Mammography screening reduces rates of breast cancer mortality

A recent study found that screening mammography significantly reduces breast cancer mortality in women with advanced and fatal breast cancers.¹ The study, published in the American Cancer Society’s Cancer, found these results to be independent of recent changes in treatment regimens.

The results show that participating in screening mammography is essential for reducing the number of deaths from breast cancer and can ultimately save lives through early detection.

While previous research has shown that invitation to and participation in mammographic screening significantly reduces rates of breast cancer mortality, it had not been addressed independently from changes in treatment. Therefore, a team of Swedish researchers evaluated this by measuring the incidence of fatal breast cancer based on the date of diagnosis and not on the date of death. 

Researchers used data from the Swedish Cancer Register on more than a half million women aged 40 to 69 from 9 Swedish counties, which accounts for approximately 30% of the Swedish screening-eligible population. The authors calculated the incidence rates of 2,473 breast cancers that were fatal within 10 years after diagnosis and of 9,737 advanced breast cancers.

The cause and date of death of each patient who died from breast cancer were retrieved from the Swedish Cause of Death Register of the Swedish National Board of Health and Welfare. The researchers also collected data on tumor characteristics to define advanced breast cancer as invasive breast cancer measuring > 20 mm and/or with ≤ 4 metastatic axillary lymph nodes.

The study ultimately showed that women who participated in screening mammography had a statistically significant 41% reduction in risk of dying from breast cancer within 10 years (relative risk, 0.59; 95% CI, 0.51-0.68 [P≤ 0.001]) and a 25% reduction in the rate of advanced breast cancers (relative risk, 0.75; 95% CI, 0.66-0.84 [P < .001]).

“The choice of whether or not to attend mammography screening becomes important in an era in which all women in a defined age cohort are invited to organized service screening, and programs are expected to describe the benefits and harms associated with participation,” said the authors.

“The benefits of participating in mammography screening are truly substantial,” noted the authors, “and save lives that would have been lost under the prevailing therapy at the time of diagnosis.”

References:

1. Duffy SW, Tabár L, Yen, AM‐F, et al. Mammography screening reduces rates of advanced and fatal breast cancers: Results in 549,091 women. Cancer. 2020. doi:10.1002/cncr.32859