Preoperative indicators of misdiagnosis in invasion depth staging of esophageal cancer: Pitfalls of magnifying endoscopy with narrow-band imaging.

OBJECTIVES: The Japan Esophageal Society classification has been widely applied for predicting the invasion depth of superficial esophageal squamous cell carcinomas (SESCCs). Although Type B2 of the classification clinically corresponds to SESCCs with muscularis mucosa or slight submucosal invasion (MM/SM1), diagnostic yield based on Type B2 is insufficient. This study aimed to investigate risk factors for misdiagnosis in preoperative invasion depth staging. METHODS: We included a total of 104 SESCCs in which Type B2 was observed by magnifying endoscopy. SESCCs were classified as either correct diagnosis (pMM/SM1, 39 lesions), overdiagnosis (epithelium or the lamina propria [pEP/LPM], 34 lesions), or underdiagnosis (deep invasion into the submucosa [pSM2-3], 31 lesions) based on pathological depth of invasion. The association between misdiagnosis and endoscopic features, including distinct features, was evaluated using logistic regression analysis. Distinct features were defined as nodular protrusion, thickness, and/or clearly depressed area. The diameter of type B2 area was endoscopically measured, and the cut-off value was determined using a receiver operating characteristic curve. RESULTS: Type B2 area <6 mm (area under the curve, 0.776) and Type B2 vessels around erosion were significantly associated with overdiagnosis (odds ratio, 16.6 and 11.0, respectively), while distinct features were significantly associated with underdiagnosis (odds ratio, 8.7). Adjusted by these misdiagnosis factors, positive predictive value of Type B2 significantly improved from 38% to 65% (P < 0.01). CONCLUSIONS: Lesions with a small Type B2 area (<6 mm) and/or Type B2 vessels around erosion should be diagnosed as EP/LPM and lesions with distinct features as SM2-3.