Changes in 1‐year relative survival of patients with cancer during the <scp>COVID</scp> ‐19 pandemic in Denmark, Finland, Iceland, Norway, and Sweden: A population‐based cohort study

During the first year of the COVID-19 pandemic, reported cancer cases declined in the Nordic countries, potentially reflecting delays in cancer diagnosis. We compared 1-year relative survival (RS) and excess mortality of patients diagnosed with cancer in the Nordic countries in March-December 2020 with that expected based on patients diagnosed in 2011-2019. We used flexible parametric RS models, defining excess mortality as the difference in total mortality between patients with cancer and the national population without cancer. We report the ratio between the observed and expected excess mortality (EMR) and the difference in 1-year RS in percentage points (pp) by country, age, sex, and cancer site. Excess mortality of patients diagnosed during the pandemic was increased in all Nordic countries except Iceland. Swedish men had the highest EMR of 1.12 (95% CI 1.06, 1.17), corresponding to a 1.4 pp reduction in 1-year RS (87.1%-85.8%). In women, the highest EMR was 1.10 (95% CI 1.03, 1.18) in Norway, corresponding to a 1-year RS decrease of 1.2 pp (86.6%-85.5%). The largest site-specific decreases in 1-year RS were observed for liver cancer in Finnish and Swedish men, with decreases of 10.2 pp (45.3%-35.1%) and 7.2 pp (55.7%-48.5%), respectively. We found reduced 1-year RS among Nordic patients diagnosed with cancer during the COVID-19 pandemic in 2020, especially in older patients and those with aggressive cancers. These reductions coincided with restrictions and potential delays in seeking healthcare.