MIB-1 (Ki-67) immunostaining of breast cancer cells in cytologic smears.

Objective: The reliability of immunocytochemical evaluation of proliferation activity was tested using the monoclonal antibody MIB-1 on cytologic specimens.

Study Design: The study comprised 83 frozen tissue smears (FTSs) and 51 fine needle aspirates (FNAs) from 119 breast cancer patients. MIB-1 labeling indexes (LIs) were compared with various tumor parameters assessed on histologic material.