Background and Objective:
Recent scientific studies show that the COVID-19 pandemic affected the cancer screening programs and, consequently, cancer incidence in different countries worldwide. This study investigated the impact of the two lockdowns in March 21 to May 3, 2020 (first lockdown) and December 9, 2020 to March 7, 2021 (second lockdown), on gastrointestinal cancers (ICD-O-3: C15 – C26) in Bavaria, Germany.

Methods:
We gathered incident cancer data including malignant and in situ cases from approximately 50% of pathological centres in Bavaria. We aggregated the number of incident gastrointestinal cancers in months stratified by cancer site and malignancy in pre-pandemic (03.2019 to 02.2020) and pandemic (03.2020 to 02.2021) periods. We estimated the relative changes of numbers of cancers between pandemic and pre-pandemic periods with corresponding confidence intervals using a Bonferroni correction (13 tests with α = 0.0038).

Results:
The number of malignant gastrointestinal cancers significantly declined from 10,587 in the pre-pandemic period to 9,749 in the pandemic period with a relative difference of -7.9% (95% CI: -11.6% to -4.1%). It significantly reduced for colon cancer from 4,032 to 3,568 (relative change: -11.5%; 95% CI: -17.2% to -5.4%) and rectum cancer from 2,095 to 1,772 (relative change: -15.4%; 95% CI: -23.0% to -7.1%). We found no significant reductions for other sites. The number of in situ cases decreased from 451 to 327 with a relative change of -27.5% (95% CI: -41.2% to -10.5%). It also declined in colon cancer from 281 to 170 cases (relative change: -39.5%; 95% CI: -54.3% to -19.9%), but not in the other sites.

Conclusion:
The COVID-19 pandemic affected the number of pathological diagnoses of gastrointestinal cancers in Bavaria. The reduction was mainly due to the reduction in diagnoses of colon and rectum, which could be a result of decreases in screening cases during the lockdowns.