Carcinoembryonic antigen staining patterns at the invasive tumor margin predict the malignant potential of colorectal carcinoma.

Immunohistochemical carcinoembryonic antigen (CEA) staining patterns at the invasive tumor margin were correlated with malignant potential in 64 advanced colorectal carcinomas. Twenty-two (34%) carcinomas showed an apical and 42 (66%) a cytoplasmic staining pattern. Carcinomas with a cytoplasmic pattern had a higher incidence of lymph node (71 versus 41%; p < 0.05) and liver (50 versus 23%; p < 0.05) metastasis and higher levels of serum CEA (p < 0.01) than those with an apical staining pattern. Nine of 11 recurrent tumors had a cytoplasmic pattern and 2 had an apical pattern (p < 0.05). Among carcinomas having the same degree of differentiation, those with a cytoplasmic CEA staining pattern were more aggressive. Six (55%) well-differentiated carcinomas with a cytoplasmic pattern metastasized to the liver while none with an apical pattern did (p < 0.05). Moderately differentiated carcinomas with a cytoplasmic pattern had a significantly higher incidence of lymph node metastasis than those with an apical pattern (77 versus 46%; p < 0.05). When colorectal carcinomas are examined at the invasive tumor margin, an evaluation of the CEA staining pattern is useful in recognizing carcinomas having a higher potential to metastasize and recur after curative surgery.