Tumor cell proliferation, proliferative index and mitotic count in lung cancer
The rate of cellular proliferation, expressed either as a Ki-67 proliferative index (PI) by immunohistochemistry (IHC) or as a mitotic count by H&E is a reflection of tumor cell division. Although both assess the uncontrolled proliferation of a cancer, they measure different phases of the cell cycle. Like each test, as Drs. Kriegsmann and Warth mentioned, both these parameters are subject to preanalytic and analytic bias, lack of standardized methodology and interobserver variation. Despite all these drawbacks, multiple studies have shown a good correlation between Ki-67 PI and mitotic count (1-12).