 %), and a diagnostic accuracy of 96.9 % (95 % CI, 95.8-98.1 %). Conclusion The non-extension sign may be useful for accurately determining the suitability of minimally invasive endoscopic treatment. Nevertheless, considering the limitations of retrospective analysis, a further prospective study is warranted to confirm the diagnostic reliability of the non-extension sign.

Endoscopic diagnosis and treatment of esophageal adenocarcinoma: introduction of Japan Esophageal Society classification of Barrett’s esophagus

“…Non-magnified endoscopy is the primary modality for diagnosing gastrointestinal cancer, and is also helpful for diagnosing cancer invasion depth. Correlations between endoscopic macroscopic type and invasion depth of superficial EAC have been reported [31, 32], and previous studies showed that non-magnified endoscopy could accurately diagnose invasion depth in gastrointestinal cancers [33–36]. One study found that the overall correct diagnostic assessment of early esophageal cancers was high using either non-magnified endoscopy or endoscopic ultrasonography (EUS) with a 20-MHz mini-probe, with no significant differences between the two techniques (Table 4) [37].…”

Should we recommend use of non-extension sign in Europe?

“…We believe that the non-extension sign could be considered a promising sign to evaluate invasion depth but today, application of this sign by its own is difficult in Western countries. First of all, the diagnostic accuracy showed in this study (80.3 %) did not reach the accuracy of the original study (96.9 %) [4]. The authors tried to explain that difference, saying that the first study was a real-time study, while this was only based on images.…”

“…The non-extension sign is a diagnostic criterion proposed by Nagahama et al [4] which, when the gastric wall is well distended by endoscopic air insufflation, consists of a protrusion of surrounding mucosa into the lumen, resembling a trapezoidal shape. This is used to define the invasion depth of EGC as T1b2 carcinoma and showed an accuracy of 96.9 %.…”

Clinicopathological Characteristics and Endoscopic Features of Early Gastric Cancers Diagnosed After Helicobacter pylori Eradication: A Retrospective Study

“…Endoscopic features of EGCs in all cases showed a attened and extended appearance when the entire stomach wall was distended with a high volume of air. Therefore, patients were diagnosed with intramucosal gastric cancer because they were negative for the nonextension sign [12]. Three cases (case1, 3, 4) had none atrophic mucosa around EGC.…”