What are the risks of not undergoing a mammogram (mammography) screening?

Risks of Not Undergoing Mammogram Screening

Not undergoing mammogram screening significantly increases the risk of delayed breast cancer diagnosis, resulting in higher mortality rates and more aggressive treatments due to detection at later stages. 1

Evidence for Mammography Benefits

Mammography is the only screening modality proven to reduce breast cancer mortality. The evidence shows:

• Screening mammography results in at least a 22% reduction in breast cancer mortality 1
• Annual screening for women 40-84 years decreases mortality by 40% (12 lives per 1,000 women screened) 1
• Biennial screening for women 50-74 years decreases mortality by 23% (7 lives per 1,000 women screened) 1
• The Swedish Two-County trial demonstrated a 27-31% reduction in breast cancer mortality after 29 years of follow-up 1

Specific Risks of Skipping Mammogram Screening

1. Delayed Cancer Detection

• Cancers detected without screening are typically diagnosed at more advanced stages 1, 2
• Unscreened women are significantly less likely to be diagnosed with ductal carcinoma in situ (DCIS) compared to screened women 2
• Invasive cancers in unscreened women are significantly larger at diagnosis 2

2. Higher Mortality Risk

• Annual screening mammography can reduce breast cancer mortality by up to 40% 1
• Without screening, this mortality reduction benefit is completely lost

3. More Aggressive Treatment Requirements

• Later-stage cancers require more aggressive treatments including:
  • More extensive surgery (potentially losing opportunity for breast conservation)
  • Higher likelihood of requiring chemotherapy
  • More extensive lymph node dissections with increased risk of lymphedema 1
  • Higher morbidity from treatment 1

4. Missed Detection of High-Risk Lesions

• Screening allows detection of high-risk lesions like atypical ductal hyperplasia and lobular carcinoma in situ 2
• Without screening, these high-risk lesions go undetected, missing opportunities for chemoprevention and risk reduction 2

Risk Considerations by Age Group

Women 40-49 Years

• Skipping screening in this age group results in cancers being diagnosed at later stages with larger tumor sizes 2
• Annual screening beginning at 40 provides greater mortality reduction than beginning at 50 1
• The American College of Radiology recommends annual screening starting at age 40 1

Women 50-74 Years

• This is the age group with the strongest evidence for screening benefit 1
• Missing screening in this age range forgoes the clearest mortality benefit

Women ≥75 Years

• Observational studies show women aged 75 may continue to benefit from screening mammography 1
• Decision should be based on life expectancy and comorbidities rather than age alone 1
• Women with severe comorbid conditions limiting life expectancy who would not undergo intervention based on screening findings should not undergo screening 1

Special Risk Populations

For high-risk women, skipping mammography is particularly dangerous:

• Women with prior thoracic irradiation have up to 56.7-fold increased risk of breast cancer 1
• Women with BRCA1/BRCA2 mutations
• Women with strong family history of breast cancer
• Women with personal history of breast cancer or high-risk lesions

Conclusion

The evidence clearly demonstrates that not undergoing mammogram screening increases the risk of breast cancer being diagnosed at a more advanced stage, resulting in higher mortality and requiring more aggressive treatments. The benefits of screening mammography in reducing breast cancer mortality significantly outweigh the potential harms for most women.