The impact of the COVID-19 pandemic on incidence gap in screen-detectable cancers: a cohort study in Greater Poland, Poland.

Background: The global COVID-19 pandemic has had a significant impact on healthcare systems. This study aimed to assess the incidence gap in screening-detectable cancers in the Greater Poland (Poland) in 2020.

Materials And Methods: Data on breast, cervix uteri, and colorectal cancer cases diagnosed from 2010 to 2020 were obtained from the regional cancer registry. Standardized incidence ratios (SIR) and incidence rate differences (IRD) were calculated to estimate the change in incident cancer cases during the pandemic. The number of observed cases was extracted from the registry database. Simple linear regression analysis was used to predict the expected number of incident cancer cases in 2020 and the age-standardized incidence rate based on registry data from the preceding ten years (2010-2019).

Results: In 2020, the registered number of incident female breast cancer cases decreased by 12% [SIR 0.88, 95% confidence interval (CI): 0.88-0.92, observed: 1,848, expected: 2,101], resulting in an IRD of -6.3 per 100 K. The number of registered cervical cancers decreased by 15% (SIR 0.85, 95% CI: 0.73-0.98, observed: 181, expected: 213), with an IRD of -0.8 per 100 K. For colorectal cancer, there was a 16% decrease in new cases among females (SIR 0.84, 95% CI: 0.78-0.90) and a 15% decrease among males (SIR 0.85, 95% CI: 0.80-0.91), resulting in IRDs of -3.04 and -5.29 per 100K, respectively.

Conclusions: The COVID-19 pandemic led to a significant, 15% decrease in newly diagnosed screening-detectable cancer cases in 2020. Further studies are needed to investigate the impact of delayed cancer diagnoses on stage at diagnosis and survival rates.