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In 2023, SEER decided to exclude the 2020 incidence data from the estimation of joinpoint trends and risks of developing cancer (DevCan), but included it in all other SEER cancer statistics and databases (refer to the April 2023 Impact of COVID page).
Cancer incidence rates for all cancers combined fell 10% in 2020 relative to 2019 rates, due to COVID-19 pandemic-related delays in cancer diagnosis and screening. The decline of the 2020 data point led to a loss of power in joinpoint models, used for the analysis of cancer trends, due to the added variance introduced by the 2020 data point, which was much smaller than its predicted value. More information on the impact of including the 2020 incidence data in the modeling of joinpoint trends was published in a Journal of the National Cancer Institute article1.
The November 2023 SEER data submission, released in April 2024, includes new cancer cases diagnosed in 2021, the second year of the COVID-19 pandemic. After adjusting for reporting delay the 2021 incidence rates for all cancer sites combined is 9.4% higher compared to the 2020 incidence rate and 0.5% lower relative to pre-pandemic 2019 incidence rate. In order to investigate the unique challenges posed by the year 2020 when one more year of incidence data (2021) is available, we conducted analysis described in a technical report (PDF) that shows that the inclusion of 2020 incidence rates can still provide a poor fit of joinpoint models and detection of fewer joinpoints, as well as less precise annual percent change (APC). To address these issues, SEER made the following decisions for the reporting of cancer statistics through 2021:
- Continue excluding the 2020 incidence data from two cancer statistics: estimation of joinpoint trends and risks of developing cancer (DevCan). The 2021 incidence data is included in all statistics.
- The 2020 and 2021 incidence cases are available in the SEER Research Data for analysis through SEER*Stat, and all the other cancer statistics in SEER*Explorer, Cancer Stat Facts, and other web-based reports.
- For additional details on the rationale, refer to the technical report that compares the fitting of three joinpoint models using the SEER November 2023 incidence data submission (2000-2021):
- excluding 2020 and 2021 incidence data,
- including all data (2000-2021), and
- excluding 2020 and including 2021 (the preferred model).
Note on the Calculation of the 5-year and 10-year Average Annual Percent Change (AAPC)
Although we are excluding the 2020 incidence data from fitting the joinpoint models, the 5-year and 10-year AAPC are calculated using the predicted rates, i.e. the rates estimated from the joinpoint models for the years 2017-2021 and 2012-2021, respectively.
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