In this nationwide, register-based study from Sweden, incidence and short-term survival of childhood and adolescent cancers (0–19 years) diagnosed 2015–2022 were examined to assess potential pandemic-related disruptions. The study included 3,333 cases (2,069 pre-pandemic, 1,264 during the pandemic) classified by ICCC-3 and linked to the Swedish National Cancer Register. Overall incidence remained largely stable when comparing 2020–2022 to the 2015–2019 average, with an age-standardized incidence rate (ASR) of 179.5 per 1,000,000 (pre-pandemic) versus 174.7 (2020), 176.5 (2021), and 181.2 (2022). Diagnostic groups showed variable patterns: acute lymphoblastic leukemia (ALL) declined from February 2020 with a subsequent rebound in 2021; acute myeloid leukemia (AML) declined across 2020–2022 without rebound; lymphomas declined in mid-2020 and then normalized; CNS tumors showed a transient rise in 2020. Overall 1-year survival was 94.8% pre-pandemic and 95.9% during the pandemic. Adjusted 6- and 12-month mortality showed no increase; point estimates suggested possible lower 1-year mortality for ALL and CNS tumors, though imprecision existed. The main limitation was statistical uncertainty for some diagnostic groups due to small numbers.
by Christina-Evmorfia Kampitsi, Javier Louro, Hanna Mogensen, Friederike Erdmann, Kleopatra Georgantzi, Mats Heyman, Päivi Lähteenmäki, Anna Nilsson, Maria Feychting, Giorgio Tettamanti Background The COVID-19 pandemic raised concerns about diagnostic delays and treatment disruptions in childhood cancer, potentially threatening survival. We assessed childhood cancer incidence and survival in Sweden, where only few restrictions were implemented, during the pandemic period. Methods and findings We conducted a nationwide, register-based cohort study including all children and adolescents (0–19 years) with a new cancer diagnosis, defined according to the International Classification of Childhood Cancer, Third Edition (ICCC-3), reported to the Swedish National Cancer Register during 2015–2022 ( N = 3,333; 2,069 pre-pandemic and 1,264 during the pandemic). We compared quarter-specific age-standardized incidence rates (ASR) per 1,000,000 (overall and by diagnostic group) during 2020–2022 to the 2015–2019 average. Overall survival at 3, 6, and 12 months post-diagnosis was calculated using the Kaplan–Meier estimator, and mortality at the same intervals was assessed with logistic regression, adjusted for age at diagnosis, sex, and maternal education.Overall incidence rates remained largely stable during the pandemic (ASR 2015–2019 : 179.5; 95% CI [172.9,186.1], ASR 2020 : 174.7; 95% CI [160.5,189.0], ASR 2021 : 176.5; 95% CI [161.6,191.5], ASR 2022 : 181.2; 95% CI [166.3,196.2]), but diagnostic groups showed differing tendencies. Acute lymphoblastic leukemia (ALL) declined from February 2020, followed by a rebound in 2021. Acute myeloid leukemia (AML) declined throughout 2020–2022 without evidence of a rebound. Lymphomas declined in mid-2020 before returning to pre-pandemic levels. Central nervous system (CNS) tumors transiently increased in 2020. Overall 1-year survival was 94.8% (95% CI [93.9,95.8]) in the pre-pandemic period and 95.9% (95% CI [94.8,97.0]) during the pandemic. No increase in 6-month or 1-year mortality was observed; if anything, point estimates suggested lower 1-year mortality for ALL (aOR = 0.37; 95% CI [0.08,1.21]; p = 0.14) and CNS tumors (aOR = 0.61; 95% CI [0.31,1.14]; p = 0.13). The main limitation of this study was statistical uncertainty for certain diagnostic groups due to small case numbers. Conclusions Overall childhood cancer incidence and survival in Sweden showed no major changes during the COVID-19 pandemic. Fluctuations in diagnostic-group-specific incidence may reflect delayed diagnoses or shifts in disease triggers; however, the timing of the ALL decline and the lack of AML rebound challenge this interpretation. Stable or improved survival suggests that any disruptions were not associated with poorer survival up to 1 year after diagnosis.