Cancer detection in the U.S. significantly disrupted during first year of COVID-19 pandemic, partial recovery seen in 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 the JAMA Network Open, a group of researchers assessed the disruption 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 significantly disrupted oncologic services, affecting cancer screening, diagnosis, treatment, and survivorship. During the early pandemic, cancer incidence dropped nearly 9% in 2020 and by almost 50% during peak lockdown months due to resource reallocation and patient hesitancy to seek care.

Access to diagnostic cancer services was constrained, and risk tolerance for seeking care varied across sociodemographic groups.

Health systems adapted by expanding telemedicine and prioritizing cancer diagnostics. However, the effects on cancer care were dynamic. Further research is needed to assess long-term impacts and address gaps in cancer detection during the pandemic.

About the study 

The 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 replicable, and the results were cautiously interpreted, acknowledging statistical uncertainty and the dataset’s limitations. All analyses were conducted in May 2024.

The protocol for this cross-sectional study was reviewed and exempted by the institutional review board of Case Western Reserve University, as it was deemed not to involve human participant’s research. Informed consent was waived.

To estimate the percentage difference between expected and observed cancer incidence in 2020, Surveillance, Epidemiology, and End Results (SEER) data were used. Expected incidence was forecasted using join point trend modeling based on 20 years of pre-pandemic data (2000-2019). This method was extended to 2021 to assess recovery in cancer detection.

Analyses were performed for all cancer types combined and stratified by demographic, community (county-level) characteristics, and major cancer sites. All incidence rates were age-adjusted and delay-adjusted 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 (U.S.) Census Bureau. Statistical tests were conducted at the α = .05 level, and 95% confidence intervals (CIs) were calculated using standard methods.

Trend models were selected using permutation tests, and data were accessed via SEER*Stat. Trend analyses 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 cancer incidence for 2020 and 2021.

These projections were compared with the observed cancer incidence 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% female and 51.0% male. The racial and ethnic composition 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 forecasted 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, 417.94-419.86).

This reflected a percentage difference of −8.6% (95% CI, −9.1% to −8.1%) between expected and observed incidence rates. By 2021, the observed cancer incidence (458.33 per 100,000) nearly matched the expected rate of 459.06, with a non-significant percentage difference of −0.2% (95% CI, −0.7% to 0.4%), indicating a recovery in cancer detection.

The estimated national deficit 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 deficit for 2020-2021 was 127,931 cases (95% CI, −139,206 to −116,655).

Subgroup analyses revealed varying impacts of the pandemic on cancer detection by demographic and community characteristics. In 2020, cancer incidence decreased more for male patients and those with localized cancers.

Additionally, larger decreases were observed in counties with lower poverty rates, higher educational levels, and higher percentages of non-US-born residents.

Although incidence rates improved in 2021, patients living in rural counties continued to experience depressed cancer detection rates (−4.9% in rural counties not adjacent to metropolitan areas, 95% CI, −6.7% to −3.1%). Conversely, cancer incidence rates increased for female patients, those younger than 20 years, and Asian or Pacific Islander individuals.

Specific cancer sites were also affected differently. Gallbladder, eye, and orbit cancers showed sustained depressed incidence rates in 2021, while lung and bronchus, prostate, and melanoma had the largest cumulative deficits over 2020-2021.

Some cancer types, such as stomach and chronic lymphocytic leukemia, experienced a full recovery, exceeding 2021 projections.

Conclusions 

To summarize, the analysis showed that cancer detection improved in 2021 after significant disruptions in 2020, but 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 by 2021, but several still had cumulative deficits in diagnosed cases.

Continued monitoring is essential to address the gap in undiagnosed cancers, especially in rural and underserved populations, to prevent a future surge of advanced cases and mitigate disparities in cancer outcomes caused by the pandemic.