Mucin phenotypes and clinicopathological features of colorectal adenocarcinomas: Correlation with colorectal adenocarcinoma with enteroblastic differentiation

Background: The mucin phenotypes of colorectal carcinoma (CRC) is related to the biological behavior and prognosis. But there has been no studies evaluating phenotypic characteristics in a large number of cases. Furthermore, colorectal adenocarcinoma with enteroblastic differentiation (CAED) is a rare subtype of CRC and having poor prognosis. The aims of this study were to clarify the correlation between mucin phenotypes and tumor development, including biological behavior in CRC, as well as to investigate characteristic of mucin phenotypes in CAED.

Methods and results: 974 CRC cases and 42 CAED cases of CRCs were classified five types (large-intestinal, small-intestinal, gastric, mixed, and unclassified) of mucin phenotypes by using immunohistochemistry (IHC). IHC was performed on tissue microarrays with antibodies against followings: MUC2, MUC5AC, MUC6, and CD10. In CRCs, large-intestine type has a relatively better prognosis, small-intestinal type frequently shows venous invasions, and liver metastases, gastric type has more high-histological grades and lymphatic invasions, mixed type shows originating from the right side of the colon, larger tumor size and mucinous type, but less venous invasions and liver metastasis, whereas the unclassified type showed poorer prognosis in overall survival with statistical significance. The majority of CAED were found to be small-intestinal type or unclassified type.

Conclusions: The phenotypic classification is useful for predicting the prognosis of CRCs. Small-intestinal type and unclassified type showed dismal prognosis in CRCs. We speculate that CAED having aggressive behavior and poor prognosis might reflect characteristics of small-intestinal and unclassified types.