Evaluating the usefulness of considering the size and morphological type of type B2 vessel area based on Japan Esophageal Society classification in estimating tumor invasion depth in superficial esophageal squamous cell carcinomas: study protocol for a prospective observational study (Japan BEES study)

Table 2 Criteria for hypothetical depth diagnosis

	Corresponding tumor invasion depth
B2 vessel area ≤ 4 mm	EP, LPM
B2 vessel area between 4–10 mm without additional findings^a	MM, SM1
B2 vessel area ≥ 10 mm or macroscopic type 0-I/0-III in B2 vessel area	SM2-3

MM Muscularis mucosa, SM1 Upper third of the submucosal layer, EP/LPM Epithelial/lamina propria
^aAdditional findings are B2 vessel area ≤ 4 mm, B2 vessel area ≥ 10 mm, and macroscopic type 0-I/0-III in B2 vessel area

ISSN: 1471-230X