E-cadherin expression in the primary tumors and metastatic lymph nodes of poorly differentiated types of rectal cancer

Purpose. Dysfunction of E-cadherin, a cell-cell adhesion molecule, correlates with the grade of dedifferentiation and/or invasiveness of rectal cancer. However, the relationship between E-cadherin expression in the primary tumor and the potential for metastasis has never been reported. Methods. E-cadherin expression in 43 primary rectal cancer, including 10 poorly differentiated type, and their associated metastatic lymph nodes (LN mets.) were immunohistochemically evaluated. Results. Heterogeneous immunostaining, suggestive of damage to the E-cadherin-mediated cell-cell adhesion system, was seen in 13 of the 28 LN mets positive primary lesions, but in 0 of the 15 LN mets negative primaries. Furthermore, the incidence of heterogeneous immunostaining differed significantly between poorly differentiated and differentiated cancers, being seen in 8 of 10 cases and 5 of 33 cases, respectively (P = 0.0003 by Fisher's exact test). Interestingly, most of the LN mets. foci (25 of 28 cases) showed homogeneous staining regardless of the E-cadherin staining pattern of the primary lesion. Conclusion. Heterogeneous immunostaining of E-cadherin in poorly differentiated rectal cancer was associated with lymph node metastasis. Its staining pattern in metastatic lymph nodes were, however, generally homogenous.