A study conducted by researchers at the National Institutes of Health (NIH) found that cancer incidence trends in 2021 largely returned to pre-pandemic levels, following a decline in diagnoses during 2020 when screening and medical care were disrupted due to the COVID-19 pandemic. However, there was no evidence of a rebound in incidence that would account for the decrease in diagnoses in 2020, except for in breast cancer where there was an increase in diagnoses of advanced-stage disease in 2021. The study was published in the Journal of the National Cancer Institute on September 24, 2024.
A previous study had shown a significant decrease in new cancer diagnoses in early 2020, along with a reduction in the volume of pathology reports, indicating that many cancers were not being promptly diagnosed. To determine if these missed diagnoses were caught in 2021, potentially presenting as more advanced cancers, researchers from NIH’s National Cancer Institute (NCI) compared observed cancer incidence rates in 2021 to pre-pandemic trends using data from NCI’s Surveillance, Epidemiology, and End Results Program.
In order to observe a full recovery in cancer incidence, there should have been an increase over pre-pandemic levels to compensate for the missed diagnoses. The researchers analyzed overall cancer incidence rates and specifically looked at five major cancer types that vary in how they are usually detected: through screening (such as female breast and prostate cancer), due to symptoms (like lung and bronchus and pancreatic cancer), or incidentally during other medical procedures (such as thyroid cancer).
While cancer incidence rates for most specific cancers in 2021 approached pre-pandemic levels, there was no substantial rebound to explain the decline seen in 2020. Along with the rise in new diagnoses of advanced breast cancer in 2021, there was also some evidence of an increase in diagnoses of advanced pancreatic cancer. Additionally, new diagnoses of thyroid cancers in 2021 remained below pre-pandemic levels.
The researchers concluded that 2021 served as a transition year that was still influenced by new variants and waves of COVID-19 cases, which continued to impact medical care. They emphasized the importance of ongoing monitoring to gain insights into the long-term effects of the pandemic on cancer diagnoses and outcomes. The findings underscore the need for continued research to understand the lasting impacts of the pandemic on cancer detection and treatment.