What is considered "high risk?"

Arusso,

I don't have any percentage breakdown for high risk.

The most obvious high risk groups are inidividuals who have BRCA 1 and BRCA 2 genes.  Both groups are at high risk for bc and other related cancers (ovarian) and others depending upon which brca is positive (colon, melanoma, pancreatic, etc.), because there are defects in the tumor suppressor genes affecting the body's ability to defend against tumor development.

Other groups of high risk individuals include those with extensive family histories of bc, who haven't tested positive for BRCA genes, but likely have a genetic risk

There are individuals with pre-cancerous conditions which raise risk, including Lobular Carcinoma in Situ (LCIS), as well as Atypical Ductal Hyperplasia (ADH) and Atypical Lobular Hyperplasia (ALH).  Ductal Carcinoma in Situ is considered by many to be cancer and by others to be pre-invasive cancer, so at very high risk, so it is treated aggressively as if early stage cancer.

There are other pathological conditions that put individuals at risk.  I'm sure someone else can jump in with these.

The most common category to get prophylactic mastectomies is, not surprisingly, those with BRCA positive genes.  If you read through the threads here, though, you will find individuals who have gotten prophylactic mastectomies for LCIS, ADH and ALH among other conditions.  Sometimes individuals have both the high risk condition and the family history, which concerns them greatly and they have the prophylactic procedures. 

I'm sure one of our resident "statisticians" can help with the quantitative end of things, although I don't know exactly what you are looking for--what the risk is for each different category?  I have seen quotes that those with ADH have risks of 20 to 25 percent lifetime.  BRCA risks are much higher.  I wish this were an exact science.  It is not.  The Gail score does vary from others, and those are population risks, not your individual risk, which is not as easy to calculate.

arusso, 

I remember when I first came to this board 7 years ago, the generally accepted definition of "high risk" was if someone had a 5 year breast cancer risk that was 2.5% or higher, i.e. an average risk of 0.5% per year.  I just checked this out, and interestingly, the definition of high risk has been changed to a 5 year breast cancer risk of 1.67%, or 0.33% per year (Women with a five-year risk of 1.67 percent or higher are classified as "high-risk".)  This is the risk level at which Tamoxifen can be recommended and I can't help but wonder if the availability of Tamoxifen for high risk women is part of what's triggered the lowering of the bar. 

arusso, since you are 32, any calculation of your lifetime risk will assume that you live to the age of 90, another 58 years. So if your lifetime risk is 25%, that works out to an average risk of 0.43% per year. That might seem to suggest that you are "high risk". However it's important to remember that breast cancer risk isn't evenly spread across all our entires lives - breast cancer risk increases as we age. So perhaps a better way to look at it is by considering that your 25% is just a tiny bit more than double the risk of the average woman. Lifetime breast cancer risk for the average woman in North America is currently 12.4%. Breaking that 12.4% down by age, in her 30s, the average woman's risk is 0.44% - that's over the entire 10 years of her 30s.  Since your risk is approx. double the average woman's risk, it means that your risk in your 30s is around 0.9%.  That works out to 0.09% per year, which would make your 5 year risk only 0.45% - well below "high risk".  So this might be more accurate, but it's inconsistent with the recommendation that you consider taking Tamoxifen. (Breast Cancer Risk in American Women)

What did your biopsies find?  Did they find any high risk conditions or were they totally benign?  That certainly would make a difference in whether you are considered high risk or not. 

As for when a prophylactic mastectomy might be considered, I don't think there is any answer to that. I don't think that at any particular risk level, there are guidelines that say "now you should have a prophylactic mastectomy". At each risk level, different options may be presented on how to address the risk, and at higher risk levels, prophylactic mastectomy is one of the options. Prophylactic mastectomies are quite common among women who have the BRCA mutation and, to a much lesser degree, among women who've already been diagnosed with breast cancer in one breast. Some women who have high or moderate risk conditions such as LCIS or ADH also choose to have prophylactic mastectomies, sometimes with the support of their doctors and sometimes not. If your lifetime risk is 25%, I'd guess that while some doctors would discuss the option of a prophylactic mastectomy with you, few would say that it's necessary or encourage you to choose this option. 25% lifetime risk, if it is considered to be high risk (and that depends in good part on how old you are when you have this 25% risk, i.e. if it's spread over 30 years or if it's spread over 55 years), is at the low end of the 'high risk' scale. 

Not sure how much that helps!