PURPOSE: To study the safety of resuming antitumor therapy in tumor patients infected with COVID-19. METHODS: We collected the clinical information of patients with tumors who were infected with COVID-19 and resume antitumor therapy between December 2022 and June 2023. Information about antitumor therapy, COVID-19-related symptoms, laboratory tests, antitumor therapy-related adverse events (AEs), and re-infection with COVID-19 were recorded. Primary endpoints included the incidence of AEs and re-infection of COVID-19. The secondary endpoints included the incidence and duration of COVID-19 related symptoms. RESULTS: The most common COVID-19 symptoms were fever (39.5%), cough (37.2%), and fatigue (44.2%). Most patients' symptoms lasted no more than a week Two patients were re-infected with COVID-19. All-grade AEs with an incidence rate >
10% included anemia, increased gamma-glutamyl transferase (GGT), anorexia, neutropenia, hypocalcemia, leukopenia, thrombocytopenia, increased alanine aminotransferase, increased aspartate aminotransferase, hypokalemia, hyponatremia, and nausea. Grade 3-4 AEs with an incidence rate higher than 5% included anemia, neutropenia, leukopenia, thrombocytopenia, anorexia, and vomiting. The incidence of AEs before and after COVID-19 infection did not show a significant difference. CONCLUSION: Resuming antitumor therapy early after SARS-CoV-2 test turned negative did not increase antitumor therapy-related AEs or the incidence of re-infection in COVID-19 infection patients.