Cancer cases in the US continued to be underdiagnosed during the second year of the COVID-19 pandemic

By Dr. Liji Thomas, MDReviewed by Benedette Cuffari, M.Sc.Sep 13 2024

Cancer diagnosis rates improved in 2021, but gaps from 2020 still remain

Study: COVID-19 and Rates of Cancer Diagnosis in the US. Image Credit: Chinnapong / Shutterstock.com

During the coronavirus disease 2019 (COVID-19) pandemic, healthcare disruptions impacted the regularity of cancer screenings and detection programs in the United States. In 2020, there was a 13% fall in cancer incidence at all sites, with the rate being higher for specific sites, stages, and subgroups.

A recent study published in JAMA Network Open Oncology examines how the COVID-19 pandemic affected cancer diagnosis rates between 2021 and 2020.

About the study

The current population-based cross-sectional study obtained data from the Surveillance, Epidemiology, and End Results 22 (SEER-22) Registries Database, which comprises information on about 48% of the U.S. population. The study cohort included individuals diagnosed with invasive cancer who were included in 22 cancer registries that were part of SEER-22 between January 1, 2000, and December 31, 2021.  

The SEER-22 registries reported 15,78,697 cancer cases in 2020 and 2021, with these cases almost equally distributed among males and females at 50.6% and 49.4%, respectively. About 58% of cancer patients were 65 years or older.

Demographic and social data, including ethnicity, urban or rural location, age, sex, and cancer stage at diagnosis, were also analyzed.

Change in cancer incidence overall

The primary objective of the current study was to identify differences between the observed and expected rates of new cancer diagnoses for 2020 and 2021. To this end, ensemble forecasting methods indicated that the rates of observed cancer diagnoses rose in 2021 from the reduced rates observed in 2020 but did not consistently match pre-pandemic levels.

Cancer incidence at all sites was reported at a rate that was 9.4% and 2.7% lower than expected in 2020 and 2021, respectively. When both 2020 and 2021 were considered, cancer incidence declined by 6%, thus indicating that 149,577 cases may have been undiagnosed during this two-year period, 33,226 of which potentially occurred in 2021.

Change in cancer incidence by site

Cancer incidence at eleven cancer sites assessed declined in 2020 and remained persistently lower than expected in five of the eleven types of cancer in 2021, of which included lung, cervical, urinary bladder, non-Hodgkin lymphoma, and kidney cancer. Both lung and cervical cancers remained 9% and 4.5% lower than expected, respectively, in 2021.

Change in cancer incidence by screening

Among cancers for which screening is recommended, only breast cancer diagnosis in women recovered significantly in 2021 to exceed expected rates by 2.5%.

Colorectal cancer (CRC) diagnosis rates declined in 2020 and returned to pre-pandemic levels in 2021 among the cancers detected by screening. Cancer at all sites also recovered to normal rates of diagnosis in 2021 among females, those below the age of 65 years, Asians, and Pacific Islanders.

Risk of cancer incidence by stage at diagnosis

Cancer incidence at all sites was lower than expected for early and more advanced cancers by 11.9% and 6.4%, respectively, in 2020. Both early and late-stage cancer diagnosis returned to pre-pandemic levels by 2021.

Among cancers with screening recommendations, which include female breast, lung, CRC, and cervical cancers, both early and late-stage cancer diagnoses declined significantly in 2021, except for advanced cervical cancer. However, there remains a lack of data indicating that late-stage breast, CRC, and cervical cancer diagnoses exceeded expected rates in 2021.

The persistently reduced detection of lung and cervical cancers at early stages during both years suggests reduced screening for cancers at these sites due to prolonged wait times or reductions in new appointments for screening.

The incidence of any of the cancer types included in this study was significantly lower than expected for men, individuals 65 years of age and older, and Hispanic, non-Hispanic Black, and non-Hispanic White individuals. Comparatively, women 65 years of age and younger were least likely to experience any change in all-site cancer detection rates compared to male individuals of any other age.

Conclusions

The COVID-19 pandemic led to significant disruptions in cancer diagnoses that persisted into 2021, particularly for the detection of lung, cervical, bladder, and kidney cancers, as well as non-Hodgkin lymphoma. Extended wait times may have led to missed or delayed cancer screenings, which increases the risk of late-stage diagnoses and poor survival rates.

Particular attention should be directed at strategies to immediately increase cancer screenings to make up lost ground and prevent a future surplus of late-stage diagnoses.”