In a UK phase III noninferiority trial (Mammo-50) reported in The Lancet, Dunn et al found that less frequent mammographic surveillance was noninferior to annual surveillance in outcomes among patients with breast cancer aged 50 years or older.
Study Details
In the multicenter trial, 5,235 women with invasive or noninvasive breast cancer were randomly assigned between April 2014 and September 2018 to annual mammography (n = 2,618) vs less frequent mammography (n = 2,617) at 3 years post–curative surgery and were followed for 6 years. Less frequent mammography consisted of every 2 years after conservation surgery and every 3 years after mastectomy. Breast cancer–specific survival was the primary outcome measure.
Key Findings
Median follow-up was 5.7 years (interquartile range = 5.0–6.0 years), with a median of 8.7 years post–curative surgery.
At 5, years, breast cancer–specific survival was 98.1% (95% confidence interval [CI] = 97.5%–98.6%) in the annual mammography group vs 98.3% (95% CI = 97.8%–98.8%) in the less frequent mammography group (hazard ratio [HR] = 0.92, 95% CI = 0.64–1.32), demonstrating noninferiority of less frequent mammography at the prespecified 3% margin (noninferiority P < .0001).
The 5-year recurrence-free interval was 94.1% (95% CI = 93.1%–94.9%) in the annual mammography group and 94.5% (95% CI = 93.5%–95.3%) in the less frequent mammography group (adjusted HR = 1.00, 95% CI = 0.81–1.23), demonstrating noninferiority at a 2% margin (noninferiority P = .0024).
Overall survival rate at 5 years was 94.7% (95% CI = 93.8%–95.5%) in the annual group and 94.5% (95% CI = 93.5%–95.3%) in the less frequent group (adjusted HR = 1.07, 95% CI 0.87–1.33), demonstrating noninferiority at a 2% margin (noninferiority P = .0078).
A total of 224 of 345 breast cancer events (64.9%) were detected from emergency admissions or symptomatic referrals back to the hospital system, including 108 of 175 (61.7%) in the annual mammography group and 116 of 170 (68.2%) in the less frequent mammography group.
The investigators concluded: “For patients aged 50 years or older and at 3 years post diagnosis, less frequent mammograms were noninferior compared with annual mammograms for breast cancer–specific survival, recurrence-free interval, and overall survival and should be considered for this population.”
Janet A. Dunn, PhD, of the University of Warwick, is the corresponding author of The Lancet article.
Disclosure: The study was funded by the National Institute for Health Research Health Technology Assessment program. For full disclosures of the study authors, visit www.thelancet.com.
