Early, annual mammograms drive reductions in breast cancer mortalities, study finds

Women who receive early and annual breast cancer screenings have lower mortality rates and benefit more from therapy at the time of diagnosis, according to new research published Nov. 8 in the journal Cancer.  

The researchers found women who receive mammograms have a 60 percent lower risk of mortality from breast cancer within 10 years of diagnosis than those who don’t receive regular screenings. The American College of Radiology (ACR) noted the study—led by László Tabár, MD, professor emeritus of radiology and former medical director of the mammography department at Falun Central Hospital in Sweden—as definitive evidence that therapy is more effective when breast cancers are detected early with mammography.  

“The Tabár study shows beyond doubt that therapy is far more effective when breast cancers are found earlier via mammography,” Dana Smetherman, MD, chair of the ACR Breast Imaging Commission, said in a prepared statement. “Screening and therapy work hand in hand. Annual screening starting at age 40 and therapy are vital to saving the most lives.”  

Tabár and colleagues analyzed data from the Swedish Cancer Registry to find the annual incidence of breast cancer and breast cancer mortality rate in a group of women from Dalarna County, Sweden. They calculated the cohort's annual incidence of breast cancer as well as the annual incidence of breast cancer deaths from two time periods: within 10 years, and within 11 to 20 years of diagnosis.  

Women between the ages of 40 to 69 who had annual mammography screenings between 1977 and 2015 were included. Additionally, data from women who did not receive screenings between the years 1958 to 1976 (pre-screening period) were used for comparison. All patients received standard therapy in accordance with national guidelines at the time.  

From 1958 to 2015, there were 52,438 women aged 40 to 69 years. Of the 52,438 women, 4,513 were diagnosed with breast cancer. Of these women, 3,231 were studied for 20 years after diagnosis.

During this period, 1,061 women died from breast cancer within 10 years of diagnoses and 213 more died from the disease 11 to 20 years after diagnosis.  

The researchers ultimately found breast cancer mortality within 10 years of diagnosis during the screening period was 60 percent lower in those who participated in screening than those who did not. Within 20 years of diagnosis, women who did receive mammograms had a 47 percent lower risk of mortality from breast cancer than those who didn't receive regular screenings.  

“Although some consider that advances in adjuvant therapy and chemotherapy mainly are responsible for improved breast cancer prognosis in screened populations in the modern era, we believe that it is time to focus attention on the combination of diagnosis and therapy, instead of viewing them as independent, or worse, as competing interests,” the researchers wrote.  

The researchers noted that for each breast cancer death prevented by screening, a woman will gain an average of 16.5 life-years and be spared the terminal stages of the disease.   

“Our results, from precise, individual‐based data covering six decades, should provide women and their physicians with reassurance that participating in regular, high‐quality mammography screening is the best way to reduce the risk of a premature death from breast cancer,” the researchers concluded.