Purpose: Submucosa-invasive colorectal carcinoma is a colorectal carcinoma extending only into the submucosal layer. To clarify the metastatic potential of submucosa-invasive colorectal carcinoma, we studied the relationship between the immunohistochemical staining pattern of carcinoembryonic antigen (CEA) and that of lymphatic invasion/lymph node metastasis.
Methods: We investigated 49 submucosa-invasive colorectal carcinomas resected surgically or endoscopically. CEA distribution patterns of the neoplastic tissues were divided into three patterns: Pattern 1 = luminal type; Pattern 2 = apical cytoplasmic type; and Pattern 3 = diffuse cytoplasmic type. We also observed the submucosal stromal staining of CEA.
Results: Lymphatic invasion and lymph node metastasis were found in 48.8 percent (21/43) and 11.6 percent (5/43) of the Pattern 2/Pattern 3 cases, whereas these were seen in none (0/6) of Pattern 1 cases. Lymphatic invasion and lymph node metastasis were found in 63.3 percent (19/30) (chi-squared = 21.94; P < 0.001) and 16.7 percent (5/30) of the positive stromal CEA cases, whereas these were seen in 10.5 percent (2/19) and none (0/14) of the negative stromal CEA cases, respectively.
Conclusion: Pattern 2/Pattern 3 and stromal CEA can be predictors of the lymph node metastasis with 11.6 percent and 16.7 percent risks.