A multicentre, randomised, phase 3, non-inferiority trial 1 assessed annual vs less frequent mammography (2-yearly after conservation surgery; 3-yearly after a mastectomy) for women aged 50 years or older at initial diagnosis of invasive or non-invasive breast cancer and who were recurrence free 3 years post curative surgery. 5235 women were assigned to annual mammography (n=2618) or less frequent mammography (n=2617). 4576 had invasive disease, 1159 had node positive disease, and 4330 had oestrogen receptor-positive tumours. With a median of 5.7 years follow-up, 343 women died, including 116 who died of breast cancer (61 in the annual mammography group and 55 in the less frequent mammography group). 5-year breast cancer-specific survival was 98.1% (95% CI 97.5 to 98.6) in the annual mammography group and 98.3% (97.8 to 98.8) in the less frequent mammography group (hazard ratio 0.92, 95% CI 0.64 to 1.32), demonstrating non-inferiority of less frequent mammography. 5-year recurrence-free interval was 94.1% (95% CI 93.1 to 94.9) in the annual mammography group and 94.5% (93.5 to 95.3) in the less frequent mammography group.
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