Introduction The oestrogen receptor β (ERβ) is the primarily expressed ER in the large intestine and has been found to have inhibitory effects on colon cancer cells. We therefore investigated, whether the ERβ expression in tumour tissue from colorectal cancer (CRC) patients is associated with tumour/clinical characteristics.

Methods We used tissue micro arrays consisting of paired normal and tumorous tissue samples from 1262 CRC cases of a German population-based case-control study (DACHS). ERβ expression was measured via immunohistochemistry. Multinomial logistic regression was used to assess the association of ERβ expression with tumour/clinical characteristics.

Results Measurement of ERβ expression was successful in 1101 patients. ERß was strongly expressed (>50% positive cells) in normal intestinal tissue, whereas high ERβ expression was found in 16%, moderate expression in 29% and no expression in 42% of tumour samples. Strong vs no expression of ERβ was inversely associated with higher UICC stages (stage II OR=0.42, 95% CI (0.26 to 0.66); stage III OR=0.40, 95% CI (0.25 to 0.65); stage IV OR=0.52, 95% CI (0.29 to 0.92); p trend=0.01). Furthermore, cases with strong ERβ expression had a significantly smaller tumour extent (T2 OR=0.51, 95% CI (0.24 to 1.10); T3 OR=0.24, 95% CI (0.11 to 0.49); T4 OR=0.24, 95% CI (0.10 to 0.60); p trend<0.001) than cases with no expression. No significant associations were seen with histopathological grading, nodal status, distant metastasis, tumour localisation, neoadjuvant treatment, age or sex.

Conclusion We observed an association between high ERβ expression and smaller tumour extent and confirmed previous reports of an association between high ERβ expression and less advanced tumour stages.