What does the presence of a "ki-67" proliferation index suggest?

The presence of a "Ki-67" proliferation index indicates the rate of cell division in a tumor, which is a key factor in assessing the aggressiveness of a cancer. Ki-67 is a nuclear protein that is present during all active phases of the cell cycle (excluding resting phase), and its expression level in a tumor sample provides insight into how quickly the cancer cells are proliferating. A higher Ki-67 index typically correlates with a more aggressive tumor that is undergoing rapid division, while a lower index suggests slower proliferation and potentially a less aggressive tumor.

This measurement is particularly useful for oncologists and pathologists when considering treatment options and prognostic implications. In the context of tumor assessment, understanding the proliferation index helps in making informed decisions regarding therapy, especially in cancers where the rate of growth significantly impacts patient outcomes.