COVID-19(19) surgery(14) Patient(11) Cancer(9) COVID-19 pandemic(9) patients(8) performed(8) coronavirus disease(8) pandemic(7) Major(6) coronavirus(6) Result(6) postoperative(6) SARS-CoV-2(6) European(6) acute respiratory syndrome(6) surgical(6) Care(6) supplementary material(6) Infection(6) RT-PCR(6) Elective surgery(6) hospital(6) healthcare worker(5) Logistic regression(5) multicenter study(5) Factor(5) positive(5) Safety(5) invasive(5)