Cytogenetic patterns of hematologic malignancies before, during and after the COVID-19 pandemic: a single-center retrospective study in Thailand

Hematologic malignancies frequently harbor recurrent cytogenetic abnormalities that are essential for diagnosis and prognostic stratification. The COVID-19 pandemic raised concerns that infection-related biological effects or disruptions in healthcare deliverymight influence the frequency or distribution of these abnormalities. Objective: To evaluate whether the COVID-19 pandemic was associated with changes in the frequency of chromosomal abnormalities detected in hematologic malignancies. Methods: We retrospectively analyzed 3,162 bone marrow samples referred for cytogenetic testing between 2018 and 2024 at a tertiary center in Thailand. Cases were categorized into Pre-COVID (2018–2019), Peak COVID (2020–2021), and Post-COVID (2022–2024) periods. Proportions of abnormal karyotypes and recurrent cytogenetic lesions were compared using risk ratios with 95% confidence intervals and two-proportion z-tests. Results: Overall proportions of abnormal karyotypes remained largely stable across pandemic periods. In AML, complex karyotypes (10–16%) were consistent with previously reported ranges, whereas balanced translocations such as t(15;17), t(8;21), and inv(16) occurred less frequently than reported in large international cohorts. In MDS, recurrent abnormalities including del(5q), del(20q), and complex karyotypes were underrepresented relative to published literature. In ALL, the proportion of abnormal karyotypes declined during the Peak COVID period (20.7% vs. 44.4% in the Pre-COVID period, p = 0.01) but returned to baseline levels thereafter. CLL showed a marked reduction in abnormal karyotypes during the Post-COVID period (5.7% vs. 40.0% Pre-COVID, p < 0.001). No significant temporal changes were observed in MM, MPN, or lymphoma. Conclusions: The overall cytogenetic landscape of hematologic malignancies remained largely stable throughout the COVID-19 pandemic. Observed variations in ALL and CLL are more likely related to changes in healthcare access or referral patterns rather than direct biological effects of SARS-CoV-2 infection.