Abstract
BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has affected cancer care. The aim of this study was to clarify the trend of colorectal cancer (CRC) stage distribution in Japan during the COVID-19 pandemic. METHODS: In this retrospective study, we used an inpatient medical claims database established at approximately 400 acute care hospitals. From the database, we searched patients who were identified as having the main disease (using International Classification of Diseases, 10(th) revision codes [C18.0-C20]) between January 2018 and December 2020. A multivariate logistic regression analysis was used to determine the impact of the pandemic on CRC stage distribution each month, and the odds ratio (OR) for late-stage cancer was calculated. RESULTS: We analyzed 99,992 CRC patients. Logistic regression analysis, including the interaction term between increased late-stage CRC effect during the pandemic period and by each individual month, showed that the OR for late-stage CRC was highest in July during the pandemic, at 1.31 (95% confidence interval [CI], 1.13-1.52) and also significantly higher in September at 1.16 (95% CI, 1.00-1.35). CONCLUSION: We investigated the trend of CRC stage distribution during the COVID-19 pandemic using a nationwide hospital-claims database in Japan and found that the proportion of early-stage cancers tended to decrease temporarily after the state of emergency declaration due to the COVID-19 pandemic, but the effect was only temporary.