Cancer detection in the US was significantly disrupted in the first year of the COVID-19 pandemic, with a partial recovery seen in the second year.
Study: Recovery from COVID-19-related disruptions in cancer detection. Image credit: Inside Creative House/Shutterstock.com
In a recent study published in JAMA Network Open, a team of researchers assessed the lapse and recovery in cancer detection during the first two years of the coronavirus disease 2019 (COVID-19) pandemic, using national cancer incidence data from 2000 to 2021.
Background
The COVID-19 pandemic has significantly disrupted oncology services, affecting cancer screening, diagnosis, treatment and survival. During the early pandemic, cancer incidence dropped by nearly 9% in 2020 and by nearly 50% during the peak months of the lockdown due to reallocation of resources and patient reluctance to seek care.
Access to diagnostic cancer services was limited and risk tolerance for seeking care differed between sociodemographic groups.
Health systems adapted by expanding telemedicine and prioritizing cancer diagnosis. However, the implications for cancer care have been dynamic. Further research is needed to assess long-term effects and address gaps in cancer detection during the pandemic.
About the study
Study design, analysis and presentation followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines for cross-sectional studies. The research team clearly described the study setting, patient inclusion criteria and data collection methods.
Statistical methods were designed to be reproducible and results were interpreted carefully, recognizing statistical uncertainty and data set limitations. All analyzes were conducted in May 2024.
The protocol for this cross-sectional study was reviewed and waived by Case Western Reserve University’s institutional review board as it was deemed not to involve human participant research. Informed consent was not accepted.
Surveillance, Epidemiology and End Results (SEER) data were used to estimate the percentage difference between expected and observed cancer incidence in 2020. The expected incidence was predicted using link trend modeling based on 20 years of pre-pandemic data (2000-2019). This method has been extended to 2021 to assess recovery in cancer detection.
Analyzes were performed for all cancer types combined and stratified by demographics, community characteristics (county level), and major cancer sites. All incidence rates were age-adjusted and lagged when possible. Demographic information included a race and ethnicity variable, categorized into five mutually exclusive groups.
The national deficit in observed cancer cases was modeled by extrapolating SEER data to national population estimates from the National Cancer Institute and the United States (US) Census Bureau. Statistical tests were performed at the α = 0.05 level and 95% confidence intervals (CIs) were calculated using standard methods.
Trend models were selected using permutation tests and data were accessed through SEER*Stat. Trend analyzes were conducted using the Joinpoint Regression Program.
Study results
The study analyzed 15,831,912 patients diagnosed with malignant cancer between January 1, 2000 and December 31, 2021. Using data from patients diagnosed between 2000 and 2019 (n=14,246,457), a trend model was developed to project the expected incidence cancer 2020 and 2021.
These predictions were compared to the observed incidence of cancer during the pandemic years, where 759,810 and 825,645 cases were observed in 2020 and 2021, respectively.
The study included patients with a median age of 65 years (IQR, 56–75 years), with 49.0% women and 51.0% men. The racial and ethnic makeup included 0.4% American Indian or Alaska Native, 10.4% Black, 5.0% Asian or Pacific Islander, 11.1% Hispanic, and 72.4% White.
In 2020, the predicted cancer incidence rate was 458.12 per 100,000 population (95% CI, 456.71-459.54), but the observed incidence was significantly lower at 418.90 per 100,000 population (95% CI, 441, 94, 441).
This reflected a percentage difference of −8.6% (95% CI, −9.1% to −8.1%) between the expected and observed incidence rates. By 2021, the observed cancer incidence (458.33 per 100,000) almost matched the expected rate of 459.06, with a nonsignificant percentage difference of −0.2% (95% CI, −0.7% to 0, 4%), indicating a recovery in cancer detection.
The estimated national shortfall in cancer diagnoses was 125,167 cases in 2020 (95% CI, −131,771 to −118,503), which decreased to 2,764 cases in 2021 (95% CI, −11,833 to 6,402). The cumulative shortfall for 2020–2021 was 127,931 cases (95% CI, −139,206 to −116,655).
Subgroup analyzes revealed varying effects of the pandemic on cancer detection by demographic and community characteristics. In 2020, the incidence of cancer decreased most among male patients and those with localized cancer.
Additionally, larger declines were seen in counties with lower poverty rates, higher education levels, and higher percentages of non-US-born residents.
Although incidence rates improved in 2021, patients living in rural counties continued to have depressed cancer detection rates (−4.9% in rural counties not adjacent to metropolitan areas, 95% CI, −6.7% to − 3.1%). In contrast, cancer rates increased for female patients, those younger than 20, and people from Asia or the Pacific Islands.
Specific cancer sites were also affected differently. Gallbladder, eye, and orbit cancers showed consistently depressed incidence rates in 2021, while lung and bronchus, prostate, and melanoma had the largest cumulative deficits in 2020-2021.
Some types of cancer, such as gastric lymphocytic leukemia and chronic lymphocytic leukemia, showed a full recovery, surpassing 2021 forecasts.
conclusions
In summary, the analysis showed that cancer detection improved in 2021 after a significant hiatus in 2020, but the recovery varied by patient demographics, community characteristics, and cancer type. An estimated 127,931 cancer cases went undiagnosed due to the pandemic.
Most cancer sites had incidence rates close to baseline levels by 2021, but several still had cumulative shortfalls in diagnosed cases.
Continued surveillance is essential to address the gap in undiagnosed cancers, especially in rural and underserved populations, to prevent a future increase in advanced cases and to mitigate disparities in cancer outcomes driven by the pandemic.
