The coronavirus disease 2019 reported in Wuhan, China, in December 2019, has expanded in Japan, and has had a signi cant impact on patient consultation behavior and medical treatment. In particular, cancer patients are more susceptible to infections because of the immunosuppressive state caused by both surgery and anticancer treatments. Therefore, discontinuation, postponement, or change of the regimen of postoperative adjuvant chemotherapy is being considered. Thus, we investigated how the outbreak of COVID-19 actually affects the implementation of adjuvant chemotherapy in our hospital. We retrospectively investigated patients undergoing surgery for colorectal cancer, and compared the result for one year before and after January 2020, when COVID-19 initially occurred in Tokyo. As a result, there was a negative correlation between the ratio of surgeries for colorectal cancer to the number of hospitalized patients at the surgical department and the infection status of COVID-19 in Tokyo (r = -0.431), However, there was no signi cant difference in the number of patients classi ed as High risk Stage II or Stage III for postoperative diagnosis before and after the outbreak (P = 0.882). Although some patients were concerned about the risk of infection, there was no change in the rate of adjuvant chemotherapy (P = 0.321) and its regimen (P = 0.678) before and after the outbreak. Based on this survey, despite the absence of suf cient evidence for treatment under the COVID-19 epidemic, these ndings suggest that adjuvant chemotherapy could be performed as usual by ensuring risk management such as securing beds and manpower.