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Cancer patients experienced significantly higher rates of COVID-19-related deaths compared with the general public, according to two retrospective studies from the U.S. and Canada.

In a cross-sectional study published in , researchers found that the winter Omicron surge of 2021-2022 was particularly deadly, as the number of deaths among U.S. cancer patients increased by 18% compared with the winter surge of the wild-type variant (December 2020-February 2021), reported Chi-Fu Jeffrey Yang, MD, of Massachusetts General Hospital in Boston, and colleagues.

In contrast, there were 21% fewer COVID deaths in the general population during the winter Omicron surge compared with the previous winter's surge.

These findings "suggest that patients with cancer had a disparate burden of COVID-19 mortality during the winter Omicron wave compared with the general U.S. population," Yang and colleagues wrote. "With the emergence of new, immune-evasive SARS-CoV-2 variants, many of which are anticipated to be resistant to monoclonal antibody treatments, strategies to prevent COVID-19 transmission should remain a high priority."

Findings on COVID mortality across all cancer sites evaluated were consistent, with the exception of brain, thyroid, and bladder cancers.

COVID mortality increased the most among patients with lymphoma (mortality ratio 1.38, 95% CI 1.31-1.45) during the winter Omicron wave compared with the wild-type period.

Yang's group suggested that the greater mortality burden experienced by cancer patients was likely due to the increased transmissibility of the Omicron variant, a relaxation in policies geared to prevent COVID transmission, reduced effectiveness of vaccines in patients with cancer, and a greater risk of severe disease in those individuals.

In another study published in , researchers found that patients with hematologic malignancies were at increased risk of COVID infection from January 2020 through November 2021 compared with the general Canadian population (adjusted HR 1.19, 95% CI 1.13-1.25), while those with solid tumors were at a lower risk (aHR 0.93, 95% CI 0.91-0.95).

Notably, both groups of cancer patients had increased risks of 14-day hospitalization and 28-day mortality, reported Kelvin K.W. Chan, MD, PhD, of the Odette Cancer Centre at Sunnybrook Health Sciences Centre in Toronto, and colleagues:

• Hematologic malignancies: aHR 1.75 (95% CI 1.57-1.96) and aHR 2.03 (95% CI 1.74-2.38), respectively
• Solid tumors: aHR 1.11 (95% CI 1.05-1.18) and aHR 1.31 (95% CI 1.19-1.44)

Following hospitalization, the 28-day mortality rate after COVID infection was 50.7% in patients with hematologic malignancies and 45.8% in those with solid tumors.

However, the risk of 21-day intensive care unit (ICU) admission in patients with hematologic malignancies (aHR 1.14, 95% CI 0.93-1.40) or solid tumors (aHR 0.93, 95% CI 0.82-1.05) was not significantly different from the risks among people without cancer.

"These findings highlight the importance of prioritization strategies regarding ICU access to reduce the mortality risk in increased-risk populations, such as patients with cancer," Chan and team wrote.

Chan and colleagues also noted that COVID risk decreased stepwise with increasing numbers of COVID vaccine doses received (one dose: aHR 0.63, 95% CI 0.62-0.63; two doses: aHR 0.16, 95% CI 0.16-0.16; three doses: aHR 0.05, 95% CI 0.04-0.06).

Study Details

In their study, Yang and colleagues used data from the CDC's Wide-Ranging Online Data for Epidemiologic Research (WONDER) database to identify 34,350 patients (57.8% men) with cancer and 628,156 members of the general public (55.9% men) who died from COVID-19 during the wild-type variant wave (December 2020-February 2021), the Delta wave (July 2021-November 2021), and the winter Omicron wave (December 2021-February 2022).

The authors noted that the number of patients with cancer who died from COVID in the WONDER database was likely underestimated, since patients with a remote history of cancer may not have had cancer recorded in their death certificate and may not have been included in the study cohort. In addition, the database does not include data on vaccination status or cancer staging.

For the Canadian cohort study, Chan and team used data from the Ontario Cancer Registry on 11,732,108 community-dwelling adults from January 2020 through November 2021.

Of these adults, 279,287 had cancer (57.2% women, mean age 65.9) and 11,452,821 people did not have cancer (45.7% women, mean age 65.9). Overall, 4.1% developed COVID.

The cumulative incidence of COVID infection was 2.9% among those with solid tumors, 3.5% among those with hematologic malignancies, and 4.0% in the non-cancer population.

Study limitations included the fact that the authors did not have access to data on patients admitted to hospice or patients' preferences for hospitalization or ICU admission at the individual level.

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