Impact of chemotherapy on COVID-19 vaccination in patients with gastrointestinal cancer.

Abstract

32 Background: Multiple doses of vaccine against COVID-19 provide cancer patients with the opportunity to continue their cancer treatment. We previously reported the results that COVID-19 vaccination are tolerable, and treatment schedule changes could be minimized in gastrointestinal (GI) cancer patients receiving chemotherapy. In the present study, we investigated the differences in the occurrence of vaccine-related adverse events (AEs) in patients receiving chemotherapy and those not receiving chemotherapy. Methods: 141 patients with GI cancer who had two doses of mRNA COVID-19 vaccine (Pfizer-BioNTech or Moderna) between May 2021 and April 2022 with sufficient data on vaccination were included in this retrospective observational study at the Tokyo Medical and Dental University hospital. This study combined two different cohorts: an evaluation cohort of 89 patients (median age 70 years, male 57.8%) receiving chemotherapy; and a control cohort of 52 patients under follow-up after radical surgery (median age 68.5 years, male 69.2%). All patients had no history of COVID-19 infection. Treatment- and vaccine-related AEs were recorded by outpatient interviews and self-reports. Results: Patient characteristics of the two cohorts were similar except for the location of primary tumor: colorectal (80.9% vs 7.7%) and gastric (15.7% vs 88.5%). There were no significant differences in comorbidities between the cohorts (67.4% vs 55.8%). In the evaluation cohorts, 65 patients (73.0%) had vaccine-related AEs: injection site pain (68.5%), fever (9.0%), fatigue (6.7%), headache (3.4%), gastrointestinal symptoms (2.2%), redness (1.1%) and sleepiness (1.1%) after the first dose; and 66 patients (74.2%) had vaccine-related AEs with increased rate of fever (32.6%) and fatigue (19.1%) after the second dose. In the control cohort, vaccine-related AEs occurred in 28 (53.8%) after the first dose and 37 (71.2%) patients after the second doses, and similarly, fever and fatigue increased after the second dose. There were no significant differences in the number of vaccine-related AEs and their changes between cohorts. There was no treatment- and vaccine-related deaths. Conclusions: The results of this study suggest that systemic chemotherapy in patients with GI cancer does not have a marked negative effect on COVID-19 vaccination.