What does KI-67 number mean?

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WaveWhisperer
WaveWhisperer Member Posts: 898
edited June 2014 in IDC (Invasive Ductal Carcinoma)

I keep seeing additional information in the biopsy and pathology reports. What is KI-67 and what does the percentage number mean? Is a low number favorable or not favorable? How does it influence a doctor's recommendation for follow-up treatments after surgery?

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  • SpecialK
    SpecialK Member Posts: 16,486
    edited November 2011

    WaveWhisperer - KI-67 percentages indicate the measurement of a protein that increases as cells divide, which is informative of the rate of cell growth.  A low number indicates slow growth, low is 10% or less, intermediate is 10-20%, high is 20% or above.  The KI-67 number is one of the tools used by oncologists to determine if chemotherapy may be appropriate.

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  • WaveWhisperer
    WaveWhisperer Member Posts: 898
    edited November 2011

    Wow, thanks for that quick and knowledgeable answer!!!

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  • Anonymous
    Anonymous Member Posts: 1,376
    edited November 2011

    Also, my surgeon at Memorial Sloan Kettering says they do not put much stock in it. It is only representative of the particular specimen grabbed in the biopsy--- not necessarily indicative of the entire tumor's agressiveness.

    FWIW

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  • weesa
    weesa Member Posts: 707
    edited November 2011

    This is the one feature of my path report I have never been able to figure out. My Ki-67 is 75%, pretty high. My mitotic rate is a 1. These to seem to contradict each other.

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  • SpecialK
    SpecialK Member Posts: 16,486
    edited November 2011

    weesa - my KI-67 was 43%, mitotic rate 1 - seems inconsistent to me too!

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  • WaveWhisperer
    WaveWhisperer Member Posts: 898
    edited November 2011

    Oh, dear, now there's one more term I'm not familiar with -- mitotic rate. What is it and where do I look for it on my biopsy or path reports???

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  • SpecialK
    SpecialK Member Posts: 16,486
    edited November 2011

    wavewhisperer - kind of the same thing  - speed of cell turnover.  If your pathologist used the Nottingham score on your path report it is comprised of three parts:  mitotic rate, tubule formation and nuclear pleomorphism.  All three are given a score and that is what detrmines the grade of your tumor. 

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  • WaveWhisperer
    WaveWhisperer Member Posts: 898
    edited November 2011

    Special K, thanks for the additional info!

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  • peggy_j
    peggy_j Member Posts: 1,700
    edited November 2011

    SpecialK wrote: If your pathologist used the Nottingham score on your path report it is comprised of three parts:  mitotic rate, tubule formation and nuclear pleomorphism.  All three are given a score and that is what detrmines the grade of your tumor. 

    Thanks for posting this helpful explanation.

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