Mammography Screening Reduces Rate of Advanced and Fatal Breast Cancer
by Hannah Slater/Cancer Network/Home of the journal Oncology
A contemporaneous comparison of women participating in breast cancer screening versus those not participating found that mammography screening reduces the rate of advanced and fatal breast cancers.1
“This study shows that participation in breast cancer screening substantially reduces the risk of having a fatal breast cancer,” Stephen Duffy, MSc, from Queen Mary University in London, said in a press release.2 “Because the comparison of participating with non-participating persons was contemporaneous — with mammography screening and breast cancer treatment belonging to the same time period — it is not affected by potential changes in treatment of breast cancer over time.”
Of 549,091 women, representing approximately 30% of the Swedish screening-eligible population, the researchers calculated the incidence rates of 2,473 breast cancers that were fatal within 10 years after diagnosis and the incidence rates of 9,737 advanced breast cancers (defined as invasive breast cancer measuring >20 mm and/or with ≥4 metastatic axially lymph nodes). Moreover, data on each breast cancer diagnosis and the cause and date of death of each breast cancer case were collected from national Swedish registries. Tumor characteristics were gathered from regional cancer centers.
Ultimately, women who participated in mammography screening were found to have a statistically significant 41% reduction in their risk of dying of 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 < 0.001). Even further, a conservative estimate suggested a significant 34% reduction in cancers that were fatal within 10 years among screening participants.