Expression and Prognostic Value of Oestrogen Receptor Beta in Colorectal Cancer

Differences between men and women in the incidence and biological mechanisms of colorectal cancer (CRC) suggest that estrogens may play a role in the pathogenesis of this disease. The identification of the human estrogen receptor beta (ERβ) and its expression in the intestinal mucosa led to further studies that revealed that estrogens have a protective function against CRC mediated by the activation of ERβ. However, ERβ expression and its role in CRC is controversial. The purpose of this study was to determine the distribution and prognostic value of ERβ expression in the intestinal mucosa of patients diagnosed and surgically treated for CRC, and its association with other known prognostic factors. A total of 109 paraffin-embedded samples of the wild-type ERβ isoform were analyzed by immunohistochemical nuclear staining in patients with colorectal adenocarcinoma. Clinical/pathological and survival data were collected. Immunohistochemical quantification was performed using the category scoring system, which has been validated for assessing estrogen receptor alfa. The wild-type ERβ isoform -also called ERβ1- was positive in 101 patients (92.7%) and negative in nine patients (7.3%). Univariate analysis revealed that the absence of expression of the ERβ1 gene was correlated with mucinous adenocarcinoma (p < 0.05). Also, a non-significant tendency was observed for ERβ expression to be down-regulated in advanced tumors. With a median follow-up of 47 months, the overall survival and progression-free survival were not found to be associated with ERβ1 expression (p = 0.2). Although the wild-type ERβ isoform was expressed in most study patients with colorectal cancer, it does not seem to have any prognostic value for the course of the disease. Further studies should be conducted to investigate whether the down-regulation of ERβ expression has any biological function in mucinous colorectal cancer.