Potential global loss of life expected due to COVID-19 disruptions to organised colorectal cancer screening

Abstract

Background: Screening for colorectal cancer (CRC) decreases cancer burden through removal of precancerous lesions and early detection of cancer. The COVID-19 pandemic has disrupted organised CRC screening programs worldwide, with some programs completely suspending screening and others experiencing significant decreases in participation and diagnostic follow-up. This study estimated the global impact of screening disruptions on CRC outcomes, and potential effects of catch-up screening.

Methods: Organised screening programs were identified in 29 countries, and data on participation rates and COVID-related changes to screening in 2020 were extracted where available. Four independent microsimulation models (ASCCA, MISCAN-Colon, OncoSim, and Policy1-Bowel) were used to estimate the long-term impact on CRC cases and deaths, based on decreases to screening participation in 2020. For countries where 2020 participation data were not available, changes to screening were approximated based on excess mortality rates. Catch-up strategies involving additional screening in 2021 were also simulated.

Findings: In countries for which direct data were available, organised CRC screening volumes at a country level decreased by an estimated 1.3-40.5% in 2020. Globally, it is estimated that COVID-related screening decreases led to a deficit of 7.4 million fewer faecal screens performed in 2020. In the absence of any organised catch-up screening, this would lead to an estimated 13,000 additional CRC cases and 7,900 deaths globally from 2020 to 2050; 79% of the additional cases and 85% of additional deaths could have been prevented with catch-up screening, respectively.

Interpretation: COVID-19-related disruptions to screening will cause excess CRC cases and deaths, but appropriately implemented catch-up screening could have reduced the burden by over 80%. Careful management of any disruption is key to improving the resilience of colorectal cancer screening programs.

Funding: The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by Cancer Council New South Wales, Health Canada, and Dutch National Institute for Public Health and Environment.

Keywords: Bowel cancer; COVID; COVID-19; Cancer policy; Cancer screening; Colorectal cancer; Coronavirus; Epidemiology; Global health; Modelling; Policy evaluation; Public health.

Fig. 1

High-level schematic of the modelling method for generating estimates of the global impact of COVID-related organised screening decreases on long-term CRC burden. For additional details, see Appendix B—Additional modelling methods. CRC: Colorectal cancer.

Fig. 2

Relative decreases to organised screening participation in 2020 vs local 2020 excess all-cause mortality rates. For areas where 2020 screening data was unavailable, the best fit was used to calculate the imputed screening decrease. These decreases were used to model Scenario A.1 and A.2. The shaded region shows the 95% confidence interval for the imputed values.

Fig. 3

Scenario A: Global cumulative additional CRC cases (panel A) and CRC deaths (panel B), with modelled 2020 observed decreases in screening volume and imputed decreases based on local COVID-19 death rates where local data is not available. Results are shown without (Scenario A.1) and with (Scenario A.2) catch-up in each panel. All results are relative to the comparator (status quo participation rates in 2020). Shaded regions show the range between the estimates generated by the four models.

Fig. 4

Scenario B.1: Additional CRC cases and deaths over 2020–2050 attributable to a hypothetical 25% relative decrease in all countries without robust 2020 screening data available. No catch-up screening was modelled for this scenario. All results are relative to the comparator (status quo participation rates in 2020) and are organised in order of additional cases.