COVID-19(10) Patient(8) Treatment(8) conducted(6) Cancer(6) SARS-CoV-2(6) patients(6) Care(6) reported(6) Retrospective study(4) Immune checkpoint inhibitor(4) seronegative(4) was collected(4) Research(4) cancer patient(4) statistical test(4) combinations(4) MOST(4) vaccination(4) proportion(4) activity(4) clinical trial(4) titer(4) questionnaire(4) dose(4) were measured(4) Side effect(4) Cutoff(4) Vaccine(4) greater(4)