<scp>MUC1</scp> in Colorectal Carcinoma: Association With Prognosis and Putative Anoikis‐Resistant Structures

Mucin 1 (MUC1) is overexpressed in colorectal cancer (CRC), yet its prognostic value is controversial. In vitro, MUC1 promotes anoikis resistance. Putative anoikis-resistant (AR) structures are clusters of carcinoma cells surviving without matrix contact, and are associated with adverse prognosis. We explored the prognostic role of MUC1 in CRC and its association with putative AR structures. We studied 118 patients with CRC, including 52 with nodal metastases. Immunohistochemical MUC1 expression was analyzed in primary tumors and nodal metastases by estimating the proportions of MUC1-positive carcinoma cells within different subpopulations. In primary tumors, MUC1 expression was increased in most putative AR structure types, and abundant AR structures were associated with elevated MUC1. MUC1 in primary tumors was not prognostic. In nodal metastases, MUC1 levels correlated with those in primary tumors but were lower. High MUC1 levels in both primary tumors and metastases were associated with worse prognosis as compared with expression decreasing in nodal metastases. High MUC1 expression in nodal metastases was associated with synchronous distant metastasis and adverse prognosis. In conclusion, primary tumor MUC1 is not prognostic. In nodal metastases, high MUC1 associates with distant metastasis and poor outcomes. Putative AR structures show high MUC1 expression supporting its role in anoikis resistance.