Post written by Yohei Koyama, MD, PhD, from the Endoscopy Division, National Cancer Center Hospital, and the Department of Gastroenterology and Hepatology, Tokyo Medical University Hospital, and Masayoshi Yamada, MD, PhD, from the Endoscopy Division and the Department of Genetic Medicine and Services, National Cancer Center Hospital, Tokyo, Japan.
For this study, we aimed to investigate the endoscopic findings that predict muscularis propria invasive (T2) colorectal cancer (CRC) and to establish a scoring system that can effectively differentiate deep submucosal invasive (invasion depth ≥1000 μm [T1b]) CRC from T2 CRC.
Although T1b CRC has a higher than 10% overall risk of lymph node metastasis (LNM), recent studies have reported that the frequency of LNM of T1b CRC without any other risk factors (lymphovascular invasion, grade 2 or 3 tumor budding, and histologic features of poorly differentiated adenocarcinoma/mucinous carcinoma) is approximately 1% to 2%.
Therefore, expanding the criteria of endoscopic submucosal dissection (ESD) for T1b CRC is under discussion. However, reports of endoscopic findings that predict T2 CRC are scarce, resulting in difficulty in distinguishing between T1b and T2 with the current diagnostic methods. To avoid the risk of underestimating T2 CRC as T1b CRC and subsequently performing futile ESD, establishing an endoscopic diagnostic method to distinguish between T1b and T2 is essential.
In this study, 5 independent endoscopic findings that effectively distinguish between T1b and T2 CRCs were clarified (1 point for deep depression, 2 points each for demarcated depressed area and fold convergency, and 3 points each for erosion or white plaque and Borrmann type 2 or type 3 tumor).
The sensitivity and specificity of our scoring system with the cutoff value set at 7 points were 82% and 83%, respectively, and high performance also was confirmed using internal and external validation.
To the best of our knowledge, this is the first scoring system using endoscopic findings to distinguish between T1b and T2. The new scoring system can be applied when determining the appropriate management of T1b and T2 CRCs.
Eight representative potential endoscopic findings of clinical submucosal invasion depth ≥1000 μm or muscularis propria invasive colorectal cancer. A, Loss of lobulation: without lobulation, or fused nodules. B, Deep depression: >3-mm depression vertically with or without a demarcated area (the 3 mm was determined by evaluators’ observation). C, Demarcated depressed area: definite depression with a circumferential margin. D, Protuberance within the depression: exposed neoplastic nodule within a depression resembling a submucosal tumor. E, Expanding appearance: surface of the tumor appearing under tension, with a lustering redness because of expansive growth of the tumor. F, Fold convergency: concentration of folds toward the tumor when observed under sufficient insufflation with full extension of the colorectal folds and until blood vessels surrounding the colorectal cancer can be clearly delineated. G, Erosion or white plaque: covering of tumor with a white material not easily removable after lavage. H, Borrmann type 2 or type 3 tumor: ulcerated carcinomas with sharply demarcated and raised margins or ulcerated, infiltrating carcinomas without definite limits.
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