Measurement of proliferation marker Ki67 in breast tumour FNAs using laser scanning cytometry in comparison to conventional immunocytochemistry.

BACKGROUND: A variety of markers, including Ki67, estrogen receptors (ER), and progesterone receptors (PgR), are frequently measured in fine needle aspirates from human breast carcinomas. Previously, we demonstrated the use of laser scanning cytometry (LSC) for the measurement of Ki67, ER, and PgR in a human breast carcinoma cell line, MCF7 (21). In the present study, we investigated the expression of Ki67 in breast tumour fine needle aspirates (FNAs) using LSC and compared the results to the data obtained using conventional immunocytochemistry (ICC).
METHODS: A total of 11 sets of cytospins of FNAs taken from breast tumours at various stages of tamoxifen treatment were used. For LSC, the cytospins were stained for Ki67 with fluorescein using immunofluorescence; the nuclei were counterstained with propidium iodide. A parallel set of cytospins was stained using horseradish peroxidase and diaminobenzidine and scored manually by conventional light microscopy.
RESULTS: Values for Ki67 obtained using the LSC were generally lower than ICC scores. The changes in Ki67 measured by the LSC were almost all parallel to those obtained by manual scoring of immunocytochemical stains.
CONCLUSIONS: It should be possible to use LSC for the routine measurement of Ki67 marker in FNAs from human breast carcinomas. Copyright 2003 Wiley-Liss, Inc.