Ki-67 labeling index indicates?

Ki-67 labeling index indicates?

• A. Cellular proliferation rate
• B. Degree of differentiation
• C. Necrosis extent
• D. Level of inflammation

Answer: (A)

Ki-67 labeling index measures cellular proliferation. Ki-67 is a nuclear protein expressed in all actively cycling cells (G1, S, G2, and M phases) but absent in resting cells (G0). By staining tissue for Ki-67, we determine what fraction of cells are positive, reflecting the tissue’s growth fraction. A higher index indicates more cells are actively dividing, which in tumors often corresponds to faster growth and can influence prognosis and treatment decisions. It does not measure differentiation, necrosis, or inflammation—those aspects are assessed by other features and markers. Remember that the index can vary within a tumor and can be affected by sampling and staining methods.

Ki-67 labeling index measures cellular proliferation. Ki-67 is a nuclear protein expressed in all actively cycling cells (G1, S, G2, and M phases) but absent in resting cells (G0). By staining tissue for Ki-67, we determine what fraction of cells are positive, reflecting the tissue’s growth fraction. A higher index indicates more cells are actively dividing, which in tumors often corresponds to faster growth and can influence prognosis and treatment decisions. It does not measure differentiation, necrosis, or inflammation—those aspects are assessed by other features and markers. Remember that the index can vary within a tumor and can be affected by sampling and staining methods.