| Discussions with women | Additional comments for clinicians |
| What is breast density? |
- Dense breast tissue is not abnormal. Almost half of women have dense breast tissue.
- If you have category "c" breast tissue density, your risk is the same as the risk associated with having a second-degree relative (eg, aunt) who had breast cancer.
- If you have breast density category "d" (extremely dense), your risk is the same as having a first-degree relative with breast cancer.
- Dense breast tissue can make it challenging for the radiologist to identify abnormalities and interpret the examination; thus, the accuracy of mammography is lower.
- Although your risk for developing breast cancer is modestly higher if you have dense breasts, you are not at increased risk for dying of breast cancer.
| - About 43% of United States women have "dense" breast tissue (defined as category "c" [heterogeneously dense] or category "d" [extremely dense] tissue).
- Dense tissue on mammography can mask abnormalities, thus reducing the sensitivity of mammography. The sensitivity of mammography by density category is "a," 88.2%; "b," 82.1%; "c," 68.9%; and "d," 62.2%.[1]
- The increased risk for breast cancer among women with dense breasts is similar to that of having a relative with a history of breast cancer.
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| Calculate her breast cancer risk |
- Many online tools allow you to calculate your risk for a breast cancer diagnosis (eg, estimated risk for a diagnosis in the next 5 or 10 years, or over your lifetime).
- If your lifetime risk for breast cancer is <15%, then no additional screening beyond mammography is generally recommended.
- If your lifetime risk is 15 to 20%, the ACR and ACS suggest that you discuss your concerns and preferences with your provider to determine whether you should have additional screening with other tests. However, not all societies recommend this, and it remains an uncertain area.
- If your calculated lifetime risk is >20%, some groups recommend supplemental MRI annually (eg, alternate every 6 months with mammography and then 6 months later with MRI).
| - The Breast Cancer Risk Assessment tool (www.cancer.gov/bcrisktool/Default.aspx) is an update of the Gail model from the BCSC.[2] This tool does not include breast density information.
- The Tyrer–Cuzick tool is electronically available and may be downloaded from www.ems-trials.org/riskevaluator/.[3] This tool includes information on breast density and takes a little longer to use.[4]
- The approach to supplemental screening for intermediate-risk patients (lifetime risk of 15 to 20%) is controversial. Among major societies, only the ACR and ACS recommend shared decision-making and, potentially, additional screening.
- Many women assume that their risk for breast cancer is higher than it is. The "1-in-9" estimate women may have heard is 1 in 9 women will be diagnosed with breast cancer, not die of breast cancer. Women in the United States are more likely to die of cardiovascular disease than breast cancer.
- Explain risk estimates using absolute numbers and both positive and negative framing (eg, among 1000 women with category "c" density and no other risk factors, the number estimated to be diagnosed with breast cancer over 10 years is 20, meaning 980 in category "c" will not be diagnosed with breast cancer over the next decade).
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| Provide information on screening methods |
- Although screening mammography is not perfect, it is the best-studied tool we have and the only imaging tool that confers reduced deaths from breast cancer.
- Digital mammography is more accurate than the older film mammography if you have dense tissue. 3D tomosynthesis is a newer imaging test that has been less well studied; it may have a lower false-positive and higher cancer detection rate, but the examination may incur additional cost and expose you to more radiation.
| - A randomized controlled trial reported increased accuracy of digital over film mammography for women with dense breasts.[5] However, almost all mammograms in the United States are now digital, so this is less clinically relevant.
- Although 3D tomosynthesis has a lower false-positive rate and may detect more cancer cases, it requires additional exposure to radiation if combined with digital mammography, and women may have to cover the additional cost.
- A large DBT clinical trial is ongoing for patients who want to participate (http://ecog-acrin.org/tmist).[6]
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| Provide information on screening interval |
- If you have dense breasts, consider annual screening.
- If you have fatty (eg, nondense) breasts and no other risk factors, screening every 2 years may be a reasonable risk–benefit balance.
| - The lifetime benefit of annual versus biennial screening among women in their 50s with no other risk factors except density increases the number of breast cancer–related deaths averted by about 2 per 1000 women.
- The risk for false-positive results is almost twice as high with annual than biennial screening; the risk for overdiagnosis and overtreatment also increases with annual screening.
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| Provide information on ultrasonography and MRI |
- Potential benefits
- Ultrasonography and MRI may be able to detect additional cancer that would not be seen on your mammogram.
- Earlier detection from screening may allow less aggressive surgery, chemotherapy, and radiation therapy.
- Potential harms
- Your risk for false-positive results increases with ultrasonography and MRI. False-positive results are when you are asked to return for additional testing but do not have breast cancer. This can be a stressful experience for some women.
- Your risk for having a breast biopsy when you do not have breast cancer increases.
- You will be at increased risk for overdiagnosis (breast cancer that would cause no harm during your lifetime). Because we cannot identify which cancer cases are "overdiagnosed," you may receive overtreatment (eg, unnecessary chemotherapy or surgery).
- Your cost will be higher (especially with MRI).
- IV gadolinium (which has uncertain long-term risks) is required for breast MRI.
| - No long-term studies have provided data on breast cancer mortality for ultrasonographic or MRI supplemental screening.
- Although IV gadolinium carries a risk for nephrogenic sclerosis, this risk primarily affects patients with ESRD who are receiving dialysis. Current practice is to screen patients who may be at risk for kidney disease before administering gadolinium.
- An FDA communication reported the potential adverse effects of gadolinium accumulation in the brain in autopsy findings.
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| Counsel all women on risk reduction |
- A healthy lifestyle has been associated with lower risk for breast cancer (eg, limit postmenopausal weight gain, maintain an exercise regimen, limit alcohol intake).
- If you are at very high risk, you may consider medications (eg, chemoprevention).
- We would discuss prophylactic surgery only if you were at extremely high risk (eg, you had a BRCA genetic mutation).
| - Discuss chemoprevention for women with a 5-year breast cancer risk of ≥3%.[7]
- For women with BRCA mutations, discuss referral to a specialty clinic for counseling and discussion on the role of potential prophylactic mastectomy.
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| Informed decision making |
- What is your understanding of the benefits versus harms?
- What are your personal values and goals for screening?
- I encourage you to make an informed decision that is right for you.
| - A woman's decision may not be what the clinician would recommend.
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