Officially High Risk, how does Tyrer-Cusick even work?

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Roccoriel
Roccoriel Member Posts: 17
edited October 2021 in High Risk for Breast Cancer

Hi Everyone!

I'm officially considered high risk and am getting an MRI within the month as a baseline (had my mammo/ultrasound last month and both were as clean as I ever get - cysts...). My main risk factor is my mother (dx at 61 at stage 4), no other breast cancer history in my family. She did not have any harmful variants come up on her genetic test. I also have dense breasts (but this is presumably pretty normal since I'm 35?). I have had one breast biopsy (dx: fibroadenoma, fibrocystic change with focal ductal hyperplasia). I have questions...and my doctor couldn't answer them. Does anyone here know where I could go (or know the answers)?

First: the focal ductal hyperplasia: my doctor said that only atypical increases risk (which is not what I have seen - I've seen that there is some risk involved in moderate to florid usual hyperplasia). How can I tell from the description if it is mild (no risk) or moderate/florid (some risk)?

Second: how does Tyrer-Cusick even work? If I just include my mom's history, I have about a 23% risk. If I include the hyperplasia (which, should I?), it goes up to 41%, which is higher than if I had ADH (huh?). It doesn't include density until I am 40, but if I twist the knobs on age, suddenly my risk is nearly 50%! This seems quite high to me, especially considering I've seen studies that (for example) density and UDH together lead to a 2.45x risk increase, while these are 2x and 1.5-2x risk increases separately, indicating that risk is overlapping not entirely cumulative.

I'm just so confused. It seems like risks jump astronomically. The doctor also said that she "wasn't sure" if she should include the biopsy results or not, since it was "just a fibroadenoma" (since she doesn't seem to count the hyperplasia). But she put the higher number (including my biopsy) on the appointment for the MRI.

Thanks for reading...sorry for the long message and confusion.

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  • Roccoriel
    Roccoriel Member Posts: 17
    edited June 2021

    Sorry to bump my own post (not sure if that is allowed), but I have an MRI Thursday and I'm so nervous about it. I've been thinking a lot about the 23% vs. 41% risk and still don't understand it. I don't know how to determine if the focal hyperplasia should be treated like mild hyperplasia or moderate/florid hyperplasia. Does anyone have any words of wisdom or advice?

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  • ShetlandPony
    ShetlandPony Member Posts: 4,924
    edited June 2021

    I think you need to get yourself to a breast cancer specialist who CAN answer your questions about your risk. It might be a cancer genetics person even though your mom's test did not show a mutation, because these people know how to add up risk factors. But it might be a medical or surgical oncologist with a specialization in breast cancer. If you are in the USA, try calling the nearest NCCN center and tell the intake person what kind of consultation you need.

    https://www.nccn.org/home/member-institutions/

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  • Roccoriel
    Roccoriel Member Posts: 17
    edited June 2021

    Thank you for the link. I will reach out to them and see what they say!


    The hospital/practice I'm going to is supposedly a "breast center of excellence", which is partially why I was surprised that she was not answering my questions, and gave me information that appears to be different that both the model and the research (if usual hyperplasia doesn't increase risk, why does my risk in the model nearly double?).


    Thank you so much for replying.

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  • mariposa1
    mariposa1 Member Posts: 1
    edited October 2021

    I would also like to know more about how these models work.  I just had my first mammogram at 43 and got a callback, which is highly unnerving. The callback was ok but the center where I had my testing had me take the risk assessment and placed me in high risk because i have 3 aunts that have the brca1 gene mutation. My father tested negative and I have as well.

    What I can’t quite figure out is how, when I went to the official ibis site and entered the data my risk was way lower.  The questions were fairly similar with a few exceptions.  

    In some ways it will be good to be able to monitor everything if I am truly as high risk as what they say but in other ways it seems to put me at different risk, significantly different risk, depending on where I fill out the form.

    Am I the only one wondering about why these results are so different even through it’s the same risk assessment model being used? 

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  • leaf
    leaf Member Posts: 8,188
    edited October 2021

    In my humble opinion, breast cancer risk models in general are more art than science. They may give you a 3 figure number (such as 47.8%, taking a number out of the air), but they do not tell you how much confidence you should put in that number. They don't tell you how well they know that 48.7% number.

    I do not have the expertise to tell you why.

    Since I am not a saint, scientist or epidemiologist, the numbers I want are what is MY risk of breast cancer, not how many people in my country will get breast cancer because I am selfish.

    I am NOT a statistic guru. I have classic LCIS, and a gene mutation, while NOT BRCA, is in the BRCA pathway. Only after about 4 consults, including 2 to an NCI-certified tertiary institution, that my GP told me we really don't know my lifetime risk.

    I have been given numbers as varied as "something between 10% and 40% but probably closer to 10% than 40% - if you want better numbers go to the literature" from one of the NCI-certified consults (note that the 'average' woman in the US has about a 12% lifetime risk of BC, and I had never heard of LCIS reducing breast cancer risk), to, in a non-peer reviewed model, up to 85% lifetime risk. Well, 10% is a bit different than 85%. But these are different models. I was told I was high risk, but in other academic papers I would be grouped in a medium risk group. If my risk was really 10%, that would be lower than the average for the general population of women!

    So, how 'high' is 'high risk'? How long is a piece of string? We don't know.

    From what I understand, to develop a model, they need to have all sorts of data on people that do and do not have breast cancer. After they develop the model, they should be comparing their results with their population. So, taking numbers out of the air, the model may predict that 148 people in a population will get breast cancer, and the actual number may be 150. That would be a good model _for the population_.

    But it does not tell you WHICH individual people will get breast cancer. It can give you no information if Leticia, Peter and Nicole will get breast cancer and Felipe, Anh and A.J. will not. A model can be great for the first (148 instead of 150 people in a particular population will get breast cancer, so they can hire the correct number of oncologists, for example.) It can also be awful in the second: if you place Leticia in the breast cancer group, there might be a 60% chance that you are correct and a 40% chance you are wrong. Remember, 50%-50% is a random coin toss, so a 50%-50% model is no good at all. That is what happened in the Gail model in this paper .https://academic.oup.com/jnci/article/98/23/1673/2...So a model that is correct 60% of the time and wrong 40% of the time is better than pure random chance, but not really very good.

    This paper opined the Tyrer-Cusick model was not accurate for atypical hyperplasia https://pubmed.ncbi.nlm.nih.gov/20606088/ or for LCIS https://pubmed.ncbi.nlm.nih.gov/31559544/

    From what I understand, you have to have a risk factor at least as potent as a BRCA mutation to tell a breast cancer population from a benign population. And even then there is quite a bit of overlap. They just do not understand what exactly puts someone at risk for breast cancer.

    I have seen this happen in other medical situations, where a doctor might tell you that you are at 60% risk for something. But they forget to tell you how WELL they know that number. Especially for YOUR risk, not the risk of people in the whole population.

    Unfortunately, there is a lot we don't know about breast cancer.

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