This observational, population-based, cohort study was conducted in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology guidelines. It was approved by the regional ethics committee in the Republic of Korea and institutional review boards of the eight participating institutions. Due to the anonymity of the data, the requirement for informed consent was waived.
The study timeline was determined by the phased social distancing measures implemented in the Republic of Korea in response to the COVID-19 pandemic. The study focused on patients with CRC who underwent surgical treatment from 2018 to 2020. The pre-COVID-19 period extended from 2018 to February 2020, and the COVID-19 period began in March 2020 with the identification of the first COVID-19 case in the Republic of Korea and subsequent government measures to prevent the spread of the disease.
Eight institutions across the Republic of Korea participated in the study, including Asan Medical Center, Seoul St. Mary's Hospital, Korea University Anam Hospital, Samsung Medical Center, Pusan National University Yangsan Hospital, Gangnam Severance Hospital, Kyungpook National University Chilgok Hospital, and Chonnam National University Hwasun Hospital. These institutions are tertiary medical centers, varying in location and size.
