SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. It is estimated that approximately 300,590 new cases of breast cancer will be diagnosed in 2023 and about 43,700 individuals will die of the disease, largely due to metastatic recurrence. Breast cancer is the second leading cause of cancer death in women, in the U.S.
Currently, the major national health care organizations in the US have different recommendations for screening mammography which has led to some confusion and emotional counterarguments. These several different recommendations include 1) Annual screening at ages 40 to 84 years 2) Annual screening at ages 45 to 54 years and then biennially at ages 55 to 79 years 3) Biennial screening at ages 50 to 74 years.
Elderly women with a history of breast cancer have a higher risk for a second breast cancer diagnosis. However, appropriate mammographic surveillance methods for this patient group, remains unclear. The widespread practice of annual surveillance mammograms for an unspecified period of time after treatment for early breast cancer can be a significant burden of health care costs in the US.
Mammo-50 trial is a multicenter, randomized Phase III study conducted to assess annual mammography versus less frequent mammography for up to 9 years, in women 50 years or older at the time of their diagnosis with breast cancer. The goal of this study was to determine the optimum frequency and duration of mammographic surveillance. In this study 5,235 women were randomly assigned 1:1 to undergo annual mammograms (N=2618) or less frequent mammograms (N=2617). Less frequent mammography was defined as every 2 years in patients who underwent breast-conservation surgery (N=2099) and every 3 years in patients who had a mastectomy (N=518). Eligible enrolled patients were 50 years of age or older, had undergone curative-intent treatment for invasive or non-invasive breast cancer, and were 3 years post-surgery. Approximately 83% of women were aged 55-75 years, and 87% had invasive disease between the two cohorts. The compliance rates were 83% for the annual mammogram group and 69% for the less frequent mammography group. Approximately 35% of patients missed mammograms due to the COVID-19 pandemic. The Primary study outcomes were Breast Cancer-specific survival and cost effectiveness, whereas Secondary outcomes included Recurrence Free Interval and Overall Survival.
The researchers noted that the efficacy outcomes with regards to breast cancer-specific survival, 5-year recurrence-free interval and OS were similar between the two cohorts of patients. The breast cancer-specific survival at 5 years was 98.1% among patients in the annual mammography cohort and 98.3% among patients in the less frequent mammography cohort. The 5-year Recurrence Free interval rates were 94.1% for the annual mammography group and 94.5% among patients in the less frequent mammography cohort. The 5-year Overall Survival was 94.7% in the annual mammography cohort and 94.5% in the less frequent mammography cohort. Even though compliance in the less frequent mammography group was lower, a sensitivity analysis confirmed this had no effect on the outcomes.
It was concluded from this trial that less frequent mammograms were no worse than undergoing annual mammograms for this group of women,
Mammographic surveillance in early breast cancer patients aged 50 years or over: Results from the Mammo-50 non-inferiority trial of annual versus less frequent mammography. Dunn JA, Donnelly P, Elbeltagi N, et al. Presented at SABCS 2023. December 5-9, 2023. San Antonio, TX. Abstract GS03-02.
