Meeting Coverage
SABCS
December 9, 2023
SAN ANTONIO — Women ages >50 who de-escalated to less-frequent mammography 3 years after curative surgery for early-stage breast cancer had similar outcomes to women who received annual mammography, according to a phase III study.
In the Mammo-50 trial, after a median follow-up of 5.7 years for alive patients, breast cancer-specific survival was 98.1% and overall survival (OS) was 94.7% among patients randomized to annual mammography, compared with 98.3% and 94.5%, respectively, among patients assigned to less frequent mammography, reported Janet Dunn, PhD, of the University of Warwick in England.
“Mammo-50 provides evidence for changing clinical practice,” Dunn said in a presentation at the San Antonio Breast Cancer Symposium.
Current guidelines in the U.S. and Europe recommend annual surveillance mammograms for an unspecified period after treatment for early breast cancer, whereas U.K. guidelines recommend annual surveillance mammograms for up to 5 years, then reverting to every 3 years, without specified risk stratification. However, the optimal screening schedule has not been evaluated in large clinical trials, she said.
“We know that annual mammograms are a significant cost burden to the health system and also causes anxiety to patients,” she said.
Mammo-50 enrolled 5,235 women (around 44% were ages 60-70) at the time of breast cancer diagnosis who had undergone treatment with curative intent for invasive or noninvasive breast cancer and who were 3 years postsurgery. They were randomized from April 2014 to September 2018 to receive annual mammography or less-frequent mammography, defined as every 2 years in patients who underwent breast conservation surgery and every 3 years in those who underwent mastectomy. The study had a noninferiority-inferiority design.
The hazard ratio (HR) for less frequent mammography compared with annual mammography on breast cancer-specific survival was 0.92 (95% CI, 0.64-1.32), with noninferiority (NI) of less frequent mammograms demonstrated at a 3% margin (NI P<0.0001) and 1% margin (NI P=0.003).
noninferiority of less frequent mammograms on OS was demonstrated at 2% margin, with an HR 1.08 (95% CI 0.87-1.33, NI P=0.008)
As with the mortality outcomes, recurrence-free survival was also similar between arms: 5.9% of patients in the annual mammography arm and 5.5% in the de-escalation arm had a recurrence. The HR for less frequent mammography versus annual mammography on recurrence-free survival was 1.00 (95% CI 0.81-1.24), with noninferiority of less frequent mammograms demonstrated at a 2% margin (NI P=0.006).
A total of 15,967 mammograms were performed in the annual arm and 8,662 in the less frequent arm. Compliance with the allocated schedule was 83% women in the annual arm versus 69% in the less frequent arm. Of the 452 women who missed their scheduled mammogram, 35% did so because of the COVID-19 pandemic. The 76% overall who complied defined the per protocol but the conclusions didn’t change after a sensitivity analysis of the compliant population,