Immunophenotypic profiles and prognosis for colorectal mucinous adenocarcinomas are dependent on anatomic location

Background: The prognostic value of mucinous adenocarcinomas (MCAs, exhibiting >50% extracellular mucin) of the colorectum, in relation to their anatomic location is not well studied.

Materials and methods: We compared MCAs (n = 175) with non-MCAs (NMCAs, n = 1015) and the cancer-specific survival rates were evaluated, based on their anatomic site, by univariate Kaplan-Meier and multivariate Cox methods. Subsets of these tumors were immunostained for MUC1, MUC2, Bcl-2, and p53.

Results: MCAs were more commonly found in the right colon, were of high-grade, and were more prevalent in younger patients (<40 years). They exhibited strong expression of MUC2 and Bcl-2 and showed less p53 nuclear staining. In contrast, most NMCAs were low-grade with high expression of MUC1. MCAs of the rectum were associated with poorer outcomes relative to NMCAs (HR 1.85, CI 95% 1.15-2.97), even though the distributions of advanced-stage tumors were similar.

Conclusion: Late-stage disease and age were poor independent prognostic indicators of cancer-specific deaths across all tumor locations. In summary, rectal MCAs have a poor prognosis.