Q&A: A mammographer's take on the dense breast cancer risk issue

Marla Lander, MD, Breast Health CenterThe New England Journal of Medicine recently released a study that concluded that women with dense breasts face more difficulty in breast cancer detected but also have a three times greater risk of cancer.

Health Imaging News spoke to Marla Lander, MD, founder of the Breast Health Center in Indio, Calif., to get the perspective of an experienced mammographer regarding what having dense breasts means for women — and the healthcare providers that care for them — and what course of action should be taken.

Lander is currently involved in a nationwide study of U-System’s automated 3-D digital breast ultrasound system, SomoVu, to test its effectiveness in detecting lesions and occult malignancies in women with dense breast tissue, especially those that were missed by conventional mammograms.

How do women go about determining if they have dense breasts?

If a female of screening age wants to find out if she has dense breasts, she can ask her primary care physician/ordering physician about her BI-RADS density category, as listed in her mammography report. BI-RADS is the national reporting system for mammography, mandated by law. There are two BI-RADS numbers on every mammogram report. One of them has to do with breast density, and the one towards the end of the report has to do with the level of suspicion of the finding on the mammogram. So, what they want to do is look at the density number which is rated on a scale of one to four. Anything in the three or four category is a dense breast.

What are your thoughts on the NEJM report?

It has been known for a long time that there is increased prevalence of breast cancer in women with dense breasts, but this is only valid in certain subtypes of dense breasts. There have been extensive studies on this subject during the past 30-plus years. There’s a much more scientific classification system based on actual pathophysiology instead of percent density present on the mammogram, as is used in the BI-RADS system. I am referring to the Tabar Classification System of mammographic parenchymal patterns, after Dr. Laszlo Tabar, the leader of the largest screening mammography trial in the world. Dr. Tabar published a study in JAMA, in 1982, where he prospectively looked at over 27,000 mammograms, and analyzed whether some breast patterns were at more risk of developing cancer than others. This latest NEJM study was a retrospective one involving three centers, and only around 1,100 paired mammograms. In his study, Dr. Tabar established five mammographic patterns based on thorough large section histologic-mammographic correlation and three of them include dense breasts. Tabar has a pattern 1 which can be scattered glandular density or can include dense tissue. The Tabar patterns one, four, and five are the dense patterns, but only four and five have the increased risk. And pattern four, which is an adenosis pattern, is only found in about 12 percent of the population, and pattern five in about 7 percent of the population. The 1982 study demonstrated double the prevalence of cancer in these two patterns as compared to the other three. So, importantly, you’ve got the vast majority of the population that is not going to have the high-risk dense breast tissue.

For women with dense breasts, what course of action should they take?

The first thing is not to panic because age is a much more significant risk factor than breast density. Taken together, with certain mammographic patterns, they are at higher risk.

What I’m afraid of for women in this nation is that they’ll get their BI-RADS category and go ‘oh my gosh, I have dense breasts, I’m at increased risk’ and then there will be wide spread hysteria. But if they are a pattern one, which is the vast majority of the dense mammograms, they are not at increased risk, other than being female and aging. This latest study might cause some generalized alarm that does not need to be there. It’s only the women with Tabar patterns four and five who need to be concerned about this increased risk, and that is only a maximum of 19 percent of the population.

What type of screening is most effective, and practical?

There is no exam out there that can replace mammography. One of the things brought up in the NEJM and certain letters that came after it was that you could do digital mammography. I don’t think this is much more beneficial than film screen to a well-trained breast radiologist. It still has the limitations inherent in mammography, and I am in no way putting down mammography which has been proven to save lives.

I think the most important second step would be ultrasound. It’s just so instrumental. In my practice, for the last 10 years, if women had dense breasts and were at an increased risk, such as with a strong family history, I always invited and encouraged them to come back for a whole breast ultrasound. However, very importantly, it can’t be done to the exclusion of a mammogram. You really need both together; ultrasound is an adjunctive tool.

So a multi-modality approach is best? What about MRI?

Absolutely. MRI could help too, except MRI is only 65 percent sensitive for ductal carcinoma in situ (DCIS), involves an injection, is time consuming, and is a very expensive diagnostic test. Ultrasound is about one-eighth the cost of a breast MRI. 

Also, there are over 25 different types of breast cancer and MRI is notoriously insufficient at finding one particular type: invasive lobular carcinoma (ILC) – which accounts for about 20 percent of all breast cancers. That’s the one that mammography typically misses too, but ultrasound is excellent at picking it up. There are specific indications to use MRI.  It certainly could help with dense breasts, but it is not a practical, nationwide answer to the dilemma.

It sounds like ultrasound makes a great secondary tool?

Another major benefit of screening ultrasound in dense breast tissue is in the case of an identified breast cancer.  An uncommonly known fact is that 60 percent of breast cancers are multifocal.  This means that when one cancer has been found, and that person has dense tissue, a thorough, bilateral ultrasound should ensue to discover if there are additional foci.

A multi-modality approach seems problematic from a cost standpoint. What are your thoughts?

The major benefit of the current NEJM article is that we hope to raise awareness of a problem that faces the breast imager everyday, and that is dense breast tissue and the need for screening tools in addition to the mammogram.  If Medicare and insurance companies would recognize this need and cover the expense of this very important adjunctive screening tool, I think we would  find a lot more cancers, and catch them much earlier in their evolution, when cure and less aggressive measures are adequate for treatment. It would help revolutionize this field and ultimately cut costs nationally, because small, early cancers don’t require the extensive use of expensive treatments. 

We are basically advocating bilateral breast ultrasound, scanning the dense areas. In these cost conscious days, it does not make sense for breast imagers to do full breast ultrasounds of all of their patients with dense breasts. This would be too time consuming, and our breast centers are already so packed, often requiring many weeks of waiting just to get in for a mammogram.  Clearly, ultrasound should play a key role. In order to make this readily available to the public, and practical to interpret and administer, automated breast ultrasound will become a necessity.