ABSTRACT
The Coronavirus disease-19 (COVID-19) pandemic dramatically impacted on oncologic patients' care. Since the introduction of vaccines and the demonstration of their benefit on frail patients, COVID-19 vaccinations were indicated also for oncologic population. However, data about the impact of anticancer-treatments and the timing between vaccinations and systemic therapy de-livery were not available. We aimed to evaluate potential factors influencing the outcome of COVID-19 vaccination in cancer patients. We prospectively collected data of patients undergoing COVID-19 vaccination with gas-tro-entero-pancreatic and neuroendocrine neoplasms, treated at our Institute, between 03/2021 and 12/2021. We enrolled 46 patients, 63.1% males; at the time of data collection 86.9% received two-doses of Pfizer-BioNTech and the remains Moderna vaccine. All patients obtained a subsequent im-mune-response. A significantly lower values of IgG for patients treated with chemotherapy versus other anti-cancer agents (p=0.004). No significant effect on immune-response was reported for both vaccinations performed ≤7 vs >7 days from the last systemic treatment (p=0.77) and lymphocytes count (p=0.11). The findings suggest that the optimal timing for COVID-19 vaccination and lymphocytes count are not the issue but rather the quality of the subset of lymphocytes before the vaccination to deter-mine the efficacy level of immune-response in this population.