Assessment of Unwanted Side Effects of Vaccines in Cancer Patients: Where Do We Stand in Vaccination? Where Should Our Next Step Be?

For cancer patients, vaccination against diseases that can be prevented by vaccination is a crucial but often disregarded matter. Our aim was to find out how adult immunization guidelines were being used and to investigate undesirable effects after vaccination. Vaccination status against hepatitis A and hepatitis B virus, tetanus-diphtheria, pneumococcus, influenza and meningococcus of 535 patients with solid organ malignancies who were referred to the Adult Vaccination Polyclinic from oncology outpatient clinic between July 2020 and March 2024 were documented retrospectively. Data collection and statistical analyses were performed with SPSS statistical software version 22.0. The patients’ mean age±SD was 56.8±12.3. Of the patients, 329 (61.4%) are women. Breast cancer (n= 184, 34.3%), urogenital cancers (n= 89, 16.6%), and lung cancer (n= 69, 12.8%), are the most prevalent cancers among patients applying for vaccination. Pneumococcal vaccine was the most frequently administered vaccine in 515 patients (96.2%), while influenza vaccine was the least frequently administered vaccine in 12 patients (2.2%). Fifty-three (9.9%) patients had grade 1 side effects. Pain at the injection site was the most common side effect and occurred most frequently after tetanus-diphtheria vaccination. Undesirable side effects were more frequent in 7.9% (n= 42) of patients who were under treatment (p= 0.016). However, no significant relationship was found between age, sex, the disease stage and the types of treatment received and the incidence of side effects (p> 0.05). None of the participants experienced any moderate or serious post-vaccination side effects serious enough to require medical attention. Although the pneumococcal vaccination rates in our study are greater than to the literature, the application rate of other vaccines, especially influenza vaccine, is low according to current guidelines. Increased awareness of this issue among oncology physicians is suggested by the fact that about 1/5 of patients were referred to vaccination outpatient clinics. This study is extremely valuable in demonstrating to oncology physicians the rarity of vaccine side effects. Keywords: Vaccination, Immunization, Cancer patient, Solid tumor, Post-vaccination unsiderable effect