In a recent article published in JAMA Network Open, researchers evaluated the association between the coronavirus disease 2019 (COVID-19)-triggered pandemic and cancer incidence to tell strategies potentially reducing the general public healthcare system’s vulnerability to future disruptions.

To this end, they performed a population-based cross-sectional study in Manitoba, Canada, amongst 48378 individuals diagnosed with cancer between January 1, 2015, and December 31, 2021.

Study: Recent Cancer Diagnoses Before and Throughout the COVID-19 Pandemic. Image Credit: ORION PRODUCTION / Shutterstock

Background

In Canada, like elsewhere globally, health services needed to be reorganized to supply look after COVID-19 patients. Modeling studies estimated that these people experienced more advanced disease on account of late/missed diagnosis and poor outcomes, including reduced survival.

Data on the association between the COVID-19 pandemic and cancer care health services could help discover strategies for decreasing the healthcare system’s vulnerability to similar future disruptions (because the COVID-19 pandemic).

Concerning the study

In the current study, researchers used a cross-sectional study design to look at the brand new cancer diagnoses before January 2015 and February 2020 (pre-pandemic) and after the COVID-19 pandemic began in April 2020. Moreover, they evaluated the consequences of interventions implemented to mitigate the pandemic impact between April 2020 and December 2021. They used the population-based Manitoba cancer registry data to find out cancer cases.

The first study end result was the age-normalized cancer incidence rate per 10,0000 individuals. The secondary study end result was the combination difference within the monthly cumulative counterfactual (diagnoses within the absence of COVID-19) versus fitted count.

They categorized cancers into the next sites for examination of incidence rates: lung, breast, prostate, rectal, colon, hematologic, urinary, brain and central nervous system (CNS), head and neck, breast, gynecologic, other digestive, pancreatic, endocrine, melanoma, and other. In addition they examined rectal, colon, and breast cancers individually for people <50, 50-74, and ≥75 years.

Finally, the team used interrupted time-series evaluation with an extended preintervention period that accounted for baseline or seasonal trends in cancer diagnoses. They calculated counterfactual and fitted estimate ratios and 95% confidence intervals (CIs) and used a forest plot to plot them.

Results

There have been 48378 cancer cases diagnosed in Manitoba during 2015-2021, of which 23972 occurred in females. In April 2020, there was a 23% decrease in cancer incidence; nevertheless, by June 2020, the difference between the fitted and counterfactual cancer incidence rates became insignificant.

Longer-term decreases in diagnoses occurred for breast, colon, prostate, lung, urinary, melanoma, and brain and CNS cancers. It holds for cancer incidence and cumulative deficits, especially for breast and colon cancer cases in individuals aged 50-74. 

Between April and May 2020, there have been reductions in breast and colorectal cancer screening programs and the speed of colonoscopies within the Manitoba province. Accordingly, in April 2020, there was a 46% decline in breast cancer incidence. Breast cancer incidence remained 11% lower than the counterfactual until December 2021. 

There was a decrease in breast cancer incidence only amongst women ≥75 years, likely on account of reduced availability of diagnostic mammography or hesitancy in looking for medical care through the pandemic.

Rectal cancer incidence decreased in April 2020 by 47%. By May 2020, rectal cancer incidence increased by 5% to the counterfactual, likely because they initiated triaging of people with suspected rectal cancer and performed endoscopies on people on the waitlist. Its incidence rate was insignificantly higher than the counterfactual in all three age groups.

Lung cancer incidence remained stable until December 2020 and steadily decreased by 11%. Nonetheless, the association was seen only for people ≥75 years, in whom lung cancer incidence declined by 46% in April 2020.

During this time, the speed of SARS-CoV-2 infections in Manitoba was at an all-time high, resulting in more deaths amongst vulnerable people undiagnosed but having lung cancer, advanced age, and comorbidities. Perhaps they didn’t even seek health care services.

The 12% decrease in urinary cancer incidence continued over time with none observed recovery, likely due to reduced abdominal imaging availability throughout the COVID-19 pandemic. Quite the opposite, the incidence of head, neck, and melanoma cancers, which plunged initially of the pandemic, 50% and 65% in April 2020, respectively, returned to pre-pandemic levels quickly. 

Incidence rates of brain and CNS and endocrine cancer also showed decreases of 26% between April 2020 and December 2021. Case numbers of those cancers were small; hence, the effect of the COVID-19 pandemic on the incidence of those cancers might merely be a random variation. Moreover, 

The COVID-19 pandemic showed no association with the incidence of gynecologic, prostate, pancreatic, or other cancers.

Conclusions

In the present study, the authors noted a considerable heterogeneity in the connection between the COVID-19 pandemic and cancer incidence for all cancer sites in Manitoba, Canada.

Breast, colon, and rectal cancer incidence decreased substantially between May and April 2020, while breast and lung cancer incidence showed sustained decreases only amongst individuals 75 years and older. Likewise, there was a sustained decline in urinary, brain, and CNS cancer(s) incidence rates between April 2020 and December 2021.

The study highlighted the full deficits for specific high-fatality cancers, which need healthcare service providers’ attention.