The following is a summary of “Impact of Breast Cancer Screening on 10-Year Net Survival in Canadian Women Age 40-49 Years,” published in the October 2023 issue of Oncology by Wilkinson, et al.

For a study, researchers sought to examine the impact of varying provincial/territorial mammography screening programs, some of which include women aged 40-49 years and others that do not, on 10-year breast cancer (BC) net survival (NS) among women diagnosed at ages 40-49 and 50-59.

The study utilized data from the Canadian Cancer Registry linked to death records. The cohort included Canadian women diagnosed with BC between 2002 and 2007. The analysis compared 10-year NS estimates in regions with organized screening programs that encompassed women aged 40-49 (referred to as screeners, including Northwest Territories, British Columbia, Alberta, Nova Scotia, and Prince Edward Island) and comparator regions without this inclusion (Yukon, Manitoba, Saskatchewan, Ontario, Quebec, New Brunswick, and Newfoundland and Labrador).

Among women aged 40-49 with BC, it was the leading cause of 10-year mortality (90.7% of deaths). Screeners exhibited a 10-year NS of 84.8% (95% CI, 83.8 to 85.8), which was 1.9 percentage points (pp) higher than that of comparators (82.9%; 95% CI, 82.3 to 83.5; P = .001). This difference was significant for women aged 45-49 (2.6 pp; P = .001) but not for those aged 40-44 (0.9 pp; P = .328). Furthermore, the incidence-based BC mortality rate was significantly lower among screeners for women aged 40-49 and 45-49, although not for those aged 40-44. Provincial/territorial NS significantly increased with higher mammography screening participation (P = .003). The BC incidence rate was nearly identical in screener and comparator regions for women aged 40-49 (P = .976) but significantly higher among comparators for women aged 50-59 (P < .001).

Breast cancer screening programs that include women in their 40s were linked to significantly higher 10-year BC NS in women aged 40-49, without an increase in the rate of BC diagnosis. The findings could contribute to screening guidelines for women aged 40-49.

Source: ascopubs.org/doi/full/10.1200/JCO.23.00348