Changes in the Number of Gastrointestinal Cancers and Stage at Diagnosis with COVID-19 Pandemic in Japan: A Multicenter Cohort Study

SIMPLE SUMMARY: The number of gastrointestinal cancer patients declined during the COVID-19 pandemic. In Japan, the number of early-stage gastric and colorectal cancer patients decreased significantly. However, how gastrointestinal cancers have changed with the shift to the “new normal” remains unknown. Herein, we compared the number of patients, stage at diagnosis, and detection process of the different gastrointestinal cancers in Japan across three periods: pre-COVID-19, Midst of COVID-19 pandemic, and during the transitional period to the “new normal”. The number of colorectal cancer patients decreased in the early phase of the COVID-19 pandemic. It then increased with the shift to the “new normal”, no longer differing from pre-COVID-19 levels. However, gastric cancer patients remained significantly fewer in the “new normal” period than in the pre-COVID-19 period, especially Stage I patients and patients detected through screening. Thus, people with undetected gastric cancer may not be receiving optimal screening, implying a negative prognostication for the near future. ABSTRACT: This retrospective cohort study compared the number of newly diagnosed patients, stage at diagnosis, and detection process of gastrointestinal cancers based on hospital-based cancer registry data at two tertiary Japanese hospitals. The pre-COVID-19 period was from January 2017 to February 2020, with phase 1 (midst of COVID-19 pandemic) from March to December 2020 and phase 2 (the transition period to the “new normal”) from January to December 2021. Each month, the number of patients diagnosed with esophageal, gastric, colorectal, pancreatic, liver, and biliary tract cancers were aggregated, classified by stage and detection process, and compared, including a total of 6453 patients. The number of colorectal Stage 0-II patients decreased significantly in phase 1 and increased in phase 2. The total number of colorectal cancer patients returned to pre-COVID-19 levels (mean monthly patients [SD]: 41.61 [6.81] vs. 36.00 [6.72] vs. 46.00 [11.32]). The number of patients with gastric cancer Stage I significantly decreased in phase 2 following phase 1. The number of gastric cancer patients decreased significantly from pre-COVID-19 levels (30.63 [6.62] vs. 22.40 [5.85] vs. 24.50 [4.15]). During phase 2, the number of patients diagnosed after screening with colorectal cancer increased significantly, whereas that with gastric cancer remained considerably lower. The number of Stage III colorectal and gastric cancer patients increased significantly from the pre-COVID-19 levels. Thus, gastric cancer may not be optimally screened during phases 1 and 2. There was a significant increase in patients with Stage III colorectal and gastric cancers from the pre-COVID-19 period; hence, the stage at diagnosis may have progressed.