Today two studies on COVID-19 mortality in US and Canadian cancer patients were published in JAMA Oncology and JAMA Network Open.
In JAMA Oncology, research shows US cancer patients suffered higher rates of COVID-19 mortality during the Omicron wave, while a study of 11.7 million Canadians in JAMA Network Open shows higher COVID-19 hospitalization and death rates in cancer patients in Ontario.
Omicron strain most deadly for US cancer patients
In the first study. researchers used data from the Center for Disease Control and Prevention's Wide-Ranging Online Data for Epidemiologic Research database to compare COVID-19 mortality among US patients with cancer and the general population from March 1, 2020, to May 31, 2022.
The Omicron strain of SARS-CoV-2 became dominant at a time when most of the United States had relaxed infection prevention measures related to COVID-19, and the authors hypothesized cancer patients would be less protected from infection during that time.
To compare COVID-19 mortality rates, the authors included outcomes among 34,350 patients with cancer and 628,156 members of the general public who died from COVID-19 when the wild-type (December 2020 to February 2021), Delta (July 2021 to November 2021), and Omicron (December 2021 to February 2022) variants were predominant
Cancer patients and the general public had different peaks of COVID-19 mortality. For the general population, more COVID-19 deaths occurred during the early, wild-type period of the pandemic, and for cancer patients, deaths due to COVID peaked during Omicron.
"There were 29% fewer COVID-19 deaths in the general population during the winter Omicron surge compared with the preceding year's winter surge," the authors wrote.
The greatest number of COVID-19 deaths per month for cancer patients occurred during the winter Omicron period in January 2022, when there were 18% more deaths compared with the peak of the wild-type period (January 2021) among patients with cancer.
There were 29% fewer COVID-19 deaths in the general population during the winter Omicron surge compared with the preceding year's winter surge.
COVID mortality during the Omicron period when compared with the wild-type period was significantly higher for cancer patients (mortality ratio, 1.04; 95% confidence interval [CI], 1.02 to 1.05). COVID-19 mortality increased the most, by 38% (mortality ratio, 1.38; 95% CI, 1.31 to 1.45), among patients with lymphoma during the winter Omicron period, the authors said.
The Omicron period was so deadly for cancer patients because of the "increased transmissibility of the Omicron variant, and the relaxation of policies to prevent SARS-CoV-2 transmission, reduced effectiveness of COVID-19 vaccines in patients with cancer, and greater risk of severe COVID-19 among patients with cancer," the authors concluded.
Canadian cancer patients at greater risk for COVID hospitalization
Using data from the Ontario Cancer Registry on more than 11 million Canadians, researchers found patients who contracted COVID-19 from January 1, 2020, to November 30, 2021, were at greater risk of both hospitalization and death compared to a cancer-free cohort.
Included in the study were 279,287 individuals with cancer, including 245,386 individuals with solid tumors, and 33,901 individuals with hematologic malignant neoplasms (leukemia, lymphoma).
According to the authors, the cumulative incidence of SARS-CoV-2 infection was 7,185 of 245,386 individuals (2.9%) with solid tumors, 1,193 of 33,901 individuals (3.5%) with hematologic malignant neoplasms, and 456,196 of 11,452,821 individuals (4.0%) without cancer.
Individuals with hematologic malignant neoplasms were at a greater risk of SARS-CoV-2 infection (adjusted hazard ratio [aHR], 1.19; 95% CI, 1.13 to 1.25) compared with the noncancer population, but the risk in individuals with solid tumors was lower than in the general population (aHR, 0.93).
However, both types of cancer patients were at a greater risk of 14-day hospitalization if infected with COVID-19. There was also a significant increased risk for 28-day mortality in patients with hematologic malignant neoplasms (hazard ratio [HR], 7.67; 95% CI, 6.57 to 8.96) and solid tumors (HR, 3.44; 95% CI, 3.14 to 3.77).
The increased association for hospitalization and death "remained significant in analyses adjusted for sex, age, and COVID-19 vaccination and in fully adjusted models adjusted for several individual and social determinants of the disease," the authors wrote.