Professional
Technical
In the Industry Vocabulary Test
Ki-67 index
Pronunciation: KAI sixty-seven
A proliferation marker used to grade neuroendocrine tumors based on percentage of dividing cells.
Full Definition
The Ki-67 index is a measure of cellular proliferation determined by immunohistochemical staining that identifies the percentage of tumor cells in active phases of the cell cycle. In neuroendocrine tumors, the Ki-67 index is a crucial component of the WHO grading system, with Grade 1 NETs having <3% Ki-67, Grade 2 having 3-20%, and Grade 3 having >20%. This marker helps determine prognosis and guide treatment decisions, with higher Ki-67 values indicating more aggressive tumor behavior.
Usage
Usage note: Hyphenate Ki-67 and express index as percentage.
In Context
- "The Ki-67 index was 8%, consistent with a Grade 2 neuroendocrine tumor." — pathology report
- "High Ki-67 index values above 20% indicate Grade 3 neuroendocrine carcinoma." — diagnostic criteria
Also known as
proliferation index
Ki67 labeling index
Don't confuse with
mitotic index
Ki-67 count