Incidence, Mortality and Survival Trends in Breast Cancers Coincident with Introduction of Mammography in the Nordic Countries

SIMPLE SUMMARY: Mammography has been introduced in many countries for the early detection of breast tumors and thus prevention of deaths in breast cancer. Survival in breast cancer has universally improved but it is not known to what extent mammography may have contributed to this positive development. National mammographic screening was offered to women in Finland and Sweden since the 1980s and in Denmark and Norway since the 1990s. We assessed, at the national level, if relative survival had improved after the introduction of the screening activities in age groups that were screened compared to those not screened. We observed an improvement in five-year and 10-year survival after the period of national mammography screening was in place. Timing and age-specific targeting of the improvements suggest that mammography may have contributed these. However, as we had no individual data on women who used the service, more detailed studies are needed to confirm the suggested survival advantage. ABSTRACT: Survival in female breast cancers has generally improved but the relative contribution of early detection or treatment in this positive development is not known. Our aim was to assess the possible role of national mammography screening programs in survival improvement. Such screening has been offered to women, usually at 50–69 years of age, in Finland and Sweden since the 1980s and in Denmark and Norway since the 1990s. Participation rates have been high, ranging from 60% to 90%. We analyzed incidence and mortality changes and relative 5- and 10-year survival trends in breast cancer as novel measures in these countries using the NORDCAN database. Survival trends were compared in age groups of women who were screened to those who were not screened. We observed a relative survival advantage in 5-year and 10-year survival in the screened age groups after the period of national mammography screening was in place and this was consistent in each country. Timing and age-specific targeting of the improvements suggest that mammography may have contributed to the survival benefits. However, as we had no individual data on women who used the service, more detailed studies are needed to confirm the suggested survival advantage, particularly concerning mortality in stage-specific breast cancer.