Estrogen receptor content in breast cancer: correlation between biochemical and immunohistochemical methods

Estrogen receptor content of 26 consecutive cases of ductal breast carcinoma was evaluated by using both biochemical and immunohistochemical methods. Agreement was present in 20/26 cases (76.9%). The analysis of discordant cases shows that in 5 cases disagreement is due to sampling error or to prolonged storage before biochemical evaluation. Such cases may reasonably be excluded when correlating results. Linear regression of the remaining 21 cases shows a significant relationship (r = 0.931; p less than 0.001) between biochemical and immunohistochemical values. Results show that immunohistochemical and biochemical assays are largely comparable, and stress the important role of the pathologist in tumor sampling.