By Judy Champaign, M.D., Diagnostic Radiologist
If you’re a woman or a physician who treats woman, you should be aware that starting April 1, California joins Connecticut, Virginia, Texas and New York states with a new breast density notification law.  A two paragraph statement will be included in the results letter a patient receives if dense breast tissue is reported by the interpreting radiologist on her mammogram.   It will explain that breast density may be associated with a higher risk of breast cancer and that it makes mammograms harder to read. 

Judy Champaign, M.D., Diagnostic Radiologist

This information is provided to raise awareness and to encourage a woman to start discussions with her doctor to determine which screening options are right for her.

The law does not mandate either specific additional screening such as an MRI, 3-D mammography, gamma imaging, hand held or automated breast ultrasound, nor does it mandate insurance coverage for additional screening methods.

 What is Dense Breast Tissue?

Dense breasts have a relatively high proportion of glandular or connective tissue (which is white on mammograms) relative to fat (which is gray or black.)  Cancers also appear white and can be hidden in the dense tissue--similar to a white rabbit in a snow bank.  This is nature's variation and NOT an abnormality.  About 40% of women who receive mammograms have dense breast tissue.  This is especially true of women under 50 years old.  Density is only observed on a mammogram and cannot be determined by how breasts feel by physical examination.
 

What Types of Doctor/Patient Discussions are Needed?

Breast density and its effect on mammogram interpretation has been included in reports for a long time.  Breast density is an observation that can vary by radiologist. There is reasonable consistency in the extremes of fatty (10%) and extremely dense (10%) breast tissue.  The variation can be with the categories of scattered fibroglandular tissue and heterogeneously dense the comprise the 80% between the extremes. 

Overall density is sometimes difficult to reliably quantify as breast tissue is not a cube within a capsule.  Instead, patterns are quite variable.  Sometimes the dense tissue is concentrated on one area such as directly behind the nipple or in the upper outer quadrant. There can also be variation from year to year.  The appearance can be affected by weight changes that alter the quantity of fat or by hormones.  Equipment has been developed to attempt to objectively analyze tissue, but it is not widely available and the practical impact and accuracy has not been assessed.

The law can stimulate discussion about overall risk assessment.  Dense breast tissue is a risk factor for breast cancer, but it is not the only risk factor. We don't want women to believe they are destined to have breast cancer because of dense tissue, nor do we want women with fatty breasts to be unconcerned about risks and the need for screening.  Strategies should be tailored to women as individuals.

Excellent risk assessment models exist   incorporate variables such as age, previous high risk breast biopsies, family and personal cancer history, hormonal status and so on.  It has been shown that women and their doctors over and underestimate their breast cancer risk at both ends of the risk spectrum so these models are helpful tools. 

Additional screening tests will undoubtedly find more cancer, but they will also likely result in significant increases in false positives that result in more biopsies and follow up for things that are not cancer.  Ironically, this is at a time when screening critics and U.S. Preventive Services Task Force recommendations have caused confusion for patients and doctors.

What are Additional Screening Tests?

 There’s not enough scientific evidence to show these additional screenings help reduce deaths from breast cancer. Mammography is the only screening that has been effective in doing that.  They are complementary exams and NOT substitutes for mammography. Here are some additional screening tests:

• Breast MRI:  No radiation is involved. This is a very sensitive test that is particularly recommended for women who are carriers of the BRAC1 or BRAC2 genetic mutation and for women with a greater than 20% estimated lifetime risk for breast cancer.  It is a more expensive test and does require the use of IV contrast and may be difficult for women with claustrophobia, but it can definitely identify more abnormalities than other examinations.
• Whole Breast Ultrasound Hand Held:  No radiation is involved. It requires experienced examiners as results are affected by the person performing the survey.  The American College of Radiology (ACR) studied the combined use of physician performed ultrasound and mammography in women with dense breasts at increased risk for breast cancer. More cancers were detected than with mammography alone, BUT there were 4 times more false positives and substantial increase in benign biopsies and follow ups than mammography alone.  Not all cancers were found by ultrasound.  The availability of equipment, staff and other resources are problematic. The final ACR and Society of Breast Imaging (SBI) statement could not recommend screening ultrasound for the general public or in lieu of or in addition to MRI for very high risk women.  There is still ongoing analysis of the research data.
• Whole Breast Ultrasound Automated (ABUS):  No radiation is involved.  In 2012 the first automated breast U.S. was approved by the FDA for screening purposes.   It is promising technology, but not yet widely available.  Insurance coverage may be limited.  Patients are typically charged $200-300 if it's not covered by insurance.
• Breast Specific Gamma Imaging (BSGI) also called Molecular Breast Imaging (MBI): Additional radiation is involved.  This test is highly sensitive like MRI, but is unaffected by hormonal status.  It may be able to prevent unnecessary biopsies for benign findings.  It involves IV injection and the radiation dose is of concern.
• Dedicated Breast CT:  Additional radiation is involved as is IV contrast.  This is emerging technology currently under study.
• 3D Mammography also called Digital Breast Tomosynthesis (DBT):  Additional Radiation is involved.  3D reconstruction of breast images using tomosynthesis is very promising technology for women with dense breast tissue. Two European manufacturer-specific large scale clinical trials have been undertaken. Results from the Oslo study were released January 2013. They showed significant increase in breast cancer detection by 40% and 15% reduction in false positives (call backs.)  An ACRIN study has been proposed to ascertain how DBT should be incorporated into clinical practice since issues of quality assurance, interpretation time, effect on additional  work up, overall cost to healthcare and impact on screening behaviors have not been well studied.

What to do Now

Breast notification laws can make you and your referring physician aware of issues surrounding breast density.  Better information is always good, but there are always unintended consequences of laws.

All dense breast tissue may not be the same.  Now all women categorized as heterogeneously dense or extremely dense will be told they have dense breast tissue even though the effect of density is less in the former category.  Surprisingly, there is very little in scientific literature discussing breast density laws and their effects. Many unanswered questions remain about the biology of breast cancers and breast density.

Many women, when told they have dense breast tissue, will feel they absolutely must have additional testing.  Others may be anxious and confused and drop out of screening altogether.  It is important to have as much information as possible and realistically discuss risk/benefits. 

There's not a lot you can do if you have dense breast tissue, but there may be lifestyle issues that you can control such as hormone therapy, obesity, alcohol intake, and exercise.