Decreased incidence and shift in stage distribution for colorectal cancers in Belgium during the COVID-19 pandemic

Background and study aims: The COVID-19 pandemic substantially impacted the healthcare system and society in 2020. This study assessed its possible impact on occurrence and stage of colorectal cancer diagnoses in Belgium.

Methods: Population-based data from the Belgian Cancer Registry were used to extrapolate 2017-2019 trends in incidence and stage distribution to expected counts for 2020 that were subsequently compared to the observed values. Stage-specific predictions were corrected to account for the overall decline in diagnoses.

Results: In 2020, 705 fewer than expected invasive and 255 fewer in situ colorectal cancers were diagnosed. For colon cancer, significant declines were observed in all genders and regions, mainly in the screening age group and in age 75+. For rectal cancers, there was only a significant decline in the latter two groups. Colon cancer pStage distribution did not change significantly. In situ rectal tumors showed a relative decline in Flanders and in the screening age group. In the latter group, more than expected cStage III rectal cancers were observed in women.

Conclusions: The excess decline in in situ rectal cancers is likely attributable to the temporary suspension of the colorectal screening program during the first pandemic wave. The overall decline in colon and rectal cancer incidence in Belgium in 2020 was not accompanied by a stage shift. Longer-term effects or impact on clinically relevant outcomes cannot be excluded.

Keywords: colon cancer, rectal cancer, colorectal cancer, COVID-19 pandemic, stage shift, population-based data.