COVID-19 in patients receiving treatment at an outpatient chemotherapy unit.

During the COVID-19 pandemic period, many patients who required outpatient chemotherapy developed COVID-19, requiring chemotherapy interruption. However, there are no clear guidelines regarding the safe timing for restarting chemotherapy. We conducted a retrospective study to assess when such patients can safely recommence chemotherapy. Of the 40 patients included in this study, 34 restarted anticancer drug therapy after COVID-19 infection. Six patients, four with multiple myeloma, and one each with follicular lymphoma and glioma, remained SARS-CoV-2 antigen positive >20 days after COVID-19 onset. Multiple myeloma patients recorded significantly higher frequencies of SARS-CoV-2 antigen positivity >20 days after COVID-19 onset compared with solid tumor patients, with no significant differences in the frequency of SARS-CoV-2 positivity during 5-20 days from COVID-19 onset between them. According to our data, most solid tumor patients achieved SARS-CoV-2 antigen negativity after 20 days from COVID-19 onset. On the other hand, multiple myeloma patients might need serial antigen tests before restarting anticancer therapy in the outpatient chemotherapy setting.