Colonoscopic stigmata of 1 mm or deeper submucosal invasion in colorectal cancer

PURPOSE: This study was designed to identify colonoscopic stigmata, indicating substantial invasion into the submucosa by T1 colorectal cancer with sessile morphology, including both flat and protruded types. METHODS: A total of 111 Tis or T1 colorectal cancers were studied retrospectively. The lesions were divided into two groups: Group A (n=83), Tis or T1 cancers with < 1 mm submucosal invasion; and Group B (n=28), T1 cancers with a >= 1 mm submucosal invasion. Printed photographs of the lesions were reviewed by five experienced colonoscopists who were blinded to histology. Deep depression, irregular surface, ulceration or erosion, fold convergence, and spontaneous bleeding were independently evaluated. Findings considered present by three or more reviewers were defined as positive. Kappa analysis was used to measure inter/intraobserver variability. RESULTS: Positive rates of four findings but not fold convergence were significantly higher in Group B than in Group A. Irregular surface and spontaneous bleeding were significant independent predictors of >= 1 mm submucosal invasion, with diagnostic accuracies of 85.6 and 76.6 percent, respectively. Kappa analysis demonstrated fair-to-good inter/intraobserver agreement for spontaneous bleeding and fair-to-good intraobserver agreement for irregular surface. CONCLUSIONS: Irregular surface and spontaneous bleeding were colonoscopic stigmata, indicating >= 1 mm submucosal invasion in T1 colorectal cancer.