Impact of the COVID‐19 pandemic on colorectal cancer surgery in Japan: Clinical Study Group of Osaka University―A multicenter retrospective study

Abstract Aim Due to the overwhelming spread of SARS‐CoV‐2 and its disruption of the healthcare system, delays and reduced numbers were reported for colorectal cancer screening, colonoscopies, and surgery during the COVID‐19 pandemic. This multicenter retrospective study investigated the still poorly understood impact of the COVID‐19 pandemic on colorectal cancer treatment in Japan. Methods This study was organized by the Clinical Study Group of Osaka University, which comprised 32 major institutions in Osaka. We retrospectively analyzed the number of surgeries and colonoscopies performed and the characteristics of patients who underwent surgery for colorectal cancer between March 2019 and February 2021. We compared data collected before and during the COVID‐19 pandemic. We also assessed the methods used for detecting colorectal cancer, including fecal occult blood test, abdominal symptoms, and anemia. Results The COVID‐19 pandemic caused reductions in the annual numbers of surgeries (3569 vs 3198) and colonoscopies (67 622 vs 58 183) performed in the 2020 fiscal year, compared to the 2019 fiscal year. During the COVID‐19 pandemic, a significantly lower proportion of patients were treated for clinical stages ≤I (24.2% vs 26.9%; P = .011), compared to the proportion treated before the pandemic. Fecal occult blood tests for detecting colorectal cancer were used significantly less frequently during the COVID‐19 pandemic (26.2% vs 29.6%; P = .002). These trends were more significant in larger institutions. Conclusion The COVID‐19 pandemic reduced the number of colonoscopies and surgeries performed for colorectal cancer and hindered the detection of asymptomatic early‐stage cancers, and its impact varied by hospital size.


| INTRODUC TI ON
In December 2019, the first case of a new type of infection caused by a new coronavirus variant, known as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was reported in Wuhan, China.
Subsequently, the disease spread rapidly around the world, which led to the COVID-19 pandemic. 1,2 In response to the overwhelming spread of the SARS-CoV-2 outbreak and its disruption of healthcare systems, many governments worldwide imposed lockdowns or declared states of emergency to prevent its spread. 3,4 In Japan, the first case of COVID-19 was confirmed in January 2020. That case was followed by outbreaks on board the Diamond Princess cruise ship, in February 2020, which resulted in 696 cases. 5 As the number of infections increased, on April 7, 2020, the Japanese government declared states of emergency for Tokyo, Kanagawa, Saitama, Chiba, Osaka, and Hyogo. Subsequently, the state of emergency was extended to all prefectures on April 16, 2020. As of December 2021, more than 1.7 million people had been infected, and there is no sign of the pandemic ending.
The basic routes of SARS-CoV-2 transmission were thought to be droplet and contact infections. However, the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) have suggested the possibility that infectious particles could be airborne, which could increase the risk of SARS-CoV-2 spreading during endoscopic examinations. 6,7 About 20%-50% of infected patients are asymptomatic, but nevertheless they can transmit SARS-CoV-2 to others. 8,9 The Japan Gastroenterological Endoscopy Society recommended that elective nonurgent endoscopic procedures should be delayed during a declared state of emergency, as recommended by the New York Society for Gastrointestinal Endoscopy guidelines. 10,11 Consequently, only one-quarter of the number of people screened the previous year in Japan were screened in April and May 2020.
Moreover, an international survey of 252 centers in 55 countries indicated that the number of colonoscopies performed had decreased by 85%, due to the COVID-19 pandemic. 12,13 Currently, there is concern that a decline in the number of screening and colonoscopy examinations performed during the COVID-19 pandemic may have resulted in delays in detecting early-stage colorectal cancer, which could lead to an increase in the rate of advanced colorectal cancers. Therefore, the present multicenter retrospective cohort study investigated the impact of the COVID-19 pandemic on colorectal cancer treatments, including the stage at diagnosis, in Japan.

| Outcomes
The period between March 2019 and February 2020 was defined as the period before the COVID-19 pandemic, and the period between March 2020 and February 2021 was defined as the period during the COVID-19 pandemic. To investigate the impact of the COVID-19 pandemic, we compared the numbers of surgeries and colonoscopies performed and the patient characteristics between the groups screened before and during the COVID-19 pandemic. We also evaluated differences in the methods for detecting colorectal cancer performed before and during the COVID-19 pandemic.

| Impact of the COVID-19 pandemic on patient background
Compared to the period before the pandemic, patient characteristics during the COVID-19 pandemic were not significantly

| Impact of COVID-19 on colorectal cancer treatments
The patients treated during the COVID-19 pandemic tended to be in worse condition than those treated before the pandemic, but only in institutions with more than 100 colorectal cancer surgeries per year (ASA-PS ≥3: 20.6% vs 17.2%; P = .002) ( On the other hand, these trends were not observed in institutions with fewer than 100 annual colorectal cancer surgeries (Table 6).

| DISCUSS ION
The COVID-19 pandemic has disrupted healthcare systems around the world, resulting in fewer endoscopies performed, and fewer cancers detected. 15  A previous study showed that, among patients with positive fecal occult blood tests, follow-ups that were delayed for more than 10 mo were associated with a higher risk of colorectal cancer and a more advanced stage at diagnosis, compared to follow-ups with colonoscopy between 8 and 30 d. 22