Prostate and breast cancer in four Nordic countries: A comparison of incidence and mortality trends across countries and age groups 1975-2013.

In recent decades, management of prostate and breast cancer patients has changed considerably. The purpose of our study is to interpret patterns of prostate and breast cancer incidence and mortality in four Nordic countries across age groups and time periods. Prostate and breast cancer incidence and mortality data (1975-2013) were obtained from the NORDCAN database. Joinpoint regression models were used to identify changes in the trends. A more prominent increase in prostate than breast cancer incidence was observed. From the mid-1990s, mortality rates in patients below 75 years of age have decreased for both cancers in all four countries. The relative decline in breast cancer mortality from 1985-1989 to 2009-2013 were largest in women under 50 years of age, with reductions in mortality rates ranging from 38% in Finland to 55% in Denmark. In the age group 55-74 years, mortality rates for prostate cancer declined more than for breast cancer in all countries except Denmark, ranging from 14% in Denmark to 39% in Norway. The substantial decrease in breast cancer mortality in women below regular screening age and the reductions in mortality from both cancers in Denmark from the mid-1990s are consistent with beneficial contributions from improved treatment besides mammography screening and increased PSA testing. Alongside similar mortality decreases, the larger increases in prostate cancer incidence as compared to breast cancer indicate that a higher proportion of prostate cancer cases are overdiagnosed.