The coronavirus disease 2019 (COVID-19) pandemic has caused a significant disruption to cancer diagnosis, treatment and prevention worldwide that could have serious consequences in the near future. We intend to evaluate the weight of this backlog on a community-wide scale in Madrid during the period 2020-2021, and whether a stage shift towards the advanced stage has occurred. Cancer diagnoses in the Madrid tumor registry (RTMAD) from 2019-2021 were evaluated. Absolute and percentage differences in annual volume and observed-to-expected (O/E) volume ratios were calculated. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated using the O/E ratio. The SIR for 2020-2021 compared to 2019 was 94.5% (95% CI 93.8-95.3), with unequal gender-specific cancer diagnosis recovery (88.5% for males and 102.1% for females). Most cancer types were underdiagnosed in 2020. The tendency worsened in 2021 for colorectal and prostate cancers (87.8%), but lung cancer recovered (102.1%) and breast cancer was over-diagnosed (114.4%) compared with reference pre-COVID-19 data. These changes have modified the ranking of the most frequent malignancies diagnosed in Madrid. Breast cancer has overtaken colorectal and prostate cancers, displaced to second and third position, respectively. Not only was colorectal cancer diagnosis affected more as a consequence of the COVID-19 pandemic but diagnosis of this malignancy at the advance stage also increased by 3.6% in 2020 and 4.2% in 2021 compared to the reference period of 2019. In summary, there is a large volume of undetected cancer in Madrid caused by the reduced access to care secondary to the COVID-19 pandemic, especially regarding colorectal and prostate cancer. Strategies are needed to recover the backlog of diagnoses and effectively treat these cases in the future and solve the negative impact that will be caused by the diagnostic delay. Analyzing the impact of new diagnoses suffered by each different malignancy and their recovery will help to understand how the future allocation of resources should look.
Keywords: cancer diagnosis; coronavirus disease 2019 (COVID-19); stage shift; undetected cancer.