Grand Rounds

UK Age RCT Final Results: Breast Cancer Screening Beginning at Age 40 with 23 Years Follow-Up

BACKGROUND AND PURPOSE:

The best age range for mammographic breast cancer screening is still disputed
Duffy et al. (Lancet Oncology, 2020) provides the final report from the UK Age study that sought to estimate the effect of mammographic screening at ages 40 to 48 years on breast cancer mortality

Randomized controlled trial
Participants
- Women 39 to 41 years
Interventions
- Yearly mammographic screening
  - From the year of inclusion in the trial up to and including the calendar year that they reached age 48 years
- Standard care
  - No screening until the invitation to their first National Health Service Breast Screening Programme (NHSBSP) screen at approximately age 50 years
Study design
- Women were randomized 1:2 (intervention: control)
- Intervention group: Recruited by postal invitation
- Control group: Unaware of the study
To study the timing of the mortality effect, the authors analyzed the results in different follow-up periods
- Analysis was on an intention-to-treat basis
Primary outcome
- Mortality from breast cancers diagnosed during the intervention period | Deaths from all breast cancers diagnosed after randomization, but before first NHSBSP invitation
Secondary outcomes
- Mortality from all breast cancers diagnosed after randomization until the data cutoff date
- All-cause mortality
- Incidence of breast cancer

Yearly mammogram screening group: 53,883 women | Control group: 106,953 women
Median follow-up: 22.8 years (IQR 21.8 to 24.0)
Breast cancer mortality was reduced at 10 years of follow-up (P=0.029)
- Breast cancer deaths in yearly screening group: 83
- Breast cancer deaths in control group: 219
- Relative rate (RR) 0.75 (95% CI, 0.58 to 0.97)
Breast cancer mortality was not significantly reduced after 10 years (P=0.86)
- Breast cancer deaths in yearly screening group: 126
- Breast cancer deaths in control group: 255
- RR 0.98 (95% CI, 0.79 to 1.22)
Overall, breast cancer mortality was not significantly reduced by the end of follow up (P=0.13)
- Breast cancer deaths in yearly screening group: 209 deaths
- Breast cancer deaths in control group: 474 deaths
- RR 0.88 (95% CI, 0.74 to 1.03)
There was no significant difference in all-cause mortality
- RR 1.01 (95% CI, 0·96 to 1.05; p=0·66)

Breast cancer mortality was reduced by approximately 25% in women who were invited to a program of yearly mammography screening between age 40 and 48
- There was no benefit seen after 10 years of follow-up
There was no reduction in all cause mortality

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