Mammography Guidelines for Average-Risk Women
SUMMARY:
Professional organizations continue to release evidence based guidance on mammography, with ACP the latest to provide updated recommendations. While required frequency and starting age may differ, they all emphasize shared decision making with patients, which entails counseling about uncertainty, risk/benefit and related patient values.
BENEFITS OF MAMMOGRAPHY
- Appears to decrease breast cancer mortality by 15 to 20%
- Studies demonstrate varying magnitude
- ACS (RCT data): Relative risk 0.80 to 0.82
- Recent data from the Canadian National Breast Screening Study did not show decrease when comparing mammography to controls, perhaps due to more recent improvements in treatments but does not take into account advances in imaging
- May increase life expectancy (ACS systematic review) but could not quantitate
HARMS OF MAMMOGRAPHY
False Positives (additional images and benign biopsies)
- USPSTF review
- Collaborative modeling data: Screening biennially from ages 40 to 74 years would result in 1376 false-positive results per 1000 women screened over a lifetime of screening
- ACS review of the same data
- Increased risk of false positive with dense breasts among women 40 to 49
- Callbacks minimized if prior films available
Anxiety and Distress
- May persist even if follow-up is normal
- Financial concerns as patient may be responsible for paying for additional tests
Discomfort
- USPSTF review identified mammography as being a painful procedure
- Follow-up procedures may also result in pain
Overdiagnosis and Overtreatment
- Overdiagnosis is defined as detecting a cancer that would have remained indolent and not become apparent without screening
- Overtreatment is defined as treatment for an overdiagnosed cancer
- Difficult to discern actual number of overdiagnosed cancers
◦ Collaborative modeling data (USPSTF): Screening biennially from ages 40 to 74 years would lead to 14 overdiagnosed cases of breast cancer per 1000 persons screened over the lifetime of screening with a very wide range of estimates (4 to 37 cases) across model - Other organizations such as ACS make the point that certain assumptions may not be verifiable in addition to bias in methodology and design
Diversity, Equity Inclusion Considerations
- USPSTF cites that Black women are 40% more likely to die from breast cancer than Caucasian women with more aggressive cancers at younger ages
- Urgently calling for more research to see if different screening methods are needed for Black women
- ACR updated guidelines to include transgender patients stating “Annual screening at age 40 is recommended for transfeminine (male-to-female) patients who have used hormones for ≥5 years, as well as for transmasculine (female-to-male) patients who have not had mastectomy”
PROFESSIONAL GUIDELINES:
ACOG
- Start Age
- Recommend at age 40
- Screening Interval
- Every 1 or 2 years (shared decision making)
- Stop Age
- Age 75
- > 75 shared decision making including overall health and longevity
USPSTF
- Start Age
- Recommend at 40 years
- Screening Interval: Every 2 years until 74 years
- Stop Age
- ≥ 75 years: Insufficient evidence to recommend for/against
ACS
- Start Age
- Recommend at age 45 years | Consider 40 years if patient desires
- Screening Interval
- 45 to 50 years: annual
- ≥55 years: Every 2 years or can choose annual
- Stop Age
- Continue if good health and life expectancy >10 years
ACR
- Start Age
- Recommend at 40 years
- Screening Interval: Annual
- Stop Age
- “Screening should continue past age 74 without an upper age limit, unless severe comorbidities limit life expectancy or ability to accept treatment.”
ACP
- Start Age
- Recommended at 50 years
- 40 to 49 years: Discuss risks vs benefits and patient preference (“potential harms outweigh the benefits for most women” in this age bracket )
- Screening Interval: Every 2 years
- Stop Age
- Screening not recommended for women ≥75
- Life expectancy ≤10 years
NCCN
- Start Age
- Recommend at 40 years
- Screening Interval: Annual
- Stop Age
- Upper age limit not yet established
- Consider comorbidities that may impact life expectancy (≤10 years)
American Society of Breast Surgeons
- Start Age
- Non-dense breasts (A and B density): 3D preferred modality | Age 40 | No need for supplemental imaging
- Dense breasts (C and D density): 3D preferred modality | Age 40 | Consider supplemental imaging
- Screening Interval
- Annual
- Stop Age
- When life expectancy is <10 years
ADDITIONAL KEY POINTS:
- Clinical Breast Examination (CBE)
- ACOG & NCCN: Offer every 1 to 3 years for women 25 to 39 years and annually for ≥ 40 years
- USPSTF & AAFP: Insufficient evidence to recommend for or against
- ACS, ACP & Canadian Task Force on Preventative Healthcare: Not recommended
- WHO: CBE may be of benefit for women age 50 to 69 years with poor access to healthcare resources
- Most professional organizations find insufficient evidence to recommend adjunctive screening using breast ultrasonography, MRI, Digital Breast Tomosynthesis, or other method in the setting of a normal mammogram and no other risk factors
Learn More – Primary Sources:
ACOG Practice Bulletin 179: Breast Cancer Risk Assessment and Screening in Average-Risk Women
ACOG Clinical Practice Update: Age to Initiate Routine Breast Cancer Screening
Screening for breast cancer: U.S. Preventive Services Task Force recommendation statement
AAFP: Summary of Recommendations for Clinical Preventative Services
NCCN Guidelines: Breast Cancer Screening and Diagnosis
ASBrS: Position Statement on Screening Mammography
WHO position paper on mammography screening
American Cancer Society Recommendations for the Early Detection of Breast Cancer
BI-RADS: Standardizing Breast Imaging and Reporting
WHAT IS IT?
BI-RADS: Breast Imaging Reporting and Data System, was developed by the American College of Radiology (ACR) to standardize mammogram reporting, as well as breast ultrasound and MRI reporting.
The standard mammogram report includes the following
- Indication and type of mammogram (screening/diagnostic)
- Statement regarding breast density
- Description of pertinent findings including size and location, oriented by quadrant and clock position
- Summary of important findings and BI-RADS category
KEY POINTS:
BI-RADS Classification Standardizes Findings and Recommendations for Further Management
BI-RADS 0 : Incomplete
- Recall for additional imaging/comparison with prior examinations, or both
BI-RADS 1: Negative (Essentially 0% chance of malignancy)
- Routine screening
BI-RADS 2: Benign (Essentially 0% likelihood of malignancy)
- Routine screening
BI-RADS 3: Probably benign (> 0% but ≤ 2% likelihood of malignancy)
- 6 month follow-up or continued surveillance
BI-RADS 4: Suspicious (> 2% but < 95% likelihood of malignancy)
- 4A: Low suspicion for malignancy (> 2% to ≤ 10% likelihood)
- 4B: Moderate suspicion for malignancy (> 10% to ≤ 50% likelihood)
- 4C: High suspicion for malignancy (> 50% to < 95% likelihood)
- Tissue diagnosis needed for all BI-RADS 4 categories
BI-RADS 5: Highly suggestive of malignancy (95% likelihood of malignancy)
- Tissue diagnosis needed
BI-RADS 6: Known, biopsy proven malignancy
- Surgical excision when appropriate
Density Categories
- Category a: Breasts are almost entirely fatty
- Prevalence: 10% of the population
- Mammography considered highly sensitive in this setting (88%)
- Category b: There are scattered areas of fibroglandular density
- Prevalence: 43% of the population
- Still sensitive but decreased from category a (82%)
- Category c: Breasts are heterogeneously dense
- Prevalence: 39%
- Small masses may be obscured
- Sensitivity drops to 69%
- Note: Breast cancer risk is 1.2 relative risk compared to average breast density
- Category d: Breasts are extremely dense
- Significantly lowers sensitivity of mammography (62%)
- Note: Breast cancer risk is 2.1 relative risk compared to average breast density
Learn More – Primary Sources:
ACOG Practice Bulletin No 164. Diagnosis and Management of Benign Breast Disorders
ACR BI-RADS® Atlas, Breast Imaging Reporting and Data System
ACOG Committee Opinion 625: Management of with Dense Breasts Diagnosed with Mammography