Cancer was underdiagnosed in the United States during the first year of the COVID-19 pandemic, according to research published in The Lancet Oncology.

Researchers found that stage I cancer was more likely to be underdiagnosed than later-stage cancers, and underdiagnosis of early-stage cancer was more likely in medically underserved populations.

In this cross-sectional study, researchers examined data from 2,404,050 adults from the National Cancer Database who were diagnosed with a primary cancer from January 1, 2018, through December 31, 2020.

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The number of new cancer diagnoses was around 70,000 per month from January 2018 until the pandemic was declared in March 2020. In April 2020, the number of new cancer diagnoses was 36,679. That number increased to 62,674 in June 2020 but decreased slightly to 58,293 in November 2020 and 59,474 in December 2020.

Although all stages of cancer were underdiagnosed in 2020 relative to 2019, the reduction in annual rates of diagnosis was greater for stage I disease (17.2%) than for stage IV disease (9.8%).

“The changes in monthly diagnosis number and stage distribution were similar for nearly all major cancer types,” the researchers wrote.

Overall, the odds of being diagnosed with stage I disease (rather than later-stage disease) were lower in 2020 than in 2019 (adjusted odds ratio [aOR], 0.946; 95% CI, 0.939-0.952). The odds of being diagnosed with stage IV disease (rather than earlier-stage disease) were higher in 2020 than in 2019 (aOR, 1.074; 95% CI, 1.066-1.083).

This pattern was most evident in certain medically underserved populations. For instance, Hispanic patients were less likely to be diagnosed with stage I disease (aOR, 0.922; 95% CI, 0.899-0.946) and more likely to be diagnosed stage IV disease (aOR, 1.110, 95% CI, 1.077-1.144) in 2020 than in 2019.

Patients who were Asian American or Pacific Islander were also less likely to be diagnosed at stage I (aOR, 0.924; 95% CI, 0.892-0.956) and more likely to be diagnosed at stage IV (aOR, 1.096; 95% CI, 1.052-1.142) in 2020 than in 2019.

The same pattern was seen in uninsured patients (stage I aOR, 0.917; 95% CI, 0.875-0.961; stage IV aOR, 1.102; 95% CI, 1.055-1.152) and those living in socioeconomically deprived areas (stage I aOR, 0.931; 95% CI, 0.917-0.946; stage IV aOR, 1.106; 95% CI, 1.087-1.125).

“Substantial cancer underdiagnosis and decreases in the proportion of early stage diagnoses occurred during 2020 in the USA, particularly among medically underserved individuals,” the researchers concluded. “Monitoring the long-term effects of the pandemic on morbidity, survival, and mortality is warranted.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Han X, Yang NN, Nogueira L, et al. Changes in cancer diagnoses and stage distribution during the first year of the COVID-19 pandemic in the USA: A cross-sectional nationwide assessment. Lancet Oncol. 2023;24(8):855-867. doi:10.1016/S1470-2045(23)00293-0

This article originally appeared on Cancer Therapy Advisor