Cancer incidence trends in 2021 largely returned to what they were before the COVID-19 pandemic, according to a study by researchers at the National Institutes of Health (NIH).

However, there was little evidence of a rebound in incidence that would account for the decline in diagnoses in 2020, when screening and other medical care was disrupted.

One exception was breast cancer, where the researchers did see an uptick in diagnoses of advanced-stage disease in 2021.

The study appears Sept.24, 2024, in the Journal of the National Cancer Institute.

A previous study showed that new cancer diagnoses fell abruptly in early 2020, as did the volume of pathology reports, suggesting that many cancers were not being diagnosed in a timely manner.

To determine whether these missed diagnoses were caught in 2021, possibly as more advanced cancers, researchers from NIH's National Cancer Institute (NCI) compared observed cancer incidence rates for 2021 with those expected from pre-pandemic trends using data from  NCI's Surveillance, Epidemiology, and End Results Program. 

A full recovery in cancer incidence should appear as an increase over pre-pandemic levels (also known as a rebound) to account for the missed diagnoses.

 The researchers looked at cancer overall, as well as five major cancer types that vary in how they are typically detected: through screening (female breast and prostate cancer), due to symptoms (lung and bronchus and pancreatic cancer), or incidentally during other medical procedures (thyroid cancer).

Cancer incidence rates overall and for most specific cancers approached pre-pandemic levels, with no significant rebound to account for the 2020 decline.

However, in addition to an uptick in new diagnoses of advanced breast cancer in 2021, the data also provided some evidence of an increase in diagnoses of advanced pancreatic cancer.

Also, new diagnoses of thyroid cancers in 2021 were still below pre-pandemic levels.

The researchers concluded that 2021 was a transition year that was still affected by new variants and new waves of COVID-19 cases, which continued to impact medical care.

They said the findings highlight the need for ongoing monitoring to understand the long-term impacts of the pandemic on cancer diagnoses and outcomes.

Source: NIH/National Cancer Institute