Interlaboratory reproducibility of the immunocytochemical assessment of oestrogen and progesterone receptors and proliferative activity in fine needle aspiration of breast cancer.

ABSTRACT

The purpose of this study was to establish the interlaboratory reproducibility of immunocytochemical analysis of oestrogen (ER) and progesterone (PR) expression and Mib1 growth fraction on fine needle aspiration (FNA) smears. A set of 44 immunostained slides for ER, PR and Mib1 were randomly selected from the archives of the Center for the Study and Prevention of Cancer (CSPO) of Florence, Italy, and submitted for reading to 6 Italian laboratories. The generalized kappa statistic was used as an indicator of agreement among the six laboratories. A good correlation for ER and PR was evident. For Mib1 the results showed some discrepancies. In addition to adequate standardization of procedures, these data confirm that the reliability of the immunocytochemistry is strictly linked to accurate analysis of the results.