Negative impact of COVID-19 associated health system shutdown on patients diagnosed with colorectal cancer: a retrospective study from a large tertiary center in Ontario, Canada.

Forse, C. L.; Petkiewicz, S.; Teo, I.; Purgina, B. M.; Klaric, K.-A.; Ramsay, T.; Wasserman, J. K.

Background: In March 2020, a directive to halt all elective and non-urgent procedures was issued in Ontario, Canada because of COVID-19. The directive caused a temporary slowdown of screening programs including surveillance colonoscopies for colorectal cancer (CRC). Our goal was to determine if there was a difference in patient and tumour characteristics between CRC patients treated surgically prior to the COVID-19 directive compared to CRC patients treated after the slowdown. Methods: CRC resections collected within the Champlain catchment area of eastern Ontario in the six months prior to COVID-19 (August 1, 2019-January 31, 2020) were compared to CRC resections collected in the six months post-COVID-19 slowdown (August 1, 2020-January 31, 2021). Clinical (e.g. gender, patient age, tumour site, clinical presentation) and pathological (tumour size, tumour stage, nodal stage, lymphovascular invasion) features were evaluated using chi-square tests, T-tests and Mann-Whitney tests where appropriate. Results: 343 CRC specimens were identified (175 pre-COVID-19, 168 post-COVID-19 slowdown). CRC patients treated surgically post-COVID-19 slowdown had larger tumours (44 mm vs. 35 mm; p = 0.0048) and were more likely to have presented emergently (24% vs .10%; p < 0.001). While there was a trend towards higher tumour stage, nodal stage, and clinical stage, these differences did not reach statistical significance. Other demographic and pathologic variables including patient gender, age, and tumour site were similar between the two cohorts. Interpretation: The COVID-19 slowdown resulted in a shift in the severity of disease experienced by CRC patients in Ontario. Pandemic planning in the future should consider the long-term consequences to cancer diagnosis and management.