The level of erbB-2 expression in both the tumour tissue and serum of indiv
iduals with colorectal carcinoma is unclear. This study aims to clarify exp
ression levels and to relate these to a range of clinicopathological parame
ters. Overexpression of erbB-2 was detected in 25% of patient tumour tissue
and an elevation in serum concentration of the extracellular domain (ECD)
of erbB-2 was detected in 10% of patients. Surprisingly, an elevated serum
ECD concentration did not correlate with erbB-2 overexpression within the p
rimary tumour, and neither tumour or serum levels of the protein correlated
with any clinicopathological parameters examined. These results indicate t
hat erbB-2 overexpression in tissue and serum are not uncommon in colorecta
l carcinoma, but may not be useful as predictors of disease outcome.