When Should Routine Mammography Begin?
Women should begin routine mammography screening at age 40 years. 1, 2
Current Recommendations for Average-Risk Women
The recommendations for when to begin routine mammography screening have evolved over time, with different organizations providing varying guidance:
- The American College of Radiology (ACR) recommends annual mammographic screening beginning no later than age 40 for women at average risk 1
- The American Cancer Society (ACS) updated their guidelines in 2015, recommending that:
- Women should undergo regular screening mammography starting at age 45 years (strong recommendation) 1
- Women aged 40-44 years should have the opportunity to begin annual screening (qualified recommendation) 1
- Women aged 45-54 years should be screened annually 1
- Women aged 55 years and older should transition to biennial screening or have the opportunity to continue screening annually 1
Evidence Supporting Early Screening
Starting mammography screening at age 40 provides significant benefits:
- Mortality reduction is greater when screening begins at age 40 rather than age 45 or 50 1
- Annual screening results in more screening-detected tumors, smaller tumor sizes, and fewer interval cancers than longer screening intervals 2
- A mortality reduction of up to 40% is possible with regular screening beginning at age 40 2
- Women screened in their 40s are more likely to have early-stage disease, negative lymph nodes, and smaller tumors than unscreened women 2
Risk-Benefit Analysis
The decision to begin screening at age 40 versus 45 involves weighing several factors:
Benefits:
- A 15% reduction in breast cancer mortality for women aged 40-49 years after 10 years of screening 3
- Earlier detection leads to less aggressive treatment options and improved survival 2
- A study showed women with screening-detected cancers in the 40-44 age group had significantly lower incidence of positive sentinel lymph nodes (14.3% vs 44%) compared to non-screening detected cancers 4
- Five-year overall survival was significantly better for screening-detected cancers (94% vs 80%) 4
Potential Harms:
Screening Frequency
- For women aged 40-54, annual screening is recommended for maximum benefit 1, 2
- For women aged 55 and older, either annual or biennial screening may be appropriate, with annual screening providing greater mortality reduction 1
Special Considerations
- For women with family history of breast cancer, screening should begin earlier, typically 10 years prior to the youngest age at presentation in the family, but generally not before age 30 1
- For women with lobular neoplasia or atypical hyperplasia diagnosed prior to age 40, annual screening mammography should begin at time of diagnosis but generally not before age 30 1
- Digital mammography is more sensitive but less specific than film mammography in women aged 40-49 years 3
Duration of Screening
- Women should continue screening mammography as long as their overall health is good and they have a life expectancy of 10 years or more 1
- There is no upper age limit agreed upon for screening mammography 1
- Screening recommendations should be based on life expectancy and competing comorbidities, rather than age alone 1
Global Perspective
Most international guidelines recommend mammographic screening between ages 40-74 years, with ages 50-69 considered the optimal age group for screening by many guidelines 5. However, the trend is increasingly recognizing the benefits of starting at age 40.
Conclusion
While there are varying recommendations, beginning routine mammography at age 40 provides the greatest mortality reduction and allows for earlier detection and treatment of breast cancer. The benefits of starting screening at age 40 outweigh the potential harms, particularly for women who wish to maximize the life-saving benefits of screening.