Indications For Use
Proliferation index is an important prognostic factor in breast cancer. The Ki-67 protein is expressed in all phases of the cell cycle except G0 and serves as a good marker for proliferation. Studies that have evaluated proliferation index by Ki-67 IHC in breast cancer have shown a significant correlation between high proliferation rates and shorter disease free and overall survival(1-4).
The Ki-67 proliferation index is assessed by point counting 500 to 1000 cells and is reported as percent positive cells. The cut-off to define a high Ki-67 proliferation index is not well-established or universally agreed upon. In our laboratory, we use 20 percent positive cells to define "positive" (i.e. high risk) based on the results of studies we feel are currently the best available in the medical literature (1, 2). See detailed staining procedure.
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