The Disruption and Recovery of Cancer Diagnoses Following COVID-19
As we begin 2025, discussions of flu-like illnesses are extremely relevant, especially ongoing issues related to the COVID-19 pandemic. A critical question to consider is: to what extent was cancer detection in the U.S. disrupted during the pandemic's first year, and how much progress was made toward recovery in the second year?
A recent study examining nearly 16 million patients diagnosed with invasive cancer between 2000 and 2021 revealed the estimated cancer incidence was 9% below projections in 2020. However, by 2021, actual incidence rates aligned with projections. These findings highlight the need for continued recovery in cancer detection efforts to address cases that went undiagnosed during the pandemic.
The COVID-19 pandemic disrupted the timely diagnosis of cancer, which remained the second leading cause of death in the U.S. throughout this period. The study involved an epidemiologic analysis of nationally representative, population-based cancer incidence data from the Surveillance, Epidemiology, and End Results (SEER) Program. The analysis included patients diagnosed with cancer between January 1, 2000, and December 31, 2021. Conducted in May 2024, the study utilized the April 2024 SEER data release, which provides incidence data up to December 31, 2021.
Differences between the expected and observed cancer incidence in 2020 were compared with 2021, with additional analyses by demographic subgroups (sex, race and ethnicity, and age group) and community (county-level) characteristics. A key strength of this study was the use of data from SEER, representing almost 50% of the US population. Additionally, the approach is easily reproducible, facilitating the continued monitoring of these epidemiologic trends.
The analysis could have been strengthened by utilizing a unified, high-quality national cancer registry encompassing 100% of the U.S. population. However, such a registry does not currently exist. The most comprehensive resource available is the National Cancer Data Base (NCDB), which covers approximately 70% of U.S. cancer cases. This limitation likely affected the estimates of cancer cases and deficits in diagnoses, as the figures were extrapolated to the national level using data from the SEER program. While the resulting estimates aligned reasonably well with other widely cited sources, including the American Cancer Society and the CDC's U.S. Cancer Statistics, they were modestly lower—by about 6%—than these alternative benchmarks.
This cross-sectional study of nationally representative cancer registry data from the SEER Program found a meaningful recovery in cancer detection rates in 2021 following significant disruptions in 2020. However, an estimated 127,931 patients nationwide remained undiagnosed in 2021, potentially leading to profound and long-lasting consequences. These findings underscore the urgent need to reestablish timely care for patients with undiagnosed cancer during the pandemic to mitigate worsening disparities in cancer outcomes and to reduce future cancer-related morbidity and mortality.
