Childhood Cancer in Sweden During the COVID-19 Pandemic: Incidence and Survival in a Nationwide

Sweden’s pediatric cancer patterns during COVID-19: overall stability with group-specific shifts

• This nationwide, register-based cohort study evaluated cancer incidence and survival in children and adolescents (0–19 years) diagnosed with cancer (ICCC-3) in Sweden from 2015 to 2022 (N = 3,333; 2,069 pre-pandemic, 1,264 during the pandemic).
• The pandemic period analyzed spanned 2020–2022, with comparisons of quarterly age-standardized incidence rates (ASR) per 1,000,000 to the 2015–2019 baseline.
• Survival was assessed via Kaplan–Meier estimates for 3, 6, and 12 months post-diagnosis, and mortality was examined with logistic regression adjusted for age at diagnosis, sex, and maternal education.
• Acknowledged limitation: limited precision for some diagnostic groups due to small case numbers.

• Across the cohort, total cancer incidence remained largely stable during the pandemic, with ASR values hovering near the pre-pandemic baseline (2015–2019 ASR: 179.5; 2020: 174.7; 2021: 176.5; 2022: 181.2 per million).
• Diagnostic groups showed variable trajectories:
• Acute lymphoblastic leukemia (ALL): incidence declined from February 2020, followed by a rebound in 2021.
• Acute myeloid leukemia (AML): incidence declined across 2020–2022 without evidence of rebound.
• Lymphomas: incidence declined mid-2020 and then returned to pre-pandemic levels.
• Central nervous system (CNS) tumors: transiently increased in 2020.
• The timing and magnitude of these group-specific fluctuations are noted, but overall illness incidence did not show dramatic nationwide disruption.

• Overall 1-year survival remained high: 94.8% pre-pandemic vs 95.9% during the pandemic.
• No evidence of increased short-term mortality during the pandemic; point estimates for ALL and CNS tumors suggested possible, though imprecise, reductions in 1-year mortality (ALL aOR ~0.37; CNS ~0.61) but with wide confidence intervals and non-significant p-values.
• Six- and 12-month mortality did not rise; the data imply that any disruptions did not translate into worse short-term survival up to one year after diagnosis.

• The authors interpret the stability in overall incidence and survival as indicating no major deterioration in pediatric cancer outcomes during Sweden’s relatively relaxed pandemic restrictions.
• They caution that observed fluctuations by diagnostic group might reflect delayed diagnoses or changes in disease triggers; however, the ALL decline without a AML rebound challenges simple explanations solely based on diagnostic delay.
• The principal constraint is statistical uncertainty for certain disease subgroups due to small numbers, limiting precise subgroup conclusions.

• In Sweden, pandemic-era cancer care did not appear to compromise short-term survival at the population level for children and adolescents with cancer.
• Group-specific incidence changes warrant awareness of potential delays in diagnosis for ALL, lymphomas, and AML, though survival did not worsen in the observed intervals.