Pb2288: incidence of newly diagnosed aggressive non-hodgkin’s lymphoma before and during the covid-19 pandemic in israel - a single center retrospective study

Topic: 19. Aggressive Non-Hodgkin lymphoma - Clinical Background: As part of the general objections of certain subgroups to Coronavirus disease 2019 (COVID-19) vaccination, concerns have been raised that the vaccine and/or the viral infection itself propagate an increased incidence of lymphoma. Aims: To analyze trends in the incidence of newly diagnosed aggressive non-Hodgkin’s lymphoma (NHL) before and during the COVID-19 pandemic and prior and following the implementation of nation-wide vaccination. Methods: We retrospectively reviewed data of all patients diagnosed and treated for aggressive NHL between 9/2017 and 8/2022. Cases were identified by a combination of presence of a new ICD-9 diagnosis of an aggressive lymphoma and administration of a CHOP/CHOP-like chemotherapy regimen. The cohort was divided into two 30-month periods: ‘pre-pandemic’ 9/2017-2/2020 and ‘COVID-19’ 3/2020-8/2022. The ‘COVID-19’ period was further divided into two 15m periods - ‘pre-vaccine’ (until 5/2021) also representing the era of major quarantine, and ‘post-vaccine’ which represents the time after the administration of the first mRNA COVID-19 vaccine and the following vaccine boosters. The baseline demographic and characteristics and the clinical outcomes were extracted from the patients’ electronic medical records. Throughout all periods our clinic was open for frontal visits. Results: During the study, a total of 535 patients (46.5% women) were diagnosed with aggressive NHL. The median (IQR) age was 68.2 (56.5-75.2) years; 284 (53.1%) new aggressive NHL cases were observed in the pre-pandemic period and 251 (46.9%) in the COVID-19 period (Figure 1); no statistical difference was observed (p=0.4). Baseline demographics and disease characteristics were similar between the two periods. Histological subtypes were similar between the periods (94.0% vs. 92.4% B-cell NHLs, p=0.5; of which 9.4% vs. 9.1% represented a transformation from a prior mature B cell lymphoma, p=0.9). There was no difference in the 1-year overall survival between groups (84.0% vs. 78.7%, p=0.5). Comparing the pre-vaccine and post-vaccine epochs during the COVID-19 pandemic, there was no clear increase in the incidence of newly diagnosed aggressive NHL patients. Moreover, there was no difference in the rate of hospitalization for severe COVID-19 between these sub-groups (5.6% n=8 vs. 6.4% n=7, p=0.8). Summary: We did not observe a significant increase in the incidence of new cases of aggressive lymphomas following the COVID-19 pandemic or the institution of a national vaccination program. Figure 1: Incidence of newly diagnosed aggressive non-Hodgkin’s lymphoma before and during the COVID-19 pandemic in Israel.Keywords: High-grade non-Hodgkins-lymphoma, Lymphoma, Non-Hodgkin’s lymphoma, COVID-19