TEST ACRONYM

FULL TERMINOLOGY

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DEFINITION

Ki-67 is a test that detects a protein that is important in cell growth in the nucleus of the cancer cells. If a cell is about to divide there is a lot of this protein present within the nucleus and this can be seen by a special staining technique with a microscope. The higher the number, the greater the growth rate of the cancer. Very fast-growing cancers can have Ki-67 levels of 60 to 80 percent, indicating that 60 to 80 percent of the cells are preparing to divide.

WHEN TEST WOULD BE PERFORMED

If your cancer appears to be aggressive, your doctor may order this test to see if Ki-67 is affecting your tumor growth.

INFORMATION VALUE

Ki-67 is currently considered the most reliable way of estimating how fast the breast cancer grows. Faster growing cancers tend to also have a higher potential to spread to other areas of the body. Knowing your Ki-67 score helps you and your doctor decide what treatment will work best for you.

CAUTION

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