This study was designed to look for significant correlations between location of early colorectal cancer, distance from muscularis mucosae to muscularis propria, and the frequency of lymph node metastasis.Methods:
A total of 166 early colorectal cancers, including 67 surgically resected lesions, were evaluated. The cancers were divided into two groups: metastatic and nonmetastatic. Cancer lesions were further subtyped at the fold-top or fold-bottom. Macroscopic classifications and histology were performed. Absolute invasive depth and distance from muscularis mucosae to muscularis propria was measured. Multivariate analysis was used to assess relationships among the variables.Results:
The percentage of polypoid cancer lesions at fold-bottom was higher than at fold-top (74.5vs. 51.8 percent), whereas flat-type cancer lesions at fold-bottom occurred less often than at fold-top (8.2vs. 30.4 percent). Logistic regression showed that deep absolute invasive depth, lymphatic and vessel invasion, and cancer location (at fold-bottom) were the significant risk factors for early colorectal cancers leading to lymph-node metastasis. The distance from muscularis mucosae to muscularis propria with lymph-node metastasis (1,396.7 ± 728.4 μm) was shorter than without lymph-node metastasis (3,533.9 ± 2,507.8 μm;P< 0.01). Multivariate analysis showed that distance from muscularis mucosae to muscularis propria was a statistically significant factor for early colorectal cancers leading to lymph node metastasis (P= 0.0054).Conclusions:
We conclude that early colorectal cancers at the fold-top or with a long distance from muscularis mucosae to muscularis propria have less tendency to metastasize to lymph nodes. Clinically, these results provide evidence of a new indicator of endoscopic mucosal resection for early colorectal cancers at the fold-top.