According to the National Cancer Institutes’ (2019) latest statistics, over 268,000 women in the United States will be diagnosed with invasive breast cancer this year. While research has made great progress in the area of treatment, the best strategy to improve breast cancer survival rates is to catch it early before it has metastasized. Screening plays a significant role in my annual health care routine due to my strong family history of breast cancer. My primary care providers and specialists recommended that I obtain a breast magnetic resonance imaging (MRI) each year, alternating every 6 months with mammography. In talking with my two sisters, I discovered that they were being given different advice on screening from their health care providers. In addition, the guidelines vary among several leading societies regarding the age to begin initial screening, frequency, and methods for screening. The recent changes to the guidelines are controversial, confusing and are being debated within the medical community. I’ve attempted to provide a simplified summary of the screening guidelines in this blog.
Screening Methods
First, let’s briefly review the screening methods that are available today.
- Mammogram: remains the standard imaging tool used to detect breast cancer. Studies support this method which has been shown to decrease cancer-related mortality (Venkataraman & Slanetz, 2019).
- Screening mammogram: performed in women with no clinical symptoms or complaints
- Diagnostic mammogram: performed in women who have breast symptoms (palpable lump, nipple discharge, or focal pain) or a prior abnormal screening mammogram (mass, calcification, asymmetry)
- Surveillance mammogram: performed in women who have a history of breast cancer.
- Digital breast tomosynthesis (DBT): also known as 3-D mammography, a series of mammograms are taken at various angles and compiled to create a 3-D image; radiation dose is higher, however it may detect more cancers with a lower false positive rate (Venkataraman & Slanetz, 2019). This procedure is more expensive than a conventional mammogram and may not be covered by insurance.
- Ultrasound: not typically used for routine screening in women with average risk; may detect early-stage cancers not found on mammogram, specifically in women with dense breast tissue; often yields false-positive results. Ultrasound may be used as a diagnostic tool following an abnormal mammogram to determine if a mass is solid or fluid-filled.
- Clinical Breast Exam (CBE): performed by a trained health care provider, the clinical physical exam is important to evaluate breast complaints or abnormalities, but is not recommended as part of the screening process for average-risk women as it may increase false-positive rates (Elmore, 2019). However, CBE plays an important role in low-resource areas where imaging is not widely available.
- Breast Self-Exam (BSE): education on breast self-examination has not shown to improve mortality, rather it has increased the number of benign breast biopsies. Advocate for breast self-awareness, instructing patients to note any changes in their bodies and discuss them with their health care provider (Baron, 2018).
- New Imaging Technologies: other supplemental screening tools are being developed but are not routinely used in clinical settings. These include molecular breast imaging and abbreviated first post-contrast acquisition subtracted (FAST) MRI (Freer & Slanetz, 2019).
Risk Profile
Screening method and frequency is determined by a patient’s risk profile. There are several tools available to estimate a woman’s risk for developing breast cancer. The
National Cancer Institute’s Breast Cancer Risk Assessment Tool or Gail Model is used for women who have never had a diagnosis of breast cancer and who do not have a strong family history. This takes into account the patient’s age, race and ethnicity, history of breast disease, age at onset of menses, parity, and relevant family history in first-degree relatives. For women with a strong family history of breast cancer (more than two first-degree relatives with breast cancer), familial risk assessment tools will help identify women who need genetic counseling and/or genetic testing. These include Ontario Family History Risk Assessment Tool, Manchester Scoring System, Referral Screening Tool, Pedigree Assessment Tool, 7-Question Family History Screen, International Breast Cancer Intervention Study Model, and BRCAPRO (Venkataraman & Slanetz, 2019).
Major factors that determine risk category include (Elmore, 2019):
- Personal history of breast, ovarian, tubal, or peritoneal cancer
- Family history of breast, ovarian, tubal, or peritoneal cancer
- Ancestry (i.e. Ashkenazi Jewish) associated with BRCA1 or BRCA2 mutations
- Carrier of pathogenic mutation for hereditary breast and ovarian cancer (self or relative)
- Previous breast biopsy indicating high-risk lesion (i.e. atypical hyperplasia)
- Radiotherapy to the chest between age 10 and 30 years
Screening Recommendations
Screening recommendations are based on a woman’s lifetime risk of being diagnosed with breast cancer (not “dying” from breast cancer) (Elmore, 2019). Below is a summary of the frequency of mammography and supplemental screening recommendations as outlined in the latest guidelines from the
American Cancer Society (ACS) (2015),
U.S. Preventative Services Task Force (USPSTF) (2016), and the
National Comprehensive Cancer Network (NCCN) (2019).
| Breast Cancer Screening Recommendations |
| |
Average Risk
(<15%) |
Moderate Risk
(15 – 20%) |
High Risk
(>20%) |
| Risk Factors |
None of the major risk factors listed above. |
- Personal or family history of breast cancer in a first-degree relative but no known genetic syndrome.
- Extremely or heterogeneously dense breast tissue, per mammogram (Baron, et al., 2018).
|
Any of the major risk factors listed above. |
Frequency of mammogram
(Baron et al., 2018) |
Based on age and breast density:
- Under 40: screening not recommended
- 40-44: annually (NCCN) or at discretion of patient (ACS, USPSTF)
- 45-49: annually (ACS, NCCN) or at discretion of patient (USPSTF)
- Premenopausal with dense breast tissue – consider screening annually (Freer & Slanetz, 2019)
- 50-54: annually (ACS, NCCN) or biennially (screening every 2 years)(USPSTF)
- 55-74: annually (NCCN) or biennially if patient in good health and life expectancy at least 10 years (ACS, USPSTF)
- >75: biennially (ACS) or based on clinical judgment (NCCN)
|
- Annually beginning at age 30 (ACS, NCCN)
- Refer to a high-risk screening clinic for evaluation, increased surveillance, possible genetic testing, and risk reduction treatment (i.e. chemoprevention and prophylactic surgery).
|
| Supplemental screening with MRI or ultrasound |
Not recommended; limited evidence that MRI or ultrasound in addition to mammography provide additional benefit (USPSTF). |
Discuss with patient their personal preferences, risks versus benefits, insurance coverage and availability of imaging method.
No recommendation for or against annual MRI (ACS, NCCN). |
MRI annually beginning at age 30 (ACS, NCCN). |
*Note this table reflects a basic summary of the recommendations. Please refer to the complete guidelines for full details.
Breast Tissue Density
Breast tissue density is commonly categorized using the American College of Radiology’s Breast Imaging Reporting and Data System classification system (American College of Radiology, 2013):
- A - Breasts are almost entirely fatty
- B - Scattered areas of fibroglandular density
- C - Heterogeneously dense (may hide small masses)
- D - Extremely dense (decreases the sensitivity of mammography)
Approximately 50% of women in the U.S. age 40- 60 have dense breast tissue (either heterogeneously or extremely dense) which is associated with an increased risk of breast cancer but not an increased risk of death due to breast cancer. Digital mammography is the preferred method for screening over film mammography. Several states have passed legislation mandating that health care providers notify women about breast density on their mammogram reports. Some states have also required these include recommendations for supplemental screening (i.e. ultrasound and MRI) for women with dense breast tissue.
Potential Risks Related to Screening
As with any medical test or procedure, there are risks associated with breast cancer screening which include (Elmore, 2019):
- False positive results which may lead to unnecessary biopsy procedures and treatments
- Overdiagnosis (disease is found on screening, however it would have not caused morbidity or mortality if it had not been found) may result in unnecessary chemotherapy or surgery
- Patient anxiety and stress related to both false positive results and overdiagnosis
- Exposure to radiation - risk is generally low, however it may be harmful in women with BRCA1 or BRCA2 mutations
- Exposure to intravenous contrast during MRI
- Discomfort during the procedure
Conclusion
It is important for all clinicians to understand the current recommendations and to talk to their patients about their individual preferences regarding breast cancer screening. Every patient has a unique history and profile and each must take into consideration the risks versus benefits. There is no one strategy that fits all however, the better informed you are, the better advice and guidance you can provide to your patients.
Additional Reading and Resources
CE: Breast Cancer Screening - A Review of Current Guidelines
Careful Screening Could Help Some HER2+ Breast Patients Avoid Surgery
Breast Ultrasound & Cancer Detection Rates Increased Under New Laws
When Should Women Have a First Breast Screening? Not Everyone Agrees
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