Disentangling shifting demographic and treatment effects on years of life lost to cancer in Denmark

Cancer is increasingly relevant to ageing societies, yet progress in cancer control is difficult to assess when population years of life lost (YLL) to cancer appear stable. Using Danish registers, we followed 4.26 million residents aged ≥50 years (1980-2019) and estimated YLL under observed and counterfactual scenarios, separating demography and incidence from post-diagnosis outcomes. From the 1980s to the 2010s, YLL per individual changed little (men 2.3 to 2.1; women 2.5 to 2.2), while YLL per patient fell markedly (men 8.5 to 5.2; women 9.3 to 5.8). With 2010s incidence and background mortality but 1980s management, YLL per individual would have been 4.2 (men) and 3.9 (women), showing that cancer control averted about half of the life-years otherwise lost. YLL reductions were largest for localized and regional disease (~60 and ~40%) and modest for distant stage (~15%), highlighting persistent losses in advanced cancer and growing survivorship-care needs.