TOPLINE

Non-pedunculated colorectal lesions smaller than 2 cm carried substantial risk for malignancy and deep submucosal invasion, with more than 20% of early cancers in this size range showing invasion depth ≥ 1000 μm. Surface fullness, dilated blood vessels in tumor periphery, and specific endoscopic patterns were linked to increased depth of invasion.

METHODOLOGY

• Researchers conducted a retrospective analysis of 289 patients (median age, 63 years; 60.9% men) who underwent endoscopic submucosal dissection or surgical resection for non-pedunculated colorectal polyps or early-stage colorectal cancer with diameter < 2 cm at the Affiliated Hospital of Qingdao University in China between January 2015 and November 2024.
• Endoscopic features were assessed using white light endoscopy, magnified chromoendoscopy, and narrow-band imaging magnifying endoscopy.
• Tumor location, size, macroscopic morphology, pit pattern classification, Japan NBI Expert Team (JNET) classification, and pathways of colorectal cancer development were evaluated.
• Researchers constructed a preliminary nomogram and analyzed endoscopic features and risk factors associated with deep submucosal invasion.
• A total of 173 patients had early colorectal cancer, including 38 cases (22.0%) with deep submucosal invasion (≥ 1000 μm), 24 cases (13.9%) with superficial submucosal invasion, and 111 cases (64.1%) with non-submucosal invasive carcinoma.

TAKEAWAY

• Surface fullness (odds ratio [OR], 13.81; P < .001) and dilated blood vessels in tumor periphery (OR, 6.44; P = .003) were strongly associated with deep submucosal invasion.
• JNET2B classification was linked to deep submucosal invasion (OR, 6.43; P = .008), while JNET3 classification showed an even stronger association (OR, 22.94; P = .012).
• De novo carcinoma pathway was associated with deep invasion (OR, 21.61; P = .003), with 71.4% of de novo lesions showing deep submucosal invasion compared with 16.6% of adenoma-carcinoma sequence lesions.
• Chicken skin mucosa (OR, 5.71), surface depression (OR, 12.38), and invasive pit pattern (OR, 161.18) were risk factors associated with malignancy.
• The prediction model showed good discrimination, with an AUC of 0.916 in the training set and 0.881 in cross-validation.

IN PRACTICE

“Non-pedunculated colorectal lesions smaller than 2 cm carry risks of malignancy and deep submucosal invasion. Several factors including ”surface fullness, dilated blood vessels in tumor periphery, JNET2B/3 type, and de novo carcinoma pathway are significant indicators of invasive depth for submucosal deep invasion in early, non-pedunculated CRC less than
2 cm in diameter," the authors wrote. However, “further studies and more data are needed for validation.”

SOURCE

The study was led by Xiao-Yan Yin, Department of Gastroenterology, The Affiliated Hospital of Qingdao University in Qingdao, China. It was published online on July 30, 2026, in BMC Gastroenterology.

LIMITATIONS

The study had a limited sample size from a single center, which may have introduced bias. The number of deep submucosal invasion events was limited relative to the number of candidate predictors, requiring cautious interpretation and validation in larger independent cohorts. The retrospective design using static endoscopic images may have introduced assessment bias.

DISCLOSURES

The study received no specific funding. The authors reported no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.