Background: The extent and direction of the impact of COVID-19 pandemic disruptions on cancer mortality remain unclear. We assessed observed versus expected cancer mortality from 2020 to 2023 across 54 countries in 14 regions, by cancer type. Methods: Using WHO Mortality Database, we calculated age-standardized mortality rates (ASMRs) for adults (≥20 years) from all cancers combined and specifically for lung, pancreatic, breast, and leukaemia. Expected ASMRs for 2020–2023 were projected from 2015–2019 using Estimated Annual Percent Change. Rate ratios (RRs) of observed versus expected ASMRs were stratified by year, age group, cancer type, country, and region. Results: The analysis included over 2·3 million annual cancer deaths across 54 countries. Lung cancer was the leading cause of death in 45 countries. Eastern Europe had the highest mortality in 2020–2023, with Hungary reporting the highest ASMR (222·6/100,000). Overall, observed mortality was lower than expected (RR <1). Differences were modest in 2020 but widened by 2023. The largest discrepancies were for breast cancer (RR 0·62–1·19) and leukaemia (0·67–1·18), while lung (0·87–1·16) and pancreatic cancers (0·91–1·20) showed smaller differences. Regional variation was notable, with Western Asia showing the widest difference from expected. Conclusions: Differences in expected mortality were limited for poor-prognosis cancers, while breast cancer and leukaemia were more affected during long-term healthcare disruptions. Regional disparities illustrate the negative impact of compounding crises on cancer mortality and underscore the need for resilient systems to protect cancer care during emergencies.

Rate ratio between observed and expected age-standardized mortality rates, all cancers combined, by region and age group, 2020–2023