Loss of expression of oestrogen receptor β in colon cancer and its association with Dukes' staging

Gender differences in the incidence and behaviour of colon cancer suggest a hormonal influence and epidemiological data suggest a protective effect for hormone replacement therapy. Recently it has been shown that oestrogen receptor (ER) β is the predominant ER in colon tissue. The aim of this study was to examine the expression and distribution of ERβ in normal and colorectal cancer samples, using immunohistochemistry and (in a subset of patients) real-time quantitative reverse transcriptase polymerase chain reaction in a well-defined patient cohort and to correlate this with clinico-pathological outcome. Immunohistochemical analyses of normal colon revealed strong specific nuclear immunoreactivity in all epithelial cells lining the colonic crypts. In colon cancer, ERβ expression was lost in 21% of samples irrespective of patient age or gender. Interestingly loss of ERβ expression was higher in left colon and rectal cancers (27%) compared to right colon cancers (8%). A correlation between loss of ERβ expression and advanced Dukes stage was observed. Loss of ERβ with increased Dukes' stage suggests that it may be affording a protective effect against colon carcinogenesis. Its presence may be a favourable prognostic marker in this disease and could explain the protective effect of oestrogens against colon cancer development.