Modelling scenarios for screening prioritization during the COVID-19 pandemic

As jurisdictions continue to identify and implement strategies to enable catch up of screening backlogs due to the COVID-19 pandemic, including management of downstream services, modelling can be a helpful tool to understand the anticipated impacts and outcomes of different approaches.

This analysis was conducted using OncoSim to compare strategies to reduce screening backlogs for colorectal and breast cancer in Canada.

Colorectal cancer screening

Key findings from colorectal cancer screening modelling include:

• The colorectal cancer screening analysis found that offering catch-up screening could avert most long-term consequences of the pause in screening services. However, catch-up screening would require additional follow-up colonoscopy capacity in cases where an abnormal screen result was detected.
• To balance the demand for colonoscopies, programs could consider clearing screening backlogs over the next 24 months, prioritizing those who are overdue for screening. This approach would only require increasing fecal test follow-up colonoscopies by 4% over the next 24 months and could reduce 93% of colorectal cancer deaths (i.e., 409 deaths) due to paused cancer screening.
• It is recognized that screening represents only a small proportion of colonoscopy system resources, and this analysis does not account for the overall impact of the COVID-19 pandemic on the colonoscopy system.

The colorectal cancer screening analysis was conducted as part of an international comparative modelling project with the COVID-19 and Cancer Global Modelling Consortium.

The full report for the colorectal cancer screening analysis is available on the Statistics Canada website.

Breast cancer screening

Key findings from breast cancer screening modelling include:

• The breast screening analysis compared a strategy that prioritizes first screens over women returning to subsequent screens vs. a strategy that offers no prioritization in the context of resuming screening after a 3-month screening pause.
• The analysis estimated that the strategy that prioritizes first screens would lead to ~120,000 more women receiving their first screens on schedule, and the same number of women receiving their subsequent screens one year later (i.e., three years after their previous screen).
• The difference between the two strategies was negligible across lifetime breast cancer deaths, as the strategies affected a relatively small number of women, and those who received screening later were still screened within the recommended intervals (2 to 3 years). If screening was paused for a longer period of time, more women would have been affected, and the impact could be larger.

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