Oestrogen receptors and microsatellite instability in colorectal carcinoma patients.

About 10-15% of sporadic colorectal cancers show microsatellite instability (MIN), a mutator phenotype of mismatch repair genes. It seems that oestrogens may inhibit the pathway to colorectal carcinoma which involves a mismatch repair deficiency. Oestrogen receptorial status was evaluated in the neoplastic tissue and uninvolved surrounding mucosa of 17 MIN-positive and 33 MIN-negative tumours using an immunoenzymatic assay. MIN status was examined using the polymerase chain reaction and specific microsatellite markers. MIN was significantly associated with very low levels of oestrogen receptor in tumour tissue. Our findings suggest that MIN-positive tumours might lose a possible oestrogenic modulation mechanism.