Cancer diagnosis in Catalonia (Spain) after two years of COVID-19 pandemic: an incomplete recovery

Background: This study aimed to estimate potential undetected cancers over the first 2 years of the COVID-19 pandemic in Catalonia. Methods: Cancer incidence was compared between pre-pandemic (2019) and pandemic (March 2020-January 2022) periods in the Catalan Pathology Registry (CPR) according to sex, age, and tumor site. The correlation between cancer diagnosis and COVID-19 health care workload was also evaluated by means of the Pearson's correlation coefficient (R). The expected incident cancers (E) during the pandemic were estimated by applying 2019 CPR cancer incidence specific rates by sex and 5-year age groups to the 2020 and 2021 Catalan population pyramids. CPR incident cancers were considered observed (O). Standardized incidence ratios (SIR) and 95% confidence intervals (CIs) were calculated using the O/E ratio. Results: After two pandemic years, cancer diagnosis decreased by 12% (SIR 0.88, 95% CI 0.87-0.89), or similar to 7700 undetected cancers (13 000 with nonmelanoma skin cancer). Without nonmelanoma skin cancer, 72% of the cancer underdiagnosis was generated in 2020. Diagnoses decreased more in men (whole pandemic -14%; 2020 -21%; 2021 -8%) than in women (-9%, -19%, -3%, respectively), dropping significantly overall in all pandemic waves but the fifth (first -37%, second -16%, third -8%, fourth -6%, fifth -2%, sixth -6%), and across all adult age groups. In the first wave, CPR cancer diagnosis was inversely correlated with COVID-19 caseload in primary care (R -0.91, 95% CI -0.97 to -0.75) and occupancy in conventional hospital wards (R -0.91, 95% CI -0.99 to -0.48) and intensive care (R 0.91, 95% CI 95% -0.98 to -0.70). Conclusions: Our study evaluated the overall pandemic impact on cancer diagnosis on a large scale and with minimal selection bias, showing that as of February 2022, cancer detection in Catalonia had not yet recovered to pre-pandemic levels. Pending cancer incidence data from population-based cancer registries, early CPR data could inform the development of Spanish cancer control plans.