This bill is extremely important in and of itself. But I also find the fight around the bill really interesting. It highlights some not-so-flattering aspects of our nation's healthcare system as well as the extreme importance of being a well informed, proactive patient in the era of more personalized cancer care.
More on that tomorrow. First, today, let's lay a foundation and focus on the basic facts of the case.
The bill: SB 791 would require that, following a mammogram, women with dense breast tissue be informed by the radiology lab that: 1) they do, in fact, have dense breast tissue, 2) that dense breast tissue makes mammography a less effective screening method, and 3) that they may want to discuss the value of additional screening with their doctor.
What is dense breast tissue? It is not a disease or condition. Women's breasts differ with regard to their fat content. Breasts composed of less fat and more glandular and connective tissue are denser. Denser tissue shows up darker (whiter) on a mammogram, potentially obscuring abnormalities that could be cancer, which also appear white. Here's a good link if you want to see this. A mammogram result will include a score for breast tissue density of between 1 ("almost entirely fatty") to 4 ("extremely dense tissue present").
How much less effective is mammography in women with very dense breast tissue? An often cited 2002 study of 11,000 women out of Columbia-Presbyterian Medical Center in NYC found that while mammography detected 98% of cancer in women with fatty breasts, it found only 48% in women with the densest breasts (2). There are plenty more studies on this.
But there's another troubling aspect to dense breast tissue. It doesn't just hide tumors, it's also a strong risk factor for breast cancer. In fact, it seems that having very dense breasts is a stronger risk factor than family history. So it's a double-whammy.
The association between breast density and increased breast cancer risk was actually first reported over 30 years ago. Since then there have been many confirming studies. The best estimate is that breast density in the highest quartile represents a 4-6 times higher risk of breast cancer. That means that the 25% of women with the densest breasts have about a five times higher than average risk of getting breast cancer. The paper I'm citing comes out of Germany and was published in 2009 (3). It also states that this magnitude of risk "is only topped by age and BRCA1/2 mutation."
Despite all this, a 2010 Harris Interactive poll found that 95% of women don't know their breast density. And 90% don't know that it substantially increases cancer risk. (Sorry, can only find secondary references to thee poll.) It seems clear that there's a communication problem here. And that's what SB 791 is trying to correct.
So why is the mighty California Medical Association (and several other big medical organizations) opposing the bill? They explain their position in a press release from June 2011. But I find the CMA's position and arguments unconvincing.
I also think that the communication problem that gave rise to the legislation is due to larger shortcomings of our healthcare system. Women with dense breast tissue should be cognizant of these shortcomings. And so should breast cancer patients as they navigate different aspects of their treatment in the emerging era of personalized medicine.
I'll write about that tomorrow. After that, I'll highlight some newer screening technologies featured on our main website that might be able to make a real difference for women with dense breasts.
(1) "Governor Jerry Brown...whose aura smiles and never frowns." Couldn't resist. Any time I hear the governor's name those words flow automatically. Evidence of a misspent youth. Be the first to post the reference as a comment and I'll send you a token $5 Starbuck's card.
(2) Radiology. 2002 Oct;225(1):165-75. (PubMed ID 12355001)
(3) Breast Care (Basel). 2009;4(2):89-92. Epub 2009 Apr 24.(PubMed ID 20847885)
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