At what age should women start getting mammograms?

Mammography Screening Starting Age

Women at average risk should begin annual mammography screening at age 40, which provides the greatest mortality reduction and allows detection of earlier-stage disease. 1, 2, 3

Primary Screening Recommendations by Age

Ages 40-44 Years

• Women should have the opportunity to begin annual screening mammography at age 40. 1, 2, 3
• The American College of Radiology strongly recommends annual mammography beginning no later than age 40 for all average-risk women. 1, 3, 4
• Starting at age 40 rather than 45 or 50 provides greater mortality reduction (up to 40% reduction in breast cancer deaths with regular screening). 1, 5
• One in six breast cancer cases occurs in women aged 40-49, and breast cancer is the leading cause of cancer deaths in women under 50. 6

Ages 45-54 Years

• Annual screening mammography is strongly recommended for this age group. 1, 2, 3
• The American Cancer Society provides a strong recommendation for annual screening starting at age 45. 1, 2
• This age group demonstrates the clearest benefit-to-harm ratio for annual screening. 4

Ages 55-74 Years

• Women should transition to biennial (every 2 years) screening at age 55, though annual screening remains an option based on individual preference. 1, 2, 3
• Biennial screening provides adequate mortality benefit with fewer false-positive results in this age group. 4
• Annual screening continues to provide greater mortality reduction than biennial screening, even in this older age group. 3

Ages 75 Years and Older

• Continue screening mammography as long as overall health is good and life expectancy exceeds 10 years. 1, 2, 3
• There is no agreed-upon upper age limit for screening mammography. 1, 3
• Screening decisions should be based on life expectancy and competing comorbidities rather than age alone. 1, 2

Evidence Supporting Age 40 Start

Mortality Reduction Benefits

• Randomized controlled trials demonstrate at least 22% reduction in breast cancer mortality with invitation to screening, with observational studies showing up to 40% reduction in women who are actually screened. 1, 2, 4
• Mortality reduction is significantly greater when screening begins at age 40 rather than age 45 or 50. 1, 2
• Starting annual mammograms at age 40 could save approximately 13,770 more lives annually compared to biennial screening between ages 50-74. 6

Stage at Detection

• Screen-detected tumors are typically smaller and more likely to be node-negative compared to palpation-detected cancers. 1
• Early detection allows for less invasive treatment options and more effective chemotherapy. 5
• Women screened in their 40s are more likely to have early-stage disease, negative lymph nodes, and smaller tumors than unscreened women. 5

Important Caveats and Potential Harms

False-Positive Results

• Approximately 10% of screening mammograms result in recall for additional imaging, though less than 2% result in biopsy recommendation. 2, 3
• False-positive results and unnecessary biopsies are more common in women aged 40-49 compared to older women. 3
• Recall rates are higher with annual screening, but so are life-years gained and breast cancer deaths averted. 5

Technical Limitations in Younger Women

• Mammography sensitivity is lower in younger women (approximately 75% versus 85% in women over 50) due to increased breast density. 7
• Digital breast tomosynthesis (DBT) increases cancer detection rates by 1.6-3.2 per 1,000 examinations compared to standard digital mammography and decreases recall rates. 1, 3, 4

Special Populations Requiring Earlier Screening

High-Risk Women

• Women with family history of breast cancer should begin screening 10 years prior to the youngest age at presentation in the family, but generally not before age 30. 1, 2, 3
• Women with lobular neoplasia or atypical hyperplasia diagnosed before age 40 should undergo annual screening from time of diagnosis, but generally not before age 30. 1, 2, 3
• Women with personal history of breast cancer require annual surveillance mammography. 1, 3
• Women with BRCA mutations or history of chest radiation (especially for Hodgkin's disease) require earlier screening. 8

Guideline Discordance

While multiple organizations provide screening recommendations, there are important differences:

• The American College of Radiology recommends annual screening starting at age 40 for all average-risk women. 1, 3, 4
• The American Cancer Society recommends starting at age 45 as a strong recommendation, with optional screening at ages 40-44. 1, 2, 3
• The Canadian Task Force on Preventive Health Care recommends against screening women aged 40-49 and suggests biennial screening starting at age 50. 1
• The U.S. Preventive Services Task Force recommends biennial screening starting at age 50. 3, 4

The most recent and highest quality evidence (ACR 2024 guidelines) supports starting at age 40. 1

Clinical Breast Examination

• Clinical breast examination is not recommended as a standalone screening method for average-risk women. 1, 3
• The American Cancer Society does not recommend clinical breast examination for breast cancer screening among average-risk women at any age. 1
• Breast self-examination is not recommended because there is a risk of harm from false-positive results and lack of evidence of benefit. 1