How much BC risk in breast density?

Early detection of breast cancer: benefits and risks of supplemental breast ultrasound in asymptomatic women with mammographically dense breast tissue. A systematic review.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2760575/?tool=pubmed

Validation of Results from Knowledge Discovery: Mass Density as a Predictor of Breast Cancer.

http://www.ncbi.nlm.nih.gov/pubmed/19760292?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed

As women age, breast density becomes less. If you are peri-menopausal, this may be in your favor. Having a 25% lifetime risk is not bad. How old were your mom and aunt when they had BC? Do you have any history of abnormal biopsies? Are you receiving digital mammograms?

KittyGirl, unfortunately your impression was correct.  Not only does dense breast tissue make it more difficult to see a suspicious area on a mammogram, but for some unknown biological reason, dense breast tissue is at greater risk of developing a malignant tumor.  I don't know how much greater, though.

Here's an article on the National Cancer Institute website that discusses the issue:  http://www.cancer.gov/ncicancerbulletin/NCI_Cancer_Bulletin_102108/page10

Toward the middle of that article is this statement: 

"One concern has been whether the breast cancer associated with dense breasts is due to a "masking effect," where the lack of contrast (tat is, a breast image that is very white throughout) between normal tissue and tumors in dense breasts makes it difficult to discriminate between the two.

"However, this isn't the only explanation for the relationship. "If we look at the risk association over time," says Dr. Taplin, "the longer out we go, the more evident it is that there is a fundamental risk factor that isn't about masking. It's something about the tissue itself."

IMHO, there are 3 main issues that need to be resolved. 

1) How can the mammographic density of a breast be measured objectively (not, "Oh my goodness--you have dense breasts!") and compared to a standard scale of breast density (which doesn't really exist yet)?  So far, there is no agreement on either the measurement tool or the standards to use.

2) Why is dense breast tissue at greater risk of developing malignancies?  Lots of people are working on different angles of this question; much of the evidence leans toward a higher amount of "endogenous" (in-breast) estrogen-synthesizing activity in the dense tissue.  If that were true, then dense breast tissue would be more likely to produce ER+ tumors than ER- tumors... and I don't know if that's the case.

3) What can be done to "modify" breast density; and will a reduction in density reduce the risk of BC?  I've read several times that breast density is a "modifiable" trait; but when I track down the references cited for the statement, the evidence usually isn't there.  Density generally decreases when women go through menopause; but that doesn't happen in all of us.  Women who take HRT tend to have denser breast tissue, so when they quit HRT, their tissue becomes less dense... but what if we never took HRT?  Exercise can decrease the risk of BC, but it doesn't decrease breast density -- in fact, weight loss (loss of fat) tends to increase breast density.  <sigh>  So, what is there to modify?

I wish you luck with this. Nearly 7 years into menopause, I still have "mostly" dense breast tissue in my remaining breast.  But no one seems to agree on a way to factor that into a formula (GAIL-like or otherwise) that will take it into account when predicting BC risk... or, in my case, risk of recurrence or a new primary tumor.

otter 

I guess I've been lucky with the hot-flash part of this.

I did have hot flashes fairly regularly during the first couple of years of natural menopause. Since I live in a hot climate (southeastern U.S.), I was most miserable in the summer but less so in the winter.  I followed all the common-sense guidelines, such as turning down the thermostat, dressing in layers (mostly cotton), using multiple layers of bedcovers instead of one or two heavy ones (mostly switched to cotton blankets etc.), finding things that triggered my flashes and trying to avoid them, etc.

Things calmed down a lot after those first couple of years; but being on Arimidex for BC has brought the flashes back. My med onco is very sympathetic -- when I mark "hot flashes" on my med history update at each visit, she reads it and says, "Oh, I'm so sorry...". 

My flashes still aren't bad, though -- they're really just a nuisance.  And, I never have taken any "supplements" for them.  I figure I'm taking enough stuff as it is (prescription meds) -- don't need to add anything else!  OTOH, some women have a really hard time with them and need some kind of relief.  I have no idea what my GYN would have suggested -- he wanted to put me on HRT when I hit menopause.  I declined, but got BC anyway.  <sigh>

otter 

I recently read about a study that  found that dense beast tissue may be a  growth medium for abnormal cancer cells. The article also said that when dense tissue is found  during a mammogram it is often rated: low density, medium, & high. Those with a score of 75% density or higher have the greatest risk of developing cancer. Also digital mammo find more cancer in dense tissue than film mammo. When I get my next mammo in Jan., I will definitely be asking about my breast density rating and if it has changed over the years.

I found the article at www.dslrf.org  The article was entitled  Study Finds Dense Breast Tissue Increases Breast Risk  (Jan. 31. 2007)

To kind of give you an idea of how much breast density might affect breast cancer risk-at least for a population of women (not an individual woman), this article says the relative risk is about 4, and it increases the c-statistic to about 63-66 (from, in the other paper I cited above) about 59. http://www.ncbi.nlm.nih.gov/pubmed/19276457

Note a relative risk of 4 does NOT NOT NOT mean your risk of breast cancer is 4x ~13% = 52%; it is 4x the risk of a woman WITHOUT any particular risk factors,which is something like about 3-5% = about 12-20%.   We also don't know if multiple risk factors are additive - some risk factors for breast cancer are NOT additive - such as alcohol intake.

In the paper above, "Recent attempts to improve the Gail model by adding infor- mation on other risk factors, such as breast density, have im- proved the concordance statistic somewhat by bringing it up to 0.66 (16,17). However, in most situations, even a concordance statistic of 0.66 is still too low to make management decisions for individual patients.
Why is it so difficult to develop worthwhile breast cancer pre- diction models for individuals? First, the risk factors used in cur- rent models are widely prevalent throughout the population and are neither highly sensitive nor highly specific. In addition, a risk factor must be very strongly associated with a disease (with a relative risk of about 200) to be worthwhile for screening (18), and the same appears to be the case for accurate prediction using combinations of risk factors. Most risk factors for breast cancer are relatively weak. Even “strong” risk factors, such as older age, mammographically dense breasts, and radiation exposure, are as- sociated with relative risks of less than 10. [Deleterious BRCA1 mutations in young women may be an exception (19).] http://www.ncbi.nlm.nih.gov/pubmed/17148763