Randomization: Individuals from lists of general practitioners in geographically defined areas of England, Wales, and Scotland; allocation was concealed.
Exclusions: Small (n = 30 in invited group and n = 51 in not invited group) number excluded in each group because could not locate or deceased.
Sample size: 160,921 (53,884 invited; 106,956 not invited).
Consistency of reports: Not applicable.
Intervention: Invited group aged 48 years and younger offered annual screening by MMG (double-view first screen, then single mediolateral oblique view thereafter); 68% accepted screening on first screen and 69% to 70% were reinvited (81% attended at least one screen).
Control: Those who were not invited received usual medical care, unaware of their participation, and few screened prior to randomization.
Cause of death attribution: From the National Health Service (NHS) central register, death certificate code accepted.
Analysis: Follow-up method intention-to-treat (though all women aged 50 years would be offered screening by NHS).
External audit: None.
Follow-up duration: 10.7 years.
Relative risk of breast cancer death, screening versus control (95% CI): 0.83 (0.66–1.04).
Conclusions: Not a statistically significant result, but fits with other studies.
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