Oestrogen receptor-beta as a potential target for treatment in advanced colorectal cancer: a pilot study.

Aims: Oestrogen receptor-beta (ER-β) is expressed in colorectal cancer. Theoretically, ER-β stimulation could slow down tumour proliferation, and this is supported by preclinical research data. While preparing a Phase II trial for advanced colorectal cancer patients we performed a pilot study with three questions: (i) in what percentage of patients do metastases display strong ER-β1 expression; (ii) is there any concordance in expression between primary tumours and metastases; and (iii) is the immunohistochemical (IHC) scoring procedure reproducible?

Methods And Results: Thirty patients were selected, 15 with locoregional lymph node metastases and 15 with either synchronous or metachronous hepatic metastases. All primary tumours and metastases were analysed for immunohistochemical ER-β1 expression according to a predefined scoring system. The scoring was performed independently by two pathologists in order to calculate the weighted kappa value. Strong ER-β1 expression was found in four of 15 hepatic metastases and four of 15 lymph node metastases. In 15 of 30 patients, the level of ER-β1 expression in the metastasis was concordant with that observed in the primary tumour. Weighted kappa values of IHC ER-β1 expression were satisfactory.

Conclusions: In twenty-five per cent of patients there was strong ER-β1 expression in metastases, biopsy of which will be considered mandatory for trial inclusion.