IMPACT OF THE COVID‐19 PANDEMIC ON THE DIAGNOSIS OF MATURE LYMPHOID NEOPLASMS IN BELGIUM: RESULTS FROM THE BELGIAN CANCER REGISTRY

Abstract

Introduction: Health care in Belgium was affected by the corona pandemic and the corresponding measures taken by the government since March 2020. The aim of this study is to make an estimate of the decrease in the number of new diagnoses of mature lymphoid neoplasms (MLN) due to the COVID-19 crisis in Belgium. Methods: For its standard cancer reporting, the Belgian Cancer Registry uses two data sources: • The oncological care programs from the hospitals provide structured data ('clinical network') • The pathology laboratories deliver structured files and reports ('pathology network') Thanks to expedited deliveries of data by the pathology network between January and September 2020, the Belgian Cancer Registry was able to make an estimation of the decline in the number of diagnoses by types of MLN. Since estimates were only based on pathology data and to prevent bias, all results are shown as a relative ratio between the new cancer diagnoses for incidence years 2020 and 2019. The ratios for the months January and February, both prior to the start of the COVID-19 pandemic, were expected to be around 100%. Decline = ratio-100%.Results: After a strong decline by 28% during the first wave (March-May 2020) when compared to March-May 2019, the total diagnosis of MLN reported by the pathology network stabilized around normal values compared to 2019 levels, leading to an incomplete recovery by end September 2020 (-12%). Variable effect by age group Although the 2 adult age groups, 20-79 vs 80+, exhibited the same reduction of 28% during the March-May period, a partial recovery was observed for the 20-79 age group (+4%) during the following June-September period while the older population showed a persistent reduction (-9%), leading to an overall decline of 16% for the 80+ compared to 10% for the 20-79 age group. Although subject to a low number of cases, there was no evidence of a decline in children and adolescents up to 19 years of age. Variable effect by MLN type Among B-cell MLN, the largest decrease by September was observed for mature B-cell leukemias (March-Sept:-28%; March-May:-43%). The decrease was smaller for plasma cell neoplasms (-18%;-34%), other indolent lymphomas (-14%;-40%) and Hodgkin lymphoma (-6%;-30%) while no evidence of decline for the more aggressive MLN (DLBCL and Burkitt lymphoma), except for 80+ (March-Sept:-13%). The strongest rebound in diagnosis was observed for mature T/ NK cell lymphomas which completely recovered to above 2019 levels (March-May:-22%, June-Sept: +25%). Conclusion: This study with pathology data available until the end of September suggests a heterogeneous impact of the COVID19 crisis on the different types of MLN. The largest persistent declines are observed for the more indolent MLNs, while the effect was very limited for the high-grade B-cell lymphoid neoplasms, with exception of the older population. The impact over the whole year 2020 will be presented during the meeting.