Mammography screening for women between the ages of 40 to 49 years is efficient for reducing breast cancer mortality, with reductions in breast cancer death rates in this cohort of nearly 30 percent, found a Swedish study published online Sept. 29 in Cancer.

Barbro Numan Hellquist, from the department of radiation sciences at Umea University in Sweden, and colleagues sought to evaluate Swedish mammography screening in young women, noting that while the “effectiveness of such screening for women ages 40 to 49 years still is questioned, randomized controlled trials have revealed a significant effect for women at or greater than age 40.”

The researchers compared breast cancer mortality rates between women who were living in areas of Sweden that had screening programs for the 40 to 49 year age group for at least six years during the study period between 1986 and 2005 to a control group that included women who were living in areas in which women between the ages of 40 to 49 were not invited to screening during the study period. Both the study and the control group consisting of 620,620 women made up the Mammography Screening of Young Women cohort of all Swedish counties.

The study participants were followed for an average of 16 years, with breast cancer death between ages 40 to 49 years as the primary outcome measure. A prescreening period was defined by the researchers to facilitate a comparison of mortality in the absence of screening, and no significant difference in breast cancer mortality was determined during this prescreening period.

The authors found that during the study period, however, the study group had 803 breast cancer deaths and the control group had 1,238 breast cancer deaths.  

Hellquist and colleagues noted that breast cancer risk reduction rates were greater among women between the ages of 45 to 49 years compared to rates for women between the ages of 40 to 44 years. In addition, a greater reduction was also seen when only women who actually attended screening (vs. those who were invited) were considered.

The authors estimated that breast cancer mortality reductions were estimated to be between approximately 26 to 29 percent in women between the ages of 40 to 49 years invited to screening. 

“All estimates indicated statistically significant lower breast cancer mortality rates in the counties with service screening programs with mammography for women ages 40 to 49,” concluded Hellquist.