BACKGROUND AND PURPOSE:

• Richman et al. (Annals of Internal Medicine, 2023) estimated the overdiagnosis rate associated with breast cancer screening among older women by age

METHODS:

• Retrospective cohort study
  • Data derived from SEER Medicare registry
• Population
  • Women ≥70 years
  • Recently received breast cancer screening
  • No breast cancer at baseline
• Exposures
  • Screening continuation in the next interval
  • Exit from screening
• Study design
  • Analyses used competing risk models, and were stratified by age
• Primary outcomes
  • Breast cancer diagnoses for up to 15 years of follow-up
  • Breast cancer deaths for the same period

RESULTS:

• 54,635 women
• For women aged 70 to 74, the rate of potential overdiagnosis was 31%
  • Cumulative incidence of breast cancer
    • Screened: 6.1 cases per 100 women (95% CI, 5.7 to 6.4)
    • Unscreened: 4.2 cases per 100 women (95% CI, 3.5 to 5.0)
• For women aged 75 to 84, the rate of potential overdiagnosis was 47%
  • Cumulative incidence of breast cancer for women aged 75 to 84
    • Screened: 4.9 cases per 100 women (95% CI, 4.6 to 5.2)
    • Unscreened: 2.6 per 100 women (95% CI, 2.2 to 3.0)
• For women 85 and older, the rate of potential overdiagnosis was 54%
  • Cumulative incidence of breast cancer for women aged 85 and older
    • Screened: 2.8 per 100 women (95% CI, 2.3 to 3.4)
    • Unscreened: 1.3 per 100 women (95% CI, 0.9 to 1.9)
• There was no significant reduction in breast cancer-specific death associated with screening
• Absolute risk for overdiagnosis did not differ regardless of age group
  • Range: 1.5 to 2.3 cases per 100 women screened

CONCLUSION:

• Women 70 years and older who continue breast cancer screening face a risk of overdiagnosis
• This increased risk became more marked with increasing age
• The authors state

The relative risk for overdiagnosis increases with age and is highest for the oldest women or those with lowest life expectancy

Overdiagnosis should be explicitly considered when making screening decisions, along with considering possible benefits of screening

Learn More – Primary Sources:

Estimating Breast Cancer Overdiagnosis After Screening Mammography Among Older Women in the United States