BACKGROUND AND PURPOSE:

• Burton and Stevenson (JAMA Network Open, 2020) assessed the relative mortality reductions associated with mammography and adjuvant therapy among women with early breast cancer

METHODS:

• Secondary analysis of cross-sectional studies
  • Victoria, Australia from January 1982 to December 2013
• Participants
  • Invasive breast cancer
• Data
  • Population-based surveys of breast cancer treatment: From 1986 to 1999
  • Clinical information on breast cancer incidence, mortality, and TNM stage at diagnosis: From 1986 to 2013
  • Mammography data (BreastScreen Program): From 1992 to 2007
• Exposures
  • Participation in mammography screening program
  • Receipt of adjuvant therapy after surgery for EBC
• Study design
  • Breast cancer incidence and mortality data were analyzed for all women with registered invasive breast cancer
  • Breast cancer treatment and screening data were analyzed additionally for the groups of surveyed women
  • Data were analyzed for
    • Associations between crude breast cancer mortality trends and uptake of adjuvant therapy
    • Downstaging by mammographic screening (lowering of stage)

RESULTS:

• Total of 76,630 women with breast cancer from January 1, 1982, to December 31, 2013
• Increase in breast cancer mortality from 1982 to 1994
  • 1982: 31.6 cases per 100,000 women
  • 1999: 34.3 per 100,000 women in 1994
• Significant declining trend in breast cancer mortality from 1994 to 2013
  • 2013: 23.9 per 100,000 women
  • Annual percentage change −1.3% (95% CI, −1.6% to −0.9%)
• By 1994, 74% of all women early breast cancer were receiving adjuvant endocrine therapy
  • Premenopausal: 72%
  • Postmenopausal: 29%
• Crude incidence of advanced-stage breast cancer almost doubled from 1986 to 2013
  • 1986: 12.2 per 100,000 women
  • 2013: 23.9 per 100,000 women

CONCLUSION:

• Mammography did not lead to downstaging of breast cancer from advanced to early
  • Benefit to population mortality is lacking
• The decline in Victorian breast cancer mortality can be attributed to adjuvant therapy uptake and not mammography
• The authors conclude that

We found that adjuvant therapy accounted for the observed 30% mortality decline; given this finding, we propose that BreastScreen should be terminated.

Continuous measurement of breast cancer stages at diagnosis, all-cause and breast cancer–specific mortality, and adjuvant therapy uptake should be mandatory in monitoring and evaluating mammographic screening program

Learn More – Primary Sources:

Assessment of Breast Cancer Mortality Trends Associated With Mammographic Screening and Adjuvant Therapy From 1986 to 2013 in the State of Victoria, Australia

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