ENDOSCOPIC DETECTION OF SUPERFICIAL DEPRESSED COLORECTAL TUMORS AND THEIR CLINICAL SIGNIFICANCE

Abstract

Superficial depressed-type colorectal neoplasms (Ⅱc), first reported in Japan in 1977, have since attracted attention towing to their challenging detection and high malignant potential. Regardless of size, Ⅱc lesions are prone to submucosal invasion and lymph node metastasis. Moreover, they often yield negative results in fecal immunochemical tests (FIT) and are easily overlooked during colonoscopic examinations, rendering them presumed causative lesions of post-colonoscopy colorectal cancer. Therefore, the reliable detection of Ⅱc has substantial clinical significance. Historically termed “phantom cancers”, their recognition has gradually improved with the advent of indigo-carmine dye-based chromoendoscopy and image-enhanced endoscopy, such as narrow-band imaging. Recently, the use of AI assisted detection has been anticipated; however, concerns have been raised regarding operator overreliance on AI, which may lead to diminished vigilance during procedures. To ensure accurate detection, it is essential to improve participation in initial colonoscopy, including among FIT-negative individuals, and maintain high-quality endoscopic practice with constant awareness of Ⅱc during surveillance. Furthermore, establishing systematic training and educational programs to facilitate the recognition and diagnosis of Ⅱc is warranted.